Wheat Straw-Derived Lignin Nanoparticles Combined with Postbiotics for Antimicrobial, Antibiofilm and Antioxidant Applications in Topical Formulations

Abstract

Introduction: Plant-derived bionanomaterials have emerged as an important interest as a sustainable platform for new drug delivery and antimicrobial applications. In this study a biopolymer-based lignin nanoparticles have been synthesized using wheat straw lignin. Method: Lignin for the wheat straw has been extracted and used for the preparation of nanoparticles. The lignin nanoparticles (LNPs) then characterized using UV-Vis spectroscopy, SEM, FTIR and the engineered LNPs were then mixed with cell-free supernatant (CFS) of Lactiplantibacillus plantarum to build a multifunctional, antibiotic-free nanotherapeutic system against dermatological pathogens Cutibacterium acnes using Aloe vera gel. All the combinations were checked for growth and biofilm inhibition of the pathogen. Results: Spherical to sub-spherical LNPs were formed with a mean diameter ranging between 53–107 nm. These LNPs in combination with postbiotic showed excellent growth inhibition of C. acnes (95.5%) in broth assays compared to Postbiotic CFS alone (63.6%) and to conventional antibiotic Azithromycin (35.9%). Quantitative fluorescence microscopy also confirmed a significant decrease in the amount of bacteria associated with the biofilm (47.5% relative fluorescent (RF) compared to 58.0 % for Azithromycin). The formulated nanocomposite gel also demonstrated a strong DPPH free radical scavenging activity with an in vitro Sun Protection Factor (SPF) of 10.0, while the base gel had an SPF of 0.53. Discussion: The improved antimicrobial and antibiofilm activity of the LNP–postbiotic formulation indicates a combined interaction between wheat straw-derived lignin nanoparticles and L. plantarum postbiotic metabolites leading to a greater C. acnes inhibition than the single components and the tested azithromycin control. The antioxidant and photoprotective properties of the nanocomposite gel provide additional proof of its potential as a multifunctional, sustainable, antibiotic-free topical biomaterial for acne treatment. However, further investigation may be required to assess its physicochemical stability, skin compatibility, permeation and in vivo therapeutic efficacy.