January 6, 2020 by admin 0 Comments

NiCHE Platform: Nature-Inspired Catechol-Conjugated Hyaluronic Acid Environment Platform for Salivary Gland Tissue Engineering

Authors
Sang-woo Lee, Ji Hyun Ryu, Min Jae Do, Eun Namkoong, Haeshin Lee* and Kyungpyo Park*
Abstract
Recently, there has been growing interest in replacing severely damaged salivary glands with artificial salivary gland functional units created in vitro by tissue engineering approaches. Although various materials such as poly(lactic-co-glycolic acid), polylactic acid, poly(glycolic acid), and polyethylene glycol hydrogels have been used as scaffolds for salivary gland tissue engineering, none of them is effective enough to closely recapitulate the branched structural complexity and heterogeneous cell population of native salivary glands. Instead of discovering new biomaterial candidates, we synthesized hyaluronic acid–catechol (HACA) conjugates to establish a versatile hyaluronic acid coating platform named “NiCHE (nature-inspired catechol-conjugated hyaluronic acid environment)” for boosting the salivary gland tissue engineering efficacy of the previously reported biomaterials. By mimicking hyaluronic acid-rich niche in the mesenchyme of embryonic submandibular glands (eSMGs) with NiCHE coating on substrates including polycarbonate membrane, stiff agarose hydrogel, and polycaprolactone scaffold, we observed significantly enhanced cell adhesion, vascular endothelial and progenitor cell proliferation, and branching of in vitro-cultured eSMGs. High mechanical stiffness of the substrate is known to inhibit eSMG growth, but the NiCHE coating significantly reduced such stiffness-induced negative effects, leading to successful differentiation of progenitor cells to functional acinar and myoepithelial cells. These enhancement effects of the NiCHE coating were due to the increased proliferation of vascular endothelial cells via interaction between CD44 and surface-immobilized HAs. As such, our NiCHE coating platform renders any kind of material highly effective for salivary gland tissue culture by mimicking in vivo embryonic mesenchymal HA. Based on our results, we expect the NiCHE coating to expand the range of biomaterial candidates for salivary glands and other branching epithelial organs.

January 5, 2020 by admin 0 Comments

Biobased thermoplastic elastomer with seamless 3D-Printability and superior mechanical properties empowered by in-situ polymerization in the presence of nanocellulose

Authors
Jun Mo Koo (a, b, 1), Jaeryeon Kang (a, 1), Sung-Ho Shin (a), Jonggeon Jegal (a), Hyun Gil Cha (a), Seunghwan Choy (c), Minna Hakkarainen (b), Jeyoung Park (a, d), Dongyeop X. Oh (a, d), Sung Yeon Hwang (a, d)
Abstract
A biobased and biocompatible thermoplastic elastomer (TPE) with superior 3D printability was demonstrated with great potential for customized manufacturing technologies and fabrication of biointegrated devices. The inherent structural and stereochemical disadvantages of biobased monomers, such as 2,5-furandicarboxylic acid, in comparison with today used petroleum based monomers like terephthalic acid generally lead to lower mechanical performance for the biobased replacement polymers. This is additionally enhanced by poor interfacial adhesion and fusion commonly encountered during customized manufacturing technologies like 3D printing. Herein, we demonstrate that in-situ polymerization in the presence of trace amounts of cellulose nanocrystals (CNCs) can homogeneously distribute the nanofiller leading to dramatically strengthened thermally 3D-printable bio-furan-based TPE. This TPE exhibited a tensile strength of 67 MPa which is 1.5–7-fold higher than the values reported for silicone and thermoplastic urethane, which are widely used in biomedical applications. In addition, the TPE had an impressive extensibility of 860% and negligible in vivo cytotoxicity; such properties have not been reported to date for bio-based or petrochemical TPEs. While a petrochemical 3D printed TPE counterpart retained only half of the tensile strength compared to the hot-pressed analogue, the 3D-printed biobased TPE in-situ modified with nanocellulose maintained 70–80% of its strength under the same experimental conditions. This is explained by inter-diffusion between interfaces facilitated by the nanocellulose and the furan rings. Using the ergonomic shape of a wrist as a 3D-printable design, we successfully manufactured a wearable thermal therapeutic device from the nanocellulose modified biobased TPE, giving promise for wide variety of future applications.

