http://smartech.gatech.edu/handle/1853/26722 Wednesday, October 22, 2008 Search the Channel search http://smartech.gatech.edu/simple-search http://smartech.gatech.edu/handle/1853/26725 Title: Fourth Year Colloquium, October 22, 2008 [Program] <br/> <br/>Abstract: Complete colloquium program, including abstacts and location information for the 2008 School of Chemical and Biomolecular Engineering Fourth Year Colloquium. http://smartech.gatech.edu/handle/1853/26724 Title: Dissolving Microneedles for Transdermal Drug Delivery <br/> <br/>Authors: Lee, Jeong Woo <br/> <br/>Abstract: Microfabrication technology has been adapted to produce micron- scale needles as a safer and painless alternative to hypodermic needle injection, especially for protein biotherapeutics and vaccines. This study presents a novel design that encapsulates sensitive biomolecules within microneedles that dissolve within the skin for bolus or sustained delivery and leave behind no biohazardous sharp medical waste. A novel fabrication process was developed based on casting a viscous aqueous solution during centrifugation to fill a micro-fabricated mold with biocompatible carboxymethylcellulose or amylopectin formulations. This process encapsulated sulforhodamine B, bovine serum albumin, and lysozyme as model drugs; lysozyme was shown to retain full enzymatic activity after encapsulation and to remain 96% active after storage for two months at room temperature. Microneedles were also shown to be strong enough to insert into human cadaver skin and then to dissolve within minutes. Bolus delivery was achieved by encapsulating model drug just within microneedle shafts. For the first time, sustained delivery over hours to days was achieved by encapsulating drug within the microneedle backing, which served as a controlled release drug reservoir that delivered drug by a combination of swelling the backing with interstitial fluid drawn out of the skin and drug diffusion into the skin via channels formed by dissolved microneedles. We conclude that dissolving microneedles can be designed to encapsulate sensitive biomolecules, insert into skin, and enable bolus or sustained release drug delivery. <br/> <br/>Description: 2008 Ziegler Award Winner, presented as a keynote address at the 2008 School of Chemical and Biomolecular Engineering Fourth Year Colloquium, Wednesday October 22, 2008. http://smartech.gatech.edu/handle/1853/26723 Title: Fabrication of Superhydrophobic Cellulose Surfaces via Plasma Processing <br/> <br/>Authors: Balu, Balamurali <br/> <br/>Abstract: In 1805, Young proposed a relationship between the forces acting at an interface between a liquid and solid: “…for each combination of a solid and a fluid, there is an appropriate angle of contact between the surfaces of the fluid, exposed to the air, and to the solid…” However, most real substrates exhibit a variety of contact angles, depending on whether the liquid-air interface is advancing or receding on the solid surface, rather than a unique contact angle. The range of contact angles, usually defined as the difference between the maximum and minimum contact angles observed at the advancing and receding fronts of the liquid drop, is termed contact angle (CA) hysteresis. For classifying the interaction between substrates and liquids, it is critical to specify both the CA and CA hysteresis values. As will be shown in this presentation, even if a surface is superhydrophobic (according to the common definition of a static or advancing water CA > 150°), it can be strongly adhesive to water drops. Contact angle hysteresis most closely correlates with the magnitude of these adhesive forces and by tuning the hysteresis, the dynamics of drops on superhydrophobic surfaces can be controlled, making possible numerous new applications. Superhydrophobicity has been achieved on cellulose surfaces by domain selective etching of amorphous portions of the cellulose, followed by coating of the surface structures generated with a fluorocarbon film deposited via plasma enhanced chemical vapor deposition (PECVD). The hysteresis of these superhydrophobic surfaces can be tuned between 149.8±5.8° and 3.5±1.1° through the controlled fabrication of nano-scale features on the cellulose fibers. This process takes advantage of the inherent nano-meter length scales of the amorphous and crystalline domains of cellulose fibers and the non-conformal film deposition property of PECVD process. Superhydrophobic cellulosic surfaces with tunable hysteresis (adhesion) provide control of aqueous drop mobility and thus of the transfer characteristics of water drops. Moreover, the fact that these substrates are based on cellulose fibers, a biodegradable, inexpensive, flexible, biopolymer, widens potential commercial opportunities for these materials. <br/> <br/>Description: 2008 Ziegler Award Winner, presented as a keynote address at the 2008 School of Chemical and Biomolecular Engineering Fourth Year Colloquium, Wednesday October 22, 2008.