• 한국세라믹학회지
• /
• 제56권3호
• /
• pp.211-232
• /
• 2019

Porous ceramics are promising materials for a number of functional and structural applications that include thermal insulation, filters, bio-scaffolds for tissue engineering, and preforms for composite fabrication. These applications take advantage of the special characteristics of porous ceramics, such as low thermal mass, low thermal conductivity, high surface area, controlled permeability, and low density. In this review, we emphasize the direct foaming method, a simple and versatile approach that allows the fabrication of porous ceramics with tailored microstructure, along with distinctive properties. The wet foam stability is achieved under the controlled addition of amphiphiles to the colloidal suspension, which induce in situ hydrophobization, allowing the wet foam to resist coarsening and Ostwald ripening upon drying and sintering. Different components, like contact angle, adsorption free energy, air content, bubble size, and Laplace pressure, play vital roles in the stabilization of the particle stabilized wet foam to the porous ceramics. The mechanical behavior of the load-displacements curves of sintered samples was investigated using Herzian indentations testes. From the collected results, we found that microporous structures with pore sizes from 30 ㎛ to 570 ㎛ and the porosity within the range from 70% to 85%.

• 접착 및 계면
• /
• 제24권3호
• /
• pp.105-111
• /
• 2023

최근 귀금속 산업을 포함한 다양한 산업 분야에 있어, 생물 부착 억제를 위한 코팅 방법에 대한 관심이 증가하고 있다. 특히, 패션 주얼리와 같이 피부에 밀착하여 접촉하는 악세사리나 귀걸이, 그리고 피어싱의 경우, 금속 표면의 오염으로 인하여 접촉 부위를 자극하거나 이상 반응을 유도할 수 있다. 이에 본 연구에서는 폴리에틸렌글라이콜 양 말단에 홍합의 접착 물질로 보고된 카테콜기를 도입하여 접착성 폴리에틸렌글라이콜을 합성하고, 이를 구리와 아연의 합금인 황동 표면에 코팅하여 생물 부착 억제 효과를 관찰하였다. 접착성 폴리에틸렌글라이콜이 코팅된 황동 표면은 우수한 세포 생존율을 나타낼 뿐 아니라, 단백질이나 세포의 부착을 억제하는 효과를 나타냈다. 그러므로 귀금속 산업 분야에 있어서 접착성 폴리에틸렌글라이콜을 이용한 다양한 응용이 기대된다.

• Composites Research
• /
• 제35권3호
• /
• pp.153-160
• /
• 2022

목재 섬유 기반의 셀룰로오스 나노피브릴(cellulose nanofibrils, CNF)은 생체적합특성이 우수하여 조직 공학용 스캐폴드, 약물 운반체, 상처 치유용 겔 등의 생체 의료 분야에서 많은 관심을 받고 있다. 하지만, 셀룰로오스 나노피브릴은 상대적으로 약한 기계적 강도를 나타내기 때문에 높은 기계적 특성을 요구하는 응용 분야에 사용되기 어렵다는 한계를 가지고 있다. 따라서 본 연구에서는 셀룰로오스 나노피브릴의 기계적 강도를 향상시키기 위해 TEMPO (2,2,6,6-tetramethylpiperidin-oxyl) 산화 처리된 셀룰로오스 나노피브릴에 금속 양이온을 도입하여 금속-카르복실레이트 배위 결합을 가지는 하이드로겔을 제조하였다. 또한, 큰 진폭 진동 전단(large amplitude oscillatory shear) 측정과 Live/Dead 세포 시험을 통해 하이드로겔의 비선형 점탄성 거동과 세포 생존 능력을 분석하였다. 특히, 첨가된 금속염의 종류에 따라 세포의 증식 및 생존 능력이 변화하였고, 이는 하이드로겔들의 유변 물성 특성에도 영향을 미쳤다.

