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Researchers:
Svetlana Sukhishvili

Background:
This project is focused on endowing polymer biomedical coatings with self-healing and drug-release capabilities. These polymer coatings are self-assembled using polyphosphazenes (PPzs) – ‘hybrid’ polymers with inorganic backbones and organic side groups80-81. The unprecedented intrinsic flexibility of the PPz backbone82, facile tunability of their degradation resulting in physiologically benign degradation products83-84, unique structural diversity, and a proven record of their preclinical and clinical safety85-86make PPzs promising biomaterials. PPzs can be made to have low glass transition temperature (to support film healing and bio/hemo-compatibility) and contain ionic functionalities (to enable assembly and inclusion of bioactives), as well as to exhibit a tunable degradation rate for controlled drug release. We hypothesize that PPzs are ideal candidates for constructing novel biomaterials coatings via layer-by-layer assembly of polyelectrolytes87– a technique unsurpassed in its ability to coat substrates of arbitrary shapes and host bioactive cargo88. Our preliminary experiments demonstrated that PPz-containing films could be coated on Ti and Dacron® mesh substrates, and that PPz/polycation LbL films demonstrated self-healing capabilities.

Research Plan:
The REU student will work with a graduate student to develop, construct and characterize coatings composed of PPzs and heparin – an anti-coagulant bioactive whose presence in the films is critical for enhancing biocompatibility of cardiovascular stents. The student will construct several types of the films using PPzs with varied degradation rates, and explore how degradation of PPzs affects release of heparin from the coating. While ellipsometry will be the main tool for characterization of film construction, degradation and heparin release, the student will be also be exposed to mass spectrometry analysis for quantification of the released amounts, and atomic force microscopy for studies of film healing. The student will further enrich her/his experiences by participating in group meetings of Sukhishvili’s lab. Through this summer program, the REU student will learn to design, construct and characterize bioactive coatings, and the importance of multifunctional coatings for stent-related applications.