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Yang Dae Hyeok,Yoon Goan Hee,Shin Gyun Jeong,Kim Soon Hee,Rhee John M.,Khang Gilson,Lee Hai Bang The Polymer Society of Korea 2005 Macromolecular Research Vol.13 No.2
Conventional poly(methyl methacrylate) (PMMA) bone cement has been widely used as an useful biopolymeric material to fix bone using artificial prostheses. However, many patients had to be reoperated, due to the poor mechanical and thermal properties of conventional PMMA bone cement, which are derived from the presence of unreacted MMA liquid, the shrinkage and bubble formation that occur during the curing process of the bone cement, and the high curing temperature ($above 100^{\circ}C$) which has to be used. In the present study, a composite PMMA bone cement was prepared by impregnating conventional PMMA bone cement with ultra high molecular weight polyethylene (UHMWPE) powder, in order to improve its mechanical and thermal properties. The UHMWPE powder has poor adhesion with other biopolymeric materials due to the inertness of the powder surface. Therefore, the surface of the UHMWPE powder was modified with two kinds of silane coupling agent containing amino groups (3-amino propyltriethoxysilane ($TSL 8331^{R}$) and N-(2-aminoethyl)-3-(amino propyltrimethoxysilane) ($TSL 8340^{R}$)), in order to improve its bonding strength with the conventional PMMA bone cement. The tensile strengths of the composite PMMA bone cements containing $3 wt\%$ of the UHMWPE powder surface-modified with various ratios of $TSL 8331^{R}$ and $TSL 8340^{R}$ were similar or a little higher than that of the conventional PMMA bone cement. However, no significant difference in the tensile strengths between the conventional PMMA bone cement and the composite PMMA bone cements could be found. However, the curing temperatures of the composite PMMA bone cements were significantly decreased.
Yang, Dae Hyeok,Yoon, Sun-Jung,Lee, Deok-Won MDPI 2017 INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES Vol.18 No.8
<P>The most ideal implant models in the dental and orthopedic fields to minimize the failure rate of implantation involve the improvement of osseointegration with host bone. Therefore, a focus of this study is the preparation of surface-modified titanium (Ti) samples of disc and screw types using dexamethasone (DEX) and/or growth and differentiation factor-5 (GDF-5), as well as the evaluation of their efficacies on bone formation in vitro and in vivo. X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and contact angle measurement were used to evaluate the surface chemical composition, surface morphology and wettability, respectively. The results showed that implant surfaces were successfully modified with DEX and/or GDF-5, and had rough surfaces along with hydrophilicity. DEX, GDF-5 or DEX/GDF-5 on the surface-modified samples were rapidly released within one day and released for 28 days in a sustained manner. The proliferation and bone formation of MC3T3-E1 cells cultured on pristine and surface-modified implants in vitro were examined by cell counting kit-8 (CCK-8) assay, as well as the measurements of alkaline phosphatase (ALP) activity and calcium deposition, respectively. MC3T3-E1 cells cultured on DEX/GDF-5–Ti showed noticeable ALP activity and calcium deposition in vitro. Active bone formation and strong osseointegration occurred at the interface between DEX/GDF-5–Ti and host bone, as evaluated by micro computed-tomography (micro CT) analysis. Surface modification using DEX/GDF-5 could be a good method for advanced implants for orthopaedic and dental applications.</P>
Yang, Dae Hyeok,Moon, Sang Woong,Lee, Deok-Won MDPI 2017 INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES Vol.18 No.1
<P>In this study, we prepared human bone morphogenetic protein-2 (hBMP-2)/human growth and differentiation factor-5 (hGDF-5)-coated titanium (Ti) disc and screw types for controlled release of the growth factors (GFs). The two growth factors were coated onto Ti with a smooth surface using their specific interaction with heparin, because they have heparin binding sites in their molecular structures. Efficacy of the two growth factor-coated Ti for enhancement of bone formation and osseointegration was compared to pristine Ti, and hBMP-2- and hGDF-5-coated Ti in vivo. The surface chemical composition, surface morphology, and wettability characteristics of the metal samples were determined by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and contact angle measurement, respectively. The initial burst of hBMP-2, hGDF-5, and their combination, occurred within one day of the release study, resulting in 12.5%, 4.5%, and 13.5%/3.2%, and then there was a sustained, even release of these two growth factors from the coated metal for 30 days. In vitro tests revealed that MC3T3-E1 cells cultured on the two growth factor-coated Ti had a higher proliferation rate and a higher activity