Application of bio-inks for 3D printing in tissue repair and regenerative medicine / 中国组织工程研究

BACKGROUND:With the right bio-inks,3D printing can be used to create replacements for human tissues and organs that work inside the body.In recent years,3D printing technology has developed rapidly and has great application potential in regenerative medicine. OBJECTIVE:To introduce the types of bio-inks for 3D printing,and review the classification,application,advantages and disadvantages of bio-inks,as well as the future vision. METHODS:With"3D printing,biological ink,tissue engineering,hydrogel,synthetic material,cytoactive factor"as search terms,relevant articles published on PubMed and CNKI databases from 2000 to 2022 were searched by computer and finally 83 articles were included for review. RESULTS AND CONCLUSION:3D bioprinting technology has developed rapidly over the past few decades and has received great attention in various fields,including tissue engineering and biomedicine.Compared with the limitations of traditional biological scaffold manufacturing methods in terms of function and structure,3D printing can better simulate the complex structure of biological tissues and has appropriate mechanical,rheological and biological characteristics.Bio-ink is an essential part of 3D printing.Bioscaffolds produced by printing bio-ink prepared by biological materials have great scientific potential and clinical significance in tissue repair and regenerative medicine.The research of the materials itself is also getting more and more attention from experts.Bio-inks for 3D printing come in a variety of materials,from natural to synthetic,to aggregations of cells that do not require any additional biomaterials,and their usefulness in practical use varies.In the future,more and more bio-inks will be developed for tissue engineering.It is necessary to analyze the printability of bio-inks through sufficient experimental simulation and equipment testing to meet the actual medical needs.

Applicable techniques for subchondral separation of femoral head necrosis treated by tissue engineering / 中国组织工程研究

BACKGROUND:The appearance of the crescent sign in femoral head necrosis is a"turning point"in the progression of the disease,and repairing and stabilizing the bone-cartilage interface is particularly important in preventing further progression and collapse of the femoral head.Tissue engineering offers potential advantages in the simultaneous repair and integration of the bone-cartilage interface. OBJECTIVE:To review potentially suitable techniques addressing the subchondral separation in femoral head necrosis. METHODS:Relevant articles from January 1970 to April 2023 were searched in PubMed,Web of Science,and China National Knowledge Infrastructure(CNKI)using English search terms"femoral head necrosis,avascular necrosis of femoral head,osteonecrosis of femoral head"and Chinese search terms"femoral head necrosis,subchondral bone,cartilage,integration of cartilage and subchondral bone".A total of 114 articles were included for review and analysis. RESULTS AND CONCLUSION:(1)Structural defects,ischemic and hypoxic environment,inflammatory factors,and stress concentration may cause subchondral separation in osteonecrosis of the femoral head.Subchondral bone collapse and failure of hip-preserving surgery may be associated.Integration of tissue engineering scaffolds with the bone-cartilage interface is one potential approach for treating subchondral separation in osteonecrosis of the femoral head.(2)Current literature suggests that multiphase scaffolds,gradient scaffolds,and composite materials have shown improvements in promoting cell adhesion,proliferation,and deposition of bone and cartilage matrix.These advancements aid in the integration of scaffolds with the bone-cartilage interface and have implications for the treatment of subchondral separation in osteonecrosis of the femoral head.(3)Surface modifications of scaffolds can enhance interface integration efficiency,but they have their advantages and disadvantages.Scaffolds providing different environments can induce differentiation of mesenchymal stem cells and facilitate integration between different interfaces.(4)Future scaffolds for subchondral separation in osteonecrosis of the femoral head are expected to be composite materials with gradient and differentiated biomimetic structures.Surface modifications and stem cell loading can promote integration between the bone-cartilage interface and scaffolds for therapeutic purposes,but further experimental verification is still needed.Challenges include synchronizing scaffold degradation rate with repair progress and ensuring stability between different interfaces.

