Computational Study of Cyclic Peptide-Modified Gold Nanoclusters for Enhanced Tumor-Targeted Bioimaging

High Resolution Image Download MS PowerPoint Slide Cyclic arginine–glycine–aspartic acid (RGD) peptides, known for their high affinity for integrins, a protein receptor found on cancer cell membranes, have emerged as promising candidates for the development of theranostic agents. Thus, surface modification of these peptides onto gold nanocluster (AuNC) surfaces can direct them to the targeted tumor. In the present study, we investigate the impact of cyclic peptide modification on the optical and electronic properties of AuNCs, which have potential applications in tumor-targeted bioimaging. Using time-dependent density functional theory (TD-DFT) and replica exchange molecular dynamics (REMD) simulations, we investigated how cyclic peptides such as c (RGDyC), c (RADyC), and c (isoDGRFC) influence the electronic structure and optical behavior of Au 23 (SH) 14 nanoclusters. AuNCs modified with these peptides showed significant changes in bond lengths, frontier molecular orbitals, and energy band gaps, resulting in red-shifted absorption spectra and suggesting potential for enhanced photoluminescence. Interfragment charge transfer (IFCT) calculations revealed that enhanced electron delocalization and ligand-to-metal charge transfer (LMCT) between peptides, particularly in c (isoDGRFC), and the Au core, imply that peptide modification can effectively tune the optical properties of AuNCs. This study demonstrates the potential of c (isoDGRFC)-modified AuNCs as effective bioimaging agents, particularly for targeting integrin-overexpressing tumors, which could provide better imaging contrast.