The lateral flow immunoassay (LFI) provides an unpowered and low burden solution to biological detection, but the detection targets are fixed for each device leading to slower validation of a new LFI.  Conversely, polymerase chain reaction (PCR)-based detection strategies are highly sensitive, specific, and PCR equipment can detect a new target by using new, easily-developed primer sets.  However, these solutions carry a higher burden; specifically, they require powered equipment and specialized training.  Here we present our “Dial-a-Threat" (DaT) assay concept, combining the speed and ease-of-use of an LFI with the specificity, sensitivity, and flexibility of PCR in a single-use, disposable, eye-readable colorimetric device.  Our first generation DaT assay utilizes RNA toehold switches to detect the target RNA through RNA:RNA hybridization, resulting in the translation of a reporter gene by lyophilized cell-free protein synthesis reagents embedded within a paperfluidic device.  Toehold switches can be swapped at the point of need to change the intended target organism.  Devices are constructed from a series of wax printed paperfluidic channels in chromatography paper and assembled with a 3D printed cassette.  The design is amenable to portable use in the field or a multiplexed setup for iterative testing.  The handheld device is designed to perform sample preparation steps, precluding the need for specialized training with the system.  The DaT device utilizes hydrogels to control directional diffusion and clustering of reaction components at specific sites on the paperfluidic tickets.  Automated detection, segmentation, and image processing of colorimetric reaction outputs streamline data collection and optimization.  Information gathered from each device iteration directly informs subsequent versions for improving signal output and shortening time-to-detection.  Each iteration advances the goal of developing a highly specific, sensitive assay with ultra-low burden on the end user.

Additive manufacturing and iterative design of biological detection devices

ACS Fall 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.