This work reports the fabrication of a flexible Photodetector (PD) using Carbon Dots (CDs)/Polymer composite for Deep UV (DUV) photodetection. The CDs have been prepared using a simple and inexpensive heating process. The syncretic studies reveal the disordered graphitic core with surface functional groups and the excitation-dependent character of CDs. The synthesized CDs are stabilized via Poly Vinyl Alcohol (PVA) through a synergistic effect and investigated for different compositions (2–10 weight %) of CDs. The CDs/PVA composites shows improved absorbance at 208 and 335 nm compared to pure CDs owing to the bonding between them. This advantageous property of high absorption and photo response in the DUV region is utilized by employing CDs/PVA composite as a photo-sensing layer on the ITO-coated PET substrate in the PD. The performance of the PD was measured under dark, short (254 nm) and long (365 nm) UV region. Among all the compositions, 4% CDs/PVA PD exhibits superior performance in terms of high photo-to-dark current ratio (IPh/Id), responsivity and detectivity. The PD functioning and other parameters are discussed in detail and reported.

Collagen is one of the most widely used biological materials in medical design. Collagen extracted from marine organisms can be a good biomaterial for tissue engineering applications due to its suitable properties. In this study, collagen is extracted from fish skin of Ctenopharyngodon Idella; then, the freeze drying method is used to design a porous scaffold. The scaffolds are modified with the chemical crosslinker N-(3-Dimethylaminopropyl)-N'-ethyl carbodiimide hydrochloride (EDC) to improve some of the overall properties. The extracted collagen samples are evaluated by various analyzes including cytotoxicity test, SDS-PAGE, FTIR, DSC, SEM, biodegradability and cell culture. The results of the SDS-PAGE study demonstrate well the protein patterns of the extracted collagen. The results show that cross-linking of collagen scaffold increases denaturation temperature and degradation time. The results of cytotoxicity show that the modified scaffolds have no toxicity. The cell adhesion study also shows that epithelial cells adhere well to the scaffold. Therefore, this method of chemical modification of collagen scaffold can improve the physical and biological properties. Overall, the modified collagen scaffold can be a promising candidate for tissue engineering applications.

스캐폴드는 손상된 조직을 보호, 지지하고, 세포분화 및 증식을 위한 공간을 임시로 제공하여 조직의 회복을 유도한다. 이에, 스캐폴드막은 생체친화성과 생분해성을을 지녀야 한다. 본 연구에서는 Poly(L-lactide)를 사용하였고, 상전이법을 기초로 하여 스캐폴드막을 제조하였으며, 대형공극을 형성하기 위하여 염 침출법을 복합하여 사용하였다. 그 결과 높은 공극률의 다공성 스캐폴드막을 얻을 수 있었으며, 기존의 여타 방식에 비해 월등히 간단한 방식으로 스캐폴드를 제조할 수 있다는 결론을 얻을 수 있었다.

조직공학이란 손상된 조직에 대한 대체재를 개발, 제조하는 분야이며, 기증자로부터의 조직을 직접 이식하는 방법이 가장 널리 사용되어 왔으나, 최근에는 함성소재로부터의 캐폴드막 제조에 대한 연구가 진행되고 있다. 스캐폴드막은 공극률, 공극직경 및 공극간의 높은 연결성이 요구된다. 이에 대하여 용융주조에 이은 염 침출법이 알려져 있다. 본 연구에서는 용매주조에 이은 염 침출법을 사용하였으며, 이를 통하여 높은 공극률과 공극간의 연결성은 물룬 적합한 공극직경의 우수한 스캐폴드막을 제조하였다.

