The sustained delivery system of the antiinfection peptide LL37 ? a potential new method of treatment of ocular infections. Report 3. Antimicrobial activity of LL37 encapsulated in silica nanoparticle

Purpose. To test anti-microbial activity of the anti-infection peptide (AIP) LL37 sustained delivery system (SDS) based on silica nanoparticles (SiNP). Materials and Methods. AIP LL37 (cathelicidin) was encapsulated in SiNP under magnetic stirring. For anti-microbial activity testing, St. aureus and P. aeruginosa strains in the concentration 10' PFU/ml were co-cultured for 2 hours in nutrient broth together with LL37 SDS. Bacterium strains of the same concentrations cul?tured without LL37 SDS, with free LL37 or with empty SiNP served as controls. Culture medium was collected to count bacteria titer using plaque formation assay. Results. SiNP encapsulated LL37had significant anti-microbial effect compared with controls: St. aureus titer in the culture medium contained SiNP encapsu?lated LL37was 3466.7+450.9PFU/ml, St. aureus titer in culture medium without SDS of LL37 was 410000+168226 PFU/ml (P = 0.012); P. aeruginosa titer in presence of SiNP encapsulated LL37 was 3.lxl07±l.85xl07 PFU/ml, its titer was 4.67xl0fl±2.08xl0n PFU/ml in the culture medium without SDS of LL37 (P =0.012). Conclusion. For the first time there was shown in vitro the activity of anti-infective peptide system 0f constemt drug tive peptide LL37sustained delivery system based on silica nanoparticles against delivery gram-positive and gram-negative bacteria ? St. aureus and P. aeruginosa.