Paving the way to point of care (POC) devices for SARS-CoV-2 detection

Abstract

In this work we present a powerful, affordable, and portable biosensor to develop Point of care (POC) SARS-CoV-2 virus detection. It is constructed from a fast, low cost, portable and electronically automatized potentiostat that controls the potential applied to a disposable screen-printed electrochemical platform and the current response. The potentiostat was designed to get the best signal-to-noise ratio, a very simple user interface offering the possibility to be used by any device (computer, mobile phone or tablet), to have a small and portable size, and a cheap manufacturing cost. Furthermore, the device includes as main components, a data acquisition board, a controller board and a hybridization chamber with a final size of 10 × 8 × 4 cm. The device has been tested by detecting specific SARS-CoV-2 virus sequences, reaching a detection limit of 22.1 fM. Results agree well with those obtained using a conventional potentiostat, which validate the device and pave the way to the development of POC biosensors. In this sense, the device has finally applied to directly detect the presence of the virus in nasopharyngeal samples of COVID-19 patients and results confirm its utility for the rapid detection infected samples avoiding any amplification process.

Keywords: Electronically automatized potentiostat; POC biosensor; Portable; SARS-CoV-2.

Graphical abstract

Scheme 1

Scheme of the main components of the developed portable DNA biosensing device.

Fig. 1

DPV (red line) from −0.8 to 0 V and amperometric biosensor response (blue line) applying consecutive pulse potentials from −0.8 to 0 V. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)

Scheme 2

Hardware and software levels of potentiostat design

Fig. 2

Raspberry Pi 3B + block diagram.

Fig. 3

Web Interface and an example of Data Sample Graph.

Fig. 4

Current-time response (potential pulse of 0.5V) of the AA accumulated on the electrode surface before (Probe-SH/AuNT/CSPE (black line)) and after the hybridization with the complementary (CoV-2/Probe-SH/AuNT/CSPE (blue line)) and non-complementary sequence (CoV–2NC/Probe-SH/AuNT/CSPE (red line)) for an Autolab potentiostat (A) and our portable potentiostat (B). (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)

Fig. 5

A) Temperature registered in the hybridization chamber during the hybridization event. B) Comparison of the % signal increase after hybridization with the SARS-CoV-2 sequence (500 fM) at a conventional oven and the portable chamber.

Fig. 6

Biosensor response (represented as % signal increase), for both potentiostats, to the SARS-CoV-2 sequence (CoV-2) and a non-complementary sequence (CoV–2NC), used as a control. Data are presented as mean ± SD (n = 20 different electrochemical biosensing platforms). Statistical analysis was carried out using R software (R Development Core Team, Vienna, Austria). A Student T-test, with a T-test p-value < 0.05 or confidence interval of at least 95%, has been used to consider significant (sig) differences.