Dong Woo Lim

Abstract Biomimetic scaffolds mimic important features of the extracellular matrix (ECM) architecture and can be finely controlled at the nano‐ or microscale for tissue engineering. Rational design of biomimetic scaffolds is based on consideration of the ECM as a natural scaffold; the ECM provides cells with a variety of physical, chemical, and biological cues that affect cell growth and function. There are a number of approaches available to create 3D biomimetic scaffolds with control over thei

In situ gelation of injectable polypeptide-based materials is attractive for minimally invasive in vivo implantation of biomaterials and tissue engineering scaffolds. We demonstrate that chemically cross-linked elastin-like polypeptide (ELP) hydrogels can be rapidly formed in aqueous solution by reacting lysine-containing ELPs with an organophosphorous cross-linker, beta-[tris(hydroxymethyl)phosphino]propionic acid (THPP) under physiological conditions. The mechanical properties of the cross-lin

Rapid cross-linking of elastin-like polypeptides (ELPs) with hydroxymethylphosphines (HMPs) in aqueous solution is attractive for minimally invasive in vivo implantation of biomaterials and tissue engineering scaffolds. In order to examine the independent effect of the location and number of reactive sites on the chemical cross-linking kinetics of ELPs and the mechanical properties of the resulting hydrogels, we have designed ELP block copolymers comprised of cross-linkable, hydrophobic ELP bloc

A block copolymer composed of cationic polymer and poly(ethylene glycol) (PEG) was used as a DNA carrier. Poly(2-(dimethylamino)ethyl methacrylate (DMAEMA)-co-N-vinyl-2-pyrrolidone (NVP)) having a terminal carboxylic group was synthesized by free radical polymerization using an initiator, 4,4'-azobis(4-cyanovaleric acid). The terminal carboxylic acid was activated by N-hydroxysuccinimide (NHS) with dicyclohexylcarbodiimide (DCC) and then conjugated with PEG-bis(amine). For specific gene targetin

Two enantiomeric triblock ABA copolymers composed of poly(L-lactide)–poly(ethylene glycol)–poly(L-lactide) (PLLA–PEG–PLLA) and poly(D-lactide)–poly(ethylene glycol)–poly(D-lactide) (PDLA–PEG–PDLA) were synthesized with two different middle-block PEG chain lengths by ring-opening polymerization of L-lactide and D-lactide in the presence of PEG, respectively. A pair of enantiomeric triblock copolymers were combined to form a stereocomplex by a solvent-casting method. The triblock copolymers and th

This paper reports an improvement in the purification of thioredoxin (Trx) expressed from E. coli by inverse transition cycling (ITC) using cationic elastin-like polypeptides (ELPs). Two ELP libraries having 2% and 5% lysine residues and molecular weights ranging from 4 to 61.1 kDa showed greater salt sensitivity in their inverse transition behavior than purely aliphatic ELPs. Expression yield of Trx-ELP fusions was an unpredictable function of guest residue composition, but reducing the molecul

Two enantiomeric amphiphilic graft copolymers consisting of water soluble poly(2-hydroxyethyl methacrylate) (HEMA) and biodegradable oligo(L-lactide) (OLLA) or oligo(D-lactide) (ODLA) were synthesized by free radical copolymerization. HEMA-OL(D)LA macromonomers were synthesized by ring opening polymerization of L- or D-lactide. Both HEMA-OLA macromonomers and graft copolymers were characterized by NMR spectroscopy and gel permeation chromatography. Graft copolymers and their stereocomplexes were

We have observed coherent acoustic phonons in the hexagonal manganite LuMnO3 using two-color femtosecond optical pump-probe spectroscopy. The dependence of the oscillatory component of the photoinduced reflectivity on the probe wavelength and incident angle is consistent with a propagating strain pulse. Moreover, the frequency, dephasing, and phase of the oscillation are found to be temperature dependent. In particular, a large phase shift occurs in the vicinity of the Néel temperature (TN), whi

We have observed coherent optical and acoustic phonon generation, which are strongly coupled to the charge-ordering (CO) transition in (, 0.58) using femtosecond optical pump-probe spectroscopy. Coherent optical phonons, observed at low temperatures, disappear above the charge-ordering temperature , while coherent acoustic phonons display the opposite behavior, disappearing gradually below . Coherent optical phonons are generated by the displacive excitation mechanism where their coupling to the

Polymer particles with micro- and nanoscale anisotropy have received increasing interest for their ability to simultaneously present different physical- and chemical properties. In this communication, we demonstrate that gold nanocrystals (NCs) can be selectively incorporated into one compartment of anisotropic polymer particles. Stable bicompartmental particles were prepared via electrohydrodynamic co-jetting of aqueous nanoparticle suspensions followed by thermal cross-linking. Bicompartmental

Self-assembly of thermally responsive polypeptides into unique nanostructures offers intriguing attributes including dynamic physical dimensions, biocompatibility, and biodegradability for the smart bio-nanomaterials. As elastin-based polypeptide (EBP) fusion proteins with lower critical solution temperature (LCST) are studied as drug delivery systems, EBP block copolypeptides with the resilin-based polypeptide (RBP) displaying an upper critical solution temperature (UCST) have been of great int

Surface-enhanced Raman scattering (SERS) is an optical spectroscopy technique that can detect a variety of analytes with high sensitivity and selectivity without any labels. Controlled clustering of metallic nanoparticles to prepare a new class of SERS nanotags is crucial for the ultra-sensitive detection of specific biological and chemical moieties because increased plasmonic hotspot junctions produce a greatly enhanced SERS signal. We report herein that controlled clustering of Au nanoparticle

Stimuli-responsive, polymer-based nanostructures with anisotropic compartments are of great interest as advanced materials because they are capable of switching their shape via environmentally-triggered conformational changes, while maintaining discrete compartments. In this study, a new class of stimuli-responsive, anisotropic nanofiber scaffolds with physically and chemically distinct compartments was prepared via electrohydrodynamic cojetting with side-by-side needle geometry. These nanofiber