순수용매와 혼합용매를 사용한 상전이를 통하여 poly(L-lactic acid) (PLLA) 스캐폴드 막을 제조하였다. 순수용매로서 chloroform과 1,4-dioxane을 사용하였으며, 이들 순수용매를 혼합하여 혼합용매를 제조하였다. 스캐폴드 막의 모폴로지, 기계적 특성 그리고, 물질전달 특성을 각각 SEM, 인장강도실험 및 당 확산실험을 통하여 측정, 평가하였다. 순수 chloroform 용매를 사 용한 용액으로부터는 격벽-공극 구조(solid-wall pore structure)의 스캐폴드 막이 제조되었다. 반면, 순수 1,4-dioxane 용매를 사용 한 용액으로부터는 나노섬유 구조의 스캐폴드 막이 제조되었다. 혼합용매의 경우 용매 내의 조성이 변화하면서 다양한 구조의 스 캐폴드 막이 제조되었다. 혼합용매 내 1,4-dioxane 함량이 20% 이하인 경우에는 격벽-공극 구조의 스캐폴드 막이 제조되었으며, 1,4-dioxane 함량이 20%인 경우에는 최대직경 100 μm의 거대공극을 갖는 구조를 보였다. 1,4-dioxane 함량이 25% 이상인 구간 에서는 나노섬유 구조의 스캐폴드 막이 제조되었다. 이 구간에서는 혼합용매 내 1,4 dioxane 함량이 변화함에 따라 나노섬유의 직경이 함께 변화하였다. 나노섬유의 최소직경은 15 nm 가량이었으며, 혼합용매 내의 1,4-dioxane 함량이 80 wt%일 때에 얻어졌 다. 이상의 결과를 통하여 용매의 조성은 스캐폴드 막의 구조를 결정짓는 중요한 요소가 된다는 결론을 얻을 수 있었다.

In this study, we fabricated a novel micro porous hybrid scaffold of biphasic calcium phosphate (BCP) and a polylectrolyte complex (PEC) of chitosan (CS) and hyaluronic acid (HA). The fabrication process included loading of CS-HA PEC in a bare BCP scaffold followed by lypophilization. SEM observation and porosimetry revealed that the scaffold was full of micro and macro pores with total porosity of more than 60 % and pore size in the range of 20~200μm. The composite scaffold was mechanically stronger than the bare BCP scaffold and was significantly stronger than the CS-HA PEC polymer scaffold. Bone morphogenetic growth factor (BMP-2) was immobilized in CS-HA PEC in order to integrate the osteoinductive potentiality required for osteogenesis. The BCP frame, prepared by sponge replica, worked as a physical barrier that prolonged the BMP-2 release significantly. The preliminary biocompatibility data show improved biological performance of the BMP-2 immobilized hybrid scaffold in the presence of rabbit bone marrow stem cells (rBMSC).

In this experiment, a highly porous scaffold of biphasic calcium phosphate (BCP) was prepared using the spongereplica method. The BCP scaffold was coated with 58S bioactive glass (BG) and sintered for a second time. The resulting scaffold was coated with gelatin (Gel) and cross-linked with [3-(3-dimethyl aminopropyl) carbodiimide] and N-Hydroxysuccinamide (EDC-NHS). The initial average pore size of the scaffold ranged from 300 to 700μm, with more than 85 % porosity. The coating of BG and Gel had a significant effect on the scaffold-pore size, decreasing scaffold porosity while increasing mechanical strength. The material and surface properties were evaluated by means of several experiments involving scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) and X-ray diffraction (XRD). Cytotoxicity was evaluated using MTT assay and confocal imaging of MC3T3-E1 pre-osteoblast cells cultured in vitro. Three types of scaffold (BCP, BCP-BG and BCP-BG-Gel) were implanted in a rat skull for in vivo evaluation. After 8 weeks of implantation, bone regeneration occurred in all three types of sample. Interestingly, regeneration was found to be greater (geometrically and physiologically) for neat BCP scaffolds than for two other kinds of composite scaffolds. However, the other two types of scaffolds were still better than the control (i.e., defect without treatment).

상전이 과정을 통하여 poly(L-lactic acid) 재질의 다공성 스캐폴드 막을 제조하였다. 비용매로는 에탄올을 사용하였고, 용매로서 chloroform, dichloromethane 및 1,4-dioxane을 사용하였으며, 제조한 스캐폴드 막의 모폴로지와 기계적 강도 및 물질전달 특성은 각각 SEM, 인장강도실험 및 당 확산실험을 통하여 측정, 평가하였다. chloroform을 용매로 사용한 스캐폴드 막과 dichloromethane을 용매로 사용한 스캐폴드 막은 서로 유사한 모폴로지와 기계적 특성을 보였다. 이들 스캐폴드 막은 공극 직경 3-10 µm의 다공성 스펀지 구조를 보였으며, 범위 50-80%의 공극률을 보였다. 1,4-dioxane 용매의 용액으로부터제조된 스캐폴드 막은 공극률 80% 이상의 나노섬유 형태를 보였다. 캐스팅 용액 내의 고분자 함량이 4% 이하로 낮추었을 때에는 나노섬유 구조의 바탕에 수십 µm의 거대 공극이 존재하는 높은 공극률(90%)을 갖는 스캐폴드 막이 얻어졌다. 이러한결과를 통하여 스캐폴드 막의 구조에 대하여 용매는 중요한 효과를 미치며, 상전이 과정에서 용매선택과 캐스팅 용액의 농도조절을 통하여 다양한 구조의 스캐폴드 막을 제조할 수 있다는 결론을 도출하였다.

