Injectable bioactive polymethyl methacrylate-hydrogel hybrid bone cement loaded with BMP-2 to improve osteogenesis for percutaneous vertebroplasty and kyphoplasty

Poly methyl methacrylate(PMMA)bone cement is used in augmenting and stabilizing fractured vertebral bodies through percutaneous vertebroplasty(PVP)and percutaneous kyphoplasty(PKP).However,applications of PMMA bone cement are limited by the high elasticity modulus of PMMA,its low biodegradability,and its limited ability to regenerate bone.To improve PMMA bio activity and biodegradability and to modify its elasticity modulus,we mixed PMMA bone cement with oxidized hyaluronic acid and carboxymethyl chitosan in situ cross-linking hydrogel loaded with bone morphogenetic protein-2(BMP-2)to achieve novel hybrid cement.These fabric ated PMMA-hydrogel hybrid cements exhibited lower setting temperatures,a lower elasticity modulus,and better biodegradability and biocompatibility than that of pure PMMA cement,while retaining acceptable setting times,mechanical strength,and inj ectability.In addition,we detected release of BMP-2 from the PMMA-hydrogel hybrid cements,significantly enhancing in vitro osteogenesis of bone marrow mesenchymal stem cells by up-regulating the gene expression of Runx2,Coll,and OPN.Use of PMMA-hydrogel hybrid cements loaded with BMP-2 on rabbit femoral condyle bone-defect models revealed their biodegradability and enhanced bone formation.Our study demonstrated the favorable mechanical properties,biocompatibility,and biodegradability of fabricated PMMA-hydrogel hybrid cements loaded with BMP-2,as well as their ability to improve osteogenesis,making them a promising material for use in PKP and PVP.

Structurally Diverse Polymethylated Phloroglucinol Meroterpenoids from Baeckea frutescens

Phytochemical investigation of the MeOH extract of twigs and leaves of Baeckea frutescens led to the isolation of seven new polymethylated phloroglucinol meroterpenoids(PPMs),named baeckfrutones M-S(1-7).Their structures and absolute configurations were determined by spectroscopic analyses,chiral-phase HPLC analysis,and electronic circular dichroism(ECD)calculations.PPM 1 is a novel meroterpenoid possessing a 6/6/5/3 tetracyclic skeleton in PPMs,whereas 3 and 4 are the first hydroxytasmanone type phloroglucinol-monoterpene hybrids.(+)-2 and 7 displayed potent antiinflammatory activity with IC50 values of 20.86±0.60 and 36.21±1.18 lL,respectively.

Measurement of Secondary Electron Energy Spectra of Polymethyl Methacrylate

We report on a novel and convenient method of measuring secondary electron spectra for insulators in a secondary electron yield measurement system with a planar grid analyzer configuration and a metal mesh probe. In this measurement, the planar grid is negatively biased to force some emitted secondary electrons to return to the sample surface and to neutralize charges accumulated on the sample during the previous beam irradiation. The surface potential of the sample is then measured by use of a metal mesh probe. The grid bias for neutralization corresponding to the zero surface potential is determined based on the linear relationship between the surface potential and the grid bias. Once the surface potential equals zero, the secondary electron spectra of polymethyl methacrylate（PMMA） are studied experimentally by measuring the -curve and then fitting it to Everhart＇s formula. The measurement results show that the peak energy and the full width at half maximum of the spectra are 4.26 eV and 14.06 eV, respectively.

A Novel Method for Preparing Approximately Micron-sized Polymethyl Methacrylate Microspheres with Clear Surface

Polymethyl methacrylate (PMMA) microspheres with clear surface and diameter close to 1 祄 were synthesized by newly soap-free emulsion polymerization. The results showed that the presence of ethanol and NaCl made the increase of diameter and distribution, while the presence of toluene could avoid the problem of the increase of distribution, resulting a harvest of PMMA microspheres with a diameter close to 1 祄.

