Biocompatible CuBO ₂ Nanoplates as Portable Paper-Printed Colorimetric Sensing Platforms for Quantitative Dopamine Detection

As a crucial neurotransmitter, abnormal dopamine levels in the human body are linked to various neurological and psychiatric disorders, emphasizing the need for accurate detection of dopamine both in vitro and in vivo. In this study, we propose a highly sensitive colorimetric sensor for dopamine detection using CuBO 2 nanoplates. A surface adsorption-driven metal–ligand complexation, altering the surface charge, local dielectric environment, and light-matter interactions, leads to a color change from dark blue to greenish black. The colorimetric response spanned the linear range of 1–100 μM, with a lower detection limit of 226 nM, enabling trace-level detection. A paper-printed colorimetric sensing platform was developed to enhance its practical applicability, offering simplicity, portability, and cost-effectiveness. This device provides a rapid and reliable sensing platform for dopamine detection, with significant potential in clinical diagnostics, neurological research, and ensuring food safety and quality. To validate the sensor’s employability, real sample analysis was conducted using meat extracts, demonstrating reliable performance in complex biological matrices. Additionally, the toxicity of square and rectangular nanoplates of CuBO 2 was assessed to evaluate their biocompatibility profile for potential in vitro and implantable sensor applications. The results confirmed minimal cytotoxicity for rectangular nanoplates, supporting the biocompatibility of the sensing system.