Biofilms are generally found to be present on or inside indwelling therapeutic devices like mechanical heart valves, central venous catheters, prosthetic joints, peritoneal dialysis catheters, contact lenses, pacemakers, voice prostheses, and urinary catheters (Donlan, 2001). Its microbial composition depends upon the type and the duration of action of residing devices (Donlan, 2002).

Microbial cells tend to adhere to both soft and hard varieties of contact lenses. The extent of adherence depends on various criteria vis. the nature of substrate, electrolyte concentration, water content, bacterial strain involved, and the material used in contact lenses. The microorganism commonly affecting contact lenses includes E. coli, Staphyloccocus aureus, Pseudomonas aeruginosa, Staphylococcus epidermidis, Proteus, Serratia, Candida species, and so forth (Donlan and Costerton, 2002). Prosthetic valve endocarditis is another biofilm-related complication in which biofilms are developed on mechanical heart valves and nearby organs (Mrsic et al., 2018). A wide range of microorganisms which include Staphylococcus epidermidis, Staphylococcus aureus, Acinetobacter baumannii, Pseudomonas aeruginosa, Klebsiella pneumoniae, Propionibacterium acnes, Enterococcus, Escherichia coli, Candida species, and yeasts, is known to infect different cardiac implants such as pacemakers, defibrillator, prosthetic valves, coronary artery bypass grafts, which gradually forms denser biofilms in vivo as compared to in vitro (Viola and Darouiche, 2011). These cardiac devices associated with biofilms lowers the rate of blood flow and promote hematogenous spread thereby infecting and developing biofilms in other organs (Bosio et al., 2012). Urinary catheters which are generally constructed of latex or silicone are utilized to accumulate urine during operation, prevent urine retention, and measure urine generation, in ICU. These catheters are generally administered up to the urinary bladder via the urethra. Bacterial contamination due to periurethral skin colonization results in bladder migration of the microbial cells thereby leading to biofilms establishment on these catheters (Kokare et al., 2009). Pseudomonas aeruginosa, Klebsiella pneumoniae, Enterococcus faecalis, Streptococcus epidermidis, Proteus mirabilis, and other Gram (−ve) bacteria are among the microorganisms that develop biofilms on these devices (Pelling et al., 2019). Further, these microbes develop an alkaline condition by increasing the pH which facilitates the formations of struvite biofilms inside these catheters (Neethirajan et al., 2014). Moreover, Biofilm formation on central venous catheters is quite frequent, although the location and intensity of biofilm formation are both dependent on the duration of action of these catheters. Patients with bone marrow transplants are at higher risk of biofilm infections as they require long-term vascular catheters. The development of the bacterial community depends on the fluid composition which is being administered through these catheters. For instance, gram-positive bacteria like Staphylococcus epidermidis and Staphylococcus aureus, show poor development in the intravenous fluids, while gram-negative aquatic bacteria, such as Klebsiella sp., Enterobacter sp., and P. aeruginosa, can grow well in such liquids (Raad et al., 1993) (Jamal et al., 2018). Many research reports have indicated that biofilm infections have been related to aseptic loosening of joint prostheses. Further, infections in prosthetic joints caused by Propionibacterium acnes or Staphylococcus epidermidis can lead to serious problems and a high death rate, post joint replacement operation (Del Pozo and Patel, 2009). Moreover, numerous studies have reported that microorganisms like Staphylococcus aureus, Bacillus species, Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, etc. are found to contaminate and develop biofilms in endotracheal tubes (Vandecandelaere and Coenye, 2015). Also, different bacteria of breast ducts and tissue lead to biofilm development on breast implants (Pajkos et al., 2003).

Most of the chronic infections are related to biofilms, as microbial cells present within the biofilms are resistive to the host defense system, antibiotics, and other therapies. Some of the non-device-related bacterial infections are periodontitis, osteomyelitis, cystic fibrosis, otitis media, and chronic wounds (Vestby et al., 2020).

Periodontitis is the infection of gums, generally caused due to poor oral health. Injury of soft tissues, damage to the bones supporting the teeth, and occasional tooth loss are the common characteristics of this infection (Guiglia et al., 2010). It is caused by biofilm-forming bacteria such as P. aerobicus and Fusobacterium nucleatum which colonize the teeth surface followed by mucosal cell invasion (Jamal et al., 2018). They may also alter the calcium flow within epithelial cells as well as release toxins. This may lead to the development of plaque within few weeks which can be mineralized with phosphate and calcium ions, thereby leading to the development of calculus or tartar (Overman, 2000). Also, Candida albicans are known to form biofilms on the mucosal layer of the oral cavity. And the synergistic relationship between C. albicans and Streptococcus mutans within the biofilm of oral plaque facilitates bacterial colonization and thereby promotes the formation of dental caries (Ponde et al., 2021). In addition, Osteomyelitis is the disease of bones caused by fungal or bacterial cells. Bacteria invade the bone via blood vessels, injury, or prior infections, thereby causing infection in the bone’s metaphysis. This leads to infiltration of WBCs at the site of infection which attacks the invading bacteria via phagocytosis or secretion of lytic enzymes thereby resulting in the formation of pus and further spread through bone blood vessels. This leads to blockage of proper blood flow and thereby tissue damage in the infected site of the bone (Goodrich, 2019). Cystic fibrosis is one of the most studied biofilm-associated infections which primarily affects the respiratory and the digestive system and is characterized by the generation of viscous mucus and chronic infections (Ciofu et al., 2015). In earlier stages, the airways are primarily colonized by Staphylococcus aureus and Haemophilus influenzae, while at later stages Pseudomonas aeruginosa dominates (Hector et al., 2016). Large numbers of polymorphonuclear leukocytes (PMNs) are being recruited to the infected site in response to the presence of biofilm, thereby causing persistent inflammation, airway blockage, loss of lung function, and tissue damage. Further, the anaerobic condition developed due to the metabolic activity of bacteria facilitates the biofilm mode of P. aeruginosa even more (Rada, 2017). Otitis media (OM) is a condition in which the middle ear chamber gets inflamed, commonly affecting pre-school-aged children (DeAntonio et al., 2016). OM can further be classified into chronic supportive OM (CSOM), OM with effusion (OME), and acute OM (AOM) (Schilder et al., 2017). Generally, biofilm develops in the middle-ear mucosa and middle-ear fluid in case of chronic otitis media (COM) patients. The microbial community consisting of Escherichia coli, Haemophilus influenzae, Staphylococcus aureus, Pseudomonas aeruginosa, and Moraxella catarrhalis as well as other pathogenic bacteria is responsible for the biofilm formation (Homøe et al., 2009). Any damage to living tissue is generally referred to as wounds which can be caused due to various reasons like burns, abrasions, cuts, and surgery or due to other underlying conditions like diabetes (Fijan et al., 2019). Recent studies have indicated that the biofilm mode of bacterial growth is the prime cause of chronic wound infections. Chronic wounds are generally colonized by several bacterial communities among which Staphylococcus aureus is found in majority (Brackman et al., 2013). Aerobic bacteria such as Staphylococcus aureus, Staphylococcus epidermidis, and Pseudomonas aeruginosa are generally isolated from the surface of chronic wounds whereas anaerobic bacteria such as Bacteroides sp., Clostridium sp., Peptostreptococcus sp., and Fusobacterium sp. are generally found in deeper tissue (Percival et al., 2012).