Epiphyseal distraction and hybrid reconstruction using polymethyl methacrylate construct combined with free non-vascularized fibular graft in pediatric patients with osteosarcoma around knee: A case report

BACKGROUND In children with osteosarcoma around the knee joint without epiphysis involvement,joint-sparing surgery seems to be an ideal way to retain knee joint function.However,there are two points of debate with regard to the technique:How to accurately achieve a safe surgical margin,and how to achieve intercalary reconstruction of the massive bone defect following resection of the tumor.CASE SUMMARY We present the case of an 8-year-old girl with osteosarcoma of the distal femur without involvement of the epiphysis.Epiphyseal distraction was applied to separate the epiphysis and metaphysis,and this provided a safe surgical margin.The massive bone defect was reconstructed with a custom-made antibioticloaded polymethyl methacrylate(PMMA)construct combined with a free nonvascularized fibular graft.Six months after surgery,bone union between the autograft and host bone was confirmed in both the proximal and distal femur by computer tomography(CT)examination.Moreover,considerable callus formation was found around the PMMA construct.After 28 mo of follow-up,there was no sign of recurrence or metastasis.The patient could walk without any aid and carry out her daily life activities satisfactorily.CONCLUSION In cases of osteosarcoma without epiphysis involvement,epiphyseal distraction can be easily applied to obtain a safe margin.Hybrid reconstruction with an antibiotic-loaded PMMA construct combined with a free non-vascularized fibular graft has the advantages of being easy to manufacture,less time-consuming to place,and less likely to get infected,while also ensuring bone union.Our case provides an alternative technique for biological reconstruction after joint-sparing surgery in patients with osteosarcoma around the knee without epiphyseal involvement.

Preparation and Fluorescence Properties of Polymethyl Methacrylate Resin Incorporated with Sodium Tris (Pyridine Dicarboxylato) Europate

Based on the strong fluorescence and the highly thermal stability of sodium tris (pyridine dicarboxylato) europate (Na 3Eu(DPA) 3), polymethyl methacrylate (PMMA) composite material incorporated with the complex, PMMA: Na 3Eu(DPA) 3, was prepared at 250 ℃. The fluorescence behavior of PMMA: Na 3Eu(DPA) 3 material was examined. The results show that the composite material keeps the luminescent characteristics of the Eu 3+ chelate after PMMA is incorporated with Na 3Eu(DPA) 3, and strong orange-red emission of the composite was observed. The fluorescence intensity of the composite material increases with the increase of the weight ratio of Na 3Eu(DPA) 3 to PMMA, but the relationship is not linear.

A Novel Polymethyl Methacrylate (PMMA)-TiO_2 Nanocomposite and Its Thermal and Photic Stability

A new kind of polymethyl methacrylate （PMMA）-TiO2 nanocomposite was synthesized through polymerization. The thermal and photic stability of this PMMA TiO2 nanocomposites were investigated. The as prepared samples were characterized by scanning electron microscopy （SEM）, UV-Vis spectroscopy, differential thermal analysis （DTA） and the photo-induced weight loss, The results show that the photostability of the PMMA-TiO2 nanocomposite is higher than that of the pure PMMA under UV-light irradiation, The weight loss of the pure PMMA reaches 30 % after 300 h UVirradiation, while the composite only 0.3% under the identical experimental condition. The glass transition temperature （TR） of pure PMMA is only 80℃, while the Tg of the composite reaches 258℃. Compared with pure PMMA, the thermal stability of the composite is greatly enhanced.

Effect of local massage on prevention and treatment of intra-arterial polymethyl methacrylate embolism complications:An experimental animal study

Background:Massage is generally believed to be a simple and effective method for preventing necrosis when intravascular injection emboli are suspected.Due to its good dispersive properties,polymethyl methacrylate(PMMA)was used as the test filler.The main purpose of this study was to observe whether local massage as a simple remedial measure can promote the diffusion of filler and reduce the necrosis rate for intra-arterial embolism.Methods:Rabbit ears with the central ear artery(CEA)main trunk totally or segmentally obstructed 5 min after PMMA injection were studied.In order to simulate the massage effect of the fingers,the massage group was treated with a small beauty massage bar with a fixed vibration frequency along the direction of the blood flow.CEA blood flow and skin lesions were also analyzed.Results:The baseline data were similar between the control and massage groups.Compared to the control group,the recanalization rate of the CEA trunk in the treatment group increased significantly after massage.However,there was no significant difference in the visible rate of transparent embolus on the 1st day after treatment,nor in the necrosis degree or area of soft tissue damage on the 7th day after treatment.Further analysis showed that massage tended to have a positive effect on segmentally obstructed cases at 5 min after injection but a negative effect on totally obstructed ears at 5 min.Conclusion:Local massage cannot reduce the complications of tissue necrosis after intra-arterial PMMA injection.Prevention is key to reducing complications.

