Degenerative disc disease, one of the leading musculoskeletal disorders confronting our healthcare system, is significant for its varied clinical manifestations, morbidity and costs. Degenerative disc disease is an irreversible process leading to loss of the intervertebral disc mechanical integrity. State-of-the-art spin-relaxation-based MRI techniques fall short of detecting early degenerative changes, and are insufficient in diagnosing annular tears. In collaboration with Michele Marcolongo (Department of Materials Science, Drexel University) and Edward Vresilovic (Department of Orthopaedic Surgery, Penn State College of Medicine), we are working on development of multiple quantum magnetic resonance spectroscopy and imaging methods that will provide early probes of degenerative disc disease.

Metal sites are ubiquitous in proteins.  According to various estimates, approximately one-third of all proteins and enzymes require metals as cofactors for biological function.  Proteins containing metal cofactors have the most intriguing biological functions.  Metal sites in these proteins play diverse roles, such as structural, catalytic, binding, storage, and electron transfer. A variety of techniques (X-ray crystallography, solution NMR, EPR, optical spectroscopies) have been used to elucidate the structure of metal sites and establish relationships between the structural details and the function of metalloproteins.  Despite the tremendous body of information regarding the structure and function of metal sites in metalloproteins accumulated using these different structural and spectroscopic techniques, a large number of important and interesting questions remain unanswered.  One class of metalloproteins we are interested in studying are transition-metal containing diamagnetic proteins.  The metals in these proteins are also said to be in their “spectroscopically silent” states, and solid-state NMR is one of very few methods that can directly probe these states of metals.  Our current focus is vanadium (V) containing proteins and bioinorganic solids.

 
Polyoxometalates are attractive for design of new materials, due to diverse chemistry, and favorable structural and electronic properties. Vanadium-containing polyoxometalates have become the object of interest in optoelectronics due to their putative electro-, photo-, and thermochromism, and potential applications as solid nanocomposite molecular devices. Mixed- valence V(IV)-V(V) oxoanionic clusters possess unusual magnetic properties. Incorporation of lanthanides into the oxoanion core allows for tuning the catalytic, photochemical and electronic properties of polyoxometalates. And recently, actinide derivatives of polyoxoanionic compounds have received attention due to their potential applications for actinide separations. Therefore, interest in design of polyoxoanionic materials for novel applications is ever growing. Polyoxoanionic materials are often fabricated as hybrid organic-inorganic films or as amorphous solids lacking long-range order. Therefore, these materials are not amenable to detailed structural analysis by diffraction-based methods. We have been working on development of ⁵¹V and ³¹P solid-state NMR spectroscopy as a structural probe in diamagnetic and paramagnetic polyoxoanionic solids. 

Much of our work involves development of new solid-state NMR methods for studies of structure and function of biological and inorganic materials above.