Preparation,Characterization,and Properties Of Nanohydroxyapatite/poly(Propylene Carbonate) Membrane

Objective: Jaw defect is a difficult problem for implanting doctors.The emergence of guided bone regeneration(GBR)technology has brought new hope to solve this problem.It uses membrane barrier function to regenerate bone.At present,commonly used resorbable membranes are expensive,fast absorbing,poor mechanical strength and other shortcomings,it is urgent to develop a new resorbable membrane to meet clinical needs.The purpose of this study was to attempt to synthesize a new biodegradable,biomineralized bone regeneration membrane with suitable mechanical strength and low cost.Method: 1.Nanohydroxyapatite(n HAp)was synthesized by precipitation reaction and characterized by scanning electron microscopy(SEM),X-ray diffractometer(XRD)and Fourier transform infrared(FTIR)detection to prove that the synthesized material is n HAp.2.The n HAp and poly(propylene carbonate)(PPC)were mixed into biofilm by solvent casting/particle leaching method.According to the content of n HAp,they were divided into 0%,10%,20%,30% and 40% n HAp/PPC groups.Observing the color and measuring its thickness 3.SEM was used to observe the front and back structure of the five groups n HAp/PPC membrane,as well as the distribution of n HAp and PPC.4.Material testing system(MTS)was used to test the mechanical strength and elongation at break of five groups of n HAp/PPC membranes.5.Optical contact angle measurement instrument was used to measure the hydrophilic angle of positive and negative sides of five groups n HAp/PPC membrane.6.Simulated body fluid(SBF)immersion test was used to test the mineralization ability of five groups n HAp/PPC membranes.7.In vitro degradation experiments was used to measure degradation rate of n HAp/PPC membrane.8.Cell co-culturing and cell proliferation assay were used to observe cytocompatibility,and total protein,and alkaline phosphatase(ALP)activity were measured to detect the effect of five groups n HAp/PPC membranes on cell osteogenesis.9.Fibroblast barrier experiment was used to observe the barrier function of n HAp / PPC membranes.Results: 1.As can be seen from the SEM images,the size and shape of the synthesized n HAp were more consistent,needle-shaped,with a length of about 100 nm and a width of about 20 nm.XRD images further confirmed that the synthesized material was better crystalline hydroxyapatite.FTIR further detected the chemical structure of the synthesized material.Among them,containing a small amount of Ca CO3.2.Synthetic n HAp/PPC membranes were macroscopically visible with both rough and smooth sides.With the increase of n HAp,then HAp/PPC membrane became coarse,the color changed from pale yellow translucent to white opaque,and the thickness increased from 0.61 mm to 1.13 mm.3.Scanning electron microscopy image showed the PPCs in the membrane fused with each other.n HAp particles were evenly distributed in the PPC matrix and had a good surface connection with the PPC matrix.It could be more directly observed from SEM images that the n HAp/PPC membrane prepared by solvent casting/particulate leaching had a smooth surface and a rough surface similar to the periosteal structure.4.n HAp/PPC membranes exhibited mechanical properties similar to ductile materials under tensile load(except 40% n HAp/PPC).The initial stage obeyed Hooke's law,the stress is proportional to the strain.As stress increased,the curve lost its linear nature.With the addition of n HAp,the mechanical strength of n HAp/PPC membrane first increased and then decreased.The average tensile strength of 10% n HAp/PPC membrane and 20% n HAp/ PPC membrane were higher than that of 0% n HAp/PPC membrane.While the elongation at break decreased with the increase of n HAp content.When n HAp content reached 40%,the brittleness was too large to measure.5.Except 0% n HAp/PPC smooth surface,hydrophilic angle were acute angle,and as n HAp content increases,the hydrophilic angle decreases.6.The n HAp/PPC membrane showed good mineralization ability in vitro.The higher the n HAp content,the more precipitation.7.0% n HAp/PPC membrane degradated slowly,the weight loss ratewas only 6.49 ± 0.55% after 4w.The addition of n HAp accelerated the rate of n HAp/PPC membrane degradation.The weight loss rate of 40% n HAp /PPC membrane was as high as 23.23 ± 2.73% after 4w.8.One day after co-culture of MG63 cells with n HAp/PPC,SEM images were shown that MG63 cells adhered to the rough surface of n HAp/PPC membrane with pseudopodia extending.As the n HAp content increased,the morphology of adherent MG63 cells became irregular with an increase in pseudopodia.With the extension of incubation time,the number of cells increased.The more n HAp content,the higher the cellular activity.The total protein content was positively correlated with n HAp content.The results of ALP showed that ALP activity increased with time and n HAp increased ALP activity.9.In vitro fibroblast barrier results showed that L929 cells were seen on the smooth surface of n HAp/PPC on the 1st day and the 3rd day,while no cell was seen on the bottom of the lower chamber.It shows that n HAp/PPC membrane can prevent fibroblasts from passing through.After 30 days of degradation,the n HAp / PPC membrane still has some resistance to L929 cells.Conclusion: The synthetic n HAp/PPC membrane is a good GBR membrane with biocompatibility,biodegradability and biomineralization characters.20% n HAp/PPC film is considered to be ideal GBR membrane in comprehensive tensile strength,biocompatibility and biomineralization.