Structural analysis by quenching fluorescence of nanosized bio-conjugates of alginate and Ib-M6 antimicrobial peptide

BRIAN SALVATTI; BARJA, BEATRIZ C; MERCEDES PERULLINI; FLÓREZ-CASTILLO JOHANA; SANTAGAPITTA PATRICIO

Rosario

Congreso; VI Reunión de Fotobiólogos Moleculares Argentinos VI GRAFOB 2022; 2022

Resistance to traditional antibiotics is one of the greatest challenges in public health worldwide, generating the urgent need for the development of efficient antibacterial compounds[1]. In this scenario, both their broad spectrum (against gram-negative and gram-positive bacteria, as well as antifungal and antiviral activity)[2-4] and their multiple mechanism of action [5-6] are positioning antimicrobial peptides (AMPs) at the forefront of alternative antibacterial research. In a previous work, we reported an analog of Ib-AMP4 antimicrobial peptide named Ib-M6 (sequence EWGRRMMGWGRGRRMMRRWW-NH2). This peptide is characterized by having a high positive charge (+6) due to arginine (R) residues and high hydrophobicity by tryptophane (W) residues, with antibacterial activity against Escherichia coli K-12 (IC50 = 1 μM). Although AMPs have an important activity in vitro, their properties exhibit a significant decrease in vivo due to factors such as degradation by proteases. For this reason, nanosized alginate-based particles have been obtained in a one-pot solvent-free synthesis procedure, achieving the design of a biocompatible nanocarrier for Ib-M6 antimicrobial peptide (IbM6-AMP). We demonstrate that the entrapment of IbM6-AMP in alginate nanogels hinders the degradation of the peptide by trypsin, increasing its antimicrobial activity against E. coli. The supramolecular structure of the nanocarriers was characterized by Small Angle X-ray Scattering and the accessibility of the encapsulated IbM6-AMP was assessed by fluorimetric analysis by the deactivation of the emission of the tryptophan residues mediated by two different quenchers (acrylamide and iodine