One-pot functionalization of carbon dots with ecPis-4s antimicrobial peptide

Abstract

The synthesis of nanobiostructures (CD@ecPis-4s) composed of carbon dots (CD) covalently bound to the antimicrobial peptide ecPis-4s is reported. Nanoparticle functionalization was achieved by pre-activating the oxygenated functional groups using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDAC) and ethyl (hydroxyimino)cyanoacetate in an aqueous medium. The obtained nanobiostructures were characterized by several techniques, including FTIR and 1H NMR spectroscopies. The functionalization does not compromise the optical properties of CD. The polypeptide moiety of the peptide-decorated nanoparticles retains the active α-helical conformation and lytic activity in the presence of anionic phospholipid vesicles as observed in the circular dichroism and calcein release experiments. Consequently, the CD@ecPis-4s nanobiostructures present similar activity against Gram-positive (S. aureus and S. agalactiae) and Gram-negative (E. coli and P. aeruginosa) bacteria strains when compared to the free peptide. To our knowledge, this is the first report on carbon dots containing a covalently bound antimicrobial peptide. Thereby, in an era of increasing antimicrobial resistance, the synthesis and investigations performed in this work led to materials with potential for monitoring, in loco, bacterial contamination via exposure to UV radiation.