The severe acute respiratory syndrome originated by the new coronavirus (SARS-CoV-2) that emerged in late 2019, known to be a highly transmissible and pathogenic disease, has caused the COVID-19 global pandemic outbreak. Thus, diagnostic devices that help epidemiological public safety measures to reduce undetected cases and isolation of infected patients, in addition to significantly help to control the population’s immune response to vaccine, are required. To address the negative issues of clinical research, we developed a Diagnostic on a Chip platform based on a disposable electrochemical biosensor containing laser-induced graphene and a protein (SARS-CoV-2 specific antigen) for the detection of SARS-CoV-2 antibodies. The biosensors were produced via direct laser writing using a CO₂ infrared laser cutting machine on commercial polyimide sheets. The presence of specific antibodies reacting with the protein and the K₃[Fe(CN)₆] redox indicator produced characteristic and concentration-dependent electrochemical signals, with mean current values of 9.6757 and 8.1812 µA for reactive and non-reactive samples, respectively, proving the effectiveness of testing in clinical samples of serum from patients. Thus, the platform is being expanded to be measured in a portable microcontrolled potentiostat to be applied as a fast and reliable monitoring and mapping tool, aiming to assess the vaccinal immune response of the population.

Aims The aim of the present work was to study the in vitro effect of native and recombinant Bauhinia variegata var. variegata lectins in inhibiting early adhesion of Streptococcus mutans, Streptococcus sanguis and Streptococcus sobrinus to experimentally acquired pellicle. Methods and Results Native lectin from B. variegata (BVL) was purified by affinity chromatography of extract of seeds. The recombinant lectin (rBVL‐I) was expressed in E. coli strain BL21 (DE3) from a genomic clone encoding the mature B. variegata lectin gene using the vector pAE‐bvlI. Recombinant protein deposited in inclusion bodies was solubilized and subsequently purified by affinity chromatography. The rBVL‐I was compared to BVL for agglutination of erythrocytes and initial adherence of oral bacteria on a saliva‐coated surface. The results revealed that rBVL‐I acts similarly to BVL for agglutination of erythrocytes. Both lectins showed adhesion inhibition effect on Step. sanguis, Step. mutans and Step. sobrinus. Conclusion We report, for the first time, the inhibition of early adhesion of oral bacteria by a recombinant lectin. Significance and Impact of the Study Our results support the proposed biotechnological application of lectins in a strategy to reduce development of dental caries by inhibiting the initial adhesion and biofilm formation.