| Summary: | Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2008. === Includes bibliographical references (leaves 45-47). === Microfluidic affinity-based cell capture devices are presently able to isolate specific cell populations from heterogeneous samples, such as whole blood. The impact of this potentially powerful technology, however, is restricted by the fact that there is no reliable method to release the target cells from the capture surface while preserving their integrity. This work presents the development and evaluation of a functional hydrogel coating that supplements microfluidic capture devices to enable both specific capture and release. The hydrogels are formed by ionically crosslinking a microscale pre-functionalized alginate film on top of the capture substrate. After linking the antibody to the exposed functional sites, the gels may be used to capture cells of interest from physiological solutions. The captured cells may be released by applying a gentle chelating buffer which dissolves the gel, eliminating both the specific and the non-specific cell-surface interactions. This system was evaluated for its ability to capture cells from both buffer and blood. Capture efficiency was found to be equivalent to standard affinity-based devices, and the hydrogel system released 90% of the captured cells without affecting their viability. Finally, the system was validated by capturing and releasing rare circulating tumor cells (CTCs) from the whole blood of a prostate cancer patient; specific immunostaining indicated that the released cells were CTCs based on their expression of cytokeratin and prostate specific antigen. This technology has the promise to significantly influence both clinical diagnostics and basic medical research by enabling rapid enumeration and detailed genetic and phenotypic analysis of rare cell populations. === by Ajay M. Shah. === S.M.
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