3D-printed microfluidic device for the synthesis of silver and gold nanoparticles

For the first time, a 3D-printed microfluidic device based on fused deposition modeling was created using poly (lactic acid) as the 3D-printed part on top of a poly(methyl methacrylate) slide, allowing the creation of transparent microfluidic channels and used on the continuous-flow synthesis of silver and gold nanoparticles. In order to reduce fouling inside the microchannels, the device was optimized to use a segmented flow of mineral oil. The synthesized nanoparticles were characterized by UV-Visible spectroscopy and scanning and transmission electron microscopy. Silver nanoparticles were synthesized using different concentrations of sodium borohydride and flow rates of reactants (30 and 120 mu L min(-1)) at 20 degrees C, with sizes ranging from 5 +/- 2 nm to 8 +/- 3 nm and verified to be stable for at least three weeks. Subsequently, the silver nanoparticles were applied on measurement of gallic acid using a modified carbon paste electrode. Gold nanoparticles were synthesized at 90 degrees C varying the concentration of trisodium citrate and flow rates of reactants (40 and 100 mu L min(-1)), yielding sizes from 20 +/- 9 to 34 +/- 12 nm and verified to be stable for at least three weeks. Afterwards, the gold nanoparticles were employed in surfaced enhanced Raman scattering using crystal violet as model molecule.