Surface\nFunctionalization\nof Gold Nanoparticles Using\nAlkyne Derivatives: Applications in Chemical Sensing

Colloidal gold nanoparticles\n(AuNPs) are important nanomaterials\nfor chemical sensing and therapeutics. For their application, it is\nvital to develop a reliable and robust surface functionalization method\nthat can be applied to diverse functional molecules and offer better\nstability under harsh biological conditions. Currently, thiol (SH)\nis the most commonly used functional group for forming stable covalent\nbonds with AuNPs. However, thiolated molecules typically require complicated\npreparation procedures, are susceptible to oxidation, and are not\ncompatible with many electrophiles and reducing groups. In this study,\nwe report that surface functionalization of AuNPs can be achieved\nusing alkyne derivatives, which exhibit several advantages over classical\nthiolation and peptide-bond methods, including straightforward preparation\nof alkyne derivatives, rapid and simple conjugation in buffers and\ncomplex media, higher conjugation efficiency, long-term stability,\nand resistance to decomposition under harsh conditions. Several alkynylated\nbiotin and fluorescein derivatives are prepared, and the alkynylated-AuNPs\nare characterized using a lateral flow assay, gel electrophoresis,\nand spectroscopy techniques to investigate the conjugation efficiencies,\nsize distributions, protein interaction properties, and binding mode\nof the Au–alkyne bond. We also demonstrate that alkynylated-AuNPs\ncan be used for the sensitive detection of hydrogen peroxide and streptavidin\nproteins.