Utilization of polymers as biomaterials has greatly impacted the advancement of modern medicine. Specifically, polymeric biomaterials that are biodegradable provide the significant advantage of being able to be broken down and removed after they have served their function. Applications are wide ranging with degradable polymers being used clinically as surgical sutures and implants. In order to fit functional demand, materials with desired physical, chemical, biological, biomechanical and degradation properties must be selected. Fortunately, a wide range of natural and synthetic degradable polymers has been investigated for biomedical applications with novel materials constantly being developed to meet new challenges. This review summarizes the most recent advances in the field over the past 4 years, specifically highlighting new and interesting discoveries in tissue engineering and drug delivery applications.

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Biomedical Applications of Biodegradable Polymers

Biopolymer-based hydrogels as scaffolds for tissue engineering applications: a review

Oxygen vacancies in crystal have important impacts on the electronic properties of ZnO. With ZnO2 as precursors, we introduce a high concentration of oxygen vacancies into ZnO successfully. The obtained ZnO exhibits a yellow color, and the absorption edge shifts to longer wavelength. Raman and XPS spectra reveal that the concentration of oxygen vacancies in the ZnO decreased when the samples are annealed at higher temperature in air. It is consistent with the theory calculation. The increasing of oxygen vacancies results in a narrowing bandgap and increases the visible light absorption of the ZnO. The narrowing bandgap can be confirmed by the enhancement of the photocurrent response when the ZnO was irradiated with visible light. The ZnO with oxygen vacancies are found to be efficient for photodecomposition of 2,4-dichlorophenol under visible light irradiation.

Oxygen vacancy induced band-gap narrowing and enhanced visible light photocatalytic activity of ZnO.

Synthesis methods for nanosized hydroxyapatite with diverse structures.

Optical Waveguide Theory

多尺度研究铜/金刚石界面电子及热传输特性

The anti-washout ability of calcium phosphate cement (CPC) determines its effectiveness in clinical application. In the current research, the common method for improving the anti-washout ability of CPC is to add anti-washout polymer agents. Sodium polyacrylate powder is an excellent anti-washout agent but when bonded with CPC it basically degrades the anti-washout performance of CPC after γ-ray irradiation, and is widely used in the sterilization process of CPC products. Therefore, we propose a method for the preparation of a sodium polyacrylate solution through irradiation polymerization as curing solution for CPC. This method first uses γ-ray irradiation sterilization to improve the anti-washout ability of CPC directly. It not only avoids the adverse effects of γ-rays on anti-washout agents, but also the CPC blended using this sodium polyacrylate solution had good biological properties and injectability. It provides a new method for promoting the anti-washout properties of calcium phosphate cement, which is of great significance for expanding the clinical application of CPC.

A novel anti-washout curing solution of calcium phosphate cement prepared via irradiation polymerization.

An injectable calcium phosphate bone cement was prepared by combining amorphous calcium phosphate (ACP) and