Force-Induced Enhancement of Hydrophilicity of Individual Polymethyl Methacrylate Chain

Comprehensive Summary,Polymethyl methacrylate(PMMA)has been widely applied in diverse fields such as medicine and engineering materials due to its good hydrophilicity and biocompatibility.However,another term for PMMA,Plexiglas,means that it is water insoluble.These features of PMMA are valuable but seem paradoxical.To explore the underlying mechanism of the paradoxical properties,the interactions between PMMA and water have been investigated by atomic force microscopy(AFM)-based single-molecule force spectroscopy(SMFS).The single-chain elasticity of PMMA obtained in aqueous solutions is significantly different from that obtained in non-aqueous environments,implying that PMMA can form hydrogen bonds with water molecules.

基于光纤镀膜探针的固体介质中应力波粒子速度测量技术

粒子速度是分析固体介质中应力波传播规律的一个重要参数。结合激光多普勒效应和全光纤干涉测速系统,提出了一种基于光纤镀膜探针的固体介质中应力波粒子速度的测量方法。将光纤镀膜探针嵌入有机玻璃(PMMA)中,距爆心同一半径处,采用0.125 g TNT当量的微型炸药球作为爆炸源,进行填实爆炸产生应力波,通过采集光纤探针端面的运动信息,基于短时傅里叶变换的时频分析方法,解调出端面运动速度,进而反推出粒子速度。实验结果表明:不同光纤镀膜探针测得的速度分别为22.648 m/s、23.505 m/s,将反推的粒子速度与传统的圆环型电磁粒子速度计方法获取到的数据进行对比,两者的相对偏差低于5.00%,验证了光纤镀膜探针测量固体介质中应力波粒子速度的可行性。

球形观察窗用有机玻璃的银纹损伤:乙醇和温度协同作用

聚甲基丙烯酸甲脂(PMMA)基于良好的综合性能得到广泛应用,但遇到极性溶剂时很容易发生溶胀,导致银纹的产生甚至出现开裂,严重降低了材料的服役寿命。本工作以某球形观察窗用有机玻璃为研究对象,深入探讨退火温度、退火时间、溶剂(乙醇)处理时间等因素对PMMA微观结构的影响,以及银纹产生与单轴拉伸、三点弯曲、压缩变形等力学性能的关系,研究发现在PMMA的玻璃化转变温度98℃附近进行退火容易出现肉眼可见的大尺度银纹。银纹对于力学强度的影响较小,但会降低材料的断裂应变。

Optical properties and Judd-Ofelt analysis of Nd2O3 nanocrystals embedded in polymethyl methacrylate

PMMA matrices were doped with nano-crystalline neodymium oxides synthesized by thermal decomposition process. X-ray diffraction and high-resolution transmission electron microscopy measurements were carried out to investigate the structure, phase, and the morphology of the Nd_2O_3 nanocrystals and those embedded in the PMMA matrix. The average grain sizes were estimated 35 ± 6 nm and 46 ± 4 nm for non-annealed and annealed Nd_2O_3 particles, respectively. The grain size distributions（GSD） were calculated from the diffraction peaks of the annealed and non-annealed Nd_2O_3 powders and doped PMMA samples. The mass density, refractive index. UV-Visible absorption spectra were measured and the data were analyzed using the Judd-Ofelt approach to determine the oscillator strengths, the spontaneous emission probabilities and the branching ratios as a function of the nano-crystalline Nd_2O_3 content in the range of 0.1 wt.%-20 wt.% of MMA. Luminescence spectra upon 808 nm diode laser excitation were carried out in the wavelength range of 850-1550 nm at room temperature. The photoluminescence study has shown that the reasonably sharp emission peaks were observed upon heat treatment at 800 ℃ for 24 h for all concentrations of Nd_2O_3 nanopowders in PMMA. The infrared laser transition of Nd^（3＋） ions at about 1.06 μm due to the ~4F_（3/2）→~4I_（11/2） transition was analyzed and discussed in Nd_2O_3 system for their possible applications in the photonic technology.

