Diffusion indicator for hemispheroidal and ring ultramicroelectrode geometries for E and ECʹ reactions

Promoting Electrochemical Reversibility: Concave versus Convex Electrodes

The importance of electrode shape, alongside electrode size, as key factors in controlling the reversibility or otherwise of electrochemical responses, is recognized at the microscopic level but is explored here via finite-element simulation on the macroscopic scale. Reduced overpotential is seen for concave surfaces relative to flat or convex surfaces, providing an unexplored avenue for the design and fabrication of electrodes, including composites for diverse applications where enhanced reversibility is desirable, such as in sensors and battery materials where the promotion of electrocatalytic responses is important.

Ultramicro and ultrasensitive detection of lipopolysaccharides based on triple-signal amplification via ultrafast ATRP and an ultramicroelectrode

Highly sensitive testing of trace lipopolysaccharides (LPS) is very important due to their high toxicity to the human body. Here, an ultrasensitive electrochemical sensor requiring only 5 μL solution was developed for LPS detection via triple-signal amplification based on ultrafast atom transfer radical polymerization (UATRP) and a Au ultramicroelectrode (UME). Firstly, the Au UME was modified with gold nanoparticles (nAu) and an LPS aptamer (Apt) in turn. When the Apt recognized LPS, the ATRP initiator of 4-(bromomethyl)phenylboronic acid (BPA) could be tethered to the electrode by covalent cross-linking between the phenylboronic acid moiety and the cis-diol site of LPS. Then UATRP was conducted for 2.5 min with nitrogen-doped carbon quantum dots (N-CQDs) as the photocatalyst and methylacrolein (MLA) as the monomer. After the electroactive probes of Ag nanoparticles (AgNPs) were formed on the surface of poly(MLA) by the silver mirror reaction, the electrochemical sensor was successfully prepared. Under the optimal conditions, the sensor exhibited a lower detection limit and a wider linear range when it was compared with a similar assay for LPS. In particular, the LOD of 7.99 × 10-2 pg mL-1 was better than that of the limulus amoebocyte lysate (LAL)-based technique, which is the gold standard for LPS detection. In the end, the sensor reported in this paper showed good selectivity and satisfactory feasibility for LPS detection in real biological samples and food products. The results obtained from the drug, blood and potable water samples laid a strong foundation for its clinical applications and application in other fields.