December 15, 2019 by admin 0 Comments

Heat capacity variables of thermoplastic polyurethane for high-quality 3D printing resolution and their characteristics

Authors
Kyung Seok Kang, Chanhyuk Jee, Ji-Hong Bae, Hyo Jin Jung, PilHo Huh
Abstract
The preparation of TPUs base balanced by an intelligent mix of ductility and hardness for the 3D printing systems is successfully synthesized. The larger heat capacity leads to an increase in interfacial adhesion or compatibility between the laminating layers, which could offer the good tensile strength and ductility for the 3D printing. The precisely formulated TPU has the sufficient increase in heat capacity. This work is to determine a suitable soft/hard ratio for optimizing the hot-melt 3D printing system. The precise design of TPU provide a novel perspective to produce higher resolution-quality in the 3D printing polymer field.

October 24, 2019 by admin 0 Comments

3D Printing of Zeolite for Adsorption of Radioisotopes from a Nuclear Reactor Coolant

Authors
Sujeong Lee (a), Ho Jin Ryu (a, *)
Abstract
In operating nuclear power plants, the radionuclides are present in the reactor coolant system. These radionuclides are generated primarily by activation of dissolved ions released from structural components into the coolant. These isotopes should be removed for treating liquid wastes in aspect of safety and economically. There are many studies on the adsorption of dissolved Co (Ⅱ) and Ni (Ⅱ) ions by inorganic adsorbents (e.g. molecular sieve, kaolinite clay). Treatment of the liquid wastes with the inorganic adsorbent is preferred because of its high exchange capacity, possible selectivity and specificity, good resistant to radiation. Manufacturing of ceramic filters is difficult because of brittleness of ceramics. Furthermore, fabrication cost for ceramics is five times higher than fabricating of polymers. Thus, ceramic 3D printing based on extrusion of slurry ink has an advantage in making a filter of adsorbents, because 3D printing can reduce processing time and cost to form a complex filter structure.

October 22, 2019 by admin 0 Comments

Structure establishment of three-dimensional (3D) cell culture printing model for bladder cancer

Authors
Myeong Joo Kim (#1), Byung Hoon Chi (#1), James J. Yoo (2), Young Min Ju (2), Young Mi Whang (1, ‡*), In Ho Chang (1, ‡*), Jung Weon Lee
Abstract
Purpose Two-dimensional (2D) cell culture is a valuable method for cell-based research but can provide unpredictable, misleading data about in vivo responses. In this study, we created a three-dimensional (3D) cell culture environment to mimic tumor characteristics and cell-cell interactions to better characterize the tumor formation response to chemotherapy. Materials and methods We fabricated the 3D cell culture samples using a 3D cell bio printer and the bladder cancer cell line 5637. T24 cells were used for 2D cell culture. Then, rapamycin and Bacillus Calmette-Guérin (BCG) were used to examine their cancer inhibition effects using the two bladder cancer cell lines. Cell-cell interaction was measured by measuring e-cadherin and n-cadherin secreted via the epithelial-mesenchymal transition (EMT). Results We constructed a 3D cell scaffold using gelatin methacryloyl (GelMA) and compared cell survival in 3D and 2D cell cultures. 3D cell cultures showed higher cancer cell proliferation rates than 2D cell cultures, and the 3D cell culture environment showed higher cell-to-cell interactions through the secretion of E-cadherin and N-cadherin. Assessment of the effects of drugs for bladder cancer such as rapamycin and BCG showed that the effect in the 2D cell culture environment was more exaggerated than that in the 3D cell culture environment. Conclusions We fabricated 3D scaffolds with bladder cancer cells using a 3D bio printer, and the 3D scaffolds were similar to bladder cancer tissue. This technique can be used to create a cancer cell-like environment for a drug screening platform.

