Enhancing the Stability of COVID‐19 Serological Assay through Metal–Organic Framework Encapsulation

Wang, Yixuan; Wang, Zheyu; Gupta, Prashant; Morrissey, Jeremiah J.; Naik, Rajesh R.; Singamaneni, Srikanth

Enzyme‐linked immunosorbent assay is widely utilized in serologic assays, including COVID‐19, for the detection and quantification of antibodies against SARS‐CoV‐2. However, due to the limited stability of the diagnostic reagents (e.g., antigens serving as biorecognition elements) and biospecimens, temperature‐controlled storage and handling conditions are critical. This limitation among others makes biodiagnostics in resource‐limited settings, where refrigeration and electricity are inaccessible or unreliable, particularly challenging. In this work, metal–organic framework encapsulation is demonstrated as a simple and effective method to preserve the conformational epitopes of antigens immobilized on microtiter plate under non‐refrigerated storage conditions. It is demonstrated that in situ growth of zeolitic imidazolate framework‐90 (ZIF‐90) renders excellent stability to surface‐bound SARS‐CoV‐2 antigens, thereby maintaining the assay performance under elevated temperature (40 °C) for up to 4 weeks. As a complementary method, the preservation of plasma samples from COVID‐19 patients using ZIF‐90 encapsulation is also demonstrated. The energy‐efficient approach demonstrated here will not only alleviate the financial burden associated with cold‐chain transportation, but also improve the disease surveillance in resource‐limited settings with more reliable clinical data.