3D프린팅 기술은 산업적 응용을 넘어서 기계 설비 및 각종 장비의 부품생산뿐만 아니라 의료, 식품, 패션에 이르기까지 많은 시제품들의 개발 및 연구가 진행되고 있다. 3D 프린팅 기반 기술의 적용사례를 볼 때 정밀도와 제작 속도 측면에서도 다른 산업에 충분이 활용될 수 있는 기술의 개발이 보고되고 있으나, 아직까지는 시제품 위주로 이용되고 있으며, 향후 3D 프린팅 기술은 4차산업혁명과 관련하여 광범위한 분야에서 응용될 수 있는 완성품이나 부품제작에 이용될 것으로 예상된다. 본 연구에서는 탄소나노 재료중 대표적으로 많이 이용되는 환원그래핀 [rGO(reduced graphene oxide)]과 전도성 고분자중 생체 친화적인 특성을 갖는 폴리피롤[Ppy(Polypyrrole)]의 복합체를 생분해성 고분자인 폴리카프로락톤 [PCL(polycaprolactone)]과 혼합하여 3D 프린팅용 전도성 레진을 개발하고자 하였다. 결과로, 폴리피롤과 환원그래핀 각각 5 wt%, 0.75 wt% 에서 최적의 전기적 특성을 나타내었으며, 환원그래핀의 농도에 따른 표면분석에서도 이와 부합하는 결과를 확인 할 수 있었다. 본 연구를 통하여 제조된 전도성 레진은 3D 프린팅 뿐만 아니라, 다른 산업분야의 전자재료에도 적용이 가능할 것으로 사료된다.

막유화(membrane emulsification, ME)는 SPG 막과 같이 균일한 크기의 세공을 갖는 막을 사용하여 좁은 입도분 포의 에멀젼을 제조하는 기술이다. 본 연구에서는 막유화법으로 형성시킨 다중 에멀젼을 사용하여 폴리카프로락톤(PCL) 마 이크로캡슐의 제조를 연구하였다. 먼저 초음파 유화기로 W1/O 단일 에멀젼을 제조한 후, premix 막유화를 적용하여 W1/O/W2 다중 에멀젼을 형성시킨 후 용매 증발을 통해 모델 약물인 BSA가 담지된 PCL 마이크로캡슐을 제조하였다. 연속상 에 대한 분산상의 비율(D/C ratio), PCL 농도, 유화제 농도, 모델 약물의 농도, 막간 압력차 등 막유화 변수가 제조된 마이크 로캡슐의 입경과 입도 분포에 미치는 영향을 실험하였다. Premix-ME를 적용하여 평균 입경 5~6 μm의 균일한 크기를 갖는 모델 약물 BSA의 함침량이 약 26%인 다중 코어형 PCL 마이크로캡슐을 제조할 수 있었다.

The membrane emulsification (ME) is a technology for producing emulsions with narrow size distribution by using the well-defined porous membranes such as the SPG membrane. In this work, the preparation of polycaprolactone (PCL) microcapsules by using the multiple emulsion membrane emulsification method was studied. After the making of W1/O single emulsions by sonication, then W1/O/W2 multiple emulsions were prepared by ME method. The effects of various parameters such as the ratio of disperse/continuous phase (D/C ratio), the contents of PCL, emulsifier and model drug and the transmembrane pressure on the size and distribution of PCL microcapsules were investigated. The uniform PCL microcapsules with about 5～6 μm of mean size were obtained. The model drug (BSA) release properties of the obtained PCL microcapsules also were tested.

목 적 : 후방십자인대는 무릎 관절의 안정화를 위한 중요한 인대로 인체의 균형을 유지하는데 매우 중요한 역할을 한다. 본 연구에서는 후방십자인대의 해부학적 구조에 따라 사방향 관상면 영상과 이중 사방향 시상면 영상을 획득하여 그 유용성을 평가하고자 한다. 대상 및 방법 : 2016년 12월부터 2017년 1월까지 환자 20명을 대상으로 검사하였고 SIEMENS사의 Skyra 3.0T에서 knee coil을 사용하였다. 검사 방법은 T2 COR, PD SAG을 획득하고 원위부 후방십자인대의 해부학적 구조를 고려한 PD OBL COR과 전체적인 구조를 고려한 PD Dual OBL SAG을 획득하였다. PCL의 관상면 비교를 위하여 밑단점의 길이와 폭을 측정하여 비교하였고, 시상면 평가를 위하여 기시점, 중간지점, 밑단점을 측정하여 비교하였다. 측정결과를 Mann-Whitney 방법을 사용하여 통계적 유의성을 검정하였다. 정성적 방법은 기존의 관상면, 시상면 영상과 사방향 관상면, 이중 사방향 시상면 영상에서 후방십자인대를 비교하여 미흡, 대등, 우월 세 단계로 평가하였다. 결 과 : 검사를 진행한 결과 기존 관상면 영상보다 사방향 관상면 영상에서 원위부 후방십자인대의 길이는4 7.9%, 폭 14.9% 증가하였고, 기존 시상면 영상보다 이중 사방향 시상면 영상에서 기시점 19.8%, 중간지점 18.3%, 끝단점 33%의 증가된 것 으로 측정되었다. 결 론 : 사방향 관상면 영상과 이중 사방향 시상면 영상 모두 기존 영상보다 우월한 영상 검사방법으로 평가되었다. 이에 슬 관절 후방십자인대의 해부학적 관찰에는 기존 검사 방법에 사방향 관상면 영상 검사와 이중 사방향 시상면 영상 검사를 병 행하는 것이 유용할 것으로 사료된다.

