Search

A novel electrochemical sensor was constructed based on an enzyme-mediated physiological reaction between neurotransmitter serotonin per-oxidation to reconstruct dual-molecule 4,4′-dimeric-serotonin self-assembled derivative, and the potential biomedical application of the multi-functional nano-platform was explored. Serotonin accelerated the catalytic activity to form a dual molecule at the C4 position and created phenolic radical–radical coupling intermediates in a peroxidase reaction system. Here, 4,4′ dimeric-serotonin possessed the capability to recognize intermolecular interactions between amine groups. The excellent quenching effects on top of the gold surface electrode system archive logically inexpensive and straightforward analytical demands. In biochemical sensing analysis, the serotonin dimerization concept demonstrated a robust, low-cost, and highly sensitive immunosensor, presenting the potential of quantifying serotonin at point-of-care (POC) testing. The high-specificity serotonin electrochemical sensor had a limit of detection (LOD) of 0.9 nM in phosphate buffer and 1.4 nM in human serum samples and a linear range of 10 to 400 with a sensitivity of 2.0 × 10–2nM. The bivalent 4,4′-dimer–serotonin interaction strategy provides a promising platform for serotonin biosensing with high specificity, sensitivity, selectivity, stability, and reproducibility. The self-assembling gold surface electrochemical system presents a new analytical method for explicitly detecting tiny neurotransmitter-responsive serotonin neuromolecules.

Infectious pancreatic necrosis virus (IPNV) has been identified as a viral pathogen for many fish diseases that have become a huge hurdle for the growing fishing industry. Thus, in this work, we report a label-free impedance biosensor to quantify IPNV in real fish samples at point-of-care (POC) level. High specificity IPNV sensor with a detection limit of 2.69 TCID50/mL was achieved by conjugating IPNV antibodies to portable Au disk electrode chips using human heavy chain apoferritin (H-AFN) nanoprobes as a binding agent. H-AFN probes were bioengineered through PCR by incorporating pET-28b(+) resulting in 24 subunits of 6 × his-tag and protein-G units on its outer surface to increase the sensitivity of the IPNV detection. The biosensor surface modifications were characterized by differential pulse voltammetry (DPV) and EIS methods for each modification step. The proposed nanoprobe based sensor showed three-fold enhancement in charge transfer resistance toward IPNV detection in comparison with the traditional linker approach when measured in a group of similar virus molecules. The portable sensor exhibited a linear range of 100–10000 TCID50/mL and sensitivity of 5.40 × 10–4TCID50/mL in real-fish samples. The performance of the proposed IPNV sensor was fully validated using an enzyme-linked immunosorbent assay (ELISA) technique with a sensitivity of 3.02 × 10–4TCID50/mL. Results from H-AFN nanoprobe based IPNV sensor indicated high selectivity, sensitivity, and stability could be a promising platform for the detection of similar fish viruses and other biological molecules of interest.

RNA nanotechnology offers advantages to construct thermally and chemically stable nanoparticles with well-defined shape and structure. Here we report the development of an RNA–QD (quantum dot) chimera for resistive biomolecular memory application. Each QD holds two copies of the pRNA three-way junction (pRNA-3WJ) of the bacteriophage phi29 DNA packaging motor. The fixed quantity of two RNAs per QD was achieved by immobilizing the pRNA-3WJ with a Sephadex aptamer for resin binding. Two thiolated pRNA-3WJ serve as two feet of the chimera that stand on the gold plate. The RNA nanostructure served as both an insulator and a mediator to provide defined distance between the QD and gold. Immobilization of the chimera nanoparticle was confirmed with scanning tunneling microscopy. As revealed by scanning tunneling spectroscopy, the conjugated pRNA-3WJ–QD chimera exhibited an excellent electrical bistability signal for biomolecular memory function, demonstrating great potential for the development of resistive biomolecular memory and a nano-bio-inspired electronic device for information processing and computing.

A simple and sensitive amperometric sensor was developed based on electrochemical co-reduction of graphene oxide/nanoparticle (ERGO-NP) composite films by chronoamperometry method on indium tin oxide (ITO) electrodes. By analyzing the properties of the composite films with experimental results and theoretical investigations, a comprehensive report on the physical and electrochemical interfacial properties of graphene mixed gold nanoparticles composite electrode is presented. The developed electrodes were applied for the detection of hydrogen peroxide (H2O2) based on the direct electrochemistry of horseradish peroxidase (HRP). Standard carbodiimide chemistry enabled the covalent tethering of HRP on to the modified film thus maintaining its native structures, consequently facilitating the direct electron transfer between the protein and the underlying surface. The electrochemical result revealed that the ERGO-NP/ITO electrodes exhibited much higher conductivity (ca. 5 times) when compared with unmodified electrode. The developed sensor using amperometric measurements revealed high sensitivity (1808.9 μA.mM−1cm−2), with detection limit (0.6 μM) achieved under optimized conditions toward H2O2. Further, the sensor showed good specificity, stability and reproducibility toward H2O2detection, therefore results proved that well-dispersed, high surface area and highly conductive modified surface could be a promising material for protein adsorption and fabrication of electrochemical biosensors.