Biocompatible Electrochemical Sensor Based on Platinum-Nickel Alloy Nanoparticles for In Situ Monitoring of Hydrogen Sulfide in Breast Cancer Cells

Hydrogen sulfide (H2S), an endogenous gasotransmitter, is produced in mammalian systems and is closely associated with pathological and physiological functions. Nevertheless, the complete conversion of H2S is still unpredictable owing to the limited number of sensors for accurate and quantitative detection of H2S in biological samples. In this study, we constructed a disposable electrochemical sensor based on PtNi alloy nanoparticles (PtNi NPs) for sensitive and specific in situ monitoring of H2S released by human breast cancer cells. PtNi alloy NPs with an average size of 5.6 nm were prepared by a simple hydrothermal approach. The conversion of different forms of sulfides (e.g., H2S, HS−, and S2−) under various physiological conditions hindered the direct detection of H2S in live cells. PtNi NPs catalyze the electrochemical oxidation of H2S in a neutral phosphate buffer (PB, pH 7.0). The PtNi-based sensing platform demonstrated a linear detection range of 0.013–1031 µM and the limit of detection was 0.004 µM (S/N = 3). Moreover, the PtNi sensor exhibited a sensitivity of 0.323 μA μM−1 cm−2. In addition, the stability, repeatability, reproducibility, and anti-interference ability of the PtNi sensor exhibited satisfactory results. The PtNi sensor was able to successfully quantify H2S in pond water, urine, and saliva samples. Finally, the biocompatible PtNi electrode was effectively employed for the real-time quantification of H2S released from breast cancer cells and mouse fibroblasts.

Identification of the main mixing process in the synthesis of alloy nanoparticles by laser ablation of compacted micropowder mixtures

Alloy nanoparticles offer the possibility to tune functional properties of nanoscale structures. Prominent examples of tuned properties are the local surface plasmon resonance for sensing applications and adsorption energies for applications in catalysis. Laser synthesis of colloidal nanoparticles is well suited for generating alloy nanoparticles of desired compositions. Not only bulk alloys but also compacted mixtures of single-metal micropowders can serve as ablation targets. However, it is still unknown how mixing of the individual metals transfers from the micro- to the nanoscale. This work experimentally contributes to the elucidation of the mixing processes during the laser-based synthesis of alloy nanoparticles. Key parameters, such as the initial state of mixing in the ablation target, the laser pulse duration, the laser spot size, and the ablation time, are varied. Experiments are performed on a cobalt-iron alloy, relevant for application in oxidation catalysis, in ethanol. The extent of mixing in the targets after ablation and in individual nanoparticles are studied by energy-dispersive X-ray spectroscopy and by cyclic voltammetry at relevant conditions for the oxygen evolution reaction, as model reaction. The results point at the benefits of well pre-mixed ablation targets and longer laser pulse durations for the laser-based synthesis of alloy nanoparticles. Graphical abstract

Highly efficient catalytic oxidation of 5-hydroxymethylfurfural into 2,5-furandicarboxylic acid with bimetallic Pt-Cu alloy nanoparticles catalyst

Bimetallic platinum-copper alloy nanoparticles is a highly active catalyst for the oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) under base-free conditions, with a high turnover frequency up to 135...