Breast cancer has attracted tremendous research interest in treatment development as one of the major threats to public health. The use of nanoparticle (NP) for therapeutic DNA delivery has shown promise in treating various cancer types, including breast cancer, due to their high DNA loading capacity, high cell transfection efficiency, and design versatility. However, cytotoxicity and large sizes of NPs often raise safety concerns and hinder their applications in the clinic. Here we report the development of a novel nanoparticle formulation (termed NP-Chi- xPEI) that can safely and effectively deliver DNA into breast cancer cells for successful transfection. The nanoparticle is composed of an iron oxide core coated with low molecular weight (800 Da) polyethyleneimine crosslinked with chitosan via biodegradable disulfide bonds. The NP-Chi-xPEI can condense DNA into a small nanoparticle with the overall size of less than 100 nm and offer full DNA protection. Its biodegradable coating of small-molecular weight xPEI and mildly positive surface charge confer extra biocompatibility. NP-Chi-xPEI-mediated DNA delivery was shown to achieve high transfection efficiency across multiple breast cancer cell lines with significantly lower cytotoxicity as compared to the commercial transfection agent Lipofectamine 3000. With demonstrated favorable physicochemical properties and functionality, NP-Chi-xPEI may serve as a reliable vehicle to deliver DNA to breast cancer cells.

Thin film photovoltaics (PV) present many advantages which enable their potential replacement of traditional silicon PV, but they are not yet scalable. Current research aims to enable their large-scale production to meet growing energy demands. Alongside scalable manufacturing methods and competitive device lifetimes, the transition from small-area cells to large-area modules poses a scalability barrier. I explore a novel fabrication method accelerating this transition. In fabricating thin film PV modules, large-area films are divided into multiple small-area cells by removing, or “scribing,” thin films between adjacent cells for later electrical connection. Existing scribing methods include laser and mechanical scribing, but both have drawbacks which impede device performance and scalability. My research professor and I invented a third scribing method to address these issues. Lines of solvent are printed onto a thin film device to dissolve target thin films underneath the solvent. As the solution evaporates, the “coffee-stain effect” redistributes the dissolved material to the fluid perimeter, exposing linear areas of underlying thin films. This effect is characteristic of drying liquids containing dispersed solids: liquid from the interior flows to restore liquid evaporating at the edge, carrying nearly all dispersed material to the fluid perimeter. This effect enables thin film scribing without forming performance-inhibiting film defects or toxic residues. The technology also requires low capital expenditure and is compatible with scalable roll-to-roll manufacturing. In this work, I demonstrate the invention’s feasibility and competitiveness by producing scribes comparable with existing technologies using electrohydrodynamic inkjet (EHDIJ) printing of solvent on perovskite solar cells. I authored a report, filed a provisional patent application, and now collaborate with another university to advance the technology. This invention poses a scalable solution to the transition from small-area cells to large-area modules in the thin film PV space, breaking a pivotal barrier to meeting growing energy demands.

3D printing is a popular manufacturing method due to its ability to efficiently produce intricate and lightweight parts but it comes with the drawback of parts being too brittle to be used in load bearing applications. At the Laboratory for Advanced Materials and Processing, my research centers around making printed parts more ductile by studying fiber treatments for continuous-fiber filament. Printing with this filament produces parts with high ductility because they distribute load through the printed part more evenly than chopped carbon fiber or polymer filament. The heat applied during the manufacturing and printing process of the filament makes the continuous fibers to group together, or agglomerate, which decreases the performance of the printed part because it causes applied load to not spread evenly within the filament. I am researching the effect of heat transfer on interfaces in the continuous fiber filament by using sputter deposition equipment. Depositing sputter onto a sample involves taking a disc of extremely pure source material and using a large magnetic field to displace individual atoms from the disc onto the specimen. In my experiment, I coat the yarn with aluminum and ceramic sputter. The thermally conductive aluminum sputtered yarn is expected to fail faster in a tensile test compared to the insulative ceramic sputtered yarn, because the aluminum should theoretically increase heat flow within the filament. Increased heat flow causes agglomeration of yarn in the filament, which results in a decrease of part integrity. By determining how the distribution of heat affects the mechanical behavior of continuous-fiber filament, the manufacturing and printing processes can be improved upon to avoid damage prior to use of the parts. The overall goal of my research is to improve the process of 3D printing parts with low-modulus continuous fiber filaments and therefore aid in reliably printing ductile materials.