A novel and sensitive flow injection chemiluminescence assay for sequence-specific DNA detection based on signal amplification with nanoparticles (NPs) is reported in the present work. The "sandwich-type" DNA biosensor was fabricated with the thiol-functionalized capture DNA first immobilized on an Au electrode and hybridized with one end of target DNA, the other end of which was recognized with a signal DNA probe labeled with CuS NPs and Au NPs on the 3'- and 5'-terminus, respectively. The hybridization events were monitored by the CL intensity of luminol-H2O2-Cu(2+) after the cupric ions were dissolved from the hybrids. We demonstrated that the incorporation of Au NPs in this sensor design significantly enhanced the sensitivity and the selectivity because a single Au NP can be loaded with hundreds of signal DNA probe strands, which were modified with CuS NPs. The ratios of Au NPs, signal DNA probes, and CuS NPs modified on the gold electrode were approximately 1/101/103. A preconcentration process of cupric ions performed by anodic stripping voltammetry technology further increased the sensor performance. As a result of these two combined effects, this DNA sensor could detect as low as femtomolar target DNA and exhibited excellent selectivity against two-base mismatched DNA. Under the optimum conditions, the CL intensity was increased with the increase of the concentration of target DNA in the range of 2.0 x 10(-14)-2.0 x 10(-12) M. A detection limit of 4.8 x 10(-15) M target DNA was achieved.

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Highly sensitive and efficient biosensors play a crucial role in clinical, environmental, industrial, and agricultural applications, and tremendous efforts have been dedicated to advanced electrode materials with superior electrochemical activities and low cost. Here, we report a three-dimensional binder-free Cu foam-supported Cu2O nanothorn array electrode developed via facile electrochemistry. The nanothorns growing in situ along the specific direction of <011> have single crystalline features and a mesoporous surface. When being used as a potential biosensor for nonenzyme glucose detection, the hybrid electrode exhibits multistage linear detection ranges with ultrahigh sensitivities (maximum of 97.9 mA mM(-1) cm(-2)) and an ultralow detection limit of 5 nM. Furthermore, the electrode presents outstanding selectivity and stability toward glucose detection. The distinguished performances endow this novel electrode with powerful reliability for analyzing human serum samples. These unprecedented sensing characteristics could be ascribed to the synergistic action of superior electrochemical catalytic activity of nanothorn arrays with dramatically enhanced surface area and intimate contact between the active material (Cu2O) and current collector (Cu foam), concurrently supplying good conductivity for electron/ion transport during glucose biosensing. Significantly, our findings could guide the fabrication of new metal oxide nanostructures with well-organized morphologies and unique properties as well as low materials cost.

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The class III phosphoinositide 3-kinase (PI3K) Vps34 (also known as PIK3C3 in mammals) produces phosphatidylinositol 3-phosphate [PI (3)P] on both early and late endosome membranes to control membrane dynamics. We used Vps34-deficient cells to delineate whether Vps34 has additional roles in endocytic trafficking. In Vps34 −/− mouse embryonic fibroblasts (MEFs), transferrin recycling and EEA1 membrane localization were unaffected despite elevated Rab5-GTP levels. Strikingly, a large increase in Rab7-GTP levels, an accumulation of enlarged late endosomes, and decreased EGFR degradation were observed in Vps34-deficient cells. The hyperactivation of Rab7 in Vps34-deficient cells stemmed from the failure to recruit the Rab7 GTPase-activating protein (GAP) Armus (also known as TBC1D2), which binds to PI(3)P, to late endosomes. Protein-lipid overlay and liposome-binding assays reveal that the putative pleckstrin homology (PH) domain in Armus can directly bind to PI(3)P. Elevated Rab7-GTP led to the failure of intraluminal vesicle (ILV) formation and lysosomal maturation. Rab7 silencing and Armus overexpression alleviated the vacuolization seen in Vps34-deficient cells. Taken together, these results demonstrate that Vps34 has a previously unknown role in regulating Rab7 activity and late endosomal trafficking.

A finely dispersed CuO nanoparticle electrocatalyst on a silicon nanowire (SiNW) was achieved via a designed, precursor-mediated strategy by combining metal-assisted chemical etching, electroless deposition, and thermal oxidation. The CuO assembled on silicon nanowires (CuO-SiNWs) showed a competent sensitivity of 22.27 μA/mM, a wider linear range from 0.01 to 13.18 mM, and a comparable detection limit of 1.6 μM (3S/N) for nonenzymatic H2O2 detection. The archetype sensor also demonstrated eligible selectivity against common interfering species. By the introduction of the SiNW carrier, which led to mitigated conglomeration of the electrocatalyst and a favorable microstructure of the electrocatalyst-carrier system, improved signal-concentration linearity and higher electrocatalyst utilization efficiency were obtained with CuO-SiNWs. These results demonstrated the feasibility of the synthetic strategy and the potential of the nanocomposite as a promising candidate for H2O2 sensing.

Drug delivery which can offer efficient and localized drug transportation together with imaging capabilities is highly demanded in the development of cancer theranostic approaches. Herein, we report the construction of bovine serum albumin (BSA) gold nanoclusters (BSA@AuNCs) for cell fluoresce imaging and target drug delivery. BSA@AuNCs were modified with cyclic arginine-glycine-aspartate with the product RGD-BSA@AuNCs to enhance cell internalization of the nanoclusters. Furthermore, doxorubicin hydrochloride or doxorubicin (DOX), a widely used chemotherapy drug, was also used to modify RGD-BSA@AuNCs. The final design of the DOX/RGD-BSA@AuNC system was constructed through the disulfide bond. The physical microstructure and biological characterization of the BSA@AuNCs were realized through high-resolution transmission electron microscopy and confocal laser fluorescence microscopy. As the disulfide bonds were cleaved by glutathione in cancer cells, DOX-SH molecules were released from the nanosystem to inhibit the growth of cancer cells. The as-prepared DOX/RGD-BSA@AuNC system can be used not only to deliver drug but also to achieve the antitumor effect by in vivo imaging, demonstrating its promising applications in cancer treatment.