Selecting the appropriate polymer chemistry is critical in the design of erodable polymer devices that can be used as delivery agents for the controlled release of therapeutics. Degradable polymers find use in myriad applications, from green packaging (degradable plastic bottles and shopping bags) to long-term controlled delivery of drugs, proteins and peptides. However, the basic principles governing the erosion process and design rules for modulating erosion behavior remain unclear. We aim to use the techniques of synthetic chemistry to correlate polymer structure with desirable hydrolytic degradation properties of hydroxy acid based polymers. Properties of interest include the polymer erosion mechanism, internal pH of the degradable device, and stabilization of therapeutics.
We are synthesizing fluorescent quantum dot (QD) nanoparticles by microwave enhancement chemistry in a research microwave. Fluorescent quantum dots are collections of semiconductor atoms on the order of a few nanometers. Their emission properties are dictated by the semiconductor surface state, the electronic traps of the nanoparticles, and the size and shape of the particle. Quantum dots are an emerging alternative to traditional dyes for solar cells and bioimaging because of the ability to tailor the QD surface chemistry, their high quantum efficiency, and their stable emission. Typical fluorescent dyes undergo rapid photobleaching which reduces the dyes ability to work as a label. Also, quantum dots can be tuned for visible light excitation. Visible light excitation can prevent cell death normally incurred from exciting dyes with ultraviolet light.
Polymer gels are cross-linked polymers that swell in a solvent. Since the polymer chains are covalently bonded to one another, the individual polymers cannot dissolve in the solvent. Polymeric gels find important applications in tissue engineering where they can act as a scaffold for cells. The uncross-linked polymer is usually mixed with water and cells and light cross-links reactive groups at the ends of the polymer chains together. The cells are then trapped in the gel where they can begin growing under the correct conditions and start forming tissue. Tissue scaffold gels are often made of polyethylene glycol (PEG), because PEG is known to resist nonspecific protein adsorption. Nonspecific protein adsorption is a problem with implants because proteins try to coat anything placed in the body. This nonspecific protein adsorption can set off a chemical cascade resulting in the body rejecting the implant. One of the interesting properties of PEGs are their ability to resist nonspecific protein adsorption. However, no one knows the reason proteins will not adsorb onto a surface coated with PEG. It is known that polymethylene oxide does not have this ability to resist nonspecific protein adsorption.