Plasma-based instant synthesis of functionalized gold nanoparticles for colorimetric detection of lead ions

Colorimetric sensors offer great potential for simple, rapid, non-invasive, and on-site detection of target analytes. However, it remains challenging to achieve green and instant synthesis of colorimetric sensors with high sensitivity and selectivity. This work exploits plasma electrons as reductants to realize instant synthesis of glucose functionalized gold nanoparticles (G-AuNPs) and their use for colorimetric sensing of Pb2+ ions. Crystalline G-AuNPs with Pb2+-specific functional groups are successfully generated upon plasma exposure using a one-pot microplasma system. The G-AuNPs exhibit high sensitivity and selectivity for the rapid detection of Pb2+ against other metal ions. On this basis, an advanced microfluidic plasma system integrating plasma-liquid interaction and microfluidics is developed, allowing for not only the continuous G-AuNPs synthesis but also the colorimetric Pb2+ detection within 30 s. This novel system offers a green effective strategy to prepare highly sensitive and selective colorimetric sensors, and has great potential for in-situ, real-time sensing applications.