Unveiling Synergistic Antimicrobial Action with Nisin-Silver Nanoconjugate-Loaded Dissolving Microneedles

Purpose

The research aimed to develop nisin-silver nanoconjugates within a dissolving microneedle formulation using green synthesis chemistry and solvent casting methods. The objective was to assess potential of these nanoconjugates to enhance antimicrobial efficacy against gram-positive and gram-negative bacteria, such as Bacillus subtilis and Escherichia coli, offering an alternative to conventional antibiotics that often cause resistance and side effects.

Methods

Nisin-silver nanoconjugates were developed using green synthesis chemistry and incorporated into dissolving microneedles through solvent casting methods. Optimization was conducted using 3² factorial design. Characterization included measuring particle size (288 ± 5.49 nm), polydispersity index (0.381 ± 0.57), and zeta potential (-21.4 ± 1.54 mV). ATR-FTIR studies confirmed conjugation by identifying a characteristic C-O-C stretch peak at 1019 cm^-1, and DSC studies revealed an endothermic peak at 242 °C. The microneedle formulation was tested for in-vitro release of Nisin Z over 48 h. Antimicrobial efficacy was assessed using agar disc diffusion method, demonstrating significant zones of inhibition against Bacillus subtilis, Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa.

Results

The microneedle formulation (DMN 3) showed in-vitro release of 85.03 ± 0.53% over 48 h. The antimicrobial efficacy tests showed significant inhibition zones for Bacillus subtilis (20 ± 0.5 mm), Escherichia coli (12 ± 4 mm), Staphylococcus aureus (19 ± 4 mm), and Pseudomonas aeruginosa (11 ± 3 mm).

Conclusion

The study successfully developed nisin-silver nanoconjugates incorporated into dissolving microneedles. These nanoconjugates demonstrated synergistic antimicrobial action, showing promise for treating bacterial infections effectively. This suggests they could be viable alternative to traditional antibiotics, potentially reducing the risks of resistance and side effects associated with conventional treatments.