Recycled cellulose/PVA/CMC-GO/NQS hydrogel as a noninvasive sarcosine sensor for prostate cancer screening

Recycled cellulose extracted from office wastepaper is an attractive material for manufacturing disposable sensors. By formulating a cellulose hydrogel nanocomposite, the sensitivity of the colorimetric sensor is notably improved, enabling simple observation of the color changes with the naked eye. In this study, a recycled cellulose/PVA/CMC-GO/NQS hydrogel nanocomposite was successfully prepared and applied as a noninvasive wearable sarcosine sensor integrated into a diaper. The prepared hydrogel-based colorimetric sensor operates via a nonenzymatic reaction using 1,2-naphthoquinone-4-sulfonic acid sodium salt (NQS) as a coloring reagent. NQS-functionalized graphene oxide (GO) facilitates the color-producing reaction by increasing NQS molecules adhering to both sides of the GO sheet via π-π interactions. This sensor exhibits a dramatic color change with a linear range of 0–100 μM (R² = 0.9550) and a detection limit of 10.0 μM, indicating that sarcosine can be effectively detected at its cutoff value (25.0 μM) for detecting prostate cancer (PCa). The sensing results tested in human urine samples were validated with a standard LDI-MS, which provided satisfactory results. Consequently, this sensor might be an alternative wearable sarcosine sensor for prostate cancer screening in the near future.