Automated ELISA On-Chip for the Detection of Anti-SARS-CoV-2 Antibodies

González-González, Everardo; Garcia-Ramirez, Ricardo; Díaz-Armas, Gladys Guadalupe; Esparza, Miguel; Aguilar-Avelar, Carlos; Flores-Contreras, Elda A.; Rodríguez-Sánchez, Irám Pablo; Delgado-Balderas, Jesus Rolando; Soto-García, Brenda; Aráiz-Hernández, Diana; Abarca-Blanco, Marisol; Yee-de León, José R.; Velarde-Calvillo, Liza P.; Abarca-Blanco, Alejandro; Yee-de León, Juan F.

The COVID-19 pandemic has been the most critical public health issue in modern history due to its highly infectious and deathly potential, and the limited access to massive, low-cost, and reliable testing has significantly worsened the crisis. The recovery and the vaccination of millions of people against COVID-19 have made serological tests highly relevant to identify the presence and levels of SARS-CoV-2 antibodies. Due to its advantages, microfluidic-based technologies represent an attractive alternative to the conventional testing methodologies used for these purposes. In this work, we described the development of an automated ELISA on-chip capable of detecting anti-SARS-CoV-2 antibodies in serum samples from COVID-19 patients and vaccinated individuals. The colorimetric reactions were analyzed with a microplate reader. No statistically significant differences were observed when comparing the results of our automated ELISA on-chip against the ones obtained from a traditional ELISA on a microplate. Moreover, we demonstrated that it is possible to carry out the analysis of the colorimetric reaction by performing basic image analysis of photos taken with a smartphone, which constitutes a useful alternative when lacking specialized equipment or a laboratory setting. Our automated ELISA on-chip has the potential to be used in a clinical setting and mitigates some of the burden caused by testing deficiencies.