Polymer-based antibiotic sustained-release carrier in treatment of chronic osteomyelitis / 中国组织工程研究

BACKGROUND:In the treatment strategy of chronic osteomyelitis,the local antibiotic slow-release system has attracted much attention in the clinic due to the long-term release of effective concentrations of antibiotics to control the infection,and at the same time,the ability to repair bone defects caused by debridement. OBJECTIVE:To summarize the research status of antibiotic sustained-release carriers prepared from biodegradable polymer-based materials for the treatment of osteomyelitis,and analyze the limitations and challenges. METHODS:Chinese and English key words were"polymer,composite material,osteomyelitis,infectious bone defect,drug delivery systems,antibiotic sustained-release system,3D printing".Relevant articles were searched in PubMed,Web of Science,CNKI,and WanFang databases from January 2015 to August 2023.4 351 articles were obtained in the initial examination,and 87 articles were analyzed after screening. RESULTS AND CONCLUSION:Polymer-based materials have been widely studied in the preparation of antibiotic sustained-release carriers due to their good biocompatibility,biodegradability,thermal stability,and easy processing.However,the antibiotic slow-release carrier composed of a single polymer material cannot meet the standard of infectious bone defect repair materials due to the lack of biomechanical properties.The organic-inorganic composite material carrier,which simulates the formation of natural bone tissue structure,is expected to meet this standard.3D printing technology can precisely control the size,geometry,and spatial distribution of the interconnecting pores of the carrier,and can load the effective concentration of antibiotics to achieve controlled release.The polymer material is the most suitable for 3D printing because of its good thermal stability and plasticity.Therefore,the author believes that on the basis of new biodegradable organic-inorganic composite materials and combined with 3D printing technology,the material-structure-function integrated composite antibiotic slow-release carrier to simulate the extracellular matrix microenvironment is expected to become a novel research direction in the treatment of chronic osteomyelitis.

Polyetheretherketone and its composite materials in post core crown restoration:problems and clinical application value / 中国组织工程研究

BACKGROUND:Polyetheretherketone is a special plastic polymer with good mechanical properties,biocompatibility,and chemical stability,which can be added with different fillers to form new composite materials and has potential clinical application value in post core repair. OBJECTIVE:To review the properties of polyetheretherketone and its composite materials,as well as the clinical application progress in post core repair. METHODS:CNKI database was searched using the Chinese search terms"polyetheretherketone,post core repair,metal post,fiber post,zirconia post".PubMed database was searched using English search terms"PEEK,polyetheretherketone post,post core repair,dental dowels".Search time ranged from January 2019 to October 2023.By reading literature titles,abstracts,and selecting the entire text,the inclusion and exclusion criteria were used to screen and finally include 71 articles for review. RESULTS AND CONCLUSION:Polyetheretherketone is a high-performance thermoplastic polymer.Experimental studies have proven that polyetheretherketone and its composites have advantages in mechanical properties,biocompatibility,aging resistance,chemical stability,adhesive properties,etc.,and have promising application prospects in the field of post core repair.The clinical application of polyetheretherketone and its composite materials as post core restorations is limited to anterior teeth and premolars,but they have achieved satisfactory restoration results.Polyetheretherketone and its composite materials are new materials in post core repair,and there are still many problems to be solved,such as whether the 3D printing equipment and printing process will affect the mechanical properties of the materials;short observation time for clinical repair effects,lack of long-term research validation.There is a lack of case reports on the use of polyetheretherketone and its composite materials as post and core materials for repairing molars,and further research is needed to continuously improve related studies.

