Lactose-Modified Chitosan Gold(III)-PEGylated Complex-Bioconjugates: From Synthesis to Interaction with Targeted Galectin-1 Protein

Galectins (Gal) are a family of glycan-binding proteins characterized by their affinity for beta-galactosides. Galectin-1 (Gal-1), a dimeric lectin with two galactoside-binding sites, regulates cancer progression and immune responses. Coordination chemistry has been engaged to develop versatile multivalent neo-glycoconjugates for binding Gal-1. In this study we report a fast and original method to synthesize hybrid gold nanoparticles in which a hydrochloride lactose-modified chitosan, named CTL, is mixed with dicarboxylic acid-terminated polyethylene glycol (PEG), leading to shell-like hybrid polymer-sugar-metal nanoparticles (CTL-PEG-AuNPs). The aim of this paper is to preliminarily study the interaction of the CTL-PEG-AuNPs with a target protein, namely, Gal-1, under specific conditions. The molecular interaction has been measured by Transmission Electron Microscopy (TEM), UV-vis, and Raman Spectroscopy on a large range of Gal-1 concentrations (from 0 to 10(-12) M). We observed that the interaction was strongly dependent on the Gal-1 concentration at the surface of the gold nanoparticles.