A recent study by Talanta examines the interaction between the spike (S) glycoprotein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) using a molecularly imprinted polypyrrole (MIP-Ppy) by calcns. plot Anson.
The current study revealed that the MIP-Ppy modified electrode was more sensitive to SARS-CoV-2 S glycoprotein than the non-imprinted polypyrrole (NIP-Ppy) modified electrode. This affinity of protein S can be used in the development of diagnostic sensor technologies to detect SARS-CoV-2 infection.
Study: Evaluation of the interaction between SARS-CoV-2 spike glycoproteins and molecularly imprinted polypyrrole. Image credit: Marcin Janiec / Shutterstock.com
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Biosensors typically recognize analytes using biomacromolecules, such as enzymes, antibodies, deoxyribonucleic acid (DNA), and aptamers. These bioanalytical systems are associated with several limitations, such as specific operating conditions and high production costs. This has led researchers to invest in the development of artificial biorecognition systems based on synthetic receptors and molecularly imprinted polymers (MIPs) as possible alternative solutions.
Molecular imprinting refers to the creation of artificial receptors for specific target molecules in polymers or self-assembled materials. The analyte is usually targeted by natural receptors, leading to electrochemical, optical, magnetic, and mass changes in the transducers.
Polypyrrole is widely used to design bioanalytical sensors. MIPs are made by polymerizing a monomer and crosslinker around a target molecule. Due to their thermal stability, reusability, and selectivity, MIPs are often used as recognition components in sensor design.
To fabricate MIPs, monomers are polymerized in the presence of template molecules and then extracted, followed by application of MIP-based structures to MIP-based electrochemical sensors.
Thus a cavity corresponding to the template molecule is created in the polymer during polymerization. These cavities facilitate the recognition and binding of molecules in a specific manner.
A key function of the SARS-CoV-2 S protein is to recognize and bind to cell receptors, allowing the virus to penetrate through cell membranes. Following the emergence of SARS-CoV-2, which is the etiological agent of the 2019 coronavirus disease (COVID-19), some aspects of electrochemical approaches to identify viral proteins using MIPs have been of interest.
SARS-CoV-2 S, nucleocapsid, envelope, and membrane proteins can serve as template macromolecules in MIP production. In the current study, MIP-Ppy was developed and applied to determine SARS-CoV-2 S-glycoprotein.
About the study
A working platinum electrode was electrochemically deposited with two types of polypyrrole layers, namely MIP-Ppy and NIP-Ppy. The performance of the electrodes modified by MIP-Ppy and NIP-Ppy layers was evaluated by pulsed amperometric detection (PAD).
During the evaluation of the PAD measurements, the integrated plot of the Cottrell-Anson equation was used to calculate the amount of charge flowing through the MIP-Ppy and NIP-Ppy layers.
Results of the study
When MIP-Ppy and NIP-Ppy modified electrodes were incubated in phosphate-buffered saline (PBS) containing the SARS-CoV-S spike glycoprotein, a significant reduction in current was observed. Based on the total charge versus squared time plots, as demonstrated in Anson plots, the interaction between SARS CoV-2 S-glycoproteins and MIP-Ppy was evaluated.
When the relationship between the resulting slope values of the Anson plot and glycoprotein concentration was evaluated, it was concluded that MIP-Ppy adsorbs viral glycoproteins more strongly than NIP-Ppy. Notably, Anson plot analysis showed that the SARS-CoV-2 S glycoprotein molecule interacts with MIP-Ppy and is partially adsorbed on NIP-Ppy. Thus, the interaction between SARS-CoV-2 spike glycoproteins and MIP-Ppy can be successfully assessed using Anson plots.
In addition, the calibration curve of current values for glycoprotein concentrations between zero and 25 µg/mL was presented. These results represented an exponential decrease in the calibration graph of the sketched system.
A significant difference was observed between MIP-Ppy and NIP-Ppy modified electrodes for the amount of current drop. More specifically, the MIP-Ppy modified electrode showed higher sensitivity to SARS-CoV-2 S glycoprotein compared to the NIP-Ppy modified electrode.
The calibration curve indicated that the current value measured for the MIP-Ppy modified electrode was 1.36 times higher than that of the NIP-Ppy modified electrode at an initial glycoprotein concentration of 0 µg/mL.
Additionally, a complementary cavity was bled into the Ppy after extraction of the SARS-CoV-2 S-glycoprotein from MIP-Ppy. Taken together, the results of the study indicate that this property can be used to develop a sensor for detecting SARS-CoV-2 infections.
Journal reference:
- Ratautaite, V., Boguzaite, R., Brazys, E., et al. (2022). Evaluation of the interaction between SARS-CoV-2 spike glycoproteins and molecularly imprinted polypyrrole. talent doi:10.1016/j.talanta.2022.123981