Physical methods used for the synthesis of nanoparticles include lithography techniques, mechanical milling, sputtering, electrospinning, physical vapor deposition (PVD), and so on (Khodashenas and Ghorbani, 2014). Although physical techniques are relatively quicker and do not require the use of hazardous chemicals, they have certain major limitations like the requirement of expensive equipment and infrastructure, maintenance of high pressure, and temperature (Thakkar et al., 2010).

Among chemical methods, the most widely applied methods for nanoparticles synthesis include chemical vapor deposition, sol-gel process, hydrothermal, sonochemical, wet chemical reduction, microemulsion/colloidal, pyrolysis, chemical etching, thermal ablation, laser ablation, photoreduction, and electrodeposition (Nam and Luong, 2019). The composition and the size of the produced nanoparticles depend on the reducing agents employed, reaction time, temperature, and the length of the surfactant molecule (Simeonidis et al., 2007). The use of inorganic and organic salts as reducing agents is one of the most common methods which is frequently employed due to simple procedures and minimal equipment requirements (Vijayaraghavan and Ashokkumar, 2017). The incorporation of hazardous chemicals in the synthesis, as well as the disposal of these reagents, is a key drawback of chemical techniques (Khodashenas and Ghorbani, 2014).

The biological method employs the use of various biological agents for the synthesis of nanoparticles, such as bacteria, fungus, yeast, virus, protozoan, microalgae, macroalgae, and plant biomass/extract (Shah et al., 2015) (Singh et al., 2016c). Although the biological method takes a longer time to produce nanoparticles compared to chemical and physical methods; the biological synthesis of nanoparticles has the benefits of low toxicity, cost-effectiveness, quick synthesis, ease of scaling up, and simple synthesis procedure (Sharma et al., 2019). One of the prime advantages of plant-mediated biosynthesis is that no hazardous residue products are left on the particles. When people consume them directly, such as through creams or clothing, even minute quantities of hazardous residues can make their safe application unfeasible (Sau and Rogach, 2010) (Fakhari et al., 2019) (Bhattacharya et al., 2019). Also, chemical and physical methods of nanoparticles synthesis are exorbitant due to the fixed price of reagents and apparatus. Moreover, the enormous amount of secondary products produced offers a safe disposal issue (Mirzaei and Darroudi, 2017). Unlike microorganism-assisted nanoparticle synthesis, phyto-synthesis procedures do not involve isolation of microorganisms, identification, optimization of growth conditions, culture preparation, and preservation, which are all complicated and tiresome processes (Patil and Kim, 2017). Rather, plant-assisted green synthesis is quick and straightforward, thereby offers a shorter production time, which indicates potential for scaling-up (Shankar et al., 2004) (Song and Kim, 2009) (Salunke et al., 2014). Due to these advantages, numerous research work has been done to explore the potential of biological materials for the production of metallic nanoparticles. These biologically synthesized nanomaterials have the potential to be applied in various fields like therapeutics, diagnostics, surgical nanodevice development, and commercial product production (Kuppusamy et al., 2015). Among the biological approaches of nanoparticles synthesis, the methods based on plants and microbes have been extensively reported in the literature (Gardea-Torresdey et al., 2003) (Kaler et al., 2011) (Dhillon et al., 2012) (Singh et al., 2016c). Microbial synthesis of nanoparticles is, of course, easily scalable, ecologically friendly, and compatible with the product’s usage in medicinal applications, but is often more expensive than nanoparticles synthesis from plant extract (Mittal et al., 2013).

Silver nanoparticles are the most widely studied nanoparticles for their broad-spectrum antimicrobial properties against a wide variety of pathogens. They are known to impart antibacterial properties via several mechanisms such as cell wall and membrane rupture and intracellular biomolecules damage, oxidative stress, etc (Tang and Zheng, 2018). Among various routes employed, plant-mediated synthesis of AgNPs is most preferred due to its several advantages. Numerous research has been carried out using different plants and their parts to study the antibiofilm properties of phytosynthesised AgNPs.

Regarding this, Malaikozhundan et al. have synthesized silver nanoparticles using Momordica charantia fruit extracts (Mc-AgNPs) and evaluated their antibiofilm efficacy against Aeromonas hydrophila and Enterococcus faecalis. Light microscopy and CLSM observations revealed that Mc-AgNPs exhibited significant biofilm inhibitory properties (100 μg/ml) against E. faecalis when compared to that of A. hydrophila. Further, the application of Mc-AgNPs reduced the hydrophobicity index by 76% and 88% in A. hydrophila and E. faecalis respectively as compared to untreated bacteria (Malaikozhundan et al., 2016).

A similar study done by Arya et al. indicated that AgNPs prepared using aqueous leaf extract of Acacia nilotica inhibited biofilm formation by 70% and 53% in Pseudomonas aeruginosa and Staphylococcus aureus respectively at a concentration of 0.25 µg (Arya et al., 2018).

Accordingly, Choi et al. screened the antibiofilm and antifungal properties of phytofabricated silver nanoparticles (AgNPs) synthesized using Lycopersicon esculentum extracts against Candida species. SEM analysis revealed the biofilm inhibitory effect of the fabricated AgNPs. They suggested that binding of Ag ions to cell surface resulted in membrane abnormalities, reduced biofilm development, and inhibited growth (Choi et al., 2019). Further, it has been well-established that quorum sensing plays a pivotal role in the development of biofilm. Several studies have reported inhibition of biofilm development via anti-QS agents. Regarding this, Ravindran et al. assessed the potential of Vetiveria zizanioides root extract-mediated silver nanoparticles (VzAgNPs) as a promising antibiofilm and anti-QS agent against S. marcescens. The results revealed that VzAgNPs inhibited the production of various QS-mediated virulence factors such as protease, swarming motility, lipase, prodigiosin, EPS productions, and biofilm formation in S. marcescens, thereby reducing its pathogenicity. Further, the genomic studies supported that VzAgNPs target and remarkably inhibit the expression of genes involved in virulence such as flhD, fimC, and bsbB (Ravindran et al., 2018).

