Gillian McMahon
B.Sc., Ph.D. (DCU/RCSI)
Lecturer, Analytical Chemistry

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Research

My group is the Bioanalytical Chemistry & Diagnostics Group (www.dcu.ie/bcd). The focus of our research is bioanalytical chemistry, especially for medical applications. Current projects include the development of novel bioanalytical methods for the determination of chemotherapeutic agents and their metabolites in blood, the study of crystals in the joints of patients with osteoarthritis with a view to improving diagnosis, proteomics in disease and the analysis of other pharmaceuticals in various matrices.

Analytical Techniques

Liquid chromatography, mass spectrometry and other separation, imaging and spectroscopic methods.

Some research results

Osteoarthritis project: Basic calcium phosphate (BCP) crystals are found in up to 70% of osteoarthritic joints. Current data suggest that BCP crystals represent a potential therapeutic target in OA. However, no simple test for BCP crystals is currently available. Analytically, we are working on devising sensitive and specific methods to detect and quantify BCP crystals in OA synovial fluid samples. We are using a number of approaches such as colorimetric analysis, Raman spectroscopy, atomic force microscopy and new fluorescent binding dyes for microscopy. We have also exploited this chemical specificity of bisphosphonates to create an extraction platform which can isolate calcium phosphate crystals from synovial fluid samples in a simple and selective manner. The extracted crystals can now be subjected to the analytical techniques above.

Anti-Cancer Drugs Project: Currently in Ireland, no analysis is carried out on the blood samples of cancer patients while they undergo chemotherapy. Such analytical data can be very valuable for tailoring dosing regimes and for individualisation of treatment. This project involves investigating the metabolic profiles of cancer drugs in plasma on an individual patient basis to detect how the drugs are being metabolised and to elucidate pharmacokinetic profiles. We are currently investigating the anthracycline and taxane groups of drugs and are using novel LC-MS/MS methods with on-line clean-up which will afford us greater levels of sensitivity than previously obtained, will require only limited sample volumes and which will capable of separating, quantifying and identifying all the compounds of interest in only a few minutes.

Partners

1. The Osteoarthritis project is in conjunction with Prof. Geraldine McCarthy, consultant rheumatologist from the Mater Hospital and Prof. Alastair Smith, Director of the Institute of Molecular Biophysics at the University of Leeds in the UK and is funded by Wellcome Trust.

2. The Cancer Research project is in collaboration with Dr. Robert O’Connor from The National Institute of Cellular Biology and is funded by DCU currently and previously Cancer Research Ireland.

 

Some recent publications are listed below:

1. Wall R, McMahon G, Crown J, Clynes M, O'Connor R. 2007. Rapid and sensitive liquid chromatography-tandem mass spectrometry for the quantitation of epirubicin and identification of metabolites in biological samples, Talanta, 72(1), pp145-154.
2. McMahon G, Analytical Instrumentation - A Guide to Laboratory, Portable and Miniaturised Instruments, Wiley & Sons, UK. ISBN: 9780470027950. November 2007.
3. Ruth D, McMahon G, O'Fagain C. 2006. Peptide Synthesis by Recombinant Fasciola hepatica Cathepsin L1. Biochimie, 88(1), pp117-120.
4. Lacey C, McMahon G, Morrissey A, Tobin J. 2006. A solid phase extraction and high performance liquid chromatography method for the detection of pharmaceutical compounds, Conference Proceedings of ENVIRON 2006, Environmental Sciences Association of Ireland (ESAI)
5. Schazmann B, McMahon G, Diamond D. 2005. Identification and Recovery of an Asymmetric Calix[4]arene Tetranitrile Derivative using Liquid Chromatography and Mass Spectrometry. Supramolecular Chemistry, 77 (5,, pp393-399.
6. Collins P, McMahon G, O'Brien P, O'Connor B. 2004. Purification, Sequencing and characterisation of Seprase from Bovine Serum. International Journal Of Biochemistry & Cell Biology, 36(11), pp2320-2333.
7. McMahon G, O'Malley S, Nolan K, Diamond D. 2003. Important calixarene derivatives - their synthesis and applications. ARKIVOC. vii, pp23-31.
8. Mc Mahon G, Collins P, O'Connor B. 2003. Characterisation of the active site of a newly-discovered and potentially significant post-proline cleaving endopeptidase called ZIP using LC-UV-MS. The Analyst, 128, pp670-675.
9. McMahon G, Minogue E, Diamond D. 2002. Taking a fresh look at sensors. IVD Technology. 8(3), pp43-48.
10. Lynch A, Eckhard K, McMahon G, Wall R, Kane P, Nolan K, Schuhmann W, Diamond D. 2002. Cation Binding Selectivity of Partially Substituted Calix[4]arene Esters. Electroanalysis, 14 (19-20), pp1397-1404.
11. McMahon G, Wall R, Nolan K, Diamond D. 2002. Characterisation of the Ester-Substituted Products of the Reaction of p-t-butyl calix[4]arene and Ethyl Bromoacetate using LC-UV-MS and LC-DAD. Talanta, 57(6), pp1119-1132.
12. Choudhary G, Chakel J, Hancock W, Torres-Duarte A, McMahon G, Wainer I. 1999. Investigation of the potential of capillary electrophoresis with off-line matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for clinical analysis: examination of a glycoprotein factor associated with cancer cachexia. Analytical Chemistry, 71(4), pp855-859.