Metal Nanoclusters as Biomaterials for Bioapplications: Atomic Precision as the Next Goal

Abstract

Noble metal nanoclusters (NCs) have emerged as a new class of nanomaterials which have great potential in bioapplications. Due to their ultrasmall size and versatile surface chemistry, they show excellent luminescence, high photostability, good biocompatibility, low toxicity, and a high renal clearance rate. In recent years, much work has been reported toward the bioapplications of metal NCs, especially the Au, Ag, and Cu NCs. In this Review, we first discuss the crucial factors of metal NCs for their use as biomaterials, including the size, surface chemistry, photoluminescent properties, cytotoxicity, and metabolic activity. Then, we highlight some recent advances of metal NCs in bioapplications, such as biosensing, bioimaging, biomedical diagnosis, and therapy. It is noteworthy that the metal NCs perform quite well in cancer treatment. Finally, we have briefly discussed the current challenges and our perspectives on metal NCs in bioapplication research and further transformation into clinical application.

Advances of gold nanoclusters for bioimaging

“…They suggested that AuNCs when endocytosed by cells, may interact with cell membranes and thus trigger apoptosis or necrosis of cells. As the particle size decreased, its specific surface area increased, and it was more bioactive, putting it at increased risk of toxicity ( Schrand et al., 2010 ; Yang et al., 2022 ). This size dependence is also observed in silver thiolated nanoparticles ( Yang et al., 2016 ).…”

Phosphinous Acid–Phosphinito Tetra-Icosahedral Au52 Nanoclusters for Electrocatalytic Oxygen Reduction

“…Ligand-protected gold nanoclusters have been extensively exploited in recent decades, − since their unique geometric structures and molecule-like features are vital for the advancement of many impactful research fields, including bio-labeling, , chemical sensing, , and catalysis. − Among many synthetic strategies currently used to prepare gold nanoclusters, protecting ligands play critical roles in the nanocluster formation, especially when it comes to constructing their kernel structures . While thiolate ligands are widely employed in the synthesis of gold nanoclusters containing single Au 13 icosahedral, , face-centered cubic (fcc), − body-centered cubic (bcc), , or hexagonal close-packed (hcp) − kernels, the combination of phosphine and thiolate/selenolate ligands is typically required for assemblies of icosahedral Au 13 building blocks into multiunit superstructures, often referred to as “clusters of clusters”. − For instance, bi-icosahedral Au 25 and tri-icosahedral Au 37 nanoclusters in a rod shape have been successfully prepared through the use of triphenylphosphine and aliphatic thiolates.…”

“…Ligand-protected gold nanoclusters have been extensively exploited in recent decades, 1 − 5 since their unique geometric structures and molecule-like features are vital for the advancement of many impactful research fields, including bio-labeling, 6 , 7 chemical sensing, 8 , 9 and catalysis. 10 − 13 Among many synthetic strategies currently used to prepare gold nanoclusters, protecting ligands play critical roles in the nanocluster formation, especially when it comes to constructing their kernel structures.…”

An Overview on Coinage Metal Nanocluster-Based Luminescent Biosensors via Etching Chemistry

“…The size of metal NCs is generally less than 3 nm, which is close to the electron Fermi wavelength [ 1 , 2 , 3 ]. Metal NCs therefore exhibit some unique physicochemical properties different from other nanomaterials, such as luminescence, chirality, magnetic, and catalytic properties [ 4 , 5 , 6 , 7 ]. Among them, the luminescence of metal NCs is not only adjustable, but also has the characteristics of large Stokes shift, long luminescence lifetime, and good stability [ 8 , 9 ].…”