Won‐Gun Koh

Fluorescence-based biosensor platforms have been intensively investigated not only to increase the sensitivity but also to improve the performance of biosensors. By exploiting metal from the macroscopic down to the nanoscopic surface, various architectures have been devised to manipulate fluorescence signals (enhancement, quenching) within near-optical fields. The interaction of a metallic surface with proximal fluorophores (in the range of 5-90 nm) has beneficial effects on optical properties s

We present an easy and effective method for the encapsulation of cells inside PEG-based hydrogel microstructures fabricated using photolithography. High-density arrays of three-dimensional microstructures were created on substrates using this method. Mammalian cells were encapsulated in cylindrical hydrogel microstructures of 600 and 50 micrometers in diameter or in cubic hydrogel structures in microfluidic channels. Reducing lateral dimension of the individual hydrogel microstructure to 50 micr

In the field of tissue engineering, conductive hydrogels have been the most effective biomaterials to mimic the biological and electrical properties of tissues in the human body. The main advantages of conductive hydrogels include not only their physical properties but also their adequate electrical properties, which provide electrical signals to cells efficiently. However, when introducing a conductive material into a non-conductive hydrogel, a conflicting relationship between the electrical an

The development of a lightweight, low-power, user-interactive three-dimensional (3D) touchless display in which a human stimulus can be detected and simultaneously visualized in noncontact mode is of great interest. Here, we present a user-interactive 3D touchless sensing display based on multiorder reflection structural colors (SCs) of a thin, solid-state block copolymer (BCP) photonic crystal (PC). Full-visible-range SCs are developed in a BCP PC consisting of alternating lamellae, one of whic

The fabrication of mammalian cell-containing poly(ethylene glycol) (PEG) hydrogel microstructures on glass and silicon substrates is described. Using photoreaction injection molding in poly(dimethylsiloxane) microfluidic channels, three-dimensional hydrogel microstructures encapsulating cells (fibroblasts, hepatocytes, macrophage) were fabricated with cells uniformly distributed to each hydrogel microstructure, and the number of cells in each hydrogel microstructure was controlled by changing th

Recycling is a fascinating topic in academia due to the environmental and economic benefits in industries. In this paper, we report on the method to recycle cellulose waste papers using a green (eco-friendly) approach based on ionic liquids (ILs) where the regenerated cellulose was converted to carbon dots (CDs). The addition of waste papers to the IL, 1-allyl-3-methylimidazolium chloride ([Amim][Cl]), disrupted the chemical arrangement of cellulose and completely dissolved the waste paper under

In this study, we designed a cell-adhesive poly(ethylene glycol) (PEG)-based hydrogel that simultaneously provides topographical and electrical stimuli to C2C12 myoblasts. Specifically, PEG hydrogels with microgroove structures of 3 μm ridges and 3 μm grooves were prepared by micromolding; in situ polymerization of poly(3,4-ethylenedioxythiophene) (PEDOT) was then performed within the micropatterned PEG hydrogels to create a microgrooved conductive hydrogel (CH/P). The CH/P had clear replica pat

Abstract A simple method to generate well‐defined microscopic architectures composed of electrospun nanofibers is reported and their potential application to biomedical fields are described. The photopatterning of polyethylene glycol (PEG) hydrogel on electrospun polycarprolactone (PCL) nanofibers leads to the formation of two different microdomains in nanofibrous mats: a bare nanofiber region and a hydrogel‐entrapped nanofiber region. The selective dissolution of bare nanofibers with an organic