Curcumin-Photosensitized Nanocapsules: Biocompatibility and Antimicrobial Evaluation in Primary Tooth Dentin Contaminated with Streptococcus mutans

Michelle Cristina Erckmann¹Aline Almeida²Diogo Dominguini³Daniela Becker²Josiane Khun Rutz⁴Dachamir Hotza⁵Abhishek Parolia⁶Vanessa Valgas dos Santos¹Michael Ramos Nunes^7,8Cleonice Gonçalves da Rosa¹Anelise Viapiana Masiero^1,6*

• ¹Multi-User Laboratory, Graduate Program in Environment and Health,, Planalto Catarinense University, Lages, Brazil
• ²Laboratory of Plasmas, Films, and Surfaces,, Santa Catarina State University, Joinville, Brazil
• ³Laboratory of Experimental Pathophysiology, Graduate Program in Health Sciences, University of the Extreme South of Santa Catarina, Criciuma, Santa Catarina, Brazil
• ⁴CDC-Bio Laboratory, Faculty of Dentistry, Federal University of Pelotas, Pelotas, Rio Grande do Sul, Brazil
• ⁵Graduate Program in Chemical Engineering (PosENQ) and Department of Chemical and Food Engineering (EQA),, Federal University of Santa Catarina, Florianopolis, Santa Catarina, Brazil
• ⁶Department of Endodontics, College of Dentistry and Dental Clinics, The University of Iowa, Iowa City, Iowa, United States
• ⁷Federal Institute of Santa Catarina, Lages, Brazil
• ⁸Graduate Program in Chemical Engineering (PosENQ), Federal University of Santa Catarina, Florianopolis, Santa Catarina, Brazil

Dental caries is a multifactorial disease with a notably prevalence, particularly among vulnerable populations. Streptococcus mutans (S. mutans) plays a central role in its progression through acid production and biofilm formation. Minimally invasive strategies such as photodynamic therapy (PDT), especially when integrated with advanced delivery systems, offer promising alternatives for managing carious lesions while preserving tooth structure. This study aimed to synthesize and characterize zein-based nanocapsules loaded with curcumin, assess their biocompatibility with oral mucosal cells, and evaluate their in vitro antimicrobial efficacy on primary dentin contaminated with S. mutans, both with and without photodynamic activation. The nanocapsules were synthesized via nanoprecipitation and demonstrated high high encapsulation efficiency (~100%), spherical morphology, low polydispersity (0.108), and favorable colloidal stability. Cytotoxicity assays using MTT and trypan blue demonstrated over 50% cell viability at full concentration and up to 80 µg·mL⁻¹ at intermediate concentrations. Antimicrobial testing revealed that both curcumin nanocapsules and their photosensitized counterparts significantly reduced S. mutans colony-forming units compared to untreated controls(p<0,05). These findings highlight the potential of curcumin-loaded zein nanocapsules as a biocompatible, effective, and minimally invasive therapeutic approach, particularly suited pediatric dentistry.