We demonstrate a streamlined microfluidic method that enables synthesis and <i>in-situ</i> patterning of a single layer of silver nanoparticles. The silver monolayer can act as active surface plasmon resonance substrate for precision detection of biomolecules. Compared to conventional approaches, microfluidics brings precise control over the reaction, uniform distribution of reagents, and fast kinetic mixing due to its intrinsic properties of large surface-to-volume ratio and rapid heating and mass transfer. The proposed microfluidic method also facilitates fast and green synthesis of silver nanoparticles with a very low consumption of the reagents at room temperature and pressure: 200 µL of 10% (3-Aminopropyl)triethoxysilane (APTES) in pure ethanol is pumped into the reversible spiral-shaped microchannel at a flow rate of 10 µL/min, and react with the hydroxyl groups on oxygen plasma-treated silicon substrate, serving as anchors for the seeding and subsequent growth of silver nanoparticles; then, after washing the substrate with pure ethanol, 1 mL of 50 mM silver nitrates in deionized water is pumped into the microchannel at the same flow rate, the continuous reduction of which by the APTES anchors form the silver nanoparticles with a size range of 0.775 ± 0.160 µm. The spiral-shaped microchannel provides controllable laminar flow, improved mixing, continuous synthesis, and convenient patterning for the fabrication. By tuning the flow rate and the concentration of reagents, we can easily obtain a silver monolayer, the morphology and component of which has been confirmed by scanning electron microscope and energy-dispersive X-ray analysis. The silicon substrate patterned with the silver monolayer has been exploited in surface-enhanced Raman spectroscopic detection down to 10 pM of Rhodamine B and 1 nM of 41-nt single-stranded deoxyribonucleic acids. Our strategy here provides a controllable, continuous and integrated approach of synthesizing nanomaterials for direct sensing of target materials on-chip with minimal contamination and background interference.

Microfluidic synthesis and patterning of silver nanoparticles for biomolecular sensing

2019 Fall National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.