Gold nanomaterials have widespread applications across multiple areas of science and technology. Sulfur-containing ligands (thiols and thioethers) have been traditionally used as ligands to protect and functionalize these materials. N-Heterocyclic carbenes (NHCs) have recently emerged as organic alternatives to thiols in stabilizing gold nanoparticles (AuNPs) and flat surfaces. In fact, gold-containing materials decorated with NHCs have been shown to withstand a variety of harsh conditions. However, such materials still suffer from limited stability in the presence of thiols, such as the biologically relevant glutathione, in aqueous media. Here, we report the synthesis and application of polymeric mesoionic NHC–Au­(I) complexes as precursors to polyNHC-stabilized AuNPs. Using copper-catalyzed alkyne–azide cycloaddition polymerization of diazide- and dialkyne-containing monomers, we directly install 1,2,3-triazole groups, as precursors to mesoionic carbenes, on the backbone of the resulting polymers. This effectively eliminates the need to presynthesize NHC–Au­(I)-containing monomers to access this class of polymers. Using these polymers as the substrate, the resulting robust AuNPs, protected by a catenated network of NHCs, demonstrate exceptional stabilities in aqueous media under various conditions, particularly against high concentrations of glutathione (up to 6 mM) for extended periods of time (up to 10 days). Moreover, the use of the macromolecular substrate, compared to small NHC–Au complexes used thus far yielding relatively small AuNPs (∼5 nm), results in the formation of larger AuNPs (∼12 nm). Such enhanced stabilities in aqueous media together with their larger diameters make these materials promising for potential applications in nanomedicine. To highlight their multifunctionality, we also demonstrate their catalytic activity in the reduction of 4-nitrophenol.

N-heterocyclic carbenes (NHCs) have recently emerged as viable alternatives to commonly used thiols to stabilize a variety of metal surfaces and nanoparticles. In this context, thanks to their biocompatibility and...

Polymeric nanomaterials that degrade in acidic environments have gained considerable attention in nanomedicine for intracellular drug delivery and cancer therapy. Among various acid-degradable linkages, spirocyclic acetals have rarely been used to fabricate such vehicles. In addition to acid sensitivity, they benefit from conformational rigidity that is otherwise not attainable by their non-spirocyclic analogs. Herein, amphiphilic spirocyclic polyacetals are synthesized by Cu-catalyzed alkyne–azide “click” polymerization. Unlike conventional block copolymers, which often form core–shell structures, these polymers self-assemble to form core amphiphilic assemblies capable of encapsulating Nile red as a hydrophobic model drug. In vitro experiments show that while release from these materials can occur at neutral pH with preservation of their integrity, acidic pH accelerates efficient cargo release and leads to the complete degradation of assemblies. Moreover, cellular assays reveal that these materials are fully cytocompatible, interact with the plasma membrane, and can be internalized by cells, rendering them as potential candidates for cancer therapy and/or drug delivery.

Tetraphenylethylene-functionalized amphiphilic Janus dendrimers of up to third generation are synthesized. Their self-assembly has been studied under kinetic and thermodynamic control. By varying the dendrimer generation number and the self-assembly...

Gold nanoparticles (AuNPs) have found use in broad range of applications such as in catalysis and nanomedicine. Despite the fact that thiol-based AuNPs have been widely studied, they suffer from relative instability in various conditions, such as high and low temperatures, pH variations, and are prone to oxidation. Over the last decade, N-heterocyclic carbenes (NHCs) have been under spotlight as suitable ligands to stabilize metal nanoparticles and surfaces. Although NHC-functionalized AuNPs have been shown to outperform their thiol-based analogs in terms of stability, their applications in nanomedicine have not been realized. Hybrid nanomaterials, such as AuNPs tagged with π-conjugated molecules with aggregation-induced emission (AIE) property, are promising candidates to develop fluorescent materials for cellular imaging. The combination of NHC-stabilized AuNPs with AIE to form stable, fluorescent hybrid AuNPs is of significant interest to open the door to develop new NHC-based nanomaterials. Herein, we report the synthesis and characterization of water-soluble fluorescent NHC-decorated AuNPs for potential applications in nanomedicine. Their stability in biologically relevant conditions is investigated.