The rapid sampling and efficient collection of target molecules from a real-world surface is fairly crucial for surface-enhanced Raman scattering (SERS) to detect trace pesticide residues in the environment and in agriculture fields. In this work, a versatile approach was exploited to fabricate a flexible SERS substrate for highly sensitive detection of carbaryl pesticides, using in-situ grown silver nanoparticles (AgNPs)on non-woven (NW) fabric surfaces based on mussel-inspired polydopamine (PDA) molecules. The obtained NW@PDA@AgNPs fabrics showed extremely sensitive and reproducible SERS signals toward crystal violet (CV) molecules, and the detection limit was as low as 1.0 × 10⁻¹² M. More importantly, these NW@PDA@AgNPs fabrics could be directly utilized as flexible SERS substrates for the rapid extraction and detection of trace carbaryl pesticides from various fruit surfaces through a simple swabbing approach. It was identified that the detection limits of carbaryl residues from apple, orange, and banana surfaces were approximately decreased to 4.02 × 10⁻¹², 6.04 × 10⁻¹², and 5.03 × 10⁻¹² g, respectively, demonstrating high sensitivity and superior reliability. These flexible substrates could not only drastically increase the collection efficiency from multifarious irregular-shaped matrices, but also greatly enhance analytical sensitivity and reliability for carbaryl pesticides. The fabricated flexible and multifunctional SERS substrates would have great potential to trace pesticide residue detection in the environment and bioscience fields.

In this work, a series of highly flexible and sensitive surface-enhanced Raman scattering (SERS) substrates were fabricated by the in-situ growth of silver nanoparticles (AgNPs) on polydopamine (PDA) templated filter papers (FPs), based on mussel-inspired surface chemistry. The obtained FP@PDA@AgNPs strips exhibited high sensitivity and reproducibility with Rhodamine 6G (R6G) probe molecules, with a calculated detection limit of approximately 10⁻¹⁰ M. More critically, these FP@PDA@AgNPs strips could be used as outstanding flexible SERS sensors to quickly collect and detect malachite green (MG) residues on fish scales, crab shells and shrimp skins by a swabbing extraction method. The detection limits for MG residues were calculated to be approximately as low as 0.04635 pg/cm², 0.06952 pg/cm² and 0.09270 pg/cm², respectively. This facile and efficient strategy could to be utilized as a universal approach to fabricating a variety of flexible, cheap and portable SERS sensors for surface contamination analysis, and has great potential in the environmental scientific analysis and food safety monitoring fields.

An effective and facile strategy was developed to fabricate a flexible transparent metallic grid conductor based on the coffee ring effect with an inkjet printing technique. In this system, silver nanoparticles (AgNPs) were ink-jet printed to directly assemble into twin lines on flexible poly(ethyleneterephthalate) substrates and subsequently sintered at room temperature. Taking advantage of this approach, a highly flexible and transparent AgNPs grid-based conductor was successfully fabricated with a line width of 5–6 μm. The transmittance reached 93.6%, and the sheet resistance was less than 30 Ω sq⁻¹. This simple, cost-effective and non-lithographic approach improves the current fabrication approaches for the creation of patterned microstructures and has great potential to be tailored for the fabrication of optoelectronic devices.