Richard Mendelsohn

Distinquished Professor

office: 973-353-5613

Research Interests

Our research, which has been supported for the past twenty years by the National Institutes of Health, centers around applications of infrared spectroscopy to biophysical and biomedical problems. Three projects currently underway offer a good illustration of the nature of this work. (1) We have designed and built a unique spectrometer interfaced with a surface balance to acquire IR spectra from monomolecular films of phospholipids and proteins at the air/water interface. The device has been used to test the "squeeze-out" hypothesis of lung surfactant function, a central issue in pulmonary physiology. Future work will involve precise determination of biomolecular conformation and orientation at the air/water interface. (2) We have developed IR experiments to quantitatively describe the nature and location of conformational disorder in phospholipid acyl chains. This approach has been used to determine the physical state of the membranes in living cells of a microorganism. Future work will examine the molecular basis of homeoviscous adaptation (how biological membranes respond to environmental alterations), as well as development of additional spectra-structure correlations. (3) We have undertaken the first IR Microscopy studies of bio-mineralizing tissues. Methods have been developed to determine the size and perfection of the hydroxyapatite crystals in diffraction limited (10 micron) samples, the orientation of carbonate ions which substitute for the phosphate in the hydroxyapatite lattice, and the relative amounts of mineral and protein in various tissue sites. Each of these quantities is altered during pathological states such as osteoporosis or vitamin D deficiency. Future work will attempt to develop biodiagnostic assays for the efficacy of therapeutic interventions.