Preparation and properties of a new artificial bone composite material / 中国修复重建外科杂志

OBJECTIVE@#To study the preparation and properties of the hyaluronic acid (HA)/α-calcium sulfate hemihydrate (α-CSH)/β-tricalcium phosphate (β-TCP) material (hereinafter referred to as composite material).@*METHODS@#Firstly, the α-CSH was prepared from calcium sulfate dihydrate by hydrothermal method, and the β-TCP was prepared by wet reaction of soluble calcium salt and phosphate. Secondly, the α-CSH and β-TCP were mixed in different proportions (10∶0, 9∶1, 8∶2, 7∶3, 5∶5, and 3∶7), and then mixed with HA solutions with concentrations of 0.1%, 0.25%, 0.5%, 1.0%, and 2.0%, respectively, at a liquid-solid ratio of 0.30 and 0.35 respectively to prepare HA/α-CSH/ β-TCP composite material. The α-CSH/β-TCP composite material prepared with α-CSH, β-TCP, and deionized water was used as the control. The composite material was analyzed by scanning electron microscope, X-ray diffraction analysis, initial/final setting time, degradation, compressive strength, dispersion, injectability, and cytotoxicity.@*RESULTS@#The HA/α-CSH/β-TCP composite material was prepared successfully. The composite material has rough surface, densely packed irregular block particles and strip particles, and microporous structures, with the pore size mainly between 5 and 15 μm. When the content of β-TCP increased, the initial/final setting time of composite material increased, the degradation rate decreased, and the compressive strength showed a trend of first increasing and then weakening; there were significant differences between the composite materials with different α-CSH/β-TCP proportion ( P<0.05). Adding HA improved the injectable property of the composite material, and it showed an increasing trend with the increase of concentration ( P<0.05), but it has no obvious effect on the setting time of composite material ( P>0.05). The cytotoxicity level of HA/α-CSH/β-TCP composite material ranged from 0 to 1, without cytotoxicity.@*CONCLUSION@#The HA/α-CSH/β-TCP composite materials have good biocompatibility. Theoretically, it can meet the clinical needs of bone defect repairing, and may be a new artificial bone material with potential clinical application prospect.

Advances in Research of Chitosan-based Composites for Implanted Medical Devices / 中国医疗器械杂志

It is well known that chitosan-based composites are widely used in implantable medical devices. The development of chitosan-based composite materials with different types was summarized in this paper, such as inorganic, organic and composite phases. Then, combined with the research focus, the development of 3D printing technology and chitosan-based composites was summarized. It was also pointed out that the existing problems in our research, which need to be solved urgently. At last, the development direction and broad application prospect of chitosan-based composites were prospected. And we look forward to providing reference for relevant research.

Application of bone tissue engineering materials in the treatment of bone defect diseases in vivo / 中国组织工程研究

BACKGROUND: The application of bone tissue engineering materials to treat bone defect diseases is a hot topic of current research. Material selection and design of in vivo experiments are the focus of research. OBJECTIVE: To summarize the research progress of bone tissue engineering materials for repairing bone defects in vivo in the past 10 years. METHODS: A search was conducted in CNKI, Wanfang, and PubMed with the key words of “bone tissue engineering, bone defect and in vivo experiment” for articles published from January 2010 to December 2019. Totally 264 articles were retrieved, and 74 eligible articles were finally summarized after screening. RESULTS AND CONCLUSION: Bone tissue engineering is a new method for treating bone defect diseases, but there are many types of bone tissue engineering materials in practical application. The single material inevitably has limitations in the application of materials. Composite materials can improve material properties and bone repair capacity. Simultaneously, the in vivo experiment is a powerful test to verify the practical application of the material, and it can detect the shortcomings that were not found in the in vitro experiments, and provide data support for the practical application of bone tissue engineering materials.

Construction and characterization of nano-hydroxyapatite/chitosan/polycaprolactone composite scaffolds by 3D printing / 中国组织工程研究

