Preparation And Evaluation Of A New Biomimetic Material-silicone Rubber Coated By Hydroxyapatite

Background and Objectives:Implant of soft tissue material is broadly used in plastic surgery, which is mainly useedfor correcting and repairing the tissue and organ geneogenous defect or injury. Atpresent, there are some common soft tissue implant material in clinical such as the siliconrubber (SR), hydroxyapatite (HA), expanded polytetrafluoroethylene (ePTFE), high desitypolyethylene (HDPE) and so on. SR can aviod be corroded when implanted in vivo forlong-term, with favourable pliability and mechanical property, physical and chemicalproperty, innocuity, tasteless and uncarcinogenesis. However, on the effect of stimulatingfrom outside for a long time, implant button of SR would be atrophied and stiffened,transfigure, even to be rejected from the body and cause infection, because SR is intensivehydrophobous and poor of biocompatibility. When embedded in vivo, HA could combinetogether with histiocytes, and avoid causing rejection, be with satisfactory bioactivity andhistocompatibility. Nevertheless HA is breakable, be poor of mechanical property anddifficult for elaborating and moulding, therefore HA is used in the part of lower stress orfabricate the composite materials implanting. There are various advantages anddisadvantages of each material. For this reason, to research and develope a new material isimminent, and it will promote the level of the clinic technology.In some operation of plastic surgery, we clip the material according to the sphere oftissues deletion, and un-demand to carve it. In this study, we prepare to a neotype materialapplying the HA granules on the surface of SR, which retain not only the physical andchemical property of SR, but also the biocompatibility of HA. Detecting and evaluating themechanical property, physicochemical properties and biocompatibility of the HA-1/SR andHA-2/SR materials in accordance with the national standard of biomedical materials.Methods:Part I Spray coating the two different particle diameter of HA powder HA-1(40μm) andHA-2(150μm) on the fruface of SR to prepare HA-1/SR and HA-2/SR, according to thecuring time of liquid SR. The micro-shape of HA-1/SR and HA-2/SR was observed byscanning electron microscope.Part IIThe physicochemical properties of SR、HA-1/SR、HA-2/SR were detected by fouriertransform infrared spectrometry （FTIR） and X-ray photoelectron spectroscopy （XPS）.Moreover, the mechanical properties of them were evaluated by Shore durometer and anelectronic universal material testing instrument.Part III1. The mouse embryonic fibroblast3T3cells and human dermal fibroblasts werecultivated in vitro.2. Experimental group:1) Normal group: The healthy cell;2) Apoptosis group: The dead cell;3) SR group: The cells were transplanted onto the surface of SR;4) HA-1/SR group: The cells were transplanted onto the surface of HA-1/SR;5) HA-2/SR group: The cells were transplanted onto the surface of HA-2/SR.3. After transplanted human dermal fibroblasts onto the surface of these materials andco-cultured48h growth, the framework and attachment of cell were observed by confocallaser scanning microscopy, and the bioactivity of the fibroblasts were detected by CCK-8assay, Hoechst33342and PI double staining.4. After transplanted3T3onto the surface of these materials and co-cultured48hgrowth, the expression of vinculin and OPN of cell were measured by Real-time PCR andWestern blot.Results:1. According to the regularity of SR curing, we successed preparing HA/SR. And weobserved that HA particle was uniformly distributed on the surface of SR in HA-1/SR andHA-2/SR.2. The chemical bond of HA and SR were not destroied in HA-1/SR and HA-2/SR, as itshown in FTIR and XPS. The hardness of the materials detected by Shore durometer. SR, HA-1/SR and HA-2/SR were31±2.05HA、28.14±1.83HA、26.85±1.26HA; tensilestrength of rock of them were2.97±0.6Mpa、1.88±0.12Mpa、1.63±0.15Mpa; elongation atbreak of them were450.62±63.89%、327.76±15.72%、309.16±15.92%.3. The cells were adhered on HA-1/SR and HA-2/SR, the cytoskeleton andmorphological characteristics were resorted through observed by confocal laser scanningmicroscopy; we observed that the microfilament of cell be onto SR was discrete and retracted.4. Cell vitality was detected by CCK-8. The OD of HA-1/SR(1.3877±0.0239) andHA-2/SR(1.328±0.0359) group were significant increased compared to normalgroup(1.0539±0.0314)(p<0.05), but the SR group(0.8511±0.0381) was decreasecompared to normal group(p<0.05). The relative growth rate(FGR) of these cell onto thedifferent materials were100%、76.39%、138.86%、131.91%, therefore we judged that thetoxicity level of HA-1/SR and HA-2/SR were all0, SR was1.5. The cell of SR group, HA-1/SR group and HA-2/SR group were not colored by PIstaining, and the shape and color of these cell nucleus were normal after Hoechst33342staining compare to apoptosis group.6. The expression of vinculin mRNA and OPN mRNA in HA-1/SR group andHA-2/SR group detected by Realtime-PCR were all increased compared to normal group(p<0.05), and those expressed in HA-1/SR group were higher than in HA-2/SR group(p<0.05); yet vinculin mRNA and OPN mRNA expression in SR group were decreasedcompared to normal group (p<0.05).7. Vinculin and OPN expression in HA-1/SR group and HA-2/SR group detected byWestern blot were all increased compared to normal group (p<0.05), and those expressed inHA-1/SR group were higher than in HA-2/SR group (p<0.05); yet vinculin mRNA andOPN mRNA expression in SR group were decreased compared to normal group (p<0.05).Conclusions:1.The manufacture of the HA/SR is simple, which is easy to produce and processing.2. Both the HA-1/SR and HA-2/SR are contented to the clinical requirements of softtissue material on the mechanical and physicochemical properties.3. The cell adhesion, biological activity and biocompatibility of HA-1/SR andHA-2/SR were significant improved compare to SR in vitro, and the former have an advantageto HA-2/SR. Thus paintcoat materials is more suitable to make use of human body.