SERS detects single molecules in solution

17 Jun 2002

An MIT-Berlin group (Katrin Kneipp, 100342.530@compuserve.com) has used surface enhanced Raman scattering (SERS) to detect single dye molecules attached to colloidal silver particles suspended in an aqueous solution. The SERS technique, which can be used to detect single molecules, holds promise for applications in chemistry, biology, and medicine, as well as pollution monitoring. Examples include DNA sequencing and the tracing of biomedically interesting molecules, the group reports in an upcoming Physical Review Letters.

In Raman spectroscopy the light scattered inelastically from a molecule provides information about the molecule's vibrational quantum states. The rather weak Raman effect can be strengthened by a factor of up to 14 orders of magnitude if the molecules are attached to nm-sized metal structures. Advantages of this method are that it is fast, it can supply some structural information about the molecules, and it doesn't bleach the molecules.