Swift and accurate detection of tacrolimus concentration post-organ transplantation using a photonic crystal chip

Tacrolimus (FK506) is a potent immunosuppressant widely used to prevent rejection following organ transplantation. In this study, we employed a photonic crystal microarray-based competitive assay to measure tacrolimus blood concentrations, facilitating bedside and at-home monitoring for transplant recipients. The photonic crystal microarray technology offers flexibility, cost-effectiveness, and high efficiency. When integrated with a portable fluorescence intensity detector, it enables rapid and quantitative analysis. By fabricating the photonic crystal microarray and leveraging the photonic crystal bandgap enhancement effect to amplify the fluorescence intensity of probe molecules, the detection sensitivity is significantly improved. The photonic crystal microarray demonstrated a remarkable fluorescence enhancement factor of 17.2-fold compared to conventional substrates, significantly improving the sensitivity of tacrolimus detection. The optimized system achieved a detection limit of 0.4 ng·mL⁻¹, enabling rapid and accurate quantification of tacrolimus concentration within 20 min.