Photonic Crystal Microarray–Assisted Point-of-Care Testing for Rapid and Convenient Detection of Microalbuminuria

Diabetic kidney disease (DKD) remains one of the most serious complications of type 2 diabetes, significantly impacting patients' morbidity and mortality. Microalbuminuria (mALB), a clinically validated biomarker, plays a key indicator for both early diagnosis and predicting the progression of DKD. However, existing point-of-care testing methods for albumin detection often suffer from limited sensitivity and operational complexity. To overcome these challenges, we developed and evaluated a fully printed, photonic crystal-integrated microarray-assisted point-of-care platform specifically designed for the rapid and precise detection of mALB. The system employs polymer latex microspheres, selected for their optical compatibility with detection fluorophores, as signal-enhancing carriers. By exploiting the photonic bandgap and photon localization effects inherent in photonic crystal structures, the platform significantly amplifies fluorescence signals in immunoassays, thereby substantially enhancing detection sensitivity and resolution. A detection method based on a double-antibody sandwich immunoassay was employed, enabling specific antigen-antibody binding and accurate quantification. Validation using clinical urine samples demonstrated the diagnostic efficiency of the platform. The full analysis can be executed in under 10 min, demonstrating a robust linear association between the fluorescence level and the mALB content.. The platform achieved a detection limit of 19.5 pg mL^-1 and an accuracy of up to 92.9%. Further validation with 70 clinical urine samples confirmed that the platform exhibited a good diagnostic performance, demonstrating high sensitivity, specificity, and operational stability. In summary, this photonic crystal microarray-based point-of-care system offers a sensitive, accurate, and time-efficient solution for early DKD diagnosis and long-term disease monitoring. Its convenience and portability render it ideal for frequent assessments and long-term patient care, possibly enhancing results and decreasing medical expenses.