BACKGROUND: At present, there are many types of bone defect repair scaffolds, but a single type of material is difficult to meet the requirements of bone tissue engineering scaffold materials. Several suitable materials can be combined into a composite material by appropriate methods, taking into account the advantages and disadvantages of various materials. It is the focus of scholars in recent years. OBJECTIVE: To construct nano-hydroxyapatite/chitosan/polycaprolactone composite scaffolds and analyze characterization of composite scaffolds. METHODS: Nano-hydroxyapatite/chitosan/polycaprolactone porous ternary composite scaffold material was prepared by 3D printing and molding technology. The characterization of scaffold material was studied from X-ray diffraction analysis, stent water absorption rate, stent compressive strength, stent degradation performance in vitro, stent aperture analysis, scanning electron microscope analysis and other dimensions. RESULTS AND CONCLUSION: (1) X-ray diffraction analysis showed that the crystal-shaped peak map of nano-hydroxyapatite/chitosan/ polycaprolactone scaffold materials was similar to the hydroxyapatite powder diffraction standard card, suggesting that the scaffold materials were integrated with each other through physical interaction, and did not affect the biological function of hydroxyapatite. (2) The average water absorption rate of the scaffold was 18.28%, and the hydrophilicity was good. The maximum pressure that the scaffold could withstand was 1 415 N, and the degradation rate was similar to the osteogenic rate. (3) Under a microscope, a ternary scaffold material with an aperture of 250 µm was successfully produced. The pore size was uniform and distributed regularly. (4) Scanning electron microscope demonstrated that the fibers composed of chitosan and polycaprolactone were arranged orderly and grid like, hydroxyapatite was distributed uniformly on the fiber surface in granular form, and the ternary composite material presented uniform and loose microporous structure. (5) Nano-hydroxyapatite/chitosan/polycaprolactone ternary composite scaffold material can be successfully prepared through 3D printing and molding technology, which has moderate compressive strength, certain porosity, appropriate degradation rate and water absorption rate, and can lay a foundation for repairing bone defects.

Zn and mg increase the bioactivity and osteogenic induction of hydroxyapatite biomaterial in bone repair: Clinical application and mechanism / 中国组织工程研究

BACKGROUND: Autologous bones are in high demand in the clinic, but its clinical application is limited because of insufficient sources and donor-site complications. Allogeneic bone and xenogenic bone are also limited because of immune rejection and disease transmission problems. Artificial biomaterials provide an important solution to bone defect repair. OBJECTIVE: To review the latest basic research progress and osteogenic induction mechanism of hydroxyapatite doped with divalent cations such as zinc and magnesium. METHODS: A computer-based online search of Pebmed, Wanfang and CNKI databases was performed to retrieve papers regarding bone repair with hydroxyapatite doped with divalent cations zinc and magnesium with the search terms “Zinc, magnesium, hydroxyapatite, in vivo, in vitro, osteogenic activity” in English and Chinese respectively. RESULTS AND CONCLUSION: Much is reported on the application of degradable active elements Mg and Zn and their application in hydroxyapatite for bone repair. However, most studies focus on metal or alloy implants. Mg-hydroxyapatite and Zn-hydroxyapatite composites are mostly prepared into nano-particles, dense bulk materials or active coatings of biomedical metal mateirals. Little is reported on bone-like porous bone repair materials involving Mg-hydroxyapatite and Zn-hydroxyapatite. At the same time, metal ion materials still face many challenges: First, when specific metals are released locally from stents, implants, or other release devices, their role in cell regulation and cell-cell signaling in healthy and diseased tissues should be known. Second, a large number of in vivoexperiments have confirmed that metal ions can be released from the stent without systemic toxicity, but have carcinogenic effects. Third, there is a need to further understand the mechanism linking biological property improvement and metal ion release.

Advances in the research of antibacterial properties and composite materials of nanometer zinc oxide / 中华烧伤杂志

Nanometer zinc oxide has become a new hotspot in the research of tissue engineering materials due to its excellent antibacterial properties, biocompatibility, and anti-tumor properties. In this paper, the existing research results were summarized, generalized, and analyzed. The antibacterial mechanism of nanometer zinc oxide was discussed in depth. The antibacterial properties and advantages of the latest nanometer zinc oxide composite materials were introduced in detail. In this review, we made prospect of the future application of nanometer zinc oxide.