Accordingly, Shah et al. evaluated the anti-QS property of Piper betle leaf extract (Pb) mediated AgNPs (Pb-AgNPs) against Chromobacterium violaceum and further studied the potential effect of Pb-AgNPs on QS-regulated phenotypes in PAO1 Pseudomonas aeruginosa. The data revealed that the phytofabricated Pb-AgNPs remarkably inhibited the QS-mediated virulence factors such as violacein of C. violaceum, elastase, and pyocyanin of P. aeruginosa. Moreover, these nanostructures imparted significant antibiofilm activity against P. aeruginosa, thereby suggesting their potential role in overcoming bacterial resistance against conventional antibiotics (Shah et al., 2019). In a similar study done by Srinivasan et al., the anti-QS and antibiofilm potential of Piper betle leaf extract mediated silver nanoparticles (PbAgNPs) against S. marcescens and P. mirabilis was evaluated. The data revealed PbAgNPs mediated inhibition of QS-related virulence factors such as protease, prodigiosin, exopolysaccharides, biofilm formation, and hydrophobicity productions in uropathogens. Further, the genomic analysis reported downregulated expression of flhD, flhB, and rsbA genes in P. mirabilis and fimC, fimA, flhD, and bsmB genes in S. marcescens respectively (Srinivasan et al., 2018).

Ali et al. have developed biogenic silver nanoparticles (AgNPs) employing aqueous leaf extract of Eucalyptus globulus (ELE) and evaluated their antibiofilm and antibacterial potential. After 24 h of treatment, biofilms produced by S. aureus and P. aeruginosa were shown to be inhibited by 82 ± 3% and 81 ± 5%, respectively, at 30 μg/ml (Ali et al., 2015). In 2018, research was done by Muthamil et al., phyto-synthesized silver nanoparticles (AgNPs), prepared using methanolic leaf extracts of Dodonaea viscosa and Hyptis suoveolens were assessed for their antibiofilm properties against Candida spp. AgNPs obtained from both the extract showed significant biofilm inhibitory properties with about 88% of biofilm reduction at a concentration of 10 μg/ml, as evidenced by microscopic analysis and in vitro virulence assays (Muthamil et al., 2018).

Sarathi Kannan et al. demonstrated the potential biofilm inhibitory activity of Ludwigia octovalvis leaf extracts derived silver nanoparticles (AgNPs) against Staphylococcus epidermidis and Pseudomonas aeruginosa. It was noticed that at 100 μg/ml, AgNPs imparted the highest antibiofilm activity of 62.42 and 50.62% against S. epidermidis and P. aeruginosa respectively (Sarathi Kannan et al., 2021). Moreover, Ali et al. biofabricated silver nanoparticles using bark extract of medicinal plant Holarrhena pubescens (HP-AgNPs) and screened their antibacterial and antibiofilm activity against imipenem-resistant Pseudomonas aeruginosa clinical isolates. The HP-AgNPs exhibited antibacterial and antibiofilm activity in a dose-dependent fashion as confirmed by the confocal laser scanning microscopy (Ali et al., 2018).

Also, Vijayakumar et al. prepared silver nanoparticles using garlic clove extract (G-AgNPs) and evaluated its broad-spectrum therapeutic activity including antibiofilm properties. They demonstrated that G-AgNPs (100 μg/ml) imparted significant antibacterial as well as anti-biofilm activity against clinically relevant pathogens like methicillin-resistant S. aureus and Pseudomonas aeruginosa (Vijayakumar et al., 2019). Arya et al. fabricated bio-inspired AgNPs utilizing aqueous leaf extract of Prosopis juliflora and evaluated its biofilm inhibitory properties. The data obtained from congo red agar (CRA) plate assay showed the synthesized AgNPs exhibited significant antibiofilm activity against Bacillus subtilis and Pseudomonas aeruginosa (Arya et al., 2019).

Moreover, Bharathi and her coworkers reported that silver nanoparticles synthesized using fruit extract of Cordia dichotoma (Cd-AgNPs) lead to a significant reduction in S.aureus and E.coli biofilms by 92 percent and 95 percent, respectively, at100 μg/ml concentration (Bharathi et al., 2018). Also, Majumdar et al. developed silver nanoparticles (CM-AgNPs) using fruit extract of Citrus macroptera (CM) and explored their antibiofilm potential. The biosynthesized CMAgNPs efficiently inhibited the development of biofilm in a dose-dependent manner with 70 and 80 percent of biofilm inhibition in Bacillus subtilis and Pseudomonas aeruginosa respectively, at the highest concentration (260 nM) (Majumdar et al., 2020). Interestingly, Eric and Torlak synthesized Ag nanoparticles (AgNPs) by using the aqueous leaf extract of Thymus serpyllum. The antibiofilm data revealed that AgNPs (100 μg/ml) inhibited the biofilm formation by 73% in S. aureus (Erci and Torlak, 2019).

Juan et al. synthesized silver nanoparticles by using extract of benzoin gum as bioreductant and capping agent and studied their antibiofilm activity against biofilm-producing E. coli strain. At 1, 2, 5, and 10 μg/ml concentrations, treatment for 24 h resulted in a reduction in biofilm development of about 10.9, 44.1, 54.0, and 65.5 percent, respectively thereby indicating that the AgNPs were capable to inhibit the biofilm development in E. coli (Du et al., 2016). Further, Prasad and his coworkers reported phytogenic synthesis of silver nano bactericides by utilizing Acorus calamus L. extracts. The biofilm inhibitory activity was evaluated against Helicobacter pylori clinical isolates. The synthesized NPs exhibited significant antibiofilm activity at concentration 350 μg/ml, as evidenced by crystal violet and ruthenium red assays (Prasad et al., 2019).

Interestingly, Gupta and his coworkers showed silver nanoparticles synthesized using methanolic leaf extract of Syzygium cumini have the potential to impede biofilm development of P. aeruginosa, S. aureus, and C. albicans in a concentration-dependent manner. At 250 μg/ml, AgNPs inhibited more than 90% biofilm formation, while at 125 μg/ml concentration, 85% biofilm inhibition was recorded (Gupta et al., 2014a). Moreover, Al-Ansari et al. reported the antibiofilm and antibacterial activity of Lilium lancifolium leaf extract mediated silver nanoparticles against Streptococcus pneumonia and Pseudomonas aeruginosa. Treatment with 25 μl of AgNPs imparted antibacterial activity while treatment with 50 μl showed significant antibiofilm properties, as evident from crystal violet assay and confocal micrographic images (Al-Ansari et al., 2019).

