Development of method for SARS-CoV-2 spike protein determination in saliva samples at fg mL−1 levels using electrochemically controlled preconcentration and molecularly imprinted polypyrrole sensor
Milena do Prado Ferreira , Felipe Augusto Gorla , Mariana Gava Segatelli , Sueli Fumie Yamada Ogatta , Eduardo Costa Figueiredo , César Ricardo Teixeira Tarley
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引用次数: 0
Abstract
The present study describes a novel approach for designing a highly sensitive and selective electrochemical sensor for the detection of SARS-CoV-2 in saliva samples by sensing the S-protein, using an electrochemically controlled preconcentration. The sensor is based on electropolymerized molecularly imprinted polypyrrole (PPy) onto a screen-printed carbon electrode (MIP/PPy). The morphology of the MIP/PPy sensor was evaluated by SEM and AFM. The selectivity of the MIP/PPy compared to NIP/PPy was assessed by rebinding S-protein, followed by the monitoring of the redox probe ([Fe(CN)6]3−/4−). A substantial decrease in the anodic peak current of the redox probe was noticed when using the MIP/PPy. The detectability of the sensor was greatly improved (c.a 1,000,000 fold) by using controlled electrochemical preconcentration of S-protein at +0.6 V for 1.0 min in the rebinding process. Under this condition, a low limit of detection of 6.8fg mL−1 and an analytical curve in the range of 50.0–125.0 fg mL−1 (R2 = 0.996) was obtained. The reproducibility for 10 authentic sensors was highly satisfactory with a relative standard deviation (%,RSD) of 2.8 %. Upon preparation, the sensor can be stored for up to 14 days under refrigeration, with a response efficiency greater than 85 %. The MIP/PPy exhibited high selectivity toward S-protein compared to antitrypsin, human serum albumin (HAS), transferrin, HIgG, and lysozyme. The sensor was applied for detecting SARS-CoV-2 virus through S-protein in infected patients’ saliva samples and validated by RT-PCR. In addition, the satisfactory recovery (91 to 103 %) in S-protein spiked negative samples attested to the free-interference analysis.
期刊介绍:
The Microchemical Journal is a peer reviewed journal devoted to all aspects and phases of analytical chemistry and chemical analysis. The Microchemical Journal publishes articles which are at the forefront of modern analytical chemistry and cover innovations in the techniques to the finest possible limits. This includes fundamental aspects, instrumentation, new developments, innovative and novel methods and applications including environmental and clinical field.
Traditional classical analytical methods such as spectrophotometry and titrimetry as well as established instrumentation methods such as flame and graphite furnace atomic absorption spectrometry, gas chromatography, and modified glassy or carbon electrode electrochemical methods will be considered, provided they show significant improvements and novelty compared to the established methods.