Microneedle patches integrated with lateral flow cassettes for blood-free chronic kidney disease point-of-care testing during a pandemic

Chronic kidney disease (CKD) is the most neglected chronic disease affecting over 750 million persons in the world. Currently, many patients with cancers or other chronic diseases (i.e., CKD) struggle to receive clinical treatment or examination due to hospitals cancelling or delaying in the COVID-19 pandemic, which may increase the risk of death. Cystatin C (Cys C) has been proposed as a potential glomerular filtration rate (GFR) marker for the early detection of acute kidney injury and CKD. However, most traditional methods for Cys C detection are immunoassays using serum as a sample and are tedious to perform and economically burdensome. To diagnose the disease in the early stage and carry out daily management during the current pandemic, we developed an integration of hydrogel microneedle patch (HMNP) and lateral flow cassette (LFC) to rapidly detect Cys C in skin interstitial fluid (ISF) in 25 min for blood-free CKD management anytime and anywhere by the naked eye that can reduce the impact of an individual's quality of life and life expectancy. Conceivably, this strategy presents a wide scope in the application of numerous other diseases if corresponding analytes are available in skin ISF.