Shuangfei Cai

PtCo bimetallic nanoparticles with high oxidase-like catalytic activity and their applications for magnetic-enhanced colorimetric biosensing

A novel magnetic-enhanced colorimetric assay was constructed based on aptamer conjugated PtCo bimetallic nanoparticles (NPs) with high oxidase-like catalytic activity, high water solubility, low cell toxicity, and superparamagnetic properties. It was found that the incorporation of magnetic metal Co atoms into NPs could not only be facilitated for magnetic separation, but also resulted in the significantly improved oxidase-like catalytic activity of the nanoparticles for cancer-cell detection without the destructive H2O2. The present work demonstrates a general strategy for the design of multifunctional materials based on bimetallic nanoparticles for different applications, such as biosensors, nanocatalysts and nanomedicine.

Porous Pt/Ag nanoparticles with excellent multifunctional enzyme mimic activities and antibacterial effects

Enhancing the activity of Pt-based nanocatalysts is of great significance yet a challenge for the oxygen reduction reaction (ORR). In this work, a series of porous Pt/Ag nanoparticles (NPs) were fabricated from regular PtxAg100–x (x = 25, 50, 75) octahedra by a facile and economical dealloying process. Remarkable enhancement in multiple enzyme-mimic activities related to ORR was observed for the dealloyed Pt50Ag50 (D-Pt50Ag50) NPs. This effect can be attributed to the resulting Pt-rich surface structure, increased surface area, and a synergistic effect of Pt and Ag atoms in the D-Pt50Ag50 NPs. Furthermore, the D-Pt50Ag50 NPs exerted excellent antibacterial effects on two model bacteria (gram-negative Escherichia coli and gram-positive Staphylococcus aureus). The present work represents a significant advance in the exploration of the relation between controllable synthesis of high-quality nanoalloys and their novel catalytic properties for various promising applications, including catalysts, biosensors, and biomedicine.

Cell-Capture and Release Platform Based on Peptide-Aptamer-Modified Nanowires

Nanowires have attracted much attention due to their potential bioapplications, such as delivery of drugs or sensing devices. Here we report the development of a unique cell-capture and release platform based on nanowires. The combination of nanowires, surface-binding peptides, and cell-targeting aptamers leads to specific and efficient capture of cancer cells. Moreover, the binding processes are reversible, which is not only useful for downstream analysis but also for reusability of the substrate. Our work provides a new method in the design of the cell-capture and release platform, which may open up new opportunities of developing cell-separation and diagnosis systems based on cell-capture techniques.

Molybdenum Disulfide Nanoparticles as Multifunctional Inhibitors against Alzheimer’s Disease

The complex pathogenic mechanisms of Alzheimers disease (AD) include the aggregation of β-amyloid peptides (Aβ) into oligomers or fibrils as well as Aβ-mediated oxidative stress, which require comprehensive treatment. Therefore, the inhibition of Aβ aggregation and free-radical scavenging are essential for the treatment of AD. Nanoparticles (NPs) have been found to influence Aβ aggregation process in vitro. Herein, we report the inhibition effects of molybdenum disulfide (MoS2) NPs on Aβ aggregation. Polyvinylpyrrolidone-functionalized MoS2 NPs were fabricated by a pulsed laser ablation method. We find that MoS2 NPs exhibit multifunctional effects on Aβ peptides: inhibiting Aβ aggregation, destabilizing Aβ fibrils, alleviating Aβ-induced oxidative stress, as well as Aβ-mediated cell toxicity. Moreover, we show that MoS2 NPs can block the formation of the Ca2+ channel induced by Aβ fibrils in the cell membrane for the first time. Thus, these observations suggest that MoS2 NPs have great potential for a multifunctional therapeutic agent against amyloid-related diseases.

Single-layer Rh nanosheets with ultrahigh peroxidase-like activity for colorimetric biosensing

When the dimensionality of layered compounds decreases to the physical limit, ultimate two-dimensional (2D) anisotropy and/or quantum confinement effects may lead to extraordinary physicochemical attributes. Here, we report single-layer Rh nanosheets (NSs) exhibiting ultrahigh peroxidase-like activity, far exceeding that of horseradish peroxidase (HRP) and of most known layered nanomaterial-based peroxidase mimics. Considering per NS as an active subunit, the Rh NSs displayed a catalytic rate constant (Kcat) as high as 4.45 × 105 s–1 to H2O2, two orders of magnitude higher than those of HRP and Rh nanoparticles. The high atom efficiency of the Rh NSs can be attributed to the full exposure of surface-active Rh atoms, which greatly facilitates electron transfer and formation of superoxide anions, representing reactive oxygen species in the catalytic process. As a proof-of-concept application, the Rh NSs were successfully used as peroxidase mimics for the colorimetric detection of H2O2 and xanthine, with high sensitivity and selectivity. Moreover, a simple, rapid, and sensitive Rh-based paper sensor for ascorbic acid was also developed. In summary, this work provides a novel example of single-layer metallic NSs for biosensing.

A novel strategy to construct supported Pd nanocomposites with synergistically enhanced catalytic performances

We report a facile protocol for the one-pot preparation of monodisperse Pd nanoparticles (NPs) supported on ultrathin NiCl2 nanosheets (NSs). The effective protocol can be described as in situ reduction–oxidation–assembly to create Pd/NiCl2 nanocomposites and is applicable for the development of stable yet highly active Pd-based heterogeneous catalysts for organic transformations. The Pd/NiCl2 composite displayed synergistically enhanced catalytic activity, high stability, and good recyclability for the tested model oxidation reaction. The in situ nucleation and growth of NiCl2 NS around Pd NPs guaranteed a clean metal–support interface and greatly facilitated the catalytic reaction. This work provides a novel synthesis method for supported Pd nanocomposites suitable for many important applications.

Quercetin nanoparticles with enhanced bioavailability as multifunctional agents toward amyloid induced neurotoxicity

Quercetin (Que), as one of the most potent flavonoids, has gained appreciable attention in anti-fibrosis, anti-oxidation and other therapeutic research due to its numerous pharmacological and biological functions. However, low aqueous solubility, poor permeability and instability in physiological media have limited its widespread application in the pharmaceutical field. Herein, a facile method for fabrication of Que nanoparticles (NPs) has been developed by pulsed laser ablation (PLA). Que NPs exhibited homogeneous morphology with an average diameter of 50 nm and narrow distributions, which revealed enhanced solubility and drug release activity. Owing to the advance of NPs in modulating the amyloid fibrillation process as well as the anti-oxidative ability, Que NPs were applied to regulate Aβ42 assembly and they showed multifunctional effects: inhibiting Aβ aggregation, destabilizing Aβ fibrils, decreasing Aβ-induced oxidative stress and Aβ-mediated cytotoxicity. Thus, Que NPs with enhanced bioavailability may act as a multifunctional therapeutic agent toward amyloid-related diseases.