Elastin-like polypeptide hydrogel adhesive
Commonly used tissue adhesives are in the form of polymerizing glues or hydrogels. However, cyanoacrylate-based materials from stiff adhesions and polyethylene glycol or protein based hydrogel adhesives have poor extensibility, both of which can potentially cause damage to the treatment site. In this work, we create a robust, highly deformable hydrogel using elastin-like polypeptides (ELPs) that can be used as a soft tissue adhesive that employs mussel-inspired chemistry. ELPs are recombinantly expressed proteins composed of a tandemly repeated pentapeptide, ‘Val-Pro-Gly-Xaa-Gly’, derived from mammalian elastin. ELP is ideal for developing a highly extensible hydrogel due to its characteristic behavior like an entropic spring that recoils to lower its entropy when stretched. We designed our ELPs to contain reactive amine containing ‘Lys or thiol containing ‘Cys’ residues only at the ends of the polymer chain. This allows us to crosslink the ELP chains into a near-ideal network and utilize the entire length of the polymer during hydrogel extension. We further designed the ELP chains to contain ‘Glu’ guest residues, adding carboxylic acid functional groups. The carboxylic acids are modified with dopamine to enable the hydrogels to undergo mussel-like adhesion on wet surfaces. In this manner, we create protein-based rubber-like resilient hydrogels and characterize their mechanical properties and adhesiveness to wet surfaces such as tissues.
Speaker: Malav Desai
Department of BioEngineering, UC Berkeley
Malav Desai is a Bioengineering PhD student working with Prof. Seung Wuk Lee. He obtained his B.S. degree in Biomedical Engineering at Rutgers University. His PhD work has focused on the development of recombinant protein based soft materials for various applications in bioengineering and medicine
Room Temperature Gas Sensor based on Graphene FET
Industrial development in the last century has dramatically changed the emission of many gases that are critical to the health of human beings and the climate of earth, and it has become urgent to develop miniature gas sensors that can be deployed ubiquitously for monitoring the indoor and outdoor air quality. Such sensor should have the desirable features like energy efficient, miniature size, accurate response and selectivity. We propose using graphene based field effect transistor as label-free sensor platform, to detect gas selectively by measuring its electrical properties at room temperature.
Speaker: Huiliang Liu
Department of Mechnical Engineering, UC Berkeley
Huiliang Liu is a Ph.D. candidate at Sensors and Microsystems Laboratory, Tsinghua-Berkeley Shenzhen Institute. He received his B.S. degree of Electronic Engineering from Xiamen University and M.S. degree from Tsinghua University majoring in Microelectronics. His research interests include Graphene based chemical sensors and wireless communication.