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We present a straightforward method for fabricating functional micro-, submicro-, and nano-channels embedded in a porous carbon film and the application of this microfluidic platform for electrochemical sensing. A skin layer of poly(methyl methacrylate) (PMMA) fibers was first electrospun on a thoroughly cleaned Si wafer substrate, followed by spin coating of a polyacrylonitrile (PAN) film on top of the skin. High-temperature carbonization of the composite film decomposed the PMMA fibers and produced embedded microchannels in the PAN-derived amorphous monolithic carbon electrode. The channels were decorated with Pt nanoparticles by in situ thermal decomposition of a precursor metal salt to enhance functionality of the carbon electrode. Carbon electrodes decorated with Pt nanoparticles (carbon-Pt), with and without embedded microchannels, were used to detect the food toxin aflatoxin B1 (AFB1) by surface biofunctionalization with the antibodies of AFB1 (anti-AFB1) via an electrochemical impedance technique. The aligned nanochannels in the porous carbon film act as a reaction chamber for antigen–antibody interactions and provide channels for fast electron transport toward the electrode from the electrolyte, resulting in improved electrochemical performance of the biosensor. The fabricated immunosensor is highly sensitive to 1 pg/mL of AFB1 with a concentration range of 10 −12 –10 −7 g/mL. [ABSTRACT FROM AUTHOR]

In this research, detection of trimethoprim (TMP) was carried out using a nanostructured zinc oxide nanoparticle-modified carbon paste electrode (ZnO/CPE) with an anionic surfactant and sodium dodecyl sulphate (SDS) with the help of voltametric techniques. The electrochemical nature of TMP was studied in 0.2 M pH 3.0 phosphate-buffer solution (PBS). The developed electrode displayed the highest peak current compared to nascent CPE. Effects of variation in different parameters, such as pH, immersion time, scan rate, and concentration, were investigated. The electrode process of TMP was irreversible and diffusion controlled with two electrons transferred. The effective concentration range (8.0 × 10−7 M–1.0 × 10−5 M) of TMP was obtained by varying the concentration with a lower limit of detection obtained to be 2.58 × 10−8 M. In addition, this approach was effectively employed in the detection of TMP in pharmaceutical dosages and samples of urine with the excellent recovery data, suggesting the potency of the developed electrode in clinical and pharmaceutical sample analysis. [ABSTRACT FROM AUTHOR]