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John McLean

Dean of Graduate Education and Research, College of Arts & Science
Stevenson Professor of Chemistry

Dr. McLean is currently accepting graduate students for Fall 2024 - APPLY TODAY


The McLean group research activities center around the development and application of advanced mass spectrometry technologies for structural and molecular scale measurements, primarily via ion mobility-mass spectrometry (IM-MS). IM-MS is an integrated, two-dimensional analytical technique that provides rapid (µs-ms) separations based on molecular size and mass. Our focus is on using IM-MS with other analytical separation dimensions (e.g., liquid chromatography, LC; and tandem MS) to perform broad-scale, untargeted measurements of individual molecules derived from biological origins, inclusive of metabolites, carbohydrates, lipids, peptides and proteins. This multidimensional mass spectrometry approach provides a comprehensive inventory of the individual molecules present within a given sample, which can be further interrogated on a per-dimension level to obtain specific molecular information.  For example, chemical hydrophobicity from LC, gas-phase size from IM; intrinsic mass from MS; and the connectivity of chemical bonds and function groups from tandem MS/MS. The elegance of this multidimensional MS approach is that all physiochemical properties can be obtained on a single measurement from microliters of sample, providing a basis for the rapid interrogation of large sample libraries to yield both a broad and deep chemical understanding at the systems biology level. 

Recent publications from the McLean group have described the development of next-generation IM-MS technologies and advanced informatics to interrogate data (including machine and deep learning), and applications of multidimensional MS technologies to a wide range of chemical challenges, including: chemical elucidation of pharmaceutical formulations, dynamics of protein unfolding, structural analysis of synthetic polymers, separation of chiral compounds and stereoisomers, molecular biosignatures of bio-engineered microorganisms and artificial organ constructs, isomers inherent in lipidomic studies, the chemical composition of foods, and the integration of precision metrology techniques to the ion mobility experiment.

Our current research efforts are situated at the nexus of collaborative research directions. We partner closely with world-leading institutions working in the areas of instrumentation development, biopharma, and non-profit organizations, among others, for the betterment of the environment and society. We work closely with collaborators both at Vanderbilt and beyond in medicine and health-related research where high-content, rapid chemical measurements are required. We also work closely in bioinformatics and machine-learning approaches to distill actionable information from these highly dense biomolecular datasets.