Functionalized thiazolidone-decorated lanthanum-doped copper oxide: novel heterocyclic sea sponge morphology for the efficient detection of dopamine.

Herein, we synthesized lanthanum (La)-doped sea sponge-shaped copper oxide (CuO) nanoparticles and wrapped them with novel O-, N- and S-rich (2,5)-3-acetyl-2-((3,4-dimethylphenyl)imino)-5-(2-oxoindolin-3-ylidene)thiazolidin-4-one (La@CuO-DMT). The shape and composition of the designed materials were confirmed by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and Raman spectroscopy. The graphitic pencil electrode (GPE) fabricated using La@CuO-DMT showed excellent sensing efficacy against dopamine (DA) with good selectivity, reproducibility and ideal stability. The unique morphology and massive surface defects by La@CuO offer good accessibility to DA and enhance smooth and robust channeling of electrons at the electrode-electrolyte interface. Consequently, these properties resulted in improved reaction kinetics and robust DA oxidation with an amplified faradaic response. Meanwhile, O-, N-, and S-enriched carbon support, DMT, inhibited the leaching of electrode matrixes, resulting in a superior detection limit of 423 nm and an improved sensitivity of 13.9 μA μM cm in the linear range of 10 μM to 1500 μM. Additionally, the developed sensing interface was successfully employed to analyze DA from tear samples with excellent percentage recoveries. We expect that such engineered morphology-based nanoparticles with a O-, N-, and S-rich C support will facilitate the development of DA sensors for screening of rarely studied tear samples with good sensitivity and selectivity.