We can't find the internet
Attempting to reconnect
Something went wrong!
Hang in there while we get back on track
Nanostructured gold electrodes with optimized properties for improved optical detection of polystyrene nanoparticles in suspension
Summary
Scientists developed a specialized gold sensor that can detect tiny plastic particles (nanoplastics) floating in liquid at very low concentrations—as little as 5 milligrams per liter—by giving the sensor's surface a positive electrical charge. This matters because nanoplastics are increasingly found in water and food, and better detection tools like this could eventually help scientists and regulators track how much of this pollution ends up in what we drink and eat. While this study is an early technical step rather than a health study itself, improving our ability to "see" nanoplastics is a key building block for understanding their potential risks to human health.
The manipulation of the surface properties of a plasmonic substrate is essential for achieving the proximity of an analyte to its surface as prerequisite for surface enhanced Raman scattering (SERS) spectroscopy. Here we studied the interaction of the five benzene derivatives 4-methylbenzene-1sulfonate, 4-vinylbenzenesulfonate, styrene (ethenylbenzene), polystyrene sulfonate (poly(4-vinylbenzenesulfonic acid)), and polystyrene (poly(1-phenylethylen)) for a plasmonic surface, with the intention to detect nanometer-sized polystyrene particles as nanoplastic model 2 analyte in suspension. Electrochemical roughening of screen-printed gold electrodes yielded cauliflower-like nanostructures that were (i) functionalized with self-assembled monolayers (SAMs) or (ii) polarized by applying static electric fields. We found that SAMs that lead to a positively charged electrode surface increased the signal intensities in SERS spectra of 4methylbenzene-1-sulfonate, 4-vinylbenzenesulfonate, polystyrene sulfonate and polystyrene nanoparticles. The detection of 4-methylbenzene-1-sulfonate and 4-vinylbenzenesulfonate was also enabled by application of a negative electrode potential. The strongest SERS signals of styrene were observed on a non-functionalized and neutrally polarized electrode surface, while the optimum spectral detection of the nanometer-sized polystyrene nanoparticles was attained with a positive potential. By electrokinetic manipulation, spectra of the nanospheres were obtained in suspension at a lowest concentration of 5 mg/L. Although the manipulation of both, the surface functionalization and the applied electric field improved the detection of the mono- and 1,4substituted benzene compounds, the electrosorption enables a more flexible and precise control over the adsorption/desorption process of the nanometer-sized polymer particles and is therefore a promising approach for the optical sensing of nanoplastics.