A protein-based electrochemical biosensor was developed for detection of tau protein aimed towards electrochemically sensing misfolding proteins. The electrochemical assay monitors tau–tau binding and misfolding during the early stage of tau oligomerization. Electrochemical impedance spectroscopy was used to detect the binding event between solution tau protein and immobilized tau protein (tau–Au), acting as a recognition element. The charge transfer resistance (R_ct) of tau–Au was 2.9 ± 0.6 kΩ. Subsequent tau binding to tau–Au decreased the R_ct to 0.3 ± 0.1 kΩ (90 ± 3% decrease) upon formation of a tau–tau–Au interface. A linear relationship between the R_ct and the solution tau concentration was observed from 0.2 to 1.0 μM. The R_ct decrease was attributed to an enhanced charge permeability of the tau–tau–Au surface to a redox probe [Fe(CN)₆]^3−/4−. The electrochemical and surface characterization data suggested conformational and electrostatic changes induced by tau–tau binding. The protein-based electrochemical platform was highly selective for tau protein over bovine serum albumin and allowed for a rapid sample analysis. The protein-based interface was selective for a non-phosphorylated tau441 isoform over the paired-helical filaments of tau, which were composed of phosphorylated and truncated tau isoforms. The electrochemical approach may find application in screening of the early onset of neurodegeneration and aggregation inhibitors.

In this work, we designed and developed a method to detect S1 spike protein of SARS-CoV-2.

Neuronal tau protein is one of the biomarkers of neurodegeneration which remains without a cure and differential diagnosis. Hence, novel methods are needed for detection of tau protein. Toward this aim, the detection of full-length tau441 protein was achieved using the electrochemical immunoassay based on direct immobilization of anti-tau antibodies on Au surface by using an active N-hydroxysuccinimide ester coupling chemistry (Ab-Au). The electrochemical impedance spectroscopy was used to monitor tau441 binding to Ab-Au in the presence [Fe(CN)₆]^3−/4− redox probe. The reduction in the charge-transfer resistance, R_ct, was observed upon tau441 binding to Ab-Au. Detection of tau441 was observed in μM to nM range with high specificity and selectivity. The electrochemical immunosensor exhibited minimal non-specific binding to bovine serum albumin. Tau441 did not bind to Au surface functionalized with non-tau-specific antibody MOPC-21. The electrochemical biosensor was optimized by screening various anti-tau antibodies. The tau441 binding to anti-tau antibodies was also measured using Enzyme-Linked Immunosorbent Assay (ELISA). The label-free electrochemical impedance spectroscopy immunosensor may be used for selective detection of tau protein in biological fluids, as a biomarker of neurodegeneration.

Microplastics (MPs) are a part of our daily lives and persist in the environment all across the globe. As a recently recognized emerging pollutant, there is a call to action to mitigate and monitor microplastics. Despite traditional remediation and characterization methodologies, MP-related challenges still exist. Electrochemical strategies for microplastic remediation have been reported in recent years, but very few reports exist on using electrochemical sensors for monitoring microplastics. Therefore, this minireview highlights the opportunities within the existing electrochemical remediation platforms towards sensor design and development, and elaborates on microplastic electrochemical sensors so far.

Protein-misfolding diseases are based on a common principle of aggregation initiated by intra- and inter-molecular contacts. The structural and conformational changes induced by biochemical transformations such as post-translational modifications (PTMs), often lead to protein unfolding and misfolding. Thus, these order-to-disorder or disorder-to-order transitions may regulate cellular function. Tau, a neuronal protein, regulates microtubule (MT) structure and overall cellular integrity. However, misfolded tau modified by PTMs results in MT destabilization, toxic tau aggregate formation, and ultimately cell death, leading to neurodegeneration. Currently, the lack of structural information surrounding tau severely limits understanding of neurodegeneration. This minireview focuses on the current methodologies and approaches aimed at probing tau conformation and the role of conformation in various aspects of tau biochemistry. The recent applications of nuclear magnetic resonance, mass spectrometry, Förster resonance electron transfer, and molecular dynamics simulations toward structural analysis of conformational landscapes of tau will be described. The strategies developed for structural evaluation of tau may significantly improve our understanding of misfolding diseases.