Nano-/micro-droplets for the detection of analytes
For a rapid and real-time SERS detection of organic chemicals in the air and the interfaces of air/solids, colloidal silver and/or gold nanoparticles solution is sprayed, in the form of nano-/micro-sized droplets, at the desired target area where the analytes of interest are present, e.g., in the air or onto certain organic/inorganic interfaces.
1. A process for detecting airborne analytes comprising:
(a) spraying a plurality of micro-droplets from a micro-droplet generator into a target volume of air, the micro-droplets comprising SERS-active nanoparticles, and the micro-droplet generator comprising an aerosol propellant;
(b) after analytes in the target volume of air have adsorbed onto the SERS-active nanoparticles in the micro-droplets, collecting the micro-droplets on a substrate; and,
(c) detecting via Raman spectroscopy the analytes adsorbed onto the SERS-active nanoparticles.
2. The process of claim 1 wherein the micro-droplets have a mean diameter of about 10 nm to about 500 microns.
3. The process of claim 1 wherein the nanoparticles comprise gold or silver.
4. The process of claim 1 wherein the aerosol propellant comprises compressed air, compressed nitrogen or chlorofluorocarbons.
5. The process of claim 1 further comprising: evaporating the micro-droplets after they are collected on the substrate, leaving the analytes adsorbed onto the SERS-active nanoparticles on the substrate.