Silver nanoparticles functionalized with a fluorescent cyclic RGD peptide: a versatile integrin targeting platform for cells and bacteria

Abstract

The arginine–glycine–aspartic acid (RGD) peptide sequence is known to specifically interact with integrins, which are chief receptors participating at various stages of cancer disease and in bacterial adhesion/invasion processes. In particular, vitronectin receptor (α_vβ₃) and fibronectin receptor (α₅β₁) integrins are involved respectively in tumour cell targeting and bacteria internalization inhibition. Silver nanoparticles (AgNPs) have elicited a lot of interest as a theranostic platform, owing to their unique optoelectronic as well as self-therapeutic properties as bactericides. The goal of this work was the comprehensive physicochemical characterization of a hybrid peptide–metal nanoparticle biointerface fabricated by the immobilisation, through thiol chemistry, of a fluorescent cyclic RGD peptide onto AgNPs of 13 nm diameter. RGD peptide-functionalized AgNPs were investigated by a multi-technique approach, including various spectroscopic (XPS, FTIR and UV-visible), spectrometric (ToF-SIMS) and microscopic (SEM, TEM, AFM) methods as well as dynamic light scattering and ζ-potential measurements. Proof-of-work experiments by confocal microscopy imaging of the cellular uptake by human neuroblastoma SH-SY5Y and chronic myelogenous leukaemia K562 cells, overexpressing respectively α_vβ₃ and α₅β₁ integrins, demonstrated a receptor-specific activity of the RGD peptide-functionalised AgNPs, which make them very promising as a multifaceted platform in applications with cells and bacteria.