A Plasma Pencil Atmospheric Mass Spectrometer (PPAMS) is a new surface analysis device which allows mass spectrometry (MS) to be conducted on samples under normal atmospheric conditions. This enables surface analysis on samples that could previously not be analyzed under the current standard vacuum-based techniques, broadening the field of surface analysis. However, characterization of this method of surface analysis needs to be done in order to maximize the benefits of the PPAMS device and to determine the extent to which the traditional vacuum-based methods can be replaced. This process of characterization involves determining the ionization rate of the plasma pencil probe, performing various experiments while changing parameters (i.e. sample concentration, thickness, and gas type), and comparing results to established methods. Our current investigation is focused on the determination of the ionization rate of the PPAMS device. Initial experiments were performed on polyurethane-based samples dissolved in dimethyl acetamide and spun-coated onto a gold-coated silicon wafer. These samples were then probed by the PPAMS over controlled time intervals. A multivariate statistical method, Principal Components Analysis (PCA), was used to evaluate whether the MS signals obtained varied as a function of exposure time. We hypothesized that the signal would resemble our bare gold background once all of the polyurethane had been ionized. Instead, the MS signal was found to stay constant over a 15 minute exposure time implying a longer exposure time is needed. Current work is focused on evaluating the effect of PPAMS exposure to polymer thickness as a secondary means of evaluating ionization. Future work will center on investigating the changes to the ionization rate under different experimental conditions. The results of our device characterization will provide valuable insight into the limits of the PPAMS device that will enable improved experimental design.

This project’s goal is producing microporous scaffold for tissue growth. These scaffolds are made out of crosslinked 2-hydroxyethyl methacrylate (HEMA), a hydrogel. They are formed by polymerizing the HEMA around polymethyl methacrylate (PMMA) beads that are of a constrained and predetermined size. The PMMA is washed away and we are left with a porous scaffold of precise pore size. These scaffolds are used to encourage tissue growth and reduce inflammation and the foreign body reaction. The purpose of my research is to investigate blood vessel penetration into scaffolds by producing the largest sized scaffolds I can using novel techniques. We are currently limited to tissue scaffolds of a maximum thickness of 1 mm using our current techniques. With a larger thickness our scaffolds could be used for many more applications that are presently unavailable with a thin scaffold. Our methods are varied and include creating multiple mold designs, polymerizing techniques, and chemical washing techniques. Once I can create these larger scaffolds we will test them in vivo to evaluate the foreign body reaction as well as angiogenesis in the region. There is a large range of possible future applications for these scaffolds. They could be tuned to encourage many different types of tissue growth.

Drug targeting is highly advantageous because the ability to deliver drugs exclusively to specific cells or organs reduces both the dosage and toxicity effects associated with nonspecific administration. However, targeted delivery of therapeutics is still challenging due to lack of an efficient drug carrier design. Carbohydrate complexes, such as glycolipids and glycoproteins, serve as cellular markers and receptors universally found on the outer membranes of mammalian cells. These glycoconjugates distinguish different types of cells from one another and enable cellular recognition and adhesion. Both the immune system and foreign pathogens rely on these glycoconjugates to bind and enter host cells. For viruses and bacteria, adhesion to host receptors is the first step towards infection. Because of this broad physiological usage, carbohydrates must be highly diverse, with each carbohydrate corresponding to a different receptor. By mimicking nature’s mechanism of cellular adhesion, chemists are using carbohydrates to target specific cells for drug delivery. The designed glycopolymer, as a potential drug carrier, is composed of two main components: carbohydrate for targeting cells in cell-specific manner and pyridal-disulfide (PDS) groups for bioconjugation and fluorescent labeling. In the first step of the synthesis of the glycopolymer, three different glycomonomers (mannose, galactose and N-acetyl-glucosamine) have been synthesized and characterized in order to construct structurally well-defined glycopolymers. Each glycomonomer can be utilized for the synthesis of reversible addition-fragmentation chain transfer (RAFT) glycopolymers. This carbohydrate-based polymer construct has promising potential in targeted drug delivery for its reduction in toxicity and increase in drug efficacy.