Mechanical stimulation has been reported to improve cell growth in bone and cartilage regeneration. Various research groups have described their own bioreactors that stimulate cell-seeded scaffolds. We have developed a bioreactor capable of applying controlled compressive loading to a cell-encapsulated agarose hydrogel. To compare the effect of mechanical stimulation on agarose hydrogel, we used one control group (static mode) and five experimental groups. The results show that the intermittent_3sec conditions improve proliferation of cells better than the other conditions studied.

In this article, we reported the characterization of mechanical properties for several scaffolds fabricated by different techniques: bio-plotter technique and WNM(wire-network molding). Firstly, we constructed numerical models for ABAQUS: a commercial computational analyzing program. Using ABAQUS, effective compressive are calculated and compared with the experimental results from UTM tests. The results show that the stiffness of the scaffold fabricated by WNM is stronger than that by bio-plotter technique.

Silk fibroin has been widely tested as a candidate biomaterial applicable to various attempts of tissue engineering. In order to examine bone forming ability of silk 3-D scaffold, we have developed a tibial interlocking intramedullary nailing model. A tibial intramedullary nail in the weight bearing hind limb of a rat was interlocked with a pin through a pin hole at the proximal end of the intramedullary nail. Interlocking of the intramedullary nail prevented total collapse of proximal region of a bone defect and helped maintain the critical gap that was filled with silk 3-D scaffold, though minor shinkage about 1 mm at distal region was unavoidable. Bone forming ability of an implanted silk scaffold was monitored weekly for 8~10 wks by X-ray radiography of live animals and bone formation in the scaffold was examined by H & E staining and Masson’s trichrome staining of the bone tissue recovered from the animals. Although scattered islets of bone tissue was observed in the implanted silk scaffold, bone tissue was not widely developed and implanted scaffolds of silk nanofiber and salt-leached sponge were X-ray transparent, suggesting inefficient bone formation. By contrast, X-ray image of implanted silk nanofibrous scaffold coated with hydroxyapatite was getting darkened with time, which suggests bone tissue formation in the scaffold, while untreated silk 3-D scaffold remained undisturbed. Although existence of bone tissue in the scaffold should be confirmed by histological criteria, hydroxyapatite-coated silk scaffold appeared competent to support regeneration of the long bone defects In addition, the interlocking intramedullary nailing in tibia of rat hind limb could be applicable in assessing long bone regenerative capacity of various biocompatible materials.

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.

본 연구는 마이크로 스케일의 내부 구조를 갖는 3차원 인공지지체를 제작하기 위하여 개발된 제조 시스템의 성능 분석을 위해 x-y축 정밀 스테이지 시스템으로 조립되었을 때의 해상도 및 정확도를 측정 하였으며, z축 정밀 스테이지를 분리하여 다양한 물리적 오차를 제거하였다. 기존의 x-y-z축 정밀 스테이 지 시스템을 x-y축으로 분리하고 각 축의 이동거리를 4종류(±0.25μm, ±0.5μm, ±25μm, ±50μm)로 설정하여 각 위치마다의 변위를 레이저 측정기를 이용하여 기록하였다. 가장 작은 이동거리(±0.25μm)에서의 진동이 상대적으로 가장 크게 나타났으며, y축 스테이지 위에 x축 스테이지를 조립하였기 때문에 x축 스테이지 자중에 의한 모멘텀으로 인하여 y축 스테이지 구동변위 값이 크게 나타났다. 하지만 z축 스테이지는 기존 시스템과 달리 별로도 분리하여 구동 오차를 줄였으며, 일체화된 광학시스템을 적용하여 광학오차를 감 소시켰다. 따라서 새로운 시스템에서는 500μW, 140mm/min의 가공조건에서도 마이크로 스케일의 3차원 인 공지지체 형상의 구조물을 성공적으로 제작할 수 있었다.

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.