Electrochemically accelerated adsorption of serum albumin on the surface of platinum and gold electrodes

A universal reagent for detection of emerging diseases using bioengineered multifunctional yeast nanofragments

Accurate and early detection of biomarkers provides the molecular evidence for disease management, allowing prompt actions and timely treatments to save lives. Multivalent biomolecular interactions between the probe and biomarker as well as controlled probe orientation on material surfaces are keys for highly sensitive detection. Here we report the bioengineering of programmable and multifunctional nanoprobes, which can provide rapid, specific and highly sensitive detection of emerging diseases in a range of widely used diagnostic systems. These nanoprobes composed of nanosized cell wall fragments, termed as synthetic bionanofragments (SynBioNFs), are generated by the fragmentation of genetically programmed yeast cells. SynBioNFs display multiple copies of biomolecules for high-affinity target binding and molecular handles for the precisely orientated attachment on surfaces used in diagnostic platforms. SynBioNFs are demonstrated for the capture and detection of SARS-CoV-2 virions using multiple diagnostic platforms, including surface-enhanced Raman scattering, fluorescence, electrochemical and colorimetric-based lateral flow systems with sensitivity comparable with the gold-standard reverse-transcription quantitative polymerase chain reaction.

Investigation of protein adsorption and electrochemical behavior at a gold electrode

The adsorption of two model proteins, human serum albumin and immunoglobulin G, on a gold electrode surface was investigated using 125I radiolabeling and cyclic voltammetry (CV). 125I radiolabeling was used to determine the extent of protein adsorption, while CV was used to ascertain the effect of the adsorbed protein layer on the electron transfer between the gold electrode and an electroactive moiety in solution, namely, K3Fe(CN)6. The adsorbed amounts of HSA and IgG agreed well with previous results and showed approximately monolayer coverage. The amount of adsorbed protein increased when a positive potential (700 mV) was applied to the electrode, while the application of a negative potential (-800 mV) resulted in a decrease. When the solution pH was varied to alter the charge on the protein, the adsorption trends appeared to follow electrostatic interaction, namely, greater adsorption when the electrode and the protein possessed opposite charge and vice versa. The adsorbed protein layer had the effect of blocking the electron transfer. It was possible to correlate the degree of electron blocking with the amount of adsorbed protein to show that the greater the adsorption, the larger the blocking effect. Of the two proteins used, HSA proved to be more efficient at blocking the electron transfer.

Investigation of Ig.G adsorption and the effect on electrochemical responses at titanium dioxide electrode

The adsorption of Immunoglobulin G on a titanium dioxide (TiO(2)) electrode surface was investigated using (125)I radiolabeling and electrochemical impedance spectroscopy (EIS). (125)I radiolabeling was used to determine the extent of protein adsorption, while EIS was used to ascertain the effect of the adsorbed protein layer on the electrode double layer capacitance and electron transfer between the TiO(2) electrode and the electrolyte. The adsorbed amounts of Ig.G agreed well with previous results and showed approximately monolayer coverage. The amount of adsorbed protein increased when a positive potential was applied to the electrode, while the application of a negative potential resulted in a decrease. Exposure to solutions of Ig.G resulted in a decrease of the double layer capacitance (C) and an increase in the charge-transfer resistance (R(2)) at the electrode solution interface. As more Ig.G adsorbed onto the electrode surface, the extent of C and R(2) variation increased. These capacitance and charge-transfer resistance variations were attributed to the formation of a proteinaceous layer on the electrode surface during exposure.