Highly sensitive and wash-free human serum albumin detection based on filtration-to-enhancement compound microsphere system

Human serum albumin (HSA) in blood testing is clinically important in assessing nutrition, liver and kidney function, inflammation, and chronic diseases. However, traditional HSA testing methods require large equipment, high costs and specialized operators, which cannot meet the demand for portable HSA detection. Here we present a filtration-to-enhancement compound microsphere module (F-ECMs), which achieves wash-free and highly sensitive HSA detection. The F-ECMs utilizes tightly linked filtration module and enhancement module to provide wash-free detection while reducing the limit of detection (LoD) of HSA by 2.048-fold. The filtration module utilizes 30 μm encoded microspheres to achieve wash-free detection, and the enhancement module utilizes the focusing and microcavity effects of 8 μm microsphere for fluorescence enhancement. Customized homomorphic filters can further enhance the image signal and achieve highly sensitive HSA detection. Integrated portable device and smartphone app analysis module enables point-of-care testing (POCT). In this study, the LoD of HSA in blood reaches 0.375 mg/mL and the detection range is 0.1 – 100 mg/mL. The detection time is only 20 min. Double-blind detection was performed on 29 real plasma samples from patients, and its accuracy was achieved 93.10%. This platform provides a new wash-free and fluorescence enhancement strategy for portable HSA detection with high specificity and sensitivity.