Higher-Order Assembly of Protein Protected Gold Nanoclusters using Supramolecular Host-Guest Chemistry: A 40% Absolute Fluorescence Quantum Yield

Abstract

For the last few decades, cancer has been one of the major public health concerns, and the mortality rate has become significant worldwide. However, because of the blessing of science, the early detection of tumors and the survival rate of patients have improved extra 5-years. Therefore, early-stage cancer detection and identification are critical in cancer treatment. Although priority must be given to providing the treatment option, simultaneously, it is also important to design new and improve the existing methods, which are the noble job for the scientist. Recently, gold nanoclusters (Au NCs) have emerged as a promising detection approach in biomedical imaging as it exhibits molecular like properties and good photostability. Metal nanoclusters are a unique class of ultra-small particles consisting of a few to hundreds of atoms. They feature a metal core of size ˂2 nm, which is formed due to controlled aggregation. And because of the confinement of the electrons, it exhibits optoelectronic properties such as fluorescence. In this era, scientists have reported small molecules protected gold nanoclusters, but due to lack of biocompatibility and low quantum yield, it suffers from real applications such as cell imaging etc. So, designing a biocompatible highly fluorescent gold nanocluster is a challenging task to material and synthetic chemistry. Recently, Ying et al. reported protein-protected gold nanoclusters of BSA protein, which exhibit a low quantum yield (QY~6%). To address this problem, Maity et al. have reported a highly fluorescent higher-order assembly of protein-protected gold nanoclusters using supramolecular host-guest chemistry, which exhibits 40% absolute quantum yield. Towards the end, we observed a reversible aggregation-disaggregation in the presence of cucurbit[7]uril (CB7) and adamantly amine (ADA), respectively, which is important from the fundamental point of view, where in general, protein aggregation is irreversible in nature. References: 1. Wan et al. Analyst 2020, 145, 348 2. Pradeep et al. J. Phys. Chem. C 2019, 123, 28969 3. Ying et al. J. Am. Chem. Soc. 2009, 131, 888 4. Maity et al. Nanoscale Adv. 2022, DOI: 10.1039/D2NA00123C