Researchers have created a novel caffeine sensor using zinc-doped tin oxide nanoparticles as an electrocatalyst. This study, published in the journal BME Frontiers, described a sensor that exhibits exceptional sensitivity and selectivity, opening the door for cutting-edge uses in food safety, healthcare, and environmental monitoring.
The actual sample sources, the spiking amounts of caffeine, and the amounts calculated using the fabricated sensor. Image Credit: Kumar Lab@ PEC.
The research team created the zinc-doped tin oxide (Zn-SnO₂) nanoparticles using a simple co-precipitation technique. After a controlled pH adjustment, the nanoparticles were annealed using zinc sulfate heptahydrate (ZnSO₄·7H₂O) and tin chloride dihydrate (SnCl₂·2H₂O) as precursors.
The resultant Zn-SnO₂ nanoparticles were subsequently coated onto a gold electrode using Nafion as a binder to create a highly effective working electrode.
The Zn-SnO₂ nanoparticles were characterized by X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-Vis), field emission scanning electron microscopy (FESEM), and electrochemical impedance spectroscopy (EIS).
They showed an average crystallite size of 33.23 nm and a tetragonal phase structure. The nanoparticles were uniformly spherical, with diameters ranging from 40 to 60 nm, and showed strong absorption at 260 nm, which corresponded to a bandgap energy of 3.77 eV.
According to electrochemical investigations, a bare electrode did not react to caffeine, whereas the modified electrode did. With a sensitivity of 0.605 μA μM⁻¹ cm⁻² and a detection limit of 3 μM, the reduction peak current rose linearly as the caffeine concentration increased between 5 and 50 μM.
Possible interfering substances like citric acid, ascorbic acid, glucose, sucrose, theobromine, and theophylline showed little interference with the sensor.
The sensor's practical applicability was confirmed by effectively determining the caffeine content of several actual water samples, such as tap water, groundwater, and canal water. These outcomes highlight the sensor's potential for practical uses.
The study results are noteworthy because they present a novel strategy for creating electrochemical sensors based on nanomaterials. The Zn-SnO₂ nanoparticle-based caffeine sensor is a promising instrument for various uses due to its high sensitivity and selectivity.
Environmental monitoring helps detect caffeine levels in water bodies, contributing to water pollution assessment. For food safety, the sensor ensures the quality and safety of beverages, dietary supplements, and pharmaceuticals by precisely measuring caffeine content. In healthcare, it monitors caffeine levels in the body, aiding in evaluating its effects on individual health.
To sum up, the creation of this highly effective caffeine sensor marks a substantial breakthrough in sensor research and nanotechnology. With its remarkable sensitivity, selectivity, and adaptability, the sensor has enormous potential for various uses, advancing personal healthcare, food quality control, and environmental protection.
As this area of study develops, we may anticipate more breakthroughs that use nanomaterials' special qualities to solve urgent problems across a range of sectors.
Journal Reference:
Bhanjana, G., et al. (2025) Direct Redox Sensing of Caffeine Utilizing Zinc Doped Tin Oxide Nanoparticles as Electro-Catalyst. BME Frontiers. doi.org/10.34133/bmef.0099.