Enhanced Antimicrobial Action of Chlorhexidine Loaded in Shellac Nanoparticles with Cationic Surface Functionality.

Area of Science:

• Nanotechnology
• Materials Science
• Antimicrobial Agents

Background:

• Chlorhexidine (CHX) is a widely used antiseptic, but its efficacy can be limited by formulation and delivery.
• Nanoparticle-based drug delivery systems offer potential for enhanced antimicrobial action.
• Shellac nanoparticles (NPs) provide a biocompatible platform for drug encapsulation.

Purpose of the Study:

• To develop and characterize an active nanocarrier for chlorhexidine (CHX) using dual surface-functionalized shellac NPs.
• To investigate the encapsulation efficiency, release kinetics, and antimicrobial activity of the novel CHX nanocarrier.
• To explore the impact of dual functionalization on CHX's antimicrobial enhancement.

Main Methods:

• Fabrication of CHX-loaded shellac NPs via pH-induced co-precipitation with Poloxamer 407 (P407) stabilization.
• Surface modification of NPs with octadecyl trimethyl ammonium bromide (ODTAB) to impart cationic functionality.
• Assessment of CHX encapsulation efficiency and release kinetics.
• Evaluation of antimicrobial activity against *E. coli*, *S. cerevisiae*, and *C. reinhardtii*.

Main Results:

• Dual surface functionalization of shellac NPs with ODTAB significantly amplified the antimicrobial action of CHX.
• Non-coated, CHX-loaded NPs showed inferior activity compared to free CHX due to negative surface charge.
• The enhanced activity is attributed to increased electrostatic adhesion between cationic NPs and anionic microbial cell walls, enabling targeted CHX delivery.
• Tested microorganisms included *E. coli* (Gram-negative bacterium), *S. cerevisiae* (yeast), and *C. reinhardtii* (microalgae).

Conclusions:

• Dual surface-functionalized shellac nanoparticles represent an effective nanocarrier for enhancing chlorhexidine's antimicrobial efficacy.
• The cationic surface charge is crucial for improved antimicrobial performance through enhanced cellular adhesion and targeted drug delivery.
• This novel nanocarrier system holds promise for developing advanced dental formulations to combat oral infections like gingivitis and periodontitis with potentially lower CHX concentrations.