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- 6 Materialchemie (2) (entfernen)
Electrochemical methods offer great promise in meeting the demand for user-friendly on-site devices for Monitoring important parameters. The food industry often runs own lab procedures, for example, for mycotoxin analysis, but it is a major goal to simplify analysis, linking analytical methods with smart technologies. Enzyme-linked immunosorbent assays, with photometric detection of 3,3’,5,5’-tetramethylbenzidine (TMB),form a good basis for sensitive detection. To provide a straightforward approach for the miniaturization of the detectionstep, we have studied the pitfalls of the electrochemical TMB detection. By cyclic voltammetry it was found that the TMB electrochemistry is strongly dependent on the pH and the electrode material. A stable electrode response to TMB could be achieved at pH 1 on gold electrodes. We created a smartphonebased, electrochemical, immunomagnetic assay for the detection of ochratoxin A in real samples, providing a solid basis forsensing of further analytes.
Functionalized Ti3C2Tx nanosheets based biosensor for point-of-care detection of SARS-CoV‑2 antigen
(2023)
MXenes are considered a promising class of two-dimensional materials with extraordinary physical and electrochemical properties. Distinguished features like high specific surface area and outstanding electrical conductivity make them suitable for electrochemical biosensing applications. Here, we report the development of a biosensor involving the functionalized MXene−titanium carbide nanosheets (Ti3C2Tx-NS) and monoclonal antibodies against the SARS-CoV-2 nucleocapsid protein (anti-SARS-CoV-2 mAb) to design a point-of-care device for detection of the SARS-CoV-2 nucleocapsid protein (SARS-CoV-2 NP) antigen. Few-layered titanium carbide nanosheets (denoted as FL-Ti3C2Tx-NS) have been synthesized using a single-step etching and delamination method and characterized using optical and electron microscopy techniques revealing the suitability for immunosensing applications. Binding studies revealed the excellent affinity between the biosensor and the SARS-CoV-2 NP. Electrochemical detection of SARS-CoV-2 NP is performed using differential pulse voltammetry and read by a smartphone-based user interface. The proposed FL-Ti3C2Tx-NS based biosensor offers the detection of SARS-CoV-2 NP with a limit of detection of 0.91 nM in a wide detection range in spiked saliva samples. Additionally, there is no cross-reactivity in the presence of potential interferants like SARS-CoV-2 spike glycoprotein and bovine serum albumin. These findings demonstrate the potential of MXenes in developing a rapid and reliable tool for SARS-CoV-2 NP detection. While we report the biosensing of SARS-CoV-2 NP, our system also paves the way for the detection of other SARS-CoV-2 antigens like spike protein or other biomolecules based on antigen−antibody interactions.