A rapid pathological preparation method for composite material observation / 中国修复重建外科杂志

Objective: To explore a simple and rapid pathological slices method to observe the porous structure and the composition distribution of composite materials. Methods: Taking polyurethane/small intestinal submucosa (PU/SIS) composite as an example, PU/SIS was OCT-embedded and sliced into sections by frozen section technology, after which general observation of the section integrity was carried out. After dyed with water-soluble eosin in alcoholic solution, the staining effect and the porous structure of the composite were observed under light field microscope. Sections were sealed with five different sealing methods. Group A: sealing piece using glycerogelatin method; group B: anhydrous alcohol dehydration→transparency using TO transparent reagent→sealing piece using neutral quick drying glue; group C: color separation using deionized water→air-drying→sealing piece using neutral quick drying glue; group D: air-drying→transparency using TO transparent reagent→sealing piece using neutral quick drying glue; group E: air-drying→sealing piece using neutral quick drying glue. Then, the morphology and the components distribution of the composite were observed under light field microscope, and the simple and feasible method was selected as optimum method. Results: From general observation, the frozen section of the PU/SIS composite, which was 6 μm in thickness, was complete and continuous. Although the outline of the material and the porous structure in the sections could be observed clearly under light field microscope, the two components still could not be identified by using eosin staining method. After sealing piece, the material components in groups A, B, and C still could not be identified or be dissolved and deformed; the morphology of the material in groups D and E were preserved and the two components in the composite were clearly visible. Conclusion: The morphology and the components distribution of PU/SIS frozen sections can be characterized after soluble eosin staining and neutral quick drying glue sealing.

Preparation of Polydiallyl Dimethyl Ammonium Chloride Modified Reduced Graphene Oxide/Zinc Oxide Composite Materials and Its Application in Detection of Uric Acid / 分析化学

By using Zinc nitrate as precursor and hydraZine hydrate as reducing agent, polydiallyl dimethyl ammonium chloride modified reduced graphene oxide/Zinc oxide composite materials ( PDDA-rGO/ZnO) were prepared by simultaneous reduction of graphene oxide ( GO) and Zinc nitrate.The composite materials were characteriZed by Fourier transform infrared ( FTIR ) spectroscopy, X-ray diffractometer ( XRD ) and transmission electron microscopy ( TEM) , and their electrochemical catalytic activity for uric acid was studied by cyclic voltammetry ( CV ) and linear sweep voltammetry ( LSV ) measurements.The result showed that PDDA-rGO/ZnO modified glassy carbon electrode prepared here was sensitive, reproducible and stable, and had significant electrocatalytic activity for UA.When using linear sweep voltammetry for detection of UA, the responses of modified electrode were linear with UA concentration in the ranges of 0.02-0.1 mmol/L and 0.1-1.0 mmol/L respectively, with detection limit of 15.9 nmol/L (S/N=3).

Clinical efficacy of EH composite material combined with CAD/CAM technique in plastic treatment of unilateral micrognathia / 中华医学美学美容杂志

Objective To evaluate the clinical efficacy in the treatment of unilateral micrognath ia by using EAM medical resin and hydroxyapatite (EH) composite material combined with the CAD/ CAM technique.Methods From July 2011 to October 2015,12 cases of unilateral micrognathia caused by different reasons were treated,based on the representative traits and requirements,refering to the unsymmetric counter part by right of CAD/CAM technique.By the 3-dimensional design and reconstruction,we reformed the EH composite material into purposed shape,and insert it in the operative area.Results All the materials were closely suitable to the mandible surfaces.1 case failed because the wound was torn apart;the other 11 patients recovered more than 6 months and were satisfied with the external appearance.Conclusions The EH composite materials combined with CAD/ CAM techniques could be a potential characterized remedy for the unilateral micrognathia.