黏结剂辅助微流控芯片异种键合及可行性探究

以聚甲基丙烯酸甲酯(PMMA)、聚苯乙烯(PS)、铝合金Al5052为研究对象,采用黏结剂与热压键合相结合的方法,分别进行了PMMA-PS、PMMA-Al5052异种键合正交实验。旨在探讨键合层厚度及表观形貌的变化规律,研究键合温度、压力和时间对异种键合强度的影响。结果表明:键合层厚度随温度和压力的增大而减小,而时间对键合层厚度无明显影响;聚酰亚胺(PI)辅助PMMA-PS和PMMA-Al5052的键合强度受时间影响最大,温度次之,压力最小;而溶解PMMA粉末的丙酮溶液[丙酮溶液(PMMA)]辅助PMMA-Al5052的键合强度受压力影响最大,温度次之,时间最小;同参数下PMMA-PS的键合强度远高于PMMA-Al5052。分别确立了异种键合的最优参数并得到了对应的键合强度:PI辅助PMMA-PS键合的最优参数为105℃,50 min,2.5 MPa,对应键合强度0.87 MPa;PI辅助PMMA-Al5052键合的最优参数为110℃,50 min,1.25 MPa,对应键合强度0.21 MPa;丙酮溶液(PMMA)辅助PMMA-Al5052键合的最优参数为110℃,2.5 MPa,20 min,对应键合强度0.41 MPa,均高于正交实验设计方案中的所有结果。参数一定时,PMMA-PS的键合强度远高于PMMA-Al5052的键合强度。采用丙酮溶液(PMMA)辅助键合PMMA-Al5052时,键合强度高于PI辅助的键合强度。

本体聚合PMMA基复合介质膜的储能特性研究

目前有机薄膜电容器中的介质材料多为线性电介质,这类聚合物的介电常数通常较低,造成电容器储能密度普遍偏低,而新型高储能聚合物介质材料一般又存在介质损耗高的问题。聚甲基丙烯酸甲酯(PMMA)与高储能含氟聚合物的相容性较好,常被用来改善后者的力学和击穿性能,但市售的PMMA存在本征介质损耗过高的问题。为了降低PMMA的介质损耗,本文用甲基丙烯酸甲酯(MMA)与苯乙烯(St)合成MMA-St共聚物(MS),将不同比例的MS掺入本体聚合的PMMA中形成复合体系,并研究复合体系的介电特性、储能特性及绝缘特性。结果表明:该复合体系可以显著降低PMMA的介质损耗,相较于PMMA更适合作为高储能聚合物的改性材料。其中复合10%MS的介质膜在5 500 kV/cm电场下获得了5 J/cm^(3)的放电能量密度,充放电效率达到83%。

Mechanism of brittle fracture in diamond turning of microlens array on polymethyl methacrylate

Diamond cutting is a popular method to fabricate microlens array (MLA) on polymethyl methacrylate (PMMA);however, it is limited by brittle fracture, which is formed easily on the surface of MLA during the cutting process. In this paper, the formation mechanism of the brittle fracture is studied via a series of experiments including the slow tool servo (STS) cutting experiment of MLA, surface scratching experiment and suddenstop cutting experiment. The effects of undeformed chip thickness, feed rate, and machining track on brittle fracture formation are investigated in detail. In addition, based on the fracture formation mechanism, a bi-directional cutting approach is proposed to eliminate the regional brittle fracture of the microlens during diamond cutting. An experiment was then conducted to verify the method;the results demonstrated that bi-directional cutting could eliminate brittle fracture entirely. Finally, a spherical MLA with the form error (vPV) of 60 nm and the surface roughness (Ra) of 8 nm was successfully fabricated.

Novel reparation method for polymethyl methacrylate optical windows of aircrafts damaged by service environment

The optical properties of polymethyl methacrylate(PMMA)with varying degrees of artificial scratches have been studied with the aim of reproducing the change of visibility of an aircraft’s PMMA optical windows after being damaged in their service environment.A novel maintenance method that can perfectly restore the optical property of PMMA has been identified and employed in the repair of the scratches that are formed on the surface of PMMA.This convenient and low-cost method entails polishing PMMA with different types of sandpaper to remove the scratches,and then spin-coating the repair solution in order to restore the optical properties of PMMA.The effect of this repair mechanism and parameters of the repair process were studied.The results indicated that the optical performance of PMMA is closely related to the mesh size of sandpaper,and improper parameter selection destroys the general effect of the repair.When the number of sandpaper mesh is low,the size of the abrasive particle is relatively larger,which can cause deeper friction marks on the surface of PMMA optical windows.Surface treatment using 5000 mesh sandpaper lowers surface roughness(R——a=0.566 nm),and optical transmittance in visible range can be restored to more than 88%.

Polymethyl Methacrylate-Collagen-Magnesium Hydroxyapatite Bone Cement Preparation for Orthopedic Application

In this research,bone cement was prepared by mixing 2 g of magnesium hydroxyapatite(laboratory synthesized),12 g of polymethyl methacrylate,4 g of methyl methacrylate,and collagen(1,3,and 6 g).The samples were molded in a circular shape.They were inspected by visual microscopy,FTIR,XRD,and FESEM.They were engrossed in synthesized simulated body fluid for 1 month and then inspected by visual microscopy,FTIR,XRD,and FESEM.The samples prepared from 6 g of collagen showed the highest hydroxyapatite formation(high osseointegration)than the other samples.

