Reagent Filming for Universal Point‐of‐Care Diagnostics

Abstract

health centers or outdoor clinics, compact and simple POCT platforms, such as lateral flow assay (LFA), make diagnostic tests highly accessible, affordable, and easily operable by nonexperts without complex instrumentation, allowing for disease diagnosis in resource-limited settings. [3] As such, because POCT can be used in a wide range of environments, the components used for POCT, especially bio/chemical reagents involved in assays, must be maintained robustly to ensure reproducible and reliable test results regardless of the resource setting. [4] However, diagnostic tests for POCT are engineered based on assays and sensing principles employed in solution-based conventional laboratory tests; thus, they share labile biochemical reagents (i.e., antibodies (Ab), enzymes, nucleic acids, and organic/inorganic compounds) that benefit from a cold chain (4 or −20 °C) for stable storage. Nevertheless, most communities relying on POCT have uncontrolled environments, such as much higher temperatures than in laboratory settings and restricted cold-chain infrastructure, limiting the facile translation of well-validated diagnostic assays toward accessible POCT in the field. [5] This situation introduces a critical challenge in POCT, namely, realizing cold-chain-free storage of assay reagents that require a cold chain during transportation to and storage at the end-user location.Maintaining the stability of assay reagents is essential to ensure the quality and reliability of diagnostic tests. Healthcare issues, such as the COVID-19 pandemic and the shifting of cardiovascular diseases (CVD) toward developing countries, continue to occur globally. [6] Therefore, there is an increasing need for preventive and impactful disease control via POCTbased high-performance diagnostic measures (e.g., a high-sensitivity immunoassay or point-of-care nucleic acid test [POC-NAT]), [7] which utilize multiple reagents that are more sensitive than those in conventional POCT and therefore require strict maintenance of reagent stability. To resolve this problem, many commercial assays, such as POC-NAT, have adopted lyophilized reagents stored in disposable cartridges for cold-chainfree storage. [8] However, this requires centralized manufacturing facilities entailing costly maintenance/repair, [9] thereby increasing the assay cost and potentially limiting local distribution amidst a pandemic. [10] An approach under research, wherein the assay reagents are encapsulated in tablet shapes (using compression or casting methods), has been demonstrated as effective for cold-chain-free reagent storage. [11] However, the rigid Simplifying assays while maintaining the robustness of reagents is a challenge in diagnostics. This problem is exacerbated when translating quality diagnostic assays to developing countries that lack resources and infrastructure such as trained health workers, high-end equipment, and cold-chain systems. To solve this problem, in this study, a simple solution that films assay reagents to simplify the operation of diagnostic assay...

Micro- and nanosystems for the detection of hemorrhagic fever viruses

“…138 A polyvinyl alcohol-based film with abundant hydroxyl groups was recently developed by Han et al to encapsulate a variety of reagents ranging from biological to chemical materials. 350 This method showed the capability for stable, long-term reagent storage at elevated temperatures (at 25 or 37 °C) for six months. Additionally, quality control of diagnostic platforms for mass production is essential for commercial products, 351 despite receiving less attention in academic research.…”

Printable biosensors towards next-generation point-of-care testing: paper substrate as an example

“…This method incorporates premeasure, premix, and prepackage reagents, which can deliver assay reagents without cold storage and simplify quality diagnosis. 192 According to their study, the reagent filming holds excellent potential for streamlining and strengthening biochemical assays, providing a highly feasible approach to advancing cold-chain-free diagnostics.…”

Development of Solid-State Storage for Cell-Free Expression Systems

“…Multiple methods have been employed for the deployment of lyophilized CFPS and other complex systems, including beads produced by lyophilized droplets, paper-based devices, encapsulation, and synthetic polymers. ,− Existing platforms utilizing these methods are limited in their range of potential applications due to their bespoke nature, while other generalized methods are incompatible with complex biotechnologies like CFPS. Platforms confined to paper-based, textile systems, and other polymer-based porous matrices such as those developed to detect SARS-CoV-2 are useful as diagnostic devices but have been largely limited to this function. , The mismatch between the broad applications of complex biochemical systems like CFPS and the limitations of existing lyophilized platforms highlight a need for a versatile solid-state platform for storage and on-demand applications.…”