Interestingly, Barbadi et al. compared the antibiofilm activity of Zataria multiflora aerial extract-mediated silver nanoparticles (P-AgNPs) and commercial silver nanoparticles (C-AgNPs) against Staphylococcus aureus ATCC 25923 bacteria. The data showed dose-dependent biofilm inhibitory activity, with excellent inhibition at concentration ≥8 μg/ml for both P-AgNPs and C-AgNPs. Further, they showed that plant-derived AgNPs (P-AgNPs) imparted higher biofilm inhibitory properties at lower concentrations as compared to C-AgNPs (Barabadi et al., 2021). Similarly, Moulavi et al. stated that phytofabricated AgNPs using Artemisia scoparia as bioreductant imparted relatively more antibiofilm activity as compared to commercial AgNPs against methylation-dependent restriction system (MDRS) strains. The mean MIC value for the commercial and biosynthetic AgNPs was found to be 12.81 and 8.45 μg/ml respectively, on MDRS isolates. Also, the biofabricated AgNPs exhibited superior antibiofilm activity against MDRS via unknown mechanisms (Moulavi et al., 2019).

Further, Gupta et al. showed that silver nanoparticles (AgNPs) obtained via green synthesis using leaf biomass of Psidium guajava have a remarkable ability to inhibit biofilm development of S. aureus, E. coli, and C. albicans by 96, 90, and 75% respectively, as evident from crystal violet assay (Gupta et al., 2014b). Recently, Almatroudi et al. assessed the antibiofilm activity of silver nanoparticles (Ns-AgNPs) biosynthesized using seed extract of Nigella sativa. They showed that at concentration 12.5 μg/ml, Ns-AgNPs limited the biofilm development by 84.92% for E. coli, 88.42% for Enterococcus faecalis, 81.86% for Klebsiella pneumonia, 82.84% for Staphylococcus aureus, and 49.9% for Pseudomonas aeruginosa, respectively (Almatroudi et al., 2020).

Interestingly, Kulshrestha et al. developed a bioinspired graphene oxide-silver nanocomposite (GO-Ag) by employing an eco-friendly route using Lagerstroemia speciosa (L.) Pers floral extract. It was observed that at concentrations 24 and 12 μg/ml, GO-Ag resulted in 90 and 49% biofilm reduction respectively, in Enterobacter cloacae. Similarly, 89 and 34% biofilm declination was observed in Streptococcus mutans when exposed to 47 and 24 μg/ml of GO-Ag respectively (Kulshrestha et al., 2017). Accordingly, Korkmaz et al. have synthesized silver nanoparticles (AgNPs) with the help of Mimusops elengi liquid fruit extract. According to their results, AgNPs (1250 μg/ml ) inhibited 86.36% of the biofilm formation in Escherichia coli (Korkmaz et al., 2020).

In a recent study, Nersin et al. evaluated the antibiofilm activity of biosynthesized AgNPs prepared using aqueous leaf extracts of Rhododendron ponticum. They found that almost at each concentration AgNPs imparted biofilm inhibitory activity in a dose-dependent manner. The highest concentration of AgNPs which showed maximum antibiofilm activity was 1.0 mg/ml (Nesrin et al., 2020).

Accordingly, biogenic silver nanoparticles (Ag@CC-NPs) were fabricated using aqueous extract of Carum copticum seed by Qais et al. The synthesized Ag@CC-NPs imparted biofilm inhibitory activity with 86.3%, 77.6%, and 75.1% biofilm inhibition of S. marcescens, P. aeruginosa, and C. violaceum respectively. Further at sub-MIC, Ag@CC-NPs inhibited the production of virulence factors such as pyoverdin, pyocyanin, swimming motility, elastase activity, exoprotease activity, and rhamnolipid in P. aeruginosa by 49.0, 76.9, 89.5, 53.3, 71.1, and 60.0% respectively. Moreover, virulence factors of S. marcescens viz. swarming motility, exoprotease activity, and prodigiosin production was reduced by 90.7, 67.8, and 78.4% respectively. Further, the SEM and CLSM observations showed a remarkable reduction in biofilm development on glass coverslip (Qais et al., 2020). Further, Foroohimanjili et al. investigated the antibiofilm, antibacterial, and anti quorum sensing properties of phytosynthesized silver nanoparticles (AgNPs) prepared using leaf extract of Mespilus germanica against multidrug-resistant Klebsiella pneumoniae strains. Their work revealed that at sub-MIC, AgNPs prominently inhibited the establishment of biofilm in all the biofilm-producing strains (Foroohimanjili et al., 2020).

In another study silver nanoparticles, synthesized employing aqueous leaf extracts of Moringa oleifera Lam imparted excellent biofilm eradication potential (78%) for P. aeruginosa whereas only 43% for S. epidermidis, as reported by Gokul Brindha (Gokul Brindha et al., 2020).

Interestingly, Muthuraman et al. employed a green route for the synthesis of silver nanoparticles (AgNPs) using medicinally relevant Nardostachys jatamansi rhizome extract. They showed that AgNPs (64 µM) prepared using heated plant extract exhibited superior antibiofilm activity against P. aeruginosa and S. aureus. Whereas AgNPs prepared using stirred plant extract required a relatively higher dose (500 µM) to impart their anti-biofilm effect (Muthuraman et al., 2019). In another study, Mohanta and colleagues developed biocompatible silver nanoparticles (AgNPs) utilizing foliage extracts of three different plants namely Glochidion lanceolarium, Semecarpus anacardium, and Bridelia retusa. The phytosynthesized AgNPs were screened for antibacterial and anti-biofilm activity against Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli; their data indicated promising results (Mohanta et al., 2020).

Further, Govindappa et al. assessed the antibiofilm activity of silver nanoparticles synthesized using fleshy pericarp of Punica granatum (Pfp-AgNPs). The Pfp-AgNPs were investigated for the antibiofilm effectiveness against Pseudomonas aeruginosa. The outcome revealed that the nanoformulations significantly increased the toxicity level in P. aeruginosa in a concentration-dependent fashion and led to potassium leakage, cellular damage, and biofilm inhibitory activity (Govindappa et al., 2021).

Interestingly, Al Aboody et al. synthesized silver nanoparticles (AgNP) using latex of Azadirachta indica. They demonstrated the antibiofilm activity of AgNPs against Fluconazole resistant clinical isolate of Candida tropicalis and concluded that at concentrations of 4.12 and 3.25 μg/ml, AgNPs inhibited the biofilms of fluconazole-resistant and fluconazole-susceptible C. tropicalis, respectively (Al Aboody, 2019). Velgosova et al. evaluated AgNPs and nanocomposites doped with AgNPs against biofilm development. For this, they synthesized AgNPs via green route using leaf extract of Rosmarinus officinalis. And further, doped Polyvinyl alcohol (PVA) matrix with green synthesized AgNPs to obtain polymer matrix composite (PMC) microfibers. The antibiofilm efficacy was screened against biofilm-producing one-cell green algae Parachlorella kessleri. The results revealed that there was no antibiofilm effect of pure PVA matrix whereas AgNPs and PMC (PVA-AgNP composites) microfibers showed significant antibiofilm activity (Velgosova et al., 2021).

