Synthesis and Characterization of Surface-Functionalized Magnetic Polylactide Nanospheres

Type of Document Dissertation
Author Ragheb, Ragy Tadros
URN etd-04092008-121127
Title Synthesis and Characterization of Surface-Functionalized Magnetic Polylactide Nanospheres
Degree PhD
Department Macromolecular and Science Engineering
Advisory Committee
Advisor Name Title
Dr. Judy S. Riffle Committee Chair
Dr. James E. McGrath Committee Member
Dr. Richey M. Davis Committee Member
Dr. S. Richard Turner Committee Member
Keywords

* confined impingement jet mixing
* nanoprecipitation
* surface-functionalized
* nanospheres
* magnetic
* magnetite
* poly(ethylene oxide)
* L-lactide)
* poly(D
* polylactide

Date of Defense 2008-03-28
Availability unrestricted
Abstract

Polylactide homopolymers with pendent carboxylic acid functional groups have been designed and synthesized to be studied as magnetite nanoparticle dispersion stabilizers. Magnetic nanoparticles are of interest for a variety of biomedical applications including magnetic field-directed drug delivery and magnetic cell separations. Small magnetite nanoparticles are desirable due to their established biocompatibility and superparamagnetic (lack of magnetic hysteresis) behavior. For in-vivo applications, it is important that the magnetic material be coated with biocompatible organic materials to afford dispersion characteristics or to further modify the surfaces of the complexes with biospecific moieties. The acid-functionalized silane endgroup was utilized as the dispersant anchor to adsorb onto magnetite nanoparticle surfaces and allowed the polylactide to extend into various solvents to impart dispersion stability. The homopolymers were complexed with magnetite nanoparticles by electrostatic adsorption of the carboxylates onto the iron oxide surfaces, and these complexes were dispersible in dichloromethane. The polylactide tailblocks extended into the dichloromethane and provided steric repulsion between the magnetite-polymer complexes. The resultant magnetite-polymer complexes were further incorporated into controlled-size nanospheres. The complexes were blended with poly(ethylene oxide-b-D,L-lactide) diblock copolymers to introduce hydrophilicity on the surface of the nanospheres with tailored functionality. Self-assembly of the PEO block to the surface of the nanosphere was established by utilizing an amine terminus on the PEO to react with FITC and noting fluorescence.

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