key: cord-0430540-x245zow2
authors: Xue, Jian; Li, Ying; Liu, Jie; Zhang, Zixuan; Yu, Rongjun; Huang, Yaling; Li, Chaorui; Chen, Anyi; Qiu, Jingfu
title: Highly sensitive electrochemical aptasensor for SARS-CoV-2 antigen detection based on aptamer-binding induced multiple hairpin assembly signal amplification
date: 2022-05-28
journal: nan
DOI: 10.1016/j.talanta.2022.123605
sha: f489f55b64524abab8877d53b0850e06e8358d58
doc_id: 430540
cord_uid: x245zow2

In this work, a brief electrochemical aptasensor was developed for highly sensitive detection of SARS-CoV-2 antigen utilizing an aptamer-binding induced multiple hairpin assembly strategy for signal amplification. In the presence of SARS-CoV-2, a pair of aptamers was brought in a close proximity according to the aptamer-protein antigen binding, which initiated strand displacement reaction thereby triggering a multiple hairpin assembly to obtain long linear DNA concatemers on the electrode surface. As the fabricated hairpin probes were labeled with biotin, massive streptavidin-alkaline phosphatases (ST-ALP) could be further introduced on the electrode interface via biotin-streptavidin interaction thus generating strong electrochemical signal in electrolyte solution containing 1-naphthol phosphate. Benefiting from the non-enzymatic multiple hairpin assembly signal amplification strategy, the designed aptasensor for SARS-CoV-2 spike protein detection exhibited the wide linear range from 50 fgmL−1 to 50 ngmL−1 and low detection limit of 9.79 fgmL−1. Meaningfully, this proposed electrochemical assay provided a potential application for the point of care analysis of viral diseases under ambient temperature.

barely satisfactory, because the positive antibody test may indicate past infection, or 52 just vaccinated [10] . Conversely, antigen detection-based etiological examination 53 presents specificity comparable to nucleic acid detection but needn't rigorous 54 laboratory condition, expensive instruments and professional operation [11] , which has 55 promising application to on-site diagnosis of SARS-CoV-2 infection. However, limited 56 by the affinity of antibody, classical sandwich immunoassays present significant 57 deficiency in detection sensitivity. 58 Herein, an aptamer-binding induced multiple hairpin assembly was proposed to 59 construct an electrochemical biosensor for rapid and sensitive detection of SARS-CoV-60 2 spike protein. As shown in Scheme 1, a pair of aptamers was employed to probe the 61 target SARS-CoV-2 spike protein [12] . The sandwich aptamers/spike protein proximity when not in use. 

To investigate the fabrication process of the proposed electrochemical aptasensor, 197 the different stepwise modifications were investigated using CV and EIS. In EIS, the 198 semicircle diameter is equivalent to the electron transfer resistance (Ret), which 199 controls the electron transfer kinetics of the redox probes at the electrode interface [14] . CoV-2 antigen, respectively). The detection limit was calculated to be 9.79 fg•mL -1 (S/N 235 = 3). In addition, compared with other analytical methods for SARS-CoV-2 spike 236 protein detection (Table 2) , it could be found that the prepared electrochemical 237 aptasensor possessed a broader linear range and a lower detection limit due to the non-238 enzymatic multiple hairpin assembly signal amplification strategy. Fig. 4 (A) Specificity of the aptasensor for the detection of SARS-CoV-2 against the interference 272 substances: Blank, 50 ng•mL -1 MERS-CoV spike protein, 50 ng•mL -1 SARS-CoV spike protein, 50 273 ng•mL -1 HCoV-OC43 spike protein, 50 ng•mL -1 HCoV-HKU1 spike protein, 0.5 ng•mL -1 SARS-274

CoV-2 spike protein, and the mixture of 50 ng•mL -1 MERS-CoV spike protein, 50 ng•mL -1 SARS-275

CoV spike protein, 50 ng•mL -1 HCoV-OC43 spike protein, 50 ng•mL -1 HCoV-HKU1 spike protein, Table 3 , the RSD ranged from 0.42% to 2.88%, and the 283 recovery rate ranged from 95.01% to 106.52%. These results demonstrated that the 284 designed aptasensor was applicable for detection of SARS-CoV-2 antigen in clinical 285 analysis. 

In summary, an efficient aptamer binding-induced multiple hairpin assembly signal 

Discovery of aptamers targeting the receptor-binding domain of the 363

SARS-CoV-2 spike glycoprotein

High sensitive 365 electrochemical methamphetamine detection in serum and urine via atom transfer 366 radical polymerization signal amplification

Nanogold-penetrated poly(amidoamine)

electrochemical immunoassay of cardiac biomarker using cathodic stripping 370 voltammetric method

Magnetic beads combined with carbon black-based screen-printed electrodes for 374 COVID-19: A reliable and miniaturized electrochemical immunosensor for SARS-375

CoV-2 detection in saliva

Nanozyme 377 chemiluminescence paper test for rapid and sensitive detection of SARS-CoV-2 378 antigen

Fiber-optic label-free 380 biosensor for SARS-CoV-2 spike protein detection using biofunctionalized long-381 period fiber grating

This work was sponsored by Natural Science Foundation of Chongqing