Label-free plasmonic nanostar probes to illuminate in vitro membrane receptor recognition

• Published in: Chemical science (Cambridge) Vol. 10; no. 6; pp. 1807 - 1815
• Main Authors: Sloan-Dennison, Sian, Schultz, Zachary D
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 14.02.2019
• Subjects: Amino acids; Binding sites; Chemical activity; Chemical synthesis; Colon; Electromagnetic fields; Gold; Kinases; Ligands; Optical properties; Organic chemistry; Proteins; Raman spectra; Receptors; Recognition
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/c8sc05035j

Protein-ligand recognition is a key activity where chemical signals are communicated to cells to activate various biochemical pathways, which are important for understanding membrane signaling and drug interactions. Gold nanostars are highly attractive for biological applications due to their readily modified surface chemistry, facile synthesis and optical properties. The increase in electromagnetic field at their branches increases the surface enhanced Raman scattering (SERS) making them ideal candidates as label free probes that can be used to detect a variety of cellular activities. However, the use of particles is complicated by the adsorption of proteins, which forms the protein corona. In this paper we demonstrate gold nanostars as label free probes to study the interaction between α β integrin and RGD. Nanostars functionalized with cyclic-RDGFC reduced the formation of the protein corona, due to its zwitterionic nature, indicating a small peptide approach to minimizing protein absorption. Additionally, the functionalized nanostars evince a SERS response from their interaction with α β integrin representative of the amino acids present at the binding site which is also retained in a complex biological matrix. The nanostars were used to selectively detect α β integrin on the membrane of human metastatic colon cancer cells. By exploiting the intense SERS and tunable plasmon resonance properties of gold nanostars functionalized with cyclic RGDFC, we have demonstrated a label free approach to investigate the chemical interactions associated with protein-ligand binding from both purified proteins and membrane bound receptors in cells.