Towards cold-atmospheric plasma jet printed gold nanoparticles on filter paper as a SERS substrate for detection of polystyrene particles in water

Plastic pollution is a major environmental and health threat due to its widespread presence in ecosystems and food chains. Despite extensive research on microplastics, the detection of submicron plastics remains challenging due to their distinct physical and chemical properties and the limitations of current analytical methods. SERS has attracted significant attention in recent research as an ultra-sensitive approach for detecting nanoplastics compared to other spectroscopy techniques. In this paper, a stable, biodegradable, waste-free novel paper-based SERS substrate is developed for the rapid detection of submicron (200 nm) polystyrene (PS) particles via the controlled deposition of AuNPs onto filter paper using an atmospheric cold plasma jet printing process. The density of AuNPs increases with the number of printing passes, correlating with enhanced SERS results. The resulting SERS substrates are capable of quantifying a broad range of PS concentrations (1–500 µg mL⁻¹) using just 5 µL of analyte. The fabricated SERS substrate enables reliable quantification of PS in water, exhibiting a strong linear correlation (R² = 0.993) between SERS intensity and PS concentration, with a detection limit of 10 µg mL⁻¹. These substrates demonstrate exceptional stability and reproducibility over a 10-week period, addressing key challenges associated with paper-based SERS substrates and making them suitable for long-term monitoring. Furthermore, analysis of tap water as a representative real-world sample demonstrates the practical applicability of the SERS substrate for environmental monitoring, revealing quantifiable levels of PS contamination.