Gold nanoparticles (AuNPs) are one of the most extensively exploited metal nanoparticles (NPs) paving their way in various fields of science and industry. Due to its various therapeutic properties like antibacterial, anticancer, antimalarial, and antibiofilm, there is a surge in their demand. To fulfill such demands, rigorous research is required to optimize its synthesizing approaches. Among various methods employed for the synthesis of AuNPs, a biogenic approach using plant extract is simple, effective, cheap, and eco-friendly (Ali et al., 2020). In this regard, Ali et al. developed gold nanoparticles utilizing Tinospora cordifolia plant stem (Ayurvedic medicinal plant) and assessed its biofilm inhibitory properties against Pseudomonas aeruginosa PAO1 biofilm. The SEM and crystal violet assay data revealed that the sub-MIC value of AuNPs significantly reduced the biofilm-producing capability of P. aeruginosa in a concentration-dependent manner. Their data showed that biofilm formation was inhibited up to 59.9, 36.6, 27.1% at 150, 100, and 50 μg/ml concentrations of AuNPs respectively. The CLSM analysis further indicated that the structure of the biofilm in the sub-MIC of AuNPs had abnormalities. Also, treatment of PAO1 with AuNPs at 150 μg/ml displayed internalization of the nanoparticles (Ali et al., 2020). Similarly, Manju et al., showed that gold nanoparticles biosynthesized applying essential oil of Nigella sativa (NsEO-AuNPs), efficiently inhibited the biofilm establishment of Staphylococcus aureus and Vibrio harveyi by reducing the hydrophobicity index (78 and 46% respectively) (Manju et al., 2016).

In another study, Vijayakumar et al. developed AuNPs using Musa paradisiaca peel extract (MPPE-AuNPs) and studied its biofilm inhibitory properties in multiple antibiotic-resistant Enterococcus faecalis. Confocal light microscopic observations demonstrated that the MPPE-AuNPs meritoriously repressed the biofilm formed by E. faecalis at concentration 100 µg/ml (Vijayakumar et al., 2017). Interestingly, Qais et al. biosynthesized gold nanoparticles by employing an aqueous fruit extract of Capsicum annuum (AuNPs-CA) and assessed its efficacy against the QS-regulated virulence factors and biofilms of Serratia marcescens and Pseudomonas aeruginosa. The result showed a significant reduction of QS-mediated virulent traits of P. aeruginosa PAO1 such as pyoverdin, elastase activity, exoprotease activity, pyocyanin, swimming motility, and rhamnolipids production by 72.16, 65.72, 81.12, 91.94, 46.09, 46.66%, respectively. Further, microscopic studies showed that the growth and synthesis of exopolysaccharides have been suppressed due to reduced bacterial adhesion and colonization on a solid substrate (Qais et al., 2021).

Accordingly, Perveen and colleagues fabricated biogenic gold nanoparticles by utilizing the seed extract of Trachyspermum ammi (TA-AuNPs), followed by assessing its effectiveness against biofilms of Serratia marcescens and Listeria monocytogenes. It was demonstrated that there was substantial anti-biofilm activity against both S. marcescens (81%) and L. monocytogenes (73%). Moreover, the key factors of biofilm development and maintenance such as cell surface hydrophobicity, exopolysaccharide, and motility were considerably inhibited at sub-MICs. Also, the NPs efficiently eradicated preformed established biofilms of L. monocytogenes and S. marcescens by 58 and 64%, respectively (Perveen et al., 2021).

Among several metallic nanoparticles, zinc oxide nanoparticles have held the attention of several researchers owing to their multifunctional properties and versatility. The antibacterial efficacy of zinc oxide nanoparticles has been well established against both gram-negative and gram-positive bacteria as well as against fungi. It has already been reported that ZnO NPs are nontoxic to human cells while imparting antibacterial properties via several mechanisms like the generation of ROS, the release of metal ions, etc (Gudkov et al., 2021). Further, green synthesized zinc oxide nanoparticles have been known to impart superior properties due to their eco-friendly characteristics. Regarding this several plant-based syntheses of ZnO NPs have been carried and their antibacterial and antibiofilm efficacies have been evaluated.

Interestingly, Vijayakumar et al. biologically developed Plectranthus amboinicus mediated zinc oxide nanoparticles (Pam-ZnO NPs). Their data showed that the synthesized nanoparticles exhibited antibiofilm activity at concentrations range 8–10 μg/ml against the biofilms of methicillin-resistant Staphylococcus aureus. Further, Confocal laser scanning microscopy analysis suggested that the biofilm-forming ability of S. aureus is intensely inhibited by Pam-ZnO NPs (Vijayakumar et al., 2015).

Similarly, in their other study, they reported the QS inhibitory property of zinc oxide nanoparticles synthesized using seed extract of Nigella sativa (NS-ZnNPs). Their fabricated nanoparticles inhibited QS-mediated functions of C. violaceum and inhibited the production of pyocyanin, alginate, protease, and elastase in P. aeruginosa PAO1 evidently. Also, at sub-MICs, NS-ZnNPs prevented the biofilm development as well as eradicated pre-formed biofilms of food-borne bacteria viz. C. violaceum 12472, PAO1, L. monocytogenes, E. coli. Preformed biofilms were eradicated by 66, 78, 68, and 72% in E. coli, P. aeruginosa, C. violaceum, and, L. monocytogenes respectively as observed by CV assay. Further, CLSM also confirmed the antibiofilm property of NS-ZnNPs (Al-Shabib et al., 2016).

Further, Al-Shabib et al. investigated the protein-binding and antibiofilm activity of zinc oxide nanoparticles synthesized from Ochradenus baccatus leaf extract (OB-ZnNPs). The synthesized OB-ZnNPs imparted considerable antibiofilm properties against human and foodborne pathogens (Listeria monocytogenes Chromobacterium violaceum, Serratia marcescens, P. aeruginosa, Klebsiella pneumoniae, and Escherichia coli) at sub-MICs. Further, the NPs significantly impaired swarming motility and EPS production which aids in biofilm development. Their data showed the highest inhibition of biofilm in P. aeruginosa by 84%; in E. coli by 67%; in L. monocytogenes by 78%; in K. pneumonia by 70%; in S. marcescens by 80%; and, in C. violaceum by 64% (Al-Shabib et al., 2018).

