Exploring fluoropolymers for fabrication of femtoliter chamber arrays used in digital bioanalysis.

The global supply of fluoropolymers and fluorinated solvents is decreasing due to environmental concerns regarding polyfluoroalkyl substances. CYTOP has been used for decades primarily as a component of a femtoliter chamber array for digital bioanalysis; however, its supply has recently become scarce, increasing the urgency of fabricating a femtoliter chamber array using alternative materials. In this study, we investigated the feasibility of fabricating a femtoliter chamber array using four types of fluoropolymers in stable supply as candidate substitutes and verified their applicability for digital bioanalysis. Among these candidates, Fluorine Sealant emerged as a viable option for fabricating femtoliter chamber arrays using a conventional photolithography process. To validate its efficacy, we performed various digital bioanalysis using FP-A-based chamber arrays with model enzymes such as CRISPR-Cas, horseradish peroxidase, and ß-galactosidase. The results demonstrated the similar performance to that of CYTOP, highlighting the broader utility of FP-A in digital bioanalysis. Our findings underscore the potential of FP-A to enhance the versatility of digital bioanalysis and foster the ongoing advancement of innovative diagnostic technologies.

SATORI: Amplification-free digital RNA detection method for the diagnosis of viral infections.

With the recent global outbreak of COVID-19, there is an urgent need to establish a versatile diagnostic method for viral infections. Gene amplification test or antigen test are widely used to diagnose viral infections; however, these methods generally have technical drawbacks either in terms of sensitivity, accuracy, or throughput. To address this issue, we recently developed an amplification-free digital RNA detection method (SATORI), which can identify and detect viral genes at the single-molecule level in approximately 9 min, satisfying almost all detection performance requirements for the diagnosis of viral infections. In addition, we also developed practical platforms for SATORI, such as an automated platform (opn-SATORI) and a low-cost compact fluorescence imaging system (COWFISH), with the aim of application in clinical settings. Our latest technologies can be inherently applied to diagnose a variety of RNA viral infections, such as COVID-19 and Influenza A/B, and therefore, we expect that SATORI will be established as a versatile platform for point-of-care testing of a wide range of infectious diseases, thus contributing to the prevention of future epidemics. This article is an extended version of the Japanese article published in the SEIBUTSU BUTSURI Vol. 63, p. 115-118 (2023).