Inkjet‐based microreactor for the synthesis of silver nanoparticles on plasmonic paper decorated with chitosan nano‐wrinkles for efficient on‐site Surface‐enhanced Raman Scattering (SERS)
Abstract
Abstract Here we report a synthesis approach that is simple, surfactant free, and green, and which is additionally cost effective in terms of its material requirements. The approach entails the use of an inkjet microreactor for the deposition of silver nanoparticles on the surface of office paper decorated with chitosan nano‐wrinkles for the preparation of a reproducible and sensitive paper‐based surface‐enhanced Raman scattering (SERS) substrate. Silver nanoparticles were synthesized directly in the head nozzles of the inkjet printer via the reduction of silver nitrate (AgNO 3 ) by ascorbic acid. Pre‐modification of the paper with chitosan allowed the formation of randomly oriented nano‐wrinkles on the surface, thus enabling the formation of silver nanoparticles with good hotspots. The novel paper‐based SERS substrate showed outstanding sensitivity and spot‐to‐spot reproducibility for on‐site detection using a portable Raman spectrometer with a limit of detection (LOD) of 10.7 pM. Moreover, our paper‐based SERS substrate has an excellent enhancement factor (EF) of 7.4 × 10 8 , which is difficult to achieve on a paper substrate because of the microporous nature of paper. Finally, the batch‐to‐batch reproducibility and long‐term stability of the SERS substrate under ambient conditions make this substrate a good candidate for point‐of‐care test applications.