Accordingly, Dogan and Kocabas synthesized zinc oxide (ZnO) nanoparticles (NPs) using foliage extracts of Veronica multifida under various physical conditions. The antibiofilm activity of the prepared NPs was evaluated against S. aureus and P. aeruginosa. The results revealed that in S. aureus, 10 μg/ml of ZnO NPs at pH 7 inhibited 88% of biofilm development, and 50 μg/ml ZnO NPs at pH 12 inhibited 87% of the biofilm development. While in P. aeruginosa, at both pH 7 and pH 12, the maximum biofilm inhibitory activity was observed at a concentration of 50 μg/ml (Doğan and Kocabaş, 2020). Further, Alavi et al. demonstrated the antibiofilm efficacy of zinc oxide NPs synthesized using Artemisia haussknechtii leaves extract. Their crystal violet (CV) assay analysis revealed a significant reduction in biofilm formation for S. epidermidis with 63.43% (0.562 ± 0.015) and P. aeruginosa with 62.88% (0.582 ± 0.025) at 100 μg/ml ZnO NPs. Further, Light microscopic observations showed there was a significant reduction of biofilm formation with the increase in ZnO NPs concentration (Alavi et al., 2019).

Interestingly, Vinotha et al. reported a novel fabrication of ZnO nanoparticles by utilizing foliage extract of Costus igneus (Ci-ZnO NPs). Their prepared Ci-ZnO NPs displayed encouraging antibiofilm and antibacterial activities against L. fusiformis, S. mutans, V. parahaemolyticus, and P. vulgaris bacteria at concentrations 75 and 100 μg/ml. Further, the light microscopy and CLSM analysis revealed disintegration and reduced growth of biofilm in a concentration-dependent fashion. Also, they suggested that the biofilm inhibitory activity of ZnO NPs was due to the generation of ROS and the action of surface ions released from the nanoparticles (Vinotha et al., 2019).

Similarly, Malaikozhundan et al. synthesized Withania somnifera leaf extract-assisted ZnO NPs (Ws-ZnO NPs) and evaluated its antibiofilm efficacy against S. aureus and E. faecalis. They showed that at concentration 100 μg/ml, the Ws-ZnO NPs imparted significant biofilm inhibitory activity. Further, Ws-ZnO NP’s surface activity resulted in disruption of the bacterial cell wall and biofilm inhibition. Also, excessive generation of ROS leads to enhanced antibacterial properties (Malaikozhundan et al., 2020). Accordingly, Cherian et al. developed bio-inspired zinc oxide nanoparticles (MFLE-ZnONPs) fabricated by using Myristica fragrans leaf ester (MFLE) and assessed its antibiofilm activity against methicillin-resistant Staphylococcus aureus and multi-drug resistant Escherichia coli clinical isolates. It was found that the synthesized nanoparticles showed dose-dependent declination of biofilm development in both the tested bacterial strain (Cherian et al., 2019).

Employing the alcoholic extract of Artemisia, Galederi and Teimouri fabricated ZnO-NPs and studied its inhibitory effects on biofilm development by P. aeruginosa strains. The outcomes suggested that ZnO-NPs were effective on the isolates at the minimum and maximum viscosities of 3.125 and 100 mg/ml, respectively. (Galedari and Teimouri, 2020).

Moreover, Obeizi et al. reported the antibiofilm efficacy of biogenic zinc oxide nanoparticles prepared by using Eucalyptus globulus essential oil. Their results revealed that ZnO NPs effectively inhibited biofilm development in S. aureus ATCC 25923 and P. aeruginosa ATCC 27853 in a dose-dependent manner. The percentage of biofilm inhibition at 100 μg/ml ZnO NPs was observed to be 97 and 85% against P. aeruginosa biofilm and S. aureus, respectively (Obeizi et al., 2020).

Accordingly, Basumatari et al. fabricated zinc oxide nanoparticles (ZnONPs) by utilizing an aqueous pseudostem extract of Musa balbisiana Colla ash (AEPA), a plant biowaste, and evaluated its efficacy as an antibiofilm and antibacterial agent. The AEPA mediated ZnO NPs exhibited note-worthy antibiofilm activity against P. aeruginosa, as revealed by 96-microtitre well plate and Congo red agar method. At a dosage of 100 μg/ml, the percent inhibition for P. aeruginosa was 95.13%, indicating an enhanced inhibitory impact on bacterial biofilm breakdown (Basumatari et al., 2021).

The U.S. Environmental Protection Agency (USEPA) has designated elemental copper and its compounds as antibacterial materials. Nanoformulations of Copper oxide exhibit enhanced antimicrobial activity towards pathogenic microorganisms. Further, numerous reports have also discussed the antibiofilm activity of copper oxide nanoparticles (Mahmoodi et al., 2018). Green synthesized CuO nanoparticles have been known to impart superior properties due to their less toxic nature.

Regarding this, Naseer et al. demonstrated the antibiofilm efficacy of biogenic copper oxide nanoparticles (CuO NPs) prepared by utilizing Melia azedarach and Cassia fistula leaf extracts. The results revealed that at concentration 1 μg/ml the M. azadarech derived NPs the prevented biofilm development of H. pylori and K. pneumoniae by 99.5 and 92.5% respectively. While, at the same concentration, the C. fistula-derived NPs inhibited biofilm inhibition by 100 and 99.8% for H. pylori and K. pneumoniae, respectively (Naseer et al., 2021). In another report, Suresh et al., synthesized CuNPs applying a two-stage chemical reduction method, where Hydrazine Hydrate (HH) was used as a reducing agent and Gum kondagogu extracts were used as a stabilizing agent. The SEM results revealed complete destruction of biofilm with destabilized cell masses in Klebsiella pneumoniae clinical isolates (ATCC 27736) treated with Gum kondagogu extract mediated CuNPs (Suresh et al., 2016).

Similarly, Punniyakotti et al., prepared copper nanoparticles (Cu NPs) using leaf extracts of Cardiospermum halicacabum and evaluated their antibiofilm efficacy against three clinical strains of S. aureus, E. coli, and P. aeruginosa. They demonstrated that at 100 μg/ml, Cu NPs exhibited maximum antibiofilm activity with 79, 78, and 72% of biofilm inhibition in P. aeruginosa, E. coli, and S. aureus respectively (Punniyakotti et al., 2020). Similarly, Ali and his coworkers biosynthesized terpenoids entrapped copper oxide nanoparticles (ELE-CuONPs) prepared using Eucalyptus globulus (ELE) leaf extract. The results revealed that application of ELE-CuONPs in a dose ranging from 125 to 2000 μg/ml, prevents biofilm development by 19.03 ± 9% to 60.93 ± 8%, 44.41 ± 7% to 70.75 ± 8%, and 34.41 ± 7% to 62.29 ± 8% in P. aeruginosa-621, E. coli-336, and MRSA-1, respectively, hence suggesting the promising potential of ELE-CuONPs as an anti-biofilm therapeutic (Ali et al., 2019).

