Joseph P. Park

Biologically Inspired Materials Exhibiting Repeatable Regeneration with Self-Sealing Capabilities without External Stimuli or Catalysts

A new insect-cuticle- and fruit-browning-mimetic film exhibiting simultaneous self-healing and self-sealing properties only by ambient oxygen without external stimuli is developed. The film is formed at the liquid/air interface via crosslinking of phenolic compounds and poly(amine) chains. The film can be self-healed over a hundred times under ambient air at room temperature without exogenous materials and stimuli.

Preparation of Sticky Escherichia coli through Surface Display of an Adhesive Catecholamine Moiety

ABSTRACT Mussels attach to virtually all types of inorganic and organic surfaces in aqueous environments, and catecholamines composed of 3,4-dihydroxy-l-phenylalanine (DOPA), lysine, and histidine in mussel adhesive proteins play a key role in the robust adhesion. DOPA is an unusual catecholic amino acid, and its side chain is called catechol. In this study, we displayed the adhesive moiety of DOPA-histidine on Escherichia coli surfaces using outer membrane protein W as an anchoring motif for the first time. Localization of catecholamines on the cell surface was confirmed by Western blot and immunofluorescence microscopy. Furthermore, cell-to-cell cohesion (i.e., cellular aggregation) induced by the displayed catecholamine and synthesis of gold nanoparticles on the cell surface support functional display of adhesive catecholamines. The engineered E. coli exhibited significant adhesion onto various material surfaces, including silica and glass microparticles, gold, titanium, silicon, poly(ethylene terephthalate), poly(urethane), and poly(dimethylsiloxane). The uniqueness of this approach utilizing the engineered sticky E. coli is that no chemistry for cell attachment are necessary, and the ability of spontaneous E. coli attachment allows one to immobilize the cells on challenging material surfaces such as synthetic polymers. Therefore, we envision that mussel-inspired catecholamine yielded sticky E. coli that can be used as a new type of engineered microbe for various emerging fields, such as whole living cell attachment on versatile material surfaces, cell-to-cell communication systems, and many others.

M13 Bacteriophage Displaying DOPA on Surfaces: Fabrication of Various Nanostructured Inorganic Materials without Time-Consuming Screening Processes

M13 bacteriophage (phage) was engineered for the use as a versatile template for preparing various nanostructured materials via genetic engineering coupled to enzymatic chemical conversions. First, we engineered the M13 phage to display TyrGluGluGlu (YEEE) on the pVIII coat protein and then enzymatically converted the Tyr residue to 3,4-dihydroxyl-l-phenylalanine (DOPA). The DOPA-displayed M13 phage could perform two functions: assembly and nucleation. The engineered phage assembles various noble metals, metal oxides, and semiconducting nanoparticles into one-dimensional arrays. Furthermore, the DOPA-displayed phage triggered the nucleation and growth of gold, silver, platinum, bimetallic cobalt-platinum, and bimetallic iron-platinum nanowires. This versatile phage template enables rapid preparation of phage-based prototype devices by eliminating the screening process, thus reducing effort and time.

Inactivation efficiency of DNA and RNA viruses during chitin-to-chitosan conversion

Joseph P. Park, Mi-Young Koh, Pil Soo Sung, Keumyeon Kim, Min Sun Kim, Moon Sue Lee, Eui-Cheol Shin*, Ki Hong Kim*, and Haeshin Lee* 1Graduate School of Nanoscience and Technology, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Korea 2Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Korea 3R & D Center, InnoTherapy Inc., Daejeon 305-732, Korea 4Department of Aquatic Life Medicine, Pukyoug National University, Busan 608-737, Korea