Ratiometric fluorescence sensor and smartphone-based microfluidic sensing platform based on oxidation induced Ce(III)/Ce(IV) phosphatase-like activity and complexation effect activation for sarcosine detection

Prostate cancer (PCa) has seriously affected men's quality of life and even endangered their lives. Thus, precise and reliable determination of related biomarkers in clinical samples is extremely important for early diagnosis and treatment of PCa. Sarcosine (Sar) is widely regarded as a potential biomarker for non-invasive diagnosis of PCa owing to its specific high-level expression in the development and metastasis of PCa. With the aid of Ce(III) as a bridge between 4-Methylumbelliferyl Phosphate (4-MUP) and orange emitted carbon dots (o-CDs), here we have constructed a new ratiometric fluorescence sensor for Sar determination by reasonably combining the phosphatase-like activity and complexation reaction characteristics of Ce(IV). This sensor indicates high sensitivity, exceptional selectivity, good reliability, and wide linear range of 0.2–120 μM with a detection limit of 89 nM. Besides, our proposed sensor demonstrates excellent precise and stability even in complex actual urine samples. Interestingly, an inexpensive, portable but reliable smartphone-based microfluidic sensing platform has been fabricated and successfully employed for precise determination of Sar in urine samples, which offers a powerful and convenient tool for the early diagnosis of PCa, and even inspires the research and development of other practical optical sensing devices for cancer home screening.