Effects of self-blood on the molding process of polymethyl methacrylate bone cement

ObjectiveTo 评估自我血是否在 polymethyl methacrylate (PMMA ) 的塑造的过程上有影响骨头水泥并且它是否为在 vitro 学习的临床的 practiceMethodsAn 是珍贵的，被执行确认在 PMMA 骨头水泥上评估自我血的延长效果。延长的效果到面团时间被评估(T D ) 和合用的时间(T O ) 。而且，坚硬测试，压榨的价值测试和山峰温度测试也被进行完成这 program.ResultsThe 自我血的评估，特别血浆，没有包括坚硬，漏水平和山峰温度影响它的基本特征，能极大地延长 PMMA 骨头水泥的处理时间。在另一方面，我们发现处于一些反常条件，例如与 hyperlipemia，自我血能也不过延长处理时间，将引起某 sideeffects.ConclusionWe 报告一个新有效方法由增加自我血的中等数量延长 PMMA 骨头水泥的处理时间。但是 “individualized medicine”因为象 hyperlipemia 一样的一些反常条件将引起不希望得到的副作用，应该被注意。

抗生素骨水泥治疗骨关节感染的优势与问题

背景:聚甲基丙烯酸甲酯(PMMA)骨水泥具有良好的稳定性、可塑性和空间占位能力,是目前临床上最常用的抗生素载体之一。局部应用抗生素骨水泥可以预防、延缓甚至根除骨骼肌肉系统的感染,是目前解决骨关节感染难题的常用手段。但是,抗生素的加入会显著影响聚甲基丙烯酸甲酯骨水泥的机械性能,并且有引发不良反应的可能。另外,有学者发现抗生素骨水泥的抗生素释放率很低,局部应用抗生素骨水泥并不能有效消灭细菌,且有引起细菌耐药的可能。因此,他们对抗生素骨水泥在控制感染方面的有效性提出了质疑,并引起了广泛热议。目的:综述抗生素骨水泥的优势与问题,并总结其在临床使用中的注意事项。方法:通过计算机在PubMed、万方、中国知网数据库中以“抗生素骨水泥、聚甲基丙烯酸甲酯、PMMA;Bone Cements、Anti-Bacterial Agents、Bone and Bones、joints、elution、release、Mechanical”为中、英文检索词,检索2017-01-01/2021-12-31发表的相关文献。排除与文章内容无关的、创新性差、重复的文献后,最终纳入68篇文献进行综述。结果与结论:目前,抗生素骨水泥仍是治疗骨关节感染的最佳选择之一。随着对抗生素骨水泥研究的不断深入,许多能改善其抗生素释放方式、抗菌能力和力学性能的新方法不断涌现出来,同时其在临床上的使用也得到了拓展。但仍然有许多问题尚未得到解决,还需进一步的研究,如抗生素的选择、剂量以及最佳的混合方法等。另外,通过对可加入聚甲基丙烯酸甲酯骨水泥的改性材料和抗生素替代物的开发与局部应用有望解决细菌耐药问题。相信随着医学、药学和生物材料科学的发展,抗生素骨水泥会在临床上得到更加广泛的应用。

制备条件对癸酸-硬脂酸相变微胶囊性能的影响

为制备相变温度适用于建筑领域,热性能良好、包覆率高的相变微胶囊,以最低理论共融点配比下制备的复合癸酸-硬脂酸作为芯材,甲基丙烯酸甲酯(MMA)为壁材单体,十二烷基磺酸钠与吐温40作为乳化剂,偶氮二异丁腈作为引发剂,采用原位聚合的方式制备癸酸-硬脂酸相变微胶囊。探究不同聚合条件对相变微胶囊的表观形貌、粒径、热学性能、热稳定性的影响。结果表明,在选用季戊四醇三丙烯酸酯(PETA)作为交联剂,并选取MMA∶PETA质量比=7∶3,芯壁比3∶2,反应温度70℃,反应时间4 h的条件下制备出的相变微胶囊较为理想,包覆率达62.66%,产率达到90.28%,颗粒均匀、平均粒径为81.7μm,熔融焓达82.26 J/g,热稳定性良好。