A bacterial cellulose-based and low-cost electrochemical biosensor for ultrasensitive detection of SARS-CoV-2

COVID-19 has led to over 6.8 million deaths worldwide and con-tinues to affect millions of people, primarily in low-income countries and communities with low vaccination coverage. Low-cost and rapid response technologies that enable accurate, frequent testing of se-vere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vari-ants are crucial for outbreak prevention and infectious disease con-trol. Here we produce and characterize cellulose fibers naturally generated by the bacterium Gluconacetobacter hansenii as an alter-native biodegradable substrate for manufacturing an eco-friendly diagnostic test for COVID-19. Using this green technology, we describe a novel and label-free potentiometric diagnostic test that can detect SARS-CoV-2 within 10 min and costs US$3.50 per unit. The test has bacterial cellulose (BC) as its substrate and a carbon -based electrode modified with graphene oxide and the human angiotensin-converting enzyme-2 (ACE2) as its receptor. Our device accurately and precisely detects emerging SARS-CoV-2 variants and demonstrates exceptional sensitivity, specificity, and accuracy for tested clinical nasopharyngeal/oropharyngeal (NP/OP) samples.