Interestingly, Erci and colleagues synthesized CuONPs by using various concentrations of aqueous leaf extract of Thymbra spicata to obtain Ts1CuONPs (40 ml plant extract) and Ts2CuONPs (80 ml plant extract). Their data showed, at a dosage of 100 μg/ml, the biofilm inhibition value for S.aureus was found to be 57.6 ± 1.03% and 49.1 ± 4.0% for Ts2CuONPs, Ts1CuONPs respectively (Erci et al., 2020). Accordingly, Cherian et al. manufactured CuONP via the one-pot green method by employing Cymbopogon citratus (CLE) leaf extract. The results revealed that the biofilm growth in MRSA-1 and E.coli was decreased to 49.0 ± 3.1% and 33.0 ± 3.2%, respectively on exposure to CLE-CuONPs (2000 μg/ml). Further, CLSM data suggested superior antibiofilm properties against E.coli followed by S. aureus owing to the variation in their cell wall compositions (Cherian et al., 2020).

Titanium oxide nanoparticles have a broad spectrum of applications like antibacterial, cosmetics, photocatalyst, wastewater treatment, and other medical fields. In fact, they are among the most extensively utilized nanoparticles attributed to their superior properties like non-toxic, stable, safe, and having surface activity (Al-Shabib et al., 2020). For instance, a study done by Narayanan et al. showed that TiO₂ NPs prevented the growth of bacterial pathogens via the generation of ROS, DNA, and cell membrane damage (Narayanan et al., 2021).

Accordingly, Al-Shabib and his colleagues fabricated TiO₂ NPs using root extract of Withania somnifera and evaluated its antibiofilm efficacy. Their results showed that at a concentration below MIC (0.5×MIC), TiO₂ NPs exhibited a significant inhibitory effect on biofilm development (43–71%) and mature biofilms (24–64%) in pathogens like P. aeruginosa, E. coli, Listeria monocytogenes, MRSA, Serratia marcescens, and Candida albicans. Consequently, they inferred that excessive ROS generation followed by cell death could be the possible cause for the compromised biofilm development in TiO₂ NP-treated pathogens (Al-Shabib et al., 2020).

Rajkumari and coworkers fabricated titanium dioxide nanoparticles (TiO₂ NPs) employing Aloe barbadensis leaf extract. Their results showed treatment of P. aeruginosa in biofilm mode with TiO₂ NPS leads to a significant reduction in cell viability by 30.76 ± 3.96%. Further, the MIC value of TiO₂ NPs imparted prominent antibiofilm activity against P. aeruginosa by hindering the adhesion of planktonic cells to the substratum (Rajkumari et al., 2019). Similarly, Achudhan and colleagues fabricated TiO₂ NPs using twigs and bud extract of Ficus benghalensis, Azadirachta indica twigs, and Syzygium aromaticum and evaluated their antibacterial and antibiofilm efficacy against bacteria (Citrobacter freundii and Streptococcus mutans) and fungi (Candida albicans). The green synthesized TiO₂ NPs inhibited biofilms of both the pathogens at a concentration of 100 μg/ml (Achudhan et al., 2020).

Interestingly, Dan et al., studied the antibiofilm activity of green synthesized titanium oxide using the leaf extract of Ocimum sanctum against P. aeruginosa, E. coli, S. aureus, and C. albicans. Their results showed the effective range of these NPs was between 250 and 650 μg/ml with a minimum effective dosage of 450 μg/ml against E. coli while for the remaining microbes 250 μg/ml was sufficient (Dan and Khan, 2019). Further, Jin et al. synthesized titanium dioxide nanostructures with the help of Rosa davurica leaf extract (RDL-TiO₂NPs) and evaluated its antibiofilm potential against different biofilm-producing bacteria. The minimum inhibitory concentration (MIC) of RDL-TiO₂NPs was 15.62 μg/ml for S. aureus and B. cereus, 62.5 μg/ml for S. enterica, and 31.25 μg/ml for E. coli. Also, the IC50 value for S. enterica and S. aureus were 158.75 and 76.84 μg/ml respectively. Further, the TEM and CV assay results indicated that RDL-TiONPs prevented bacterial biofilm via cell wall and membrane rupture (Jin et al., 2021).

Zubair et al. evaluated the efficacy of green synthesized TiO₂ NPs using leaf extract of Ochradenus arabicus to repress biofilm development and associated pathways in MRSA and MDR strains of P. aeruginosa isolated from foot ulcers. They studied that the constructed NPs reduced the biofilm formation by 22–70%, inhibited EPS production and cell surface hydrophobicity at sub-MICs. Further, severe impairment of motility and a prominent decrease in alginate production was also observed in P. aeruginosa. Also, significant damage (51–63 percent) to the preformed biofilms of all tested strains was observed. Moreover, the treatment of bacterial cells with TiO₂ NPs leads to increased ROS production which could be the possible reason for biofilm inhibition (Zubair et al., 2021).

Recently, iron oxide nanoparticles (IONPs) have grabbed the limelight owing to their distinctive properties like higher surface area, superparamagnetism, surface-to-volume ratio, and simple separation procedure (Ali et al., 2016). These magnetic nanoparticles are known to impart antibacterial as well as antibiofilm properties via various mechanisms such as generation of ROS, electrostatic interaction with the cell membrane and its proteins, leading to physical damage and ultimately microbial death (Thukkaram et al., 2014). Further, the use of green materials for the synthesis of IONPs offers several advantages of low toxicity, biocompatibility for medical application, and eco-friendliness (Kanagasubbulakshmi and Kadirvelu, 2017).

In this regard, Ramalingam et al., constructed plant-assisted iron oxide nanoparticles utilizing leaf extract of grey mangrove Avicennia marina and studied its antibiofilm efficacy against marine pathogenic biofilm-forming bacteria. The designed NPs restricted the initial attachment and development of biofilm in biofilm-producing bacteria like Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. Their results showed that nearly, 72% of quorum sensing factors of Pseudomonas aeruginosa, 63% of S. aureus, and about 46% of E.coli were inhibited by 200 μg/ml of FeO-NPs. Moreover, the FeO-NPs reduced the hydrophobicity index of P. aeruginosa, S. aureus, and E. coli, from 19, 15, 16% to 11, 11, and 9% respectively. Also, the designed FeO-NPs prevented the formation of EPS in P. aeruginosa, S. aureus, and E. coli from 92, 86, 90%, to 65, 60, and 69% respectively. Hence, they concluded that their designed biogenic FeO-NPs have the promising potential to be employed as an antibiofilm drug against pathogenic biofilm-producing microbes (Ramalingam et al., 2019).