Silanização de partículas de carga de compósitos odontológicos - revisão de literatura / Silanization of filler particles of dental composites - literature review

Objective: this study aimed to perform a literature review to facilitate the understanding regarding the type of silane used, as well as the processes involved in silanization of filler particles of dental composites. Literature review: the silane agent is essential to promote a bond between organic and inorganic phases of dental composites. The topics addressed in this study are: basic formulation of monomers employed in dental composites, filler particles used, the importance of the bonding agent in material composition, as well as the types of MPTS silane (γ - methacryloxypropyltrimethoxysilane), OTMS (n-octyltrimethoxysilane) UDMS (3-[(1,3(2)-dimethacryloyloxypropyl)- 2 (3)-oxycarbonylamido] propyl triethoxysilane), GPS (γ- glycidoxypropyltrimethoxysilane), and ATES (organosilanes alyltriethoxysilane), the effects of its applications and silanization processes. Final considerations: a detailed analysis of silane agents allows the knowledge of the advantages and disadvantages of these materials to lead to the improvement and subsequent development of other bonding agents that are more suitable for use in the oral cavity.

Clareamento dentário associado à facetas Indiretas em cerâmica: abordagem minimamente invasiva. / Tooth bleaching associated with ceramic veneers: a conservative approach.

O objetivo deste trabalho é relatar um caso clínico, demostrando protocolo conservador para reabilitação estética com facetas indiretas de cerâmica associadas ao clareamento dental. Paciente do gênero masculino insatisfeito em relação à estética do seu sorriso apresentou ao exame clínico restaurações em resina composta nos dentes anteriores com pigmentação e fraturas marginais. Foi realizada remoção das restaurações para avaliação dos diastemas. Inicialmente, foi realizado clareamento externo em consultório com peróxido de hidrogênio a 38%. Após uma semana, foram feitos preparos minimamente invasivos na superfície vestibular e moldagem. Os laminados foram confeccionados com cerâmica feldspática e cimentados adesivamente ao substrato dentário. Feita a cimentação, foi feito ajuste oclusal mantendo os contatos oclusais fisiológicos. A associação entre o clareamento dentário e laminados cerâmicos, com preparos conservadores, mostrou-se eficaz para a reabilitação estética e funcional do sorriso contribuindo para a satisfação do paciente.

The aim of this study is to describe a clinical case, showing conservative approach for aesthetic rehabilitation with ceramic veneers associated with tooth bleaching. A male patient presented dissatisfaction with smile was submitted to clinical examination and showing composite resin restorations on anterior teeth with marginal fractures and pigmentation. Restoration removal was performed for diastemata evaluation. Initially, was performed in-office tooth bleaching with hydrogen peroxide 38%. After one week, preparations were made with minimally removal of tooth structure at buccal surface and the impression was made. The veneers were fabricated with feldspathic ceramic and cemented adhesively to the tooth substrate. Once the luting procedure was performed, occlusal adjustment was made keeping the physiological occlusal contacts. The association between tooth bleaching and ceramic veneers with conservative approach was effective for the esthetic and functional rehabilitation of the smile contributing to patient satisfaction.

Development and properties of composite phase change material for blood preservation / 医学研究生学报

Objective:Temperature keeping is vital in the long distance transportation of red blood cell suspensions in military affairs and emergency.This study aimed to develop a composite phase change material to be used for preserving blood in long time transporation without electricity.Methods: The n-tetradecane was adsorbed to the pore structure of silica aerogel through the capillarity and hydrophobicity of silica aerogel.The efficiency of the phase change material was detected by differential scanning calorimetry.Results: The specific surface area and the adsorption capacity were 863.59 m2/g and 9.16,respectively.The phase change temperature was 5.47℃ and phase change latent heat was 180J/g.Conclusion: The n-tetradecane /silica aerogel composite phase change material could be used for blood preservation.

Advances in nano-hydroxyapatite and its composite / 医疗卫生装备

Nano-hydroxyapatite has been widely used as reconstructive and prosthetic material for osseous tissue,owing to its excellent biocompatibility and tissue bioactivity.But the poor mechanical property of hydroxyapatite restricts its further application.In order to enhance the comprehensive performance of the material,many researches have been dedicated to the synthesization of the composite materials.This article reviews the main preparation methods of nano-hydroxyapatite and the advancement in research of its composite.The directions in this research area are described as well.