Bioanalysis and Tagging using Surface Enhanced Raman Scattering and Metallic Nanoparticles

Surface enhanced Raman scattering is an extremely sensitive and selective technique that is rapidly emerging as an effective method for ultrasensitive analysis. It offers an increased enhancement over normal Raman scattering therefore is ideal for the detection of trace amounts of analyte and because of the molecularly specific spectra obtained it is ideal for detecting analytes in mixtures. The sensitivity of SERS also lends itself to stand off detection due to the intense signals which can be obtained from specially synthesised labels as well as ones which are commercially available. These labels, in combination with nanoparticles, can be used as coded labels due to their unique vibrational spectra allowing labelling of biomolecules for use in bioassays as well as tagging materials for anti-counterfeiting applications.
This project proposes to develop the technique and labels required to carry out detection of coded nanoparticles using excitation wavelengths above 785 nm e.g.1064 nm or 1280 nm in challenging environments. This will require synthesising different types of metal nanoparticles which have extinction profiles towards the infrared region of the electromagnetic spectrum and developing coatings for the nanoparticles that would protect them from various environments, while still being able to give a strong SERS response.
The aim is to develop a tagging system using SERS active labels which will allow SERS signals to be detected in the infrared where fluorescence is reduced and offers opportunities for the design of new bioassays.

Objectives
(1) To explore the synthesis of metal nanoparticles with red shifted absorbances. This will involve synthesising nanoparticles with different sizes, shapes and shell structures including gold and silver.
(2) To evaluate possible labels, both commercially available and synthesised in-house for use with 1064 nm and 1280 nm nm laser excitation with the synthesised nanoparticles to give maximum SERS enhancement.
(3) Evaluate matrices which can be used to protect or encapsulate the labelled nanoparticles and protect them from the environment and investigate the stability of the coded nanoparticles over time in challenging environments.
(4) To develop a coding scheme which will allow unique spectral signatures to be used to identify the SERS coded nanoparticles. This will involve multiplexing of different combinations of coded nanoparticles.
(5) To explore the use of these nanoparticles in a range of applications including bio analysis.

This project would suit a student with a background in chemistry or physics.