• 대한기계학회논문집A
• /
• 제32권12호
• /
• pp.1102-1106
• /
• 2008

Microfluidics deals with the behavior, precise control and manipulation of fluids at a micro scale. It has become increasingly prevalent in various applications such as biomedical applications (diagnostics, therapeutics, and cell/tissue engineering), inkjet head, and fuel cells etc. The issue of inspection and characterization of microfluidics has emerged as a major consideration in design, fabrication, and detection of microfluidic devices. In this paper, we characterize a diffusion based mixing in Y-microchannel using a fluorescent optical scanner based on a DVD pick-up module, which is widely used in optical storages. Using fluorescent dye, we measure the fluorescent intensity that represents the mixing patterns in Y-microchannel. We also compare these experimental results with computational fluid dynamics (CFD) simulation ones. It is shown that the proposed optical scanner can be used as an alternative measurement system with high performance and cost-effectiveness, compared to conventional optical tools such as epifluorescent microscopes using high resolution CCD camera and confocal microscopes with photomultiplier (PMT) detectors.

• Nuclear Engineering and Technology
• /
• 제55권8호
• /
• pp.2734-2741
• /
• 2023

Brachytherapy is a special case of radiotherapy. It should be arranged according to some principles in medical radiation applications and radiation physics. The primary principle is to use as low as reasonably achievable dose in all ionizing radiation applications for diagnostic and therapeutic treatments. Dosimetric distributions are dependent on radioactive source properties and radiation-matter interactions in an absorber medium such as phantom or tissue. In this consideration, the geometrical structure and material of the seed capsule, which surrounds a radioactive material, are directly responsible for isodose profiles and dosimetric functions. In this study, the radiometric properties of capsule material were investigated on dose distribution in a water phantom by changing its nuclear properties using the EGSnrc Monte Carlo (MC) simulation code. Effective atomic numbers of hypothetic mixtures were calculated by using different elements with several fractions for capsule material. Model 6711 brachytherapy seed was modeled by EGSnrc/Dosrcnrc Code and dosimetric functions were calculated. As a result, dosimetric parameters of hypothetic sources have been acquired in large-scale atomic number. Dosimetric deviations between the data of hypothetic seeds and the original one were analyzed. Unit dose (Gy/Particle) distributions belonging to different types of material in seed capsule have remarkably differed from the original capsule's data. Capsule type is major variable to manage the expected dose profile and isodose distribution around a seed. This study shows us systematically varied scale of material type (cross section or effective atomic number dependent) offers selective material usage in production of seed capsules for the expected isodose profile of a specific source.

• The Korean Journal of Physiology and Pharmacology
• /
• 제28권5호
• /
• pp.423-433
• /
• 2024

Dental pulp stem cells (DPSCs) are a type of adult stem cell present in the dental pulp tissue. They possess a higher proliferative capacity than bone marrow mesenchymal stem cells. Their ease of collection from patients makes them well-suited for tissue engineering applications, such as tooth and nerve regeneration. Chios gum mastic (CGM), a resin extracted from the stems and leaves of Pistacia lentiscus var. Chia, has garnered attention for its potential in tissue regeneration. This study aims to confirm alterations in cell proliferation rates and induce differentiation in human DPSCs (hDPSCs) through CGM treatment, a substance known for effectively promoting odontogenic differentiation. Administration of CGM to hDPSC cells was followed by an assessment of cell survival, proliferation, and odontogenic differentiation through protein and gene analysis. The study revealed that hDPSCs exhibited low sensitivity to CGM toxicity. CGM treatment induced cell proliferation by activating cell-cycle proteins through the Wnt/β-catenin pathway. Additionally, the study demonstrated that CGM enhances alkaline phosphatase activation by upregulating the expression of collagen type I, a representative matrix protein of dentin. This activation of markers associated with odontogenic and bone differentiation ultimately facilitated the mineralization of hDPSCs. This study concludes that CGM, as a natural substance, fosters the cell cycle and cell proliferation in hDPSCs. Furthermore, it triggers the transcription of odontogenic and osteogenic markers, thereby facilitating odontogenic differentiation.