for alkaline phosphatase (ALP), which led to a larger amount of calcium deposition and larger expressions of type I collagen (<I>COL 1</I>), <I>ALP</I>, and osteocalcin (<I>OCN</I>) mRNAs. In vivo animal tests using ten white New Zealand rabbits showed that the two growth factor-coated Ti enhanced bone formation and osseointegration at the interface between the implants and host bone. In addition, histological evaluation showed that bone remodeling, including bone formation by osteoblasts and bone resorption by osteoclasts, actively occurred between the two growth factor-coated Ti and host bone. Consequently, it is suggested that Ti surface modification with the combination of hBMP-2 and hGDF-5 for the two growth factor-coated Ti implants can improve the clinical properties of implants for orthopedic and dental applications.</P>
( Dae Hyeok Yang ),( Min Suk Lee ),( Jong Tae Ko ),( Yong Sik Kim ),( Moon Suk Kim ),( John M. Rhee ),( Gil Son Khang ),( Hai Bang Lee ) 한국조직공학과 재생의학회 2006 조직공학과 재생의학 Vol.3 No.3
Ultra high molecular weight polyethylene(UHMWPE) powders were impregnated into poly(methylmethacrylate)( PMMA) bone cement to improve the poor mechanical and thermal properties of the bone cement. But, the surface inertness of UHMWPE powder generated the poor bonding force with PMMA bone cement. The surface modification after pretreating UHMWPE powder with the three kinds of acid such as acetic, hydrochloric, and sulfuric acid has been carried out to advance the interfacial adhesion between UHMWPE powder and PMMA bone cement. The tensile strengths of reinforced PMMA bone cements with 3 wt% of surface-precoated UHMWPE powder with polyMMA after acids treatment were much higher than that(33.8 MPa) of 3 wt% of intact UHMWPE powder impregnated PMMA bone cement as well as were almost same as that(44.5 MPa) of conventional PMMA bone cement. Also, it was found that the curing temperatures of the composite PMMA bone cements were much lower than that(~103oC) of conventional PMMA bone cement. From these results, it was confirmed that acids treatment effectively modified the surface of UHMWPE powder. A possible mechanism for the surface modification of UHMWPE powder by acids treatment was proposed.
Yang, Dae Hyeok,Ko, Jong Tae,Kim, Yong Sik,Kim, Moon Suk,Shin, Hyung Sik,Rhee, John M.,Khang, Gilson,Lee, Hai Bang Informa UK (TaylorFrancis) 2006 Journal of Biomaterials Science. Polymer Edition Vol.17 No.7
<P>In our previous study, we manufactured a reinforced poly(methylmethacrylate) (PMMA) bone cement with 3 wt% of the surface-modified ultra high molecular weight polyethylene (UHMWPE) powder to improve its poor mechanical and thermal properties resulting from unreacted methylmethacrylate (MMA), the generation of bubble and shrinkage, and high curing temperature. In the present study, the effect of ratios of MMA and N,N'-dimethyl-p-toluidine (DMPT) solutions in redox polymerization system was investigated for the surface modification of UHMWPE powder. We characterized physical and chemical properties of surface-modified UHMWPE powder and reinforced bone cements by a scanning electron microscope, ultimate tensile strength (UTS) and curing temperature (Tmax). It was found that UTSs (41.3-51.3 MPa) of the reinforced PMMA bone cements were similar to those (44.5 MPa) of conventional PMMA bone cement (control), as well as significantly higher (P < 0.05) than those (33.8 MPa) of 3 wt% unmodified UHMWPE powder-impregnated bone cement. In particular, the UTS of redox polymerization system using MMA/DMPT solution was better than that of radical system using MMA/xylene solution. Also, Tmax of the reinforced PMMA bone cements decreased from 103 to 72-84 degrees C. From these results, we confirmed that the surface-modified UHMWPE powder can be used as reinforcing agent to improve the mechanical and thermal properties of conventional PMMA bone cement.</P>
( Dong Hyeok Yang ),( Seong Ill Woo ),( Dae Hyeok Kim ),( Sang Don Park ),( Ji Hun Jang ),( Jun Kwan ),( Sung Hee Shin ) 대한내과학회 2013 The Korean Journal of Internal Medicine Vol.28 No.6
Coronary stent dislodgement is a rare complication of percutaneous coronary intervention. We report a rare case of dislodgement of two intracoronary stents. On withdrawal of two balloon catheters, one with a guide wire was mechanically distorted from the left main (LM) to the proximal left anterior descending artery (LAD) while the other was dislodged from the LM to the ostial left circumflex ar-tery. The stent in the LAD could not be retrieved into the guide catheter using a Goose neck snare, because it was caught on a previously deployed stent at the mid LAD. A new stent was quickly deployed from the LM to the proximal LAD, be-cause the patient developed cardiogenic shock. Both stents, including a distorted and elongated stent, were crushed to the LM wall. Stent deployment and crushing may be a good alternative technique to retrieving a dislodged stent.