In Vivo Reporting using Nanosystems Chemistry and Optical Spectroscopy

The research focus of this feasibility account is in the application of nanoscience into living systems for improvement of health. There are two themes which run through this research focussing on diagnostics and therapeutics. Our existing Platform Grant has allowed us to start looking at functionalised nanoparticles as responsive nanosensors for analysing cell receptors and enzyme activity within cells based on the change in surface enhanced Raman scattering in a number of target systems. The focus so far has been on immunologically compromised cells and, through very exciting preliminary data and discussion with interested, more clinically based parties, we propose to use this feasibility account to allow us to conduct preliminary studies transposing our research to the next level and to that of genuine in vivo experimentation and implementation of nanoscience. So far, the focus has been on diagnostic information retrieval however, here we propose to couple this with a therapeutic aspect. The mounting of biological drugs, such as therapeutic antibodies, onto nanoparticles appears to have significant effect on the efficacy of the drug when used in vitro. To test this in vivo is very challenging and largely an unknown entity. New biological drugs that have been developed are not fully characterised in terms of where they locate within a body and where they provide their most beneficial action. Despite this, FDA approval has been given and we propose to use our combination of nanoscience, spectroscopy functionalisation and immunological/clinical expertise to create a series of cross disciplinary highly adventurous in vivo experiments with a view to pump priming a much larger and consolidated programme of work.

This was a one year proposal which brought together physical scientists and immunologists to investigate the potential for using functionalised nanoparticles as in vivo reporters of inflammation. We prepared a set of gold nanoparticles which were functionalised with a specific antibody which would immobilise the nanoparticles on inflamed tissue. We then compared these nanoparticles with fluorophores attached to the same antibody to allow a comparison between these two optical techniques which are commonly used in bioanalysis. The main hypothesis being tested was to examine whether these nanoparticle systems could be used in vivo and then how well they compared to fluorescent tags. The target we used was atherosclerotic plaque build-up in the aorta of mice. Initially we compared harvested tissues and were able to examine the aorta of mice with atherosclerotic plaques using both fluorescence and SERS and also control antibody functionalised nanoparticles and fluorophores. We were able to discriminate very accurately the sites of inflammation in the aorta using the functionalised nanoparticles and were able to prove that the signal to noise ratio was superior to that obtained by fluorescence. This gave us confidence to go ahead and try some genuine in vivo analysis where we were able to examine the plaque build-up in the mouse ear using two photon fluorescence microscopy to provide the depth penetration for the fluorescence and then using a SERS based approach to look for the functionalised nanoparticles. Again we were able to compare signal to noise ratios and found a much bigger discrimination possible using the functionalised nanoparticles. This was a highly significant finding and was the first genuine comparison between functionalised nanoparticles and SERS versus fluorescence for in vivo analysis. We have gone on from this preliminary result to seek further funding in this area to target more extensive biomedical experimentation.