Point-of-care blood tests using a smartphone-based colorimetric analyzer for health check-up

A microscale colorimetric assay was designed and implemented for the simultaneous determination of clinical chemistry tests measuring six parameters, including glucose (GLU), total protein (TP), human serum albumin (HSA), uric acid (UA), total cholesterol (TC), and triglycerides (TGs) in plasma samples. The test kit was fabricated using chromogenic reagents, comprising specific enzymes and binding dyes. Multiple colors that appeared on the reaction well when it was exposed to each analyte were captured by a smartphone and processed by the homemade Check6 application, which was designed as a colorimetric analyzer and simultaneously generated a report that assessed test results against gender-dependent reference ranges. Six blood checkup parameters for four plasma samples were conducted within 12 min on one capture picture. The assay achieved wide working concentration ranges of 10.45–600 mg dL⁻¹ GLU, 1.39–10.0 g dL⁻¹ TP, 1.85–8.0 g dL⁻¹ HSA, 0.86–40.0 mg dL⁻¹ UA, 11.28–600 mg dL⁻¹ TC, and 11.93–400 mg dL⁻¹ TGs. The smartphone-based assay was accurate with recoveries of 93–108% GLU, 93–107% TP, 92–107% HSA, 93–107% UA, 92–107% TC, and 99–113% TGs. The coefficient of variation for intra-assay and inter-assay precision ranged from 3.2–5.2% GLU, 4.6–5.3% TP, 4.3–5.3% HSA, 2.8–6.6% UA, 2.7–6.5% TC, and 1.1–3.9% TGs. This assay demonstrated remarkable accuracy in quantifying the concentration-dependent color intensity of the plasma, even in the presence of other suspected interferences commonly present in serum. The results of the proposed method correlated well with results determined by the microplate spectrophotometer (R² > 0.95). Measurement of these six clinical chemistry parameters in plasma using a microscale colorimetric test kit coupled with the Check6 smartphone application showed potential for real-time point-of-care analysis, providing cost-effective and rapid assays for health checkup testing.