Interestingly, the iron oxide nanoparticles synthesized using Thymbra spicata leaf extract imparted remarkable antibacterial properties against Salmonella typhimurium at a concentration of 100 μg/ml, as studied by Erci et al. Further, the NPs inhibited the growth of S. aureus growth and inhibited biofilm growth by 25.9 ± 3.36% at a concentration of 6.25 μg/ml. Therefore, they concluded that green synthesized FeONPs using T. spicata could serve as a potential antibacterial and antibiofilm therapeutic candidate (Erci and Cakir-Koc, 2020).

Accordingly, Ansari and his coworkers have used an extract of a polyherbal ayurvedic drug formulation, Liv 52 for the synthesis of superparamagnetic maghemite nanoparticles (L52E-γ-Fe₂O₃ NPs). Their formulated NPs imparted superior antibacterial, antifungal as well as antibiofilm properties against MRSA, MDR P. aeruginosa, and C. albicans. Further, there was significant damage in the biofilm structure of C. albicans majorly due to intense cell wall damage and inhibited hyphal growth, as observed by scanning electron microscopy. Also, the molecular docking reports showed that there was an effective interaction between Fe₂O₃ NPs and cell wall peptidoglycan and mannoprotein which may lead to the cell wall and membrane damage (Ansari and Asiri, 2021).

Cerium oxide is a cubic-fluorite type of oxide which is regarded as the most prime among the rare earth oxides. Lately, CeO₂ nanoparticles have been widely studied for a wide array of prospective applications in various fields including nanomedicine. Although, their antioxidant property has been well studied, but their antimicrobial and antibiofilm studies are still at it infancy with very limited studies (Kannan and Sundrarajan, 2014). Even though phytosynthesised CeO₂ nanoparticles have shown promising antibiofilm potential, very little research work has been done.

In this regard, Ahmed and his coworkers employed fruit extract of Phoenix dactylifera for CeO₂ and Ti-decorated CeO₂ nanoparticles synthesis. They evaluated the antibiofilm efficacy of undoped and Ti-doped CeO₂ NPs against the P. aeruginosa developed biofilm. Their result revealed that undoped CeO₂ nanoparticles prevented biofilm development by 11.0, 18.7, 31.3, and 54.5% at a concentration of 125, 250, 500, and 1000 μg/ml respectively. Similarly, 5% Ti-doped CeO₂ nanoparticles inhibited biofilm formation by 10.9, 25.0, 34.2, and 57.4% at a concentrations of 125, 250, 500, 1000 μg/ml respectively. Also, similar trends were observed with 10, 15, and 20% Ti-CeO₂ nanoparticles, with about 75% biofilm inhibition by 1000 μg/ml of 20% Ti-CeO₂ nanoparticles. Hence, their data indicated increasing the titanium doping concentration in CeO₂ nanoparticles, enhances the antibiofilm activity, possibly because of the increased titanium ions release from the formulated nanocomposite (Ahmed et al., 2020).

Accordingly, Altaf et al. found that biosynthesized cerium oxide nanoparticles (CeO₂-NPs) prepared using Acorus calamus extract prevented the growth of bacterial biofilms by more than 75 percent. The confocal and electron microscopic data revealed that the application of CeO₂-NPs prevented the development and colonization of the bacteria on solid surfaces. Moreover, dose-dependent inhibition of preformed biofilms was also observed. There was a significant reduction in the exopolysaccharides (EPS) formation by test bacteria grown in CeO₂-NPs supplemented culture media (Altaf et al., 2021).

Interestingly, Naidi et al., applied a green chemistry route for the synthesis of cerium oxide (S-CeO₂) and 1, 5, and 10% tin-doped cerium oxide nanoparticles (Sn-doped CeO₂NPs) using aqueous foliage extract of Pometia pinnata as reductant. The fabricated nanoparticles imparted substantial antibiofilm properties against S. aureus and Listeria monocytogenes at a concentration of 512 μg/ml. The 1% Sn-doped CeO₂ NPs did not exhibit any antibiofilm activity while there was a significant antibiofilm activity imparted by the 10% Sn-doped CeO₂ at a concentration of 512 μg/ml nearly similar to that of S-CeO₂ NPs (Naidi et al., 2021b). Similarly, in their other research work, they synthesized zirconium/tin-coated nanoparticles (Zr/Sn-CeO₂ NPs) using Pometia pinnata aqueous plant extract. All Zr/Sn-doped CeO₂ NPs (1, 5, and 10%) exhibited a concentration-dependent biofilm inhibition of L. monocytogenes, and only 10% Zr/Sn-dual doped-CeO₂ NPs were found to impart antibiofilm activity against S. aureus at higher concentrations. The maximum biofilm inhibition was obtained at a concentration of 512 μg/ml for all of the synthesized nanoparticles i.e. S-CeO₂ NPs, and Zr/Sn-dual doped CeO₂ NPs (Naidi et al., 2021a).

Apart from the above-mentioned nanoparticles, few other phytosynthesized nanoparticles have also been remotely evaluated for their anti-biofilm properties. Regarding this, Saleem et al. employed a green route method for the synthesis of nickel oxide nanoparticles (NiO-NPs) by utilizing Eucalyptus globulus leaf extract as a bioreductant. They prominently established the antibiofilm and antibacterial efficacy of the synthesized NPs against ESβL (+) E. coli, P.aeruginosa, and S.aureus. Further, the SEM images of NiO-NPs treated with microbial cells revealed irregular shrinkage and distortion with prominent depression/indentations with the cells. Hence, their work indicated substantial antibiofilm and antibacterial activity of plant synthesized NiO-NPs (Saleem et al., 2017).

Similarly, Prakashkumar and his coworkers fabricated biocompatible palladium nanoparticles (NG@Pd NPs) using leaf extract of Orthosiphon stamineus and evaluated its antibiofilm and antibacterial properties. The results showed enhanced bactericidal activity of NG@Pd NPs against E. coli, S. aureus, and extended-spectrum beta-lactamase strain relative to the PdNPs alone. Moreover, the antibiofilm study demonstrated inhibition of biofilm development in a concentration-dependent manner in methicillin-sensitive Staphylococcus aureus strain with the IC50 value of 15.25 ± 0.012 μg/ml, whereas the Pd NPs exhibited reduced inhibitory effect (N et al., 2021). Accordingly, Miglani and Tani-Ishii et al., constructed a biogenic selenium nanoparticle (SeNPs) using leaf extract of Psidium guajava with an aim to study its antimicrobial and antibiofilm properties against Enterococcus faecalis. Consequently, they evaluated the relative antibiofilm efficacy of five test groups namely distilled water (control), SeNPs (1 mg/ml), Calcium hydroxide (1 mg/ml), 5.25% Sodium hypochlorite, and 2% Chlorhexidine gluconate. The result revealed that SeNPs were the most efficacious among others against the biofilm of E. faecalis (Miglani and Tani-Ishii, 2021).