Design of Hydrogel Silk-Based Microarrays and Molecular Beacons for Reagentless Point-of-Care Diagnostics.

We have developed a novel microarray system based on three technologies: 1) molecular beacons designed to interact with DNA targets at room temperature (25-27°C), 2) tridimensional silk-based microarrays containing the molecular beacons immersed in the silk hydrogel, and 3) shallow angle illumination, which uses separated optical pathways for excitation and emission. Unlike conventional microarrays that exhibit reduced signal-to-background ratio, require several stages of incubation, rinsing, and stringency control, and measure only end-point results, our microarray technology provides enhanced signal-to-background ratio (achieved by separating the optical pathways for excitation and emission, resulting in reduced stray light), performs analysis rapidly in one step without the need for labeling DNA targets, and measures the entire course of association kinetics between target DNA and the molecular beacons. To illustrate the benefits of our technology, we conducted microarray assays designed for the identification of influenza viruses. We show that in a single microarray slide, we can identify the virus subtype according to the molecular beacons designed for hemagglutinin (H1, H2, and H3) and neuraminidase (N1, N2). We also show the identification of human and swine influenza using sequence-specific molecular beacons. This microarray technology can be easily implemented for reagentless point-of-care diagnostics of several contagious diseases, including coronavirus variants responsible for the current pandemic.

SARS-CoV-2 Vaccines Based on the Spike Glycoprotein and Implications of New Viral Variants.

Coronavirus 19 Disease (COVID-19) originating in the province of Wuhan, China in 2019, is caused by the severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2), whose infection in humans causes mild or severe clinical manifestations that mainly affect the respiratory system. So far, the COVID-19 has caused more than 2 million deaths worldwide. SARS-CoV-2 contains the Spike (S) glycoprotein on its surface, which is the main target for current vaccine development because antibodies directed against this protein can neutralize the infection. Companies and academic institutions have developed vaccines based on the S glycoprotein, as well as its antigenic domains and epitopes, which have been proven effective in generating neutralizing antibodies. However, the emergence of new SARS-CoV-2 variants could affect the effectiveness of vaccines. Here, we review the different types of vaccines designed and developed against SARS-CoV-2, placing emphasis on whether they are based on the complete S glycoprotein, its antigenic domains such as the receptor-binding domain (RBD) or short epitopes within the S glycoprotein. We also review and discuss the possible effectiveness of these vaccines against emerging SARS-CoV-2 variants.