Metal-Organic Framework Encapsulation for Biospecimen Preservation

Handling, transport, and storage of biospecimens such as blood and urine without refrigeration are extremely challenging. This formidable challenge leads to an inevitable reliance on a "cold chain" for shipping, handling, and storage of biospecimens throughout the world. The cold chain requirement precludes biospecimen procurement from underserved populations and resource-limited settings where refrigeration and electricity are not reliable or even available. Here, we introduce a universal biospecimen preservation approach based on nanoporous material encapsulation for preserving protein biomarkers in biofluids under normal (nonrefrigerated) storage conditions. Using urinary NGAL and serum/plasma CA-125 as the model protein biomarkers, we demonstrate that zeolitic imidazolate framework-8 (ZIF-8), a nanoporous material, encapsulation can preserve protein biomarkers in urine, serum, plasma, and blood at room temperature and 40 °C, with comparable preservation efficacy to the refrigeration method (freezing liquid samples at -20 °C). The protein biomarkers in the relevant biofluids are first encapsulated within the nanoporous crystals (i.e., ZIF-8) and then dried on paper substrates via a dry spot sample collection method, which would greatly improve biospecimen collection and handling capability in resource-limited settings. Overall, this energy-efficient and environmentally friendly approach will not only alleviate huge financial and environmental burden associated with "cold chain" facilities, but also extend biomedical research benefits to underserved populations by acquiring reliable clinical samples from regions/populations currently inaccessible.