• KSBB Journal
• /
• 제22권4호
• /
• pp.179-184
• /
• 2007

본 연구는 특정 아미노산들로 구성된 단위체가 반복되는 형태를 가지는 반복단위 단백질을 유전공학적으로 합성하는 방법들과 응용사례들을 소개하고 있다. 유전공학적 합성법은 단위체의 반복횟수를 정확하게 제어하면서 인식부위의 제한을 없애서 원하는 단백질만을 발현할 수 있도록 발전해왔으며, 최근 소개된 RDL과 CCM 방법에 의하여 가능해졌다. 반복단위 단백질의 응용사례로는 대표적으로 ELP, SLP, Prolamin 등의 단백질을 합성하여 생체재료나 약물전달시스템을 개발하는데 응용하거나, ELFSE의 drag-tag 개발에 응용되는 연구들이 진행되고 있다. 화학적으로 합성된 고분자에 비해 유전공학적으로 합성된 반복단위 고분자의 경우, 고유의 물리적 성질과 함께 환경에 미치는 유해함이 상대적으로 적다는 점 때문에 미래의 신소재로 기대되고 있다.

• 한국농업기계학회:학술대회논문집
• /
• 한국농업기계학회 2017년도 춘계공동학술대회
• /
• pp.109-109
• /
• 2017

Cirsium setidens nakai belonging to cirsium has been reported to have various physiological activities including anticancer activity because it contains polyphenols, dietary fiber, minerals and vitamins. Despite these positive positive efficacies, however, no studies have studied cirsium setidens nakai products as biomaterials such as cellular metabolism and bone formation. Thus, the aim of this study was evaluate of osteogenesis differentiation a natural material extracted from cirsium setidens nakai. The natural materials in this studys in this studywere created by 40% ethanol extraction process and then dried. FabricatedFabricatedpowders were added to a medium at various concentrations (0.01, 0.05, 0.1, 0.2, and $0.25{\mu}g/mL$), and pure medium was used as a control. The natural material caused positive increases in cell metabolic activity and mineralized bone formation without cytotoxicity. In addition, we observed higher expression of genes such as ALP, BSP, Runx2 and COL1 in cirsium setidens nakai treatment cells. As a result, this study produced and investigated cirsium setidens nakai extracts and the natural materials showed potential biomaterials. In this research indicated that the cirsium setidens nakai extracts might have promising applications in areas of agricultural, biological and food engineering as a biomaterial.

• 한국정밀공학회지
• /
• 제31권8호
• /
• pp.743-747
• /
• 2014

In this study, drop-on-demand system using piezo-elecrtric inkjet printers was employed for preparation of collagen microspheres, and its application was made to the HepG2 cell-laden microsphere preparation. The collagen microspheres were injected into beaker filled with mineral oil and incubated in a water bath at $37^{\circ}C$ for 45 minutes to induce gelation of the collagen microsphere. The size of collagen microsphere was $100{\mu}m$ in diameter and $80{\mu}m$ in height showing spherical shape. HepG2 cells were encapsulated in the collagen microsphere. The cell-laden microspheres were inspected by the microscopic images. The encapsulation of cells may be beneficial for applications ranging from tissue engineering to cell-based diagnostic assays.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2006년도 춘계학술대회 논문집
• /
• pp.203-204
• /
• 2006

Studies on some biodegradable polymers and other materials such as hydrogels have shown the promising potential for a variety of surgical applications. Postoperative adhesion caused by the natural consequence of surgical wound healing results in problems of the repeated surgery. Recently, scientists have developed absorbable anti-adhesion barriers that can protect a tissue from adhesion in case they are in use; however, they are dissolved when no longer needed. Although these approaches have been attempted to fulfill the criteria for adhesion prevention, none can perfectly prevent adhesions in all situations. Overall of this work, a new method to fabricate an anti-adhesion membrane using biodegradable polymer and hydrogel has been developed. The ideal barrier for preventing postoperative adhesion would have the following properties; it should be (i) resorbable (ii) non-reactive (iii) easy to apply (iv) capable of being fixed in position. In order to fulfill these properties, we adopted solid freeform fabrication method combined with surface modification which includes the hydrogel coating, therefore, inner or outer structure can be controlled and the property of anti adhesion can be improved.