For long term iterations, the design of the microfluidic device that uses our platform can be improved to carry out an ELISA on-chip where more samples can be processed in parallel. fundamental image analysis of photos taken having a smartphone, which constitutes a useful alternate when lacking specialized products or a laboratory setting. Our automated ELISA on-chip has the potential to be used in a medical establishing and mitigates some of the burden caused by screening deficiencies. Keywords:SARS-CoV-2, COVID-19, spike protein, ELISA, antibodies, serology, on-chip, automated, microfluidics == 1. Intro == The coronavirus disease 2019 (COVID-19) is definitely caused by the severe GATA4-NKX2-5-IN-1 acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and was officially declared like a pandemic from the World Health Corporation (WHO) in March 2020. By July 2021, public records authorized over 200 million infections, 4 million deaths, and 3 billion COVID-19 vaccine doses given worldwide; additionally, several genetic variants have been identified so far [1,2,3]. Since its Mouse monoclonal to ERK3 inception, the efforts to contain this disease have consisted of confinement and molecular diagnostics. Real-time reverse transcription-polymerase chain reaction (RT-qPCR) is considered the platinum standard method to diagnose COVID-19, which is based on the amplification of SARS-CoV-2 genes (N,E,RdRp,orf1a, andorf1b) and its detection by fluorescent reporters from nasopharyngeal swab samples [4,5]. Additional molecular methods, such as immunoassays directed to detect viral antigens or anti-SARS-CoV-2 antibodies, have proven to be of utmost importance for pandemic mitigation [6,7,8]. Understanding how the levels of anti-SARS-CoV-2 antibodies fluctuate in recovered COVID-19 individuals and vaccinated individuals is definitely fundamental to better understand the disease, especially when discrepancies have been found in earlier reports [9,10,11,12]. Under the current conditions, where millions of viral infections exist, it is undeniable that vaccination is definitely of vital importance, and immunoassays have taken a particularly relevant part in identifying and monitoring individuals immune reactions over time. Therefore, several research groups possess proposed numerous COVID-19-related immunoassays, which are primarily based on viral antigens, such as the spike protein [13], receptor-binding website (RBD) [14], and nucleoprotein [15], and include different strategies ranging from the traditional enzyme-linked immunoassay (ELISA) to more complex microfluidic immunoassays [16,17,18]. Throughout the course of the COVID-19 pandemic, several diagnostic difficulties have emerged, particularly regarding the millions of tests required to face the disease spreading. Microfluidic systems are a encouraging approach that could solve some of those problems because they enable the integration and automation of total diagnostic protocols in one chip (i.e., lab-on-a-chip), including all the methods ranging from sample preparation to the detection and quantification of the analyte of interest [19]. A lab-on-chip provides the solutions of a traditional laboratory establishing but with the advantages of miniaturization, reducing the volume of reagents and incubation instances GATA4-NKX2-5-IN-1 [20]. Some of the problems that have restricted the widespread use of these systems in medical and biomedical applications are the developing processes to mass-produce these microfluidic products and GATA4-NKX2-5-IN-1 their subsequent functionalization to attach biomolecules to their surface [21,22]. Despite this, numerous microfluidic products have been developed in response to the problems posed from the COVID-19 pandemic. For example, in the diagnostic field, Fassy et al. reported a microfluidic qPCR capable of control 192 samples in parallel and quantifying the manifestation of different SARS-CoV-2 viral genes [23], whereas for serological screening, Swank et al. developed a microfluidic immunoassay for the detection of anti-SARS-CoV-2 IgG antibodies with the capacity to analyze several samples using a minimal volume of reagents [24]. In this work, we developed an automated ELISA on-chip capable of detecting anti-SARS-CoV-2 antibodies in serum samples from COVID-19 individuals and vaccinated individuals. In this 1st approach, we tackled some of the diagnostic difficulties related to technical limitations in the existing tests, such as the requirement of expensive products and on-site detection. The fact that all the steps of the immunoassay are automated increases the reproducibility of the assay by avoiding human error. Furthermore, the platform does not require specialized training for its operation, along with other advantages derived from the use of microfluidics, such as minimum sample manipulation, the use of a reduced volume of reagents, and the possibility of reading the results using the video camera of a smartphone. == 2. Materials and Methods == == 2.1. Sample Collection and Preparation == Blood samples GATA4-NKX2-5-IN-1 were collected and provided according to the protocol.