Quantitative Nanoscale Imaging of Trace Elements in Biological Systems

The project we propose involves research into novel chemical imaging methodology for 2D and 3D visualisation of trace elements in cells and tissues with greatly improved sensitivity, easy of reliability and magnification over current approaches. The technology includes powerful lasers for the uniform and highly sensitive detection of atoms and small molecules ejected from biological specimens under bombardment from high energy particles. The result is a multi-element chemical map of the specimen showing detail on the sub-cellular length scale. We shall demonstrate the power of this approach in the detection and localisation of cancer drugs in cells and model tissues. However, the methodology we will develop will be more widely applicable in a number of important biological problems involving trace element transport, storage and distribution. This includes but is not limited to drug development, disease diagnosis and fundamental cell biology.

Analytical techniques including those able to identify and quantify trace elements in cells and tissues have contributed to a greater molecular level understanding of biology. However many important questions remain unanswered, for example concerning the cellular structures involved in processes associated with drug uptake and disease progression. To complement the range of analytical tools currently available there is a clear need for the quantitative determination of elemental species, in particular metals, at the sub-cellular level and in the context of the physiological environment. In this project we seek to demonstrate the huge advantages that the method of laser sputtered neutral mass spectrometry (L-SNMS), which has been highly successful in other disciplines, can bring to biology. The approach involves scanning a focused (50 nm) ion beam across the sample surface ejecting atomic and molecular fragments highly characteristic of the surface chemistry. A pulsed laser beam is then used to ionise all the species within a defined region above the sample, and the resultant ions are subjected to mass spectrometric detection. The result is a pixel-by-pixel series of mass spectra that can be manipulated to display chemical images, in 2D or 3D. The laser can be tuned (resonant) or detuned (non-resonant) to ionise selective atoms or all atoms within the laser focus with 100% efficiency. The focus of this project is the enahanced detection and imaging of metallo-drugs in cells and tissue models. Cell cultures and multicellular spheroids will be exposed to drug e.g. cisplatin and analysed using L-SNMS. We seek to demonstrate very significant (in excess of x10) sensitivity increases and more uniform limits of detection over the related technique of secondary ion mass spectrometry (SIMS).

The project proposed will demonstrate the full capability of our technology applied to quantitative elemental imaging in biological systems, and reveal unique potential for its development. If successful, this development will be very significant and provide an enormously powerful new tool for imaging cells and tissues to help understand cellular and metabolic processes, which could impact on research across disciplines from fundamental cell biology, through to healthcare, medicinal screening and diagnostics. Whilst these are high risk areas of research the scientific expertise and state-of-the-art instrumentation is very likely to provide exciting lines for development and provide opportunities for broader impact. The immediate beneficiaries include academic groups involved in developing related bioanalytical technologies. In the longer term this research has the potential to impact much more widely. Greater understanding at the cellular level of the role of metals in health, dietary metabolism, disease and therapeutic intervention will have widespread implications across a number of sectors. For example, private sector pharmaceutical manufacturers will gain new scientific insights to inform the design, development and commercialisation of new drugs and drug targets. This would foster economic competitiveness. Policy makers and charitable organisation will in turn have new evidence on which to base strategic decisions regarding public health, including the allocation of funding for clinical trials. This in turn would impact on the nation's health and wealth, improving quality of life.