Dual-functional Er3+-doped Ca₂SiO₄: Enhanced dopamine sensing and high-resolution latent fingerprint visualization

Dopamine (DA) detection is crucial for the assessment of various metabolic and neurological disorders, and electrochemical biosensors have been widely investigated because of their high sensitivity, rapid response, and analytical accuracy. In this work, a novel sensing platform was developed by modifying an electrode (ME) with Er-doped Ca₂SiO₄ (ECS) nanomaterials for the quantitative detection of DA. An optimized ECS loading of 4 mg produced a peak current of 297.2 μA, which was substantially higher than that of the bare electrode (197.2 μA), confirming the enhanced electrocatalytic activity of the modified electrode. The electroactive surface area was calculated to be 0.12 cm 2 , indicating improved electron-transfer characteristics. pH optimization revealed a maximum electrochemical response at physiological pH 7.0, with a slope of 0.05 V /pH, suggesting a proton–electron-coupled redox process. Scan-rate studies indicated diffusion-controlled kinetics, with strong linear correlations (R 2 = 0.99). Differential pulse voltammetry (DPV) demonstrated a linear response over the concentration range of 1–5 μM, with a limit of detection (LOD) of 0.38 μM and a limit of quantification (LOQ) of 1.28 μM. The ECS-ME retained 90.77% of its initial electrochemical response after 20 consecutive cycles and exhibited excellent repeatability (RSD = 1.55%) and reproducibility (RSD = 1.98%). Real-sample analysis yielded an average recovery of 92.1%, further confirming the reliability, stability, and practical applicability of the proposed method for DA detection. Overall, the ECS-modified electrode provides a sensitive and reliable platform for electrochemical DA determination. Additionally, β-Ca₂SiO₄:Er 3+ nanoparticles (NPs) exhibited green emission under 365 nm UV excitation and selectively adhered to fingerprint (FP) residues, enabling high-contrast visualization of latent fingerprint (LFP) ridge patterns on both smooth and challenging substrates. Uniform nanoparticle deposition facilitated the clear visualization of fine FP minutiae and accurate three-dimensional (3D) ridge profiling. These results establish ECS as an effective UV-excitable phosphor with promising potential for advanced LFP visualization and forensic applications.