AIEgen-Based Cystatin C Quantitation for Chronic Kidney Disease Monitoring

The development of affordable, user-friendly diagnostic tools for early warning and monitoring of chronic kidney disease (CKD) is crucial to reducing CKD-related morbidity and mortality. Recently, smartphones have emerged as a promising option for point-of-care testing (POCT), circumventing the need for large, specialized, and complex instruments. However, because smartphone-based optical devices typically rely on cost-effective but low-performance hardware, developing sensing schemes with robust and stable optical signals to meet the sensitivity requirements of diverse POCT applications remains challenging.

Changqing Yi (Sun Yat-Sen University), Meijin Li (Fuzhou University), and Zhaofan Luo (Seventh Affiliated Hospital of Sun Yat-Sen University) reported:

a protein-templated AIEgen, Ir@BSA, which emits intense green phosphorescence with a quantum yield up to 69.40% and a lifetime up to 1839.40 ns in aqueous solution;
a straightforward protocol for cystatin C (Cys C) quantitation employing Ir@BSA as the phosphorescent signal indicator and papain as the biomolecular recognition element; and
a smartphone-based portable phosphorescence reader (SAPD) capable of stably exciting and accurately collecting phosphorescence signals from paper-based arrays.

Quantitation of Cys C in clinical serum samples using SAPD integrated with the paper-based arrays demonstrated high sensitivity (0.36 μg mL⁻¹) and specificity, cost-effectiveness (~67.5 USD per set), portability (~450 g), good precision (RSD ≤ 8.25%), good accuracy (comparable to the clinical standard latex immune-turbidimetric method), and high throughput (16 samples per experiment). Importantly, this study highlights the significant potential of Cys C as an early warning marker of CKD progression. The reported method enables Cys C quantitation anywhere, anytime, by anyone, and is ideally suited for mass CKD screening and home monitoring, facilitating early diagnosis and proactive disease management.