Doh, Jun-Sang

Bioprinting is a promising technique for engineering composite tissues, such as osteochondral tissues. In this study, as a first step toward bioprinting-based osteochondral tissue regeneration, we systematically examined the behavior of chondrocytes and osteoblasts to hyaluronic acid (HA) and type I collagen (Col-1) hydrogels. First, we demonstrated that cells on hydrogels that were comprised of major native tissue extracellular matrix (ECM) components (i.e. chondrocytes on HA hydrogels and oste

T cells are activated by recognition of foreign peptides displayed on the surface of antigen presenting cells (APCs), an event that triggers assembly of a complex microscale structure at the T cell-APC interface known as the immunological synapse (IS). It remains unresolved whether the unique physical structure of the synapse itself impacts the functional response of T cells, independent of the quantity and quality of ligands encountered by the T cell. As a first step toward addressing this ques

Development of facile and sensitive bioassays is important for many point-of-care applications. In this study, we fulfilled such demand by synthesizing Pt-decorated magnetic nanozymes and developing a bioassay based on unique properties of the newly synthesized nanozymes. Fe 3 O 4 –Pt/core–shell nanoparticles (MPt/CS NPs) with various compositions were synthesized and characterized. Fe 3 O 4 NP itself is a good nanozyme with catalytic activity superior to that of natural enzymes, but catalytic a

A novel photoresist (PR) that can be processed under mild aqueous conditions was synthesized and used to create photogenerated polyelectrolyte bilayers. Thin films of the PR cast on polycation-coated substrates were exposed to UV irradiation to generate carboxylate groups in the photoresist. The bulk of the UV-exposed PR film was dissolved by rinsing with pH 7.4 phosphate-buffered saline, but a polyelectrolyte bilayer formed in situ at the PR/polycation interface on exposure remained bound to th

<b>Background:</b> Natural Killer (NK) cell-based immunotherapy used to treat cancer requires the adoptive transfer of a large number of activated NK cells. Here, we report a new effective method to expand human NK cells <i>ex vivo</i> using K562 cells genetically engineered (GE) to express OX40 ligand (K562-OX40L) in combination with a short exposure to soluble IL-21. In addition, we describe a possible mechanism of the NK cell expansion through the OX40 receptor-OX40 ligand axis which is depen

Adoptive cell transfer against solid tumors faces challenges to overcome tumor microenvironment (TME), which plays as a physical barrier and provides immuno-suppressive conditions. Classical cytotoxicity assays are widely used to measure killing ability of the engineered cytotoxic lymphocytes as therapeutics, but the results cannot represent the performance in clinical application due to the absence of the TME. This paper describes a 3D cytotoxicity assay using an injection molded plastic array

Polyelectrolyte microcapsules represent versatile stimuli-responsive structures that enable the encapsulation, protection, and release of active agents. Their conventional preparation methods, however, tend to be time-consuming, yield low encapsulation efficiency, and seldom allow for the dual incorporation of hydrophilic and hydrophobic materials, limiting their widespread utilization. In this work, we present a method to fabricate stimuli-responsive polyelectrolyte microcapsules in one step ba

We report a new method for the micropatterning of multiple proteins and cells with micrometer-scale precision. Microscope projection photolithography based on a new protein-friendly photoresist, poly(2,2-dimethoxy nitrobenzyl methacrylate-r-methyl methacrylate-r-poly(ethylene glycol) methacrylate) (PDMP), was used for the fabrication of multicomponent protein/cell arrays. Microscope projection lithography allows precise registration between multiple patterns as well as facile fabrication of micr

T cells navigate a wide variety of tissues and organs for immune surveillance and effector functions. Although nanoscale topographical structures of extracellular matrices and stromal/endothelial cell surfaces in local tissues may guide the migration of T cells, there has been little opportunity to study how nanoscale topographical features affect T cell migration. In this study, we systematically investigated mechanisms of nanotopography-guided migration of T cells using nanoscale ridge/groove

Cancer immunotherapies based on the ability of T cells to recognize and kill tumor cells (TCs), including immune checkpoint blockade (ICB) therapy and chimeric antigen receptor (CAR) T cell therapy, have been greatly successful recently, but they are applicable for only a fraction of patients. One of the main challenges in cancer immunotherapy is the improvement of T cell infiltration into solid tumor tissues, as T cells can exert cytotoxicity against TCs only when they are in contact with TCs.

An enzyme-mimetic nanoparticle-based point of care bioassay device is developed for rapid and sensitive detection of analytes. Digital images acquired by smart cellular phones allow quantifying the amounts of analytes. Using this new device, quantitative analysis of liquid sample is performed within 15 min with an order of magnitude enhancement of sensitivity compared with conventional Au nanoparticle-based devices.

We present new methods that enable the fabrication of multiscale, multicomponent protein-patterned surfaces and multiscale topologically structured surfaces by exploiting the merits of two well-established techniques: capillary force lithography (CFL) and microscope projection photolithography (MPP) based on a protein-friendly photoresist. We further demonstrate that, when hierarchically organized micro- and nanostructures were used as a cell culture platform, human colon cancer cells (cell line