Ultrasmall noble metal nanoparticles: Breakthroughs and biomedical implications

Abstract

As a bridge between individual atoms and large plasmonic nanoparticles, ultrasmall (core size <3 nm) noble metal nanoparticles (UNMNPs) have been serving as model for us to fundamentally understand many unique properties of noble metals that can only be observed at an extremely small size scale. With decades’efforts, many significant breakthroughs in the synthesis, characterization and functionalization of UNMNPs have laid down a solid foundation for their future applications in the healthcare. In this review, we aim to tightly correlate these breakthroughs with their biomedical applications and illustrate how to utilize these breakthroughs to address long-standing challenges in the clinical translation of nanomedicines. In the end, we offer our perspective on the remaining challenges and opportunities at the frontier of biomedical-related UNMNPs research.

Photo/electrocatalysis and photosensitization using metal nanoclusters for green energy and medical applications

“…A number of recent reviews on other biomedical applications of metal NCs have also been published. [15][16][17]…”

“…Recent synthetic innovations have allowed the fabrication of atomically precise metal nanoclusters (NCs). [8][9][10][11][12][13][14][15][16][17][18] These metal NCs contain a few to hundreds of metal atoms that are protected by organic ligands (e.g., thiolate, phosphine, small molecules, synthetic polymers, and biomolecules). Particularly, thiolate-protected metal NCs and their alloy NCs can be prepared with atomic precision as M n (SR) m (M ¼ gold (Au), silver (Ag), cupper (Cu), platinum (Pt), palladium (Pd), or other element; SR ¼ thiolate ligand) in a wide range of sizes by varying the n and m values.…”

“…By adjusting n and m, one can control the discrete electronic/ geometrical structure of M n (SR) m NCs and thereby their photosensitizing and photo/electrocatalytic capability. Recently, several excellent reviews have discussed the syntheses of metal NCs, 13 photoluminescence, 14 and their biomedical [15][16][17] and catalytic applications. 18 However, to the best of our knowledge, there are no publications focusing on the photo/electrocatalytic and photosensitizing characteristics of metal NCs for applications in the green energy and medical elds.…”

Ethylene glycol coated nanoceria protects against oxidative stress in human lens epithelium

“…53 It is noteworthy that the positive charges on the surface of nanomaterials promote cellular adhesion and penetration owing to the ionic interactions with negatively charged cell surfaces and hence their cytotoxicity is generally expected to be more pronounced compared to negatively charged nanomaterials. 54,55 It is possible that the adsorption of negatively charge coronae on the surface of EGCNPs reduced their toxicity by mitigating cell membrane damage normally associated with positive charged nanoparticles. 56 Fig.…”

Recent Advances in the Synthesis, Properties, and Biological Applications of Platinum Nanoclusters

“…Its physical and chemical properties appear to be entirely change as the size of metal continuously decreases into nanoscale because of the quantum size effect, surface effect, small size effect, and macroquantum tunnel effect [4]. For example, noble metal nanoparticles (M NPs) which are defined as the particle size ranged from 1 to 100 nm have the high surface-to-volume ratio and electrodynamic interaction, leading to emerge distinct electronic, magnetic, and optical properties in contrast to bulk counterparts or individual atoms [5,6]. In view of freely moving deloca-lized electrons in the conduction band, metals in a bulk state are good optical reflectors and electrically conducting (Figure 1).…”