Yongdong Jin

We report a direct one-pot approach, employing tetrakis(hydroxymethyl)phosphonium chloride (THPC) and 11-mercaptoundecanoic acid (11-MUA) as combined reducing/capping agents, for the rapid preparation of fluorescent gold nanoclusters (AuNCs) from HAuCl₄ in aqueous solution at room temperature. The as-prepared AuNCs exhibit a fluorescence emission at 535 nm, a quantum yield of 1.8% and average diameters of 2.0 ± 0.5 nm. The resultant MUA/THPC–AuNCs have been exploited, for the first time, for the highly sensitive and selective detection of silver ions (Ag⁺) in aqueous solution when using EDTA as a masking agent for Hg²⁺. The fluorescence intensity quenches linearly within the range of 25 nM to 3 μM with high sensitivity (LOD = 9 nM, S/N = 3) and this sensing system has been applied for environmental water sample analysis.

We report a one-pot approach to prepare fluorescent gold nanoclusters (AuNCs) from HAuCl₄ by simply using 11-mercaptoundecanoic acid (11-MUA) as a reducing and capping agent, in an aqueous solution of NaOH at room temperature. The as-prepared water-soluble AuNCs with average diameters of 1.8 ± 0.4 nm exhibit a unique fluorescence excitation at 285 nm, a maximum emission at 608 nm, and a quantum yield of 2.4%. We find that the fluorescence of 11-MUA-AuNCs can be quenched by several metal ions but selectively by Cr³⁺ ions when using EDTA as the masking agents for other metal ions. This phenomenon is further exploited as a “turn-off” fluorescent sensor for sensitive and selective detection of Cr³⁺ ions. Upon the quantitative addition of Cr³⁺ in the presence of EDTA, the fluorescence intensity quenches linearly within the range of 25 nM to 10 μM with high sensitivity (LOD = 26 nM, S/N = 3). Furthermore, the 11-MUA-AuNCs could be used to detect Cr⁶⁺ indirectly by using ascorbic acid to reduce Cr⁶⁺ into Cr³⁺ in aqueous solution.

The plasmon band of Ag nanoplates can be continuously tuned over the visible region by simply stirring with graphene oxide (GO) nanosheets, accompanied with the shape transformation from triangle to round. The ability of GO to competitively adsorb ligands (from Ag nanoplates) has been considered to response for this interesting change. Through the protection of sufficient citrate ions, the resultant Ag nanoplates exhibit the excellent stability over a long time without noticeable change of their optical properties.

The fields of biosensing and nanomedicine have recently witnessed an explosion of interest and progress in the design and study of plasmonic Au nanostructures (p‐AuNSs) or metamaterials geared towards a broad range of biological and biomedical applications. Due to their tunable and versatile plasmonic properties, such artificially engineered p‐AuNSs and materials have the potential to push biosensor sensitivity towards the single‐molecule detection limit, enabling new bioimaging modalities and new analytical techniques and tools capable of single‐molecule detection, analysis and manipulation, and to revolutionize the diagnosis and treatment of many diseases, including cancers. This report summarizes and highlights recent major advances in the emerging field of bioapplication‐oriented engineering of p‐AuNSs and hybrids, focusing on design considerations and ways to carry them out. A brief overview of the optical properties of p‐AuNSs is introduced, and then the importance of plasmonic engineering and future promising research directions and challenges in the field are discussed.

Enzyme works for plasmonic nanostructure: an interesting enzyme-responsive hybrid Ag/Au-GOx bimetallic nanoshell (NS) system is reported, in which control over the enzyme reaction of glucose oxidase (GOx) can automatically fine-tune the morphology (from complete NS to porous NS) and optical properties of the hybrid nanostructure. The phenomenon is further exploited as a new platform for sensitive optical glucose sensing.

Macroscopic free-standing Pd and Pd/Pt bimetallic monolayer nanomembranes (Pd- and Pd/Pt-FNMs) derived from the spontaneous self-assembly of the as-produced Pd NPs and Pd/Pt bimetallic NPs at the water–air interface within 15 min are fabricated, respectively. The one-step method allows the growth of high-quality Pd-based FNMs with well-defined monolayer morphology, which exhibit significantly higher electrocatalytic activity for methanol/ethanol oxidation than commercial catalysts.

This paper describes a simple and facile method for the synthesis of Ag/Au bimetallic hollow and porous nanoshells (HPNSs) with controllable porosity, using polycrystalline Ag nanoparticles as starting templates. The optical and catalytic properties of the HPNSs can be easily tuned by using hydrogen peroxide as a mild etchant to controllably dissolve Ag atoms from the precursor Ag/Au bimetallic hollow nanoshells (NSs). The surface plasmon bands of the HPNSs can be easily tuned from the visible to the near infrared (NIR) region. As a model reaction to evaluate the catalytic activity of the HPNSs, we chose the reduction of p-nitrophenol by NaBH4 to afford p-aminophenol. The porous NSs exhibit higher catalytic activity than non-porous NSs even though the latter have higher Au/Ag ratios than the former. Although the composition (Au/Ag ratio) may have some effect, the morphology (porosity) of the HPNSs plays the most important role in the catalysis. The as-synthesized plasmonic HPNSs, due to their facile aqueous-phase preparation, tunable optical properties (in the visible and NIR windows), and unique porous hollow structures, have promising potential applications in various fields ranging from biosensing, nanomedicine (drug/gene delivery, cancer theranostics, etc.), to catalysis and solar cells.