The current study was conducted in order to investigate bone formation using matrigel and angiogenic factors with HA and poly ε-caprolactone (HA/PCL) in a rat calvarial defect model. Calvarial defect formation was surgically created in Sprague Dawley rats (n=36). Rats in the control group (CD group, n=6) did not receive a graft. The HA/ PCL scaffold was grafted with matrigel (M-HA/PCL group, n=6) or without matrigel (HA/PCL group, n=6); and 100 ng of vascular endothelial growth factor with HA/ PCL scaffold containing matrigel (VEGF100 group, n=6), 100 ng (PDGF100 group, n=6) and 300 ng (PDGF300 group, n=6) of PDGF with HA/PCL scaffold containing matrigel were grafted in calvarial defects, respectively. Four weeks after surgery, bone formation was evaluated with micro computed tomography (micro CT) scanning, and histologically. According to the results, bone mineral density was significantly increased in the VEGF100, PDGF100, and PDGF300 groups compared to the HA/PCL group, in which angiogenic factors were not applied. In histological evaluation, more new bone formation around scaffolds was observed in the PDGF100 and the PDGF300 groups, compared with the VEGF100 group. Thus, the results indicate that HA/PCL containing matrigel with VEGF and PDGF is an effective grafting material for enhancement of bone formation in critical-sized bone defects. Especially, due to its price and capacity for bone formation, PDGF may be more effective than VEGF.

In this article, we proposed a novel technique to fabricate cell‐culturing scaffold, that is, the hollowcylinder‐ grain assembly technique. This technique uses hollow cylindrical particles with sub‐mm thickness. Firstly, we fabricate PCL (polycaprolactone) hollow cylinder with sub-mm thickness using lab-made stainless steel mold. After that, we put the above-mentioned fabricated particles into a metal mold of which temperature could be controlled with hot plate and heat insulation system. PCL particles in the metal mold could be assembled together without severe collapsing under adequate temperature and time. Consequently, we could fabricate scaffold or foam structure with interconnected‐porosity and observed surface of cross section of fabricated scaffold by SEM.

The electrospinning process was established as a promising method to fabricate nano and micro-textured scaffolds for tissue engineering applications. A BCP-loaded PCL micro-textured scaffold thus can be a viable option. The biocompatibility as well as the mechanical properties of such scaffold materials should be optimized for this purpose. In this study, a composite scaffold of poly (ε-caprolactone) (PCL)-biphase calcium phosphate (BCP) was successfully fabricated by electrospinning. EDS and XRD data show successful loading of BCP nano particles in the PCL fibers. Morphological characterization of fibers shows that with a higher loaded BCP content the fiber surface was rougher and the diameter was approximately 1 to 7 μm. Tensile modulus and ultimate tensile stress reached their highest values in the PCL- 10 wt% BCP composite. When content of nano ceramic particles was low, they were dispersed in the fibers as reinforcements for the polymer matrix. However, at a high content of ceramic particles, the particles tend to agglomerate and lead to decreasing tensile modulus and ultimate stress of the PCL-BCP composite mats. Therefore, the use of nano BCP content for distribution in fiber polymer using BCP for reinforcement is limited. Tensile strain decreased with increasing content of BCP loading. From in vitro study using MG-63 osteoblast cells and L-929 fibroblast like cells, it was confirmed that electrospun PCL-BCP composite mats were biocompatible and that spreading behavior was good. As BCP content increased, the area of cell spreading on the surface of the mats also increased. Cells showed the best adherence on the surface of composite mats at 50 wt% BCP for both L-929 fibroblast-like cells and MG-63 osteoblast cell. PCL- BCP composites are a promising material for application in bone scaffolds.

A highly porous Biphasic Calcium Phosphate (BCP) scaffold was fabricated by the sponge replica method with a microwave sintering technique. The BCP scaffold had interconnected pores ranging from 80 μm to 1000 μm, which were similar to natural cancellous bone. To enhance the mechanical properties of the porous scaffold, infiltration of polycaprolactone (PCL) was employed. The microstructure of the BCP scaffold was optimized using various volume percentages of polymethylmethacrylate (PMMA) for the infiltration process. PCL successfully infiltrated into the hollow space of the strut formed after the removal of the polymer sponge throughout the degassing and high pressure steps. The microstructure and material properties of the BCP scaffold (i.e., pore size, morphology of infiltrated and coated PCL, compressive strength, and porosity) were evaluated. When a 30 vol% of PMMA was used, the PCL-BCP scaffold showed the highest compressive strength. The compressive strength values of the BCP and PCL-BCP scaffolds were approximately 1.3 and 2MPa, respectively. After the PCL infiltration process, the porosity of the PCL-BCP scaffold decreased slightly to 86%, whereas that of the BCP scaffold was 86%. The number of pores in the 10 μm to 20 μm rage, which represent the pore channel inside of the strut, significantly decreased. The in-vitro study confirmed that the PCL-infiltrated BCP scaffold showed comparable cell viability without any cytotoxic behavior.

Porous poly(e-caprolactone) (PCL) scaffolds were fabricated by salt leaching method. The PCL scaffolds were treated with aqueous NaOH for 0h, 2h, 4h, 8h, and 12h at 40˚C. The NaOH-treated PCL scaffolds were dipped in CaCl2 and K2HPO4·3H2O solution alternately three times to induce apatite nuclei onto the surface of the scaffolds. The NaOH-treated PCL scaffolds were immersed into SBF solution for 1day to grow the apatite. The apatite formation were investigated as a fuction of NaOH treatment time. The hydrophilicty and surface area of the PCL scaffolds were increased with NaOH-treatment time. The NaOH-treated PCL scaffolds were successfully formed a dense and uniform bone-like apatite layer after immersion for 1 day in SBF solution.