Bimetallic nanoparticles (NPs) usually exhibit some novel properties due to the synergistic effects of the two distinct metals, which is expected to play an important role in the field of gas sensing. PdPt bimetal NPs with Pd-rich shell and Pt-rich core were successfully synthesized and used to modify SnO2 nanosheets. The 1P-PdPt/SnO2-A sensor obtained by self-assemblies of PdPt NPs exhibited temperature-dependent dual selectivity to CO at 100 °C and CH4 at 320 °C. Furthermore, the sensor possessed good long term stability and antihumidity interference. The activation energy of adsorption for CO and CH4 were estimated by the temperature-dependent response process modeled using Langmuir adsorption kinetics, which proved that the lower activation energy of adsorption corresponded to better sensing performance. The gas-sensing mechanism based on the diffusion depth of the tested gas in the sensing layer was discussed. The dramatically improved sensing performance could be ascribed to the high catalytic activity of PdPt bimetal, the electron sensitization of PdO, and Schottky barrier-type junctions at the interface between SnO2 and PdPt NPs. Our present results demonstrate that bimetal NPs with special structure and components can significantly improve the gas-sensing performance of metal oxide semiconductor and the obtained sensor has great potential in monitoring coal mine gas.
Chun Chu,Zhihong Bao,Meng Sun,Xiaowei Wang,Hongyan Zhang,Weiguo Chen,Yang Sui,Ji Li,Yuanyuan Zhuang,Dongkai Wang
The combination of chemotherapy and phototherapy has attracted increasing attention for cancer treatment in recent years. In the current study, porous PdPt bimetallic nanoparticles (NPs) were synthesized and used as delivery carriers for the anti-cancer drug doxorubicin (DOX).[email protected]NPs were modified with thiol functionalized hyaluronic acid (HA-SH) to generate[email protected]@HA NPs with an average size of 105.2 ± 6.7 nm. Characterization and in vivo and in vitro assessment of anti-tumor effects of[email protected]@HA NPs were further performed. The prepared[email protected]@HA NPs presented a high photothermal conversion efficiency of 49.1% under the irradiation of a single 808 nm near-infrared (NIR) laser. Moreover, NIR laser irradiation-induced photothermal effect triggered the release of DOX from[email protected]@HA NPs. The combined chemo-photothermal treatment of NIR-irradiated[email protected]@HA NPs exerted a stronger inhibitory effect on cell viability than that of DOX or NIR-irradiated[email protected]NPs in mouse mammary carcinoma 4T1 cells in vitro. Further, the in vivo combination therapy, which used NIR-irradiated[email protected]@HA NPs in a mouse tumor model established by subcutaneous inoculation of 4T1 cells, was demonstrated to achieve a remarkable tumor-growth inhibition in comparison with chemotherapy or photothermal therapy alone. Results of immunohistochemical staining for caspase-3 and Ki-67 indicated the increased apoptosis and decreased proliferation of tumor cells contributed to the anti-tumor effect of chemo-photothermal treatment. In addition,[email protected]@HA NPs induced negligible toxicity in vivo. Hence, the developed nanoplatform demonstrates great potential for applications in photothermal therapy, drug delivery and controlled release.Keywords:PdPt bimetallic nanoparticles;drug delivery;chemo-photothermal therapy;anti-tumor effect
In this study, we found that PdPt bimetallic alloy nanowires (Pd/Pt NWs) exhibited excellent oxidase-like activity in acidic media. Their oxidase-like activity could be readily tailored by a well-defined Pd/Pt ratio, while the nanowires with Pd/Pt ratio of 1 : 3 (defined as Pd/Pt-1 : 3 NWs) proved to exhibit the most efficient catalytic oxidation activity. By using their excellent oxidase-like activity, we developed a simple colorimetric assay to detect the activity of acid phosphatase (ACP) based on its catalytic hydrolysate, ascorbic acid (AA), which effectively inhibited the action of the Pd/Pt-1 : 3 NW-mediated TMB-oxidized chromogenic reaction. Good linearity between the absorbance change and activity of ACP was obtained in the range of 0.17–2.67 U L−1, with the limit of detection as low as 0.06 U L−1. Moreover, the proposed method was also adopted to determine the ACP activity in mimicking physiological sample solutions with satisfactory results, illustrating its great potential for biological analysis.
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