Synthesis, characterization and antimicrobial activity of PLGA nanoparticles loaded with P19 peptide against two pathogenic bacteria

Antimicrobial Peptides (AMPs) are macromolecules formed by less than 100 aminoacids and sizes 51%) in the first 20 min and then slow and controlled release up to 2880 min (>95%) (figure 3). Finally, the antimicrobial activity... [ view full abstract ]

Antimicrobial Peptides (AMPs) are macromolecules formed by less than 100 aminoacids and sizes <10kDa. These are very attractive because of fast action and wide spectrum activity against bacteria, fungi, protozoan, parasites and viruses. For this reason, peptides are generating great interest to affront health issues such as resistant pathogenic microorganisms. However, despite all the advantages offered by AMPs, these are limited in comparison to conventional therapeutic molecules due to its high susceptibility to proteolysis and denaturation. In this sense, one alternative to avoid these interferences is the nanoencapsulation with polymeric nanoparticles. This represents a viable and highly versatile way for the protection of active principles, allowing that its biological activity and structural identity be conserved. This work focuses on the synthesis, characterization and antimicrobial activity of poly (lactic-co-glycolic) acid (PLGA) nanoparticles loaded with the AMP P19 against two pathogenic bacteria, Escherichia coli O157:H7 and Methicillin Resistant Staphyloccocus aureus (MRSA), which are priority pathogens for research and development of new antibiotics according to World Health Organization (WHO). AMP P19 was designed and synthesized in our lab by Fmoc solid phase peptide synthesis. The AMP obtained was encapsulated in colloidal solution using Double Emulsion Solvent Diffusion (DES-D) method. Different concentrations of P19 were encapsulated (NP-P19) with the aim of determining the best ratio peptide/polymer, spherical and monodispersed polymeric nanoparticles of 257±2.84 nm and zeta potential of 12.90±0.80 mV were obtained (figure 1), suggesting high thermodynamic stability. This methodology allowed us to obtain an encapsulation efficiency of 80.48±1.75% (figure 2), NP-P19 showed a rapid cumulative release (>51%) in the first 20 min and then slow and controlled release up to 2880 min (>95%) (figure 3). Finally, the antimicrobial activity of free P19 and NP-P19 gainst E. coli O157: H7 and MRSA was evaluated, obtaining a Minimal Inhibitory Concentration (MIC50) for NP-P19 of 3.13 μg/mL and 0.7 μg/mL, respectively. This represents an increase in the activity of the peptide compared to the free P19 (Table 1). Our results suggest that nanoencapsulation favors the activity of antimicrobial peptides that eventually could be applied in the development of alternative therapies for infection of this pathogenic bacteria.