• Journal of International Society for Simulation Surgery
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• v.3 no.2
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• pp.49-59
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• 2016

3D printing is also known as additive manufacturing technique in which has been used in various commercial fields such as engineering, art, education, and medicine. The applications such as fabrication of tissues and organs, implants, drug delivery, creation surgical models using 3D printer in medical field are expanding. Recently, 3D printing has been developing for produce biomimetic 3D structure using biomaterials containing living cells and that is commonly called "3D bio-printing". The 3D bio-printing technologies are usually classified four upon printing methods: Laser-assisted printing, Inkjet, extrusion, and stereolithograpy. In the bio-printing, bio-inks (combined hydrogels and living cells) are as important components as bio-printing technologies. The presence of various types of bioinks, however, in this review, we focused on the bio-inks which enables bioprinting efficacy using hydrogels with living cells.

• Tissue Engineering and Regenerative Medicine
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• v.15 no.6
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• pp.761-769
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• 2018

BACKGROUND: Bioprinting has recently appeared as a powerful tool for building complex tissue and organ structures. However, the application of bioprinting to regenerative medicine has limitations, due to the restricted choices of bio-ink for cytocompatible cell encapsulation and the integrity of the fabricated structures. METHODS: In this study, we developed hybrid bio-inks based on acrylated hyaluronic acid (HA) for immobilizing bio-active peptides and tyramine-conjugated hyaluronic acids for fast gelation. RESULTS: Conventional acrylated HA-based hydrogels have a gelation time of more than 30 min, whereas hybrid bio-ink has been rapidly gelated within 200 s. Fibroblast cells cultured in this hybrid bio-ink up to 7 days showed >90% viability. As a guidance cue for stem cell differentiation, we immobilized four different bio-active peptides: BMP-7-derived peptides (BMP-7D) and osteopontin for osteogenesis, and substance-P (SP) and Ac-SDKP (SDKP) for angiogenesis. Mesenchymal stem cells cultured in these hybrid bio-inks showed the highest angiogenic and osteogenic activity cultured in bio-ink immobilized with a SP or BMP-7D peptide. This bio-ink was loaded in a three-dimensional (3D) bioprinting device showing reproducible printing features. CONCLUSION: We have developed bio-inks that combine biochemical and mechanical cues. Biochemical cues were able to regulate differentiation of cells, and mechanical cues enabled printing structuring. This multi-functional bio-ink can be used for complex tissue engineering and regenerative medicine.

• Journal of Korean Society on Water Environment
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• v.22 no.6
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• pp.996-1003
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• 2006

The absorption characteristics of powdered activated carbon doped by transition-metal nanoparticles were investigated to enhance the remove efficiencies of $TCOD_{Mn}$ and Color from the flexo-inks wastewater. According to the adsorption dynamics of PAC and MPAC, the optimal dosage of activated-carbon adsorbents was 3 g/L under the reaction conditions of pH6.0, 30 mill of reaction time, 240 rpm of mixing intensity. The removal efficiencies by the optimal dosages were maximized as 19% $TCOD_{Mn}$, 57% Color for PAC and 88% $TCOD_{Mn}$, 95% Color for MPAC. Freundlich indexes of isotherm absorption were estimated as follows: i) For PAC, k=-8.11, 1/n=2.98, r=0.91 in the raw water, and k=0.14, b/n=0.75, r=0.96 in the biological treatment water, ii) For MPAC, k=2.69, 1/n=0.21, r=0.80 in the raw water, and k=0.74, 1/n=1.17, r=0.95 in the biological treatment water. MPAC (Powdered activated carbon doped by transition-metal nanoaprticles) was very effective in the removal of organics from the raw water and biological treatment water, as Freundlich indexes of 1/n for both types of water were estimated less than 2.0.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.899-904
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• 2003

Microarrayer makes DNA chip and microarray that contain hundreds to thousands of immobilized DNA probes on surface of a microscope slide. This paper shows the development results for a printing type of microarrayer. It realizes a typical, low-cost and efficient microarrayer for generating low density microarray. The microarrayer is developed by using a robot of three-axes perpendicular type. It is composed of a computer-controlled three-axes robot and a pen tip assembly. The key component of the arrayer is the print-head containing the tips to immobilize cDNA, genomic DNA or similar biological material on glass surface. The robot is designed to automatically collect probes from two 96-well plates with up to 32 tips at the same time. To prove the performance of the developed microarrayer, the general water types of inks such as black, blue and red. The inks are distributed at proper positions of 96 well plates and the three color inks are immobilized on the slide glass under the operation procedure. As the result of the test, it can be shown that it has sufficient performance for the production of low integrated DNA chip consisted of 96 spots within 1 $cm^2$ area.

• Korean Chemical Engineering Research
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• v.46 no.4
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• pp.647-659
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• 2008

Colloids are a heterogeneous system in which particles of a few nanometers to hundreds micrometers in size are finely dispersed in liquid medium, but show homogeneous properties in macroscopic scale. They have attracted much attention not only as model systems of natural atomic and molecular self-assembled structures but also as novel structural materials of practical applications in a wide range of areas. In particular, recent advances in colloidal science have focused on nano-bio materials and devices which are essential for drug discovery and delivery, diagnostics and biomedical applications. In this review, first we introduce nano-bio colloidal systems and surface modification of colloidal particles which creates various functional groups. Then, various methods of fabrication of colloidal particles using holographic lithography, microfluidics and virus templates are discussed in detail. Finally, various applications of colloids in metal inks, three-dimensional photonic crystals and two-dimensional nanopatterns are also reviewed as representative potential applications.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.8
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• pp.1-7
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• 2019

Materials that can be used for 3D printing have been developed in terms of phase and functionality. Materials should also be easily printed with high accuracy. In recent years, the concept of 4D printing has been extended to materials whose physical properties such as shape or volume can change depending on the environment. Typically, such high-performance 3D printing materials include bio-inks and inks for sensors. This study deals with the optimization of the manufacturing method to improve the functional properties of the pressure sensitive material, which can be used as a sensor based on change of the resistance according to the pressure. Specifically, the number of milling for dispersion, the ratio of hardener for controlling elasticity, and the content of MWCNTs were optimized. As a result, a method of manufacturing a highly sensitive pressure-sensitive ink capable of use in 3D printing was introduced.

• Analytical Science and Technology
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• v.29 no.1
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• pp.35-42
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• 2016

A new nano-composite carbon ink for the development of disposable dopamine (DA) biosensors based on screen-printed carbon electrodes (SPCEs) is introduced. The method developed uses SPCEs coupled with a tyrosinase modified nano-composite carbon ink. The ink was prepared by an “in-house” procedure with reduced graphene oxide (rGO), Pt nanoparticles (PtNP), and carbon materials such as carbon black and graphite. The rGO-PtNP carbon composite ink was used to print the working electrodes of the SPCEs and the reference counter electrodes were printed by using a commercial Ag/AgCl ink. After the construction of nano-composite SPCEs, tyrosinase was immobilized onto the working electrodes by using a biocompatible matrix, chitosan. The composite of nano-materials was characterized by X-ray photoelectron spectroscopy (XPS) and the performance characteristics of the sensors were evaluated by using voltammetric and amperometric techniques. The cyclic voltammetry results indicated that the sensors prepared with the rGO-PtNP-carbon composite ink revealed a significant improvement in electro-catalytic activity to DA compared with the results obtained from bare or only PtNP embedded carbon inks. Optimum experimental parameters such as pH and operating potential were evaluated and calibration curves for dopamine were constructed with the results obtained from a series of amperometric detections at −0.1 V vs. Ag/AgCl. The limit of detection was found to be 14 nM in a linear range of 10 nM to 100 µM of DA, and the sensor’s sensitivity was calculated to be 0.4 µAµM⁻¹cm⁻².

• Journal of Life Science
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• v.19 no.8
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• pp.1119-1124
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• 2009

Hyperlipidemia has been reported to be associated with the development of fatty liver. Palmitic acid, a major saturated fatty acid, is involved in the development of diverse diseases. The activation of mitogen activated protein kinases (MAPKs), such as Jun N-terminal kinase (INKs) and p38 MAPK is implicated in the apoptosis in diverse cells. Thus, this study was conducted to investigate the effects of palmitic acid on apoptosis and its relationship between JNK and p38 MAPK in cultured rat hepatocytes. In the present study, palmitic acid (>50 uM) decreased cell proliferation and increased lactate dehydrogenase activity in hepatocytes, which was blocked by the treatment of SP600125 (a JNK inhibitor) and SB203580 (a p38 MAPK inhibitor). Indeed, palmitic acid decreased Bcl-2 expression but increased Bax expression in rat hepatocytes, which was blocked by the treatment of SP600125 and SB203580. In addition, palmitic acid decreased glutathione (GSH) content and increased lipid peroxide formation, which was blocked by the treatment of SP600125 and SB203580. Western immunoblotting analysis also revealed that palmitic acid increased JNK and p38 MAPK. In conclusion, palmitic acid induced apoptosis through oxidative stress via JNK and p38 MAPK activation in rat hepatocytes.

• Journal of the Microelectronics and Packaging Society
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• v.30 no.2
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• pp.1-12
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• 2023

In the current era of the global mobile smart device revolution, electronic devices are required in all spaces that people interact with. The establishment of the internet of things (IoT) among smart devices has been recognized as a crucial objective to advance towards creating a comfortable and sustainable future society. In-mold electronic (IME) processes have gained significant industrial significance due to their ability to utilize conventional high-volume methods, which involve printing functional inks on 2D substrates, thermoforming them into 3D shapes, and injection-molded, manufacturing low-cost, lightweight, and functional components or devices. In this article, we provide an overview of IME and its latest advances in application. We review biomimetic nanomaterials for constructing self-supporting biosensor electronic materials on the body, energy storage devices, self-powered devices, and bio-monitoring technology from the perspective of in-mold electronic devices. We anticipate that IME device technology will play a critical role in establishing a human-machine interface (HMI) by converging with the rapidly growing flexible printed electronics technology, which is an integral component of the fourth industrial revolution.