Search

A novel electrochemical immunosensor for lactate dehydrogenase (LDH) detection was proposed based on analyte‐driven catalytic reaction by attaching LDH antibodies on multi‐walled carbon nanotubes (MWCNTs) and gold nanoparticles (AuNPs) modified glassy carbon electrodes (GCE). As LDH was captured by the antibodies on electrode surface, it catalyzed the formation of pyruvate and the reduced form of nicotinamide adenine dinucleotide (NADH), thus a sensitive electrochemical signal obtained from the above redox reaction was recorded by differential pulse voltammetry (DPV). Under optimum conditions, the developed immunosensor exhibits high sensitivity for LDH quantification ranging from 0.001 μg/mL to 0.5 μg/mL with a low detection limit at 0.39 ng/mL. This developed immunosensor reveals ideal accuracy and feasibility for LDH detection in Streptococcus uberis (S. uberis) induced bovine mammary epithelial cells (MECs) samples by comparison with conventional commercial kit, which shows remarkably application potential in diseases diagnosis. [ABSTRACT FROM AUTHOR]

A novel electrochromic biosensor has been developed by coupling the chemical sensing reactions at closed bipolar electrode (BPE) to the electrochemical reactions at the driving electrode for colorimetric detection of fumonisin B 1 (FB 1). Here, BPE is not only served as the sensing electrode, but also acted as a vital bridge to form electric connection between sensing and reporting solution. The conductive bridge was formed by connecting glassy carbon electrode (GCE) in sensing cell to Pt wire in reporting cell with electric wire. In order to achieve FB 1 detection, a recognition probe was prepared by conjugating Au nanoparticles (NPs) labeled FB 1 aptamer to capture DNA-Fe 3 O 4 NPs surface. After the chemical reduction of silver ion on Au NPs, the prepared probes were introduced to GCE surface to catalyze the decomposition of H 2 O 2 to oxygen bubbles by silver particles. The accumulation of numerous bubbles led to a significant decrement of the effective area of GCE cathode and current flow through the electric bridge which was reported by the inhibited electro-deposition of Prussian blue (PB) at ITO driving electrode in sensing cell. After adding FB 1 , Au NPs –aptamer was liberated from Fe 3 O 4 NPs –capture DNA surface, resulting in a decreased amount of silver particles assembled on GCE and an increased amount of PB deposited at ITO electrode. This indirect colorimetric strategy provides a simple and portable for bioanalysis. • A novel smartphone based electrochromic biosensor for FB 1 detection is designed in closed BPEdevice. • Chemical reaction occurred at the cathode of BPE is reported by the electrochemical reactions at driving electrode. • Decomposition of H 2 O 2 to oxygen bubbles in the sensing process is employed to adjust the effective area of BPE. • The separations of reporting and sensing solution can avoid the chemical interfere between them. [ABSTRACT FROM AUTHOR]

Resistance is of great importance for controlling the current flow through bipolar electrodes (BPEs) and the electrochemiluminescence (ECL) signal at the BPE anode. In this work, we firstly studied the effect of the iR drop between the BPE cathode and anode on the electrochemical performance of a closed BPE device. Due to the significant iR loss between the two poles of the BPE, an increased external voltage, applied on the driving electrodes, was required to trigger the redox reactions at the BPE. Accordingly, the peak voltages (forward and reverse scan) shifted to larger values, whereas the current flow through the BPE was remarkably reduced. Moreover, these factors were closely dependent on the concentration of Fe(CN) 6 3−/Fe(CN) 6 4−, the scan rate, and the resistance wired between glassy carbon electrodes (GCEs). Principally, it was proven that the peak-to-peak separation was enlarged as the scan rate and the concentration of Fe(CN) 6 3−/Fe(CN) 6 4− increased, even when the resistance between the two BPE poles was zero, indicating that the ohmic effect of the electrochemical cell is significant. Excellent linear relationships could be observed between the peak voltages and the resistance, enabling the designation of novel biosensors by connecting sensing units with tunable resistance between the GCEs. The noncontact electrochemical measurement could therefore be promising in biosensing applications. [ABSTRACT FROM AUTHOR]