October 16, 2019 by admin 0 Comments

Evaluation of Sericin Containing Gel as a Photoinitiator-Free Printable Biomaterial

Authors
Mijin Jang, Bo Kyung Park, Jeung Soo Huh, Jeong Ok Lim
Abstract
Current major challenge in three-dimensional (3D) printing of biological tissues is lack of proper printable biomaterials. Development of 3D printable biomaterials for safely and efficiently printing biological substitute is challenging. Most of the hydrogel-based biomaterials include photoinitiator to be crosslinked by either ultraviolet or visible light to obtain mechanically stable gel. However, use of crosslinking chemical has concerns for its potential harm to biological substances. Our study aimed to formulate and optimize a new printable biomaterial without any crosslinking chemical, still having appropriate rheological, chemical, and biological properties. We investigated the potential of a silk protein, sericin, which is known to be mechanically stable and has anti-inflammatory and angiogenic properties. The results demonstrated that a sericin-based hydrogel can be an excellent material as it is easy to print, gelling, not toxic, stable, and cost effective.

October 1, 2019 by admin 0 Comments

The Evolution of Bio-based Plastics beyond Petrochemical Plastics

Authors
Dongyeop Oh, Hwang Seongyeon, Park Jeyeong
Abstract
Environmental and health concerns force the search for sustainable plastics that utilise bio-derived monomers. However, previously reported bio-derived thermosets or thermoplastics rarely offer thermal/mechanical properties, scalability, or recycling that match those of petrochemical plastics. Here, we report the production of high performance bio-based plastics. 1. tough biodegradable plastics. 2. high Tg super engineering bio-based plastics.

October 1, 2019 by admin 0 Comments

Polyimide for Flexible Organic Electronic Device Substrates

Authors
Seung Woo Lee (†)
Abstract
For flexible organic electronic device substrates, polymer materials should provide high gas barriers, flexibility, toughness and processability and desirable thermal and chemical properties. Of the many available polymeric materials, polyimides (PIs) have been widely used in the electronic device industry due to their high glass transition temperature, dimensional stability and heat resistance, as well as their excellent mechanical, adhesion and dielectric properties. Several concepts of colorless PI films have recently been proposed that reduce charge-transfer complexation by introducing fluorine groups, asymmetrical and bulky pendent units, or alicyclic units in the polymer structure to overcome the drawbacks of PI films.

August 30, 2019 by admin 0 Comments

Bioprinting Technologies in Tissue Engineering

Authors
Bengi Yilmaz, Aydin Tahmasebifar, Erkan Türker Baran
Abstract
Bioprinting technology is a strong tool in producing living functional tissues and organs from cells, biomaterial-based bioinks, and growth factors in computer-controlled platform. The aim of this chapter is to present recent progresses in bioprinting of nerve, skin, cardiac, bone, cartilage, skeletal muscle, and other soft tissues and highlight the challenges in these applications. Various composite bioinks with bioactive ceramic-based scaffolds having patient-specific design and controlled micro-architectures were used at clinical and preclinical applications successfully for regeneration of bone. In nerve tissue engineering, bioprinting of alginate- and gelatin-based gel bioinks by extrusion presented a controllable 3D microstructures and showed satisfactory cytocompatibility and axonal regeneration. Bioprinting of cardiac progenitors in biopolymers resulted in limited success, while the use of bioinks from extracellular matrix induced satisfactory results in cardiac regeneration. Osteochondral scaffold bioprinting is challenging due to the complex hierarchical structure and limited chondral regeneration. Therefore, current approaches focused on osteochondral scaffold with vascular network and mimicking hierarchical structures. The applications of bioprinting in other types of tissues were also studied, and results showed significant potentials in regeneration of tissues such as cornea, liver, and urinary bladder.

August 21, 2019 by admin 0 Comments

An interview with Heon Ju Lee on ROCKIT Healthcare’s novel bioprinting treatment for dermal scarring

Authors
Heon Ju Lee
Abstract
In this exclusive interview, Heon Ju Lee discusses ROCKIT healthcare’s novel bioprinting technique used to treat patients with dermal scarring. This interview was conducted by Mike Gregg, Commissioning Editor of the Journal of 3D Printing in Medicine.Dr Heon Ju Lee is the Chief Technology Officer and Managing Director of ROKIT. He is developing the service platform technology for artificial organ regeneration and supervises the overseas business development for the propagation of such service platforms. The focus of these platforms, bringing bio 3D print-based medical therapies into the operating room, on tissues that are relatively easy to fabricate structurally with the current technology, this includes skin, cartilage, hair, retina and heart patch regeneration. Dr Lee has a PhD from MIT in mechanical engineering and has been working as a 3D/4D printing group leader at KIST.