Abstract
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.
Highlights
6H2 O, ≥99.9), ascorbic acid (AA, C6 H8 O6, ≥ 99.1%), polyvinylpyrrolidone (PVP, (C6 H9 nitric oxide (NO))n ), sodium sulfide (Na2 S, ≥99.0%), and all other chemicals were purchased from SigmaAldrich
0.5 g of ascorbic acid (AA) as a reducing agent and 0.8 g of PVP as a surfactant were added to the above mixture, which was stirred for another 30 min
Breast cancer cells (MDA-MB-231, ATCC, Manassas, VA, USA) and mouse fibroblasts (L929, ATCC, Manassas, VA, USA) were cultured in DMEM supplemented with 10% fetal bovine serum (FBS) (Gibco, Amarillo, TX, USA), 100 U mL−1 penicillin, and 100 μg mL−1 streptomycin
Summary
Platinum(II) acetylacetonate (Pt(acac)2, ≥97%), nickel(II) nitrate hexahydrate (Ni(NO3)2.6H2O, ≥99.9), ascorbic acid (AA, C6H8O6, ≥ 99.1%), polyvinylpyrrolidone (PVP, Platinum(II) acetylacetonate (Pt(acac)2 , ≥97%), nickel(II) nitrate hexahydrate (Ni(NO3 ). 6H2 O, ≥99.9), ascorbic acid (AA, C6 H8 O6 , ≥ 99.1%), polyvinylpyrrolidone (PVP, (C6 H9 NO)n ), sodium sulfide (Na2 S, ≥99.0%), and all other chemicals were purchased from SigmaAldrich (St. Louis, MO, USA). Sodium phosphate monobasic (NaH2 PO4 ) and sodium phosphate dibasic (Na2 HPO4 ) were used for the preparation of 0.05 M phosphate buffer (PB). Hydrochloric acid (HCl, 36.5–38.0%) and sodium hydroxide (NaOH, ≥98.0%) were used to adjust the pH of the PB. Double distilled (DD) water and ethanol were used for washing and other experiments. Three-pole screen-printed electrodes (SPEs) were purchased from Zensor (Taipei, Taiwan) (model TE-100)
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