Characterization of PLGA nanoparticles for stabilization and controlled release of antimicrobial peptides into marine bivalves

Nanoparticles (NPs) have revolutionized the field of medicine and veterinary for both detection and treatment of infection diseases, however, their utilization to supply drugs or bioactive metabolites to marine invertebrates has been insufficiently investigated. Antimicrobial peptides (AMPs) have gained increasing attention as potential alternatives to overcome the shortcomings associated with conventional therapeutic strategies. Using an emulsion/evaporation approach, spherical poly(lactic- co -glycolic acid) (PLGA) NPs charged with D-Caerin (D-CAE) peptide have been prepared. The obtained NPs showed a bimodal size distribution, with mean diameters of 130 ± 4 and 421 ± 19 nm. Among the tested formulation, NPs with a peptide/polymer ratio of 0.02 exhibited the best physico-chemical properties, achieving encapsulation efficiencies of 70 %. Release studies demonstrated that 73.5 % of the peptide was liberated from loaded the NPs within 40 h. Furthermore, the D-CAE peptide retained its antimicrobial activity following encapsulation in PLGA NPs and exhibited bactericidal effects against two prevalent pathogens in aquaculture species. Finally, it has been shown that peptide-loaded NPs are effectively ingested by clam post-larvae, suggesting the potential of peptide-PLGA NPs as biocompatible nanocarriers for delivery of AMPs into bivalves and other invertebrates. • D-CAE-PLGA NPs show synthesis yields of 91 % and encapsulation efficiencies of 70 %. • About 73.5 % of the peptide is released from loaded NPs after 40 h. • D-CAE-PLGA NPs exhibit bactericidal activity against two aquaculture pathogens. • D-CAE is effectively delivered into clam's larvae from PLGA NPs without toxicity. • Nanoencapsulation improves AMP stability and bioavailability for aquaculture.