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Highlights in Chemical Technology

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Analyte sensing made easy

17 August 2009

Spanish scientists have made antibody-coated nanoparticles that can detect bioanalytes indicative of drug abuse.

metabolite binding to antibody-coated nanoparticles

When the metabolite binds to the antibodies it causes a change in the SERS spectrum

Ramón Alvarez-Puebla and colleagues at the University of Vigo attached antibodies specific to a major cocaine metabolite, benzoylecgonine, to the surface of carbon nanotube-supported silver nanoparticles. They then added a solution of benzoylecgonine, which bound to the antibodies and caused a change in their structure. The team showed that surface-enhanced Raman spectroscopy (SERS) could be used to monitor the structural changes and determine the metabolite concentration.

The method can be performed in biological fluids, such as saliva or urine, says Alvarez-Puebla, and can determine not only the drug's presence but also the amount consumed. It could also be used to detect disease-related biomolecules, he suggests.

"It is a very elegant approach that takes an unintended consequence and uses it as a detection method - a slick trick!"
- Douglas Stuart, University of West Georgia, Carrollton, US
Current SERS analytical techniques usually require preparatory steps, such as the incorporation of labels that give a signal when molecules of interest are present. '[This method] is interesting because you do not need to prepare the sample at all,' Alvarez-Puebla comments. The method's sensitivity matches that of established techniques, he adds.

Douglas Stuart from the University of West Georgia, Carrollton, US, who specialises in SERS and nanotechnology, is impressed by the work. 'It is a very elegant approach that takes an unintended consequence [the structural change of the antibody] and uses it as a detection method - a slick trick!'

The group are now working on developing new sensors, including those capable of monitoring more than one analyte, for use in high-throughput screening.

Matthew Batchelor

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Link to journal article

Label-free SERS detection of relevant bioanalytes on silver-coated carbon nanotubes: The case of cocaine
Marcos Sanles-Sobrido, Laura Rodríguez-Lorenzo, Silvia Lorenzo-Abalde, África González-Fernández, Miguel A. Correa-Duarte, Ramón A. Alvarez-Puebla and Luis M. Liz-Marzán, Nanoscale, 2009, 1, 153
DOI: 10.1039/b9nr00059c

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