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Ultrathin Cu-TCPP Nanosheet-Based Electrochemical Microsensor for Detecting the Immunosuppressive Drug Mycophenolic Acid
(2023-12-22)
Deng, Mingshi
;
Jin, Wei
;
Yang, Wenjuan
;
Tian, Lingling
;
Gao, Xinghua
Mycophenolic acid (MPA), which is a potent immunosuppressant, has been widely used to prevent organ rejection after organ transplantation. In clinical practice, it is essential to monitor the free MPA concentration. Herein, convenient and fast electrochemical microsensing technology is developed for directly detecting the MPA concentration. To implement this method, ultrathin copper-based metal-organic framework (Cu-MOF) nanosheets with a thickness of about 6.6 nm are used to detect MPA. An analysis of electrochemical behavior reveals the direct electrochemical catalytic oxidation mechanism of MPA molecules on a Cu(II) tetrakis(4-carboxyphenyl)porphyrin (Cu-TCPP)-modified electrode. Furthermore, electrochemical testing results show that the ultrathin Cu-TCPP nanosheet-based microsensor exhibits high sensitivity and specificity for MPA in the nano- to micromolar range, with a detection limit of 10 nM. X-ray absorption spectroscopy (XAS) characterization reveals that the unsaturated metal ions in ultrathin nanosheets are the active sites responsible for boosting the catalytic oxidation of MPA molecules. High-performance liquid chromatography-tandem mass spectrometry further shows the catalytic oxidation product of MPA and that the phenolic hydroxyl group in the MPA molecule is the active site where the catalytic reaction occurs. The considerable sensing performance of the Cu-TCPP nanosheet-based microsensor proves that it is possible to develop a fast and convenient method for the direct high-frequency monitoring of immunosuppressive drugs.
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1T-Phase molybdenum sulfide/cobalt oxide nanopillars hybrid nanostructure coupled with nitrogen-doped carbon thin-film as high efficiency electrocatalyst for oxygen evolution
(2022-02-15)
Ying, Zi
;
Lv, Yu
;
Song, Haixiang
;
Ma, Yujie
;
Chen, Riming
High efficient and durable catalysts are always needed to lower the kinetic barriers as well as prolong the service life associated with oxygen evolution reaction (OER). Herein, a sequential synthetic strategy is considered to prepare a hierarchical nanostructure, in which each component can be configured to achieve their full potential so that endows the resulting nanocatalyst a good overall performance. In order to realize this, well-organized cobalt oxide (Co<inf>3</inf>O<inf>4</inf>) nanopillars are firstly grown onto ultrathin 1T-molybdenum sulfide (1T-MoS<inf>2</inf>) to obtain high surface area electrocatalyst, providing electron transfer pathways and structural stability. After that, zeolitic imidazolate framework-67 (ZIF-67) derived carbonization film is further in situ deposited on the surface of nanopillars to generate plentiful active sites, thereby accelerating OER kinetics. Based on the combination of different components, the electron transfer capability, catalytic activity and durability are optimized and fully implemented. The obtained nanocatalyst (defined as 1T-MoS<inf>2</inf>/Co<inf>3</inf>O<inf>4</inf>/CN) exhibits the superior OER catalytic ability with the overpotential of 202 mV and Tafel slope of 57 mV·dec−1 at 10 mA·cm−2 in 0.1 M KOH, and good durability with a minor chronoamperometric decay of 9.15 % after 60,000 s of polarization.
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RhIr@MoS2 nanohybrids based disposable microsensor for the point-of-care testing of NADH in real human serum
(2020-08-01)
Ji, Dongqing
;
Ying, Zi
;
Zhang, Yuan
;
Chen, Wei
;
Janyasupab, Metini
Dihydronicotinamide adenine dinucleotide (NADH) is an important enzyme in all living cells, which is found to be abnormally expressed in cancer cells. Since it is redox-active, an electrochemical detection method would be suitable for monitoring its concentration in biological fluids. Here we present a strategy for specific determination of NADH in real human serum by using RhIr@MoS<inf>2</inf> nanohybrids based microsensor. To implement the protocol, RhIr nanocrysrals are in-situ grown onto MoS<inf>2</inf> interlayers forming a nanohybrid structure (RhIr@MoS<inf>2</inf>). After being locally deposited on an electrochemical microsensor, it could be used for the analysis of NADH. The developed RhIr@MoS<inf>2</inf> nanohybrids based microsensor possesses the ability for analyzing NADH at the applied potential of 0.07 V (much lower than most reported values). The detection limit is evaluated as low as 1 nmol/L even in bovine serum albumin (BSA) media. In addition, the sampling analysis of human serum from cancer patients and health controls shows that the microsensor displays good diagnostic sensitivity and specificity, illustrating that this developed detection technique is a relatively accurate method for measuring NADH in biological fluids. The proposed electrochemical microsensor assay also owns the benefits of convenience, disposable and easy processing, which make it a great possibility for future point-of-care cancer diagnosis.
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Phase-Regulated Sensing Mechanism of MoS2 Based Nanohybrids toward Point-of-Care Prostate Cancer Diagnosis
(2020-05-01)
Ying, Zi
;
Feng, Lingyan
;
Ji, Dongqing
;
Zhang, Yuan
;
Chen, Wei
Alpha-methylacyl-CoA racemase (AMACR) has been proven to be consistently overexpressed in prostate cancer epitheliums, and is expected to act as a positive biomarker for the diagnosis of prostate carcinoma in clinical practice. Here, a strategy for specific determination of AMACR in real human serum by using an electrochemical microsensor system is presented. In order to implement the protocol, a self-organized nanohybrid consisting of metal nanopillars in a 2D MoS<inf>2</inf> matrix is developed as material for the sensing interface. The testing signal outputs are strongly enhanced with the presence of the nanohybrids owing to that the metal pillars provide an efficient mass difussion and electron transfer path to the MoS<inf>2</inf> film surface. Furthermore, the phase-regulated sensing mechanism over MoS<inf>2</inf> is noticed and demonstrated by density functional theory calculation and experiments. The explored MoS<inf>2</inf> based nanohybrids are employed for the fabrication of an electrochemical microsensor, presenting good linear relationship in both ng µL−1 and pg µL−1 ranges for AMACR quantification. The sampling analysis of human serum indicates that this microsensor has good diagnostic specificity and sensitivity toward AMACR. The proposed electrochemical microsensor system also demonstrates the advantages of convenience, cost-effectiveness, and disposability, resulting in a potential integrated microsystem for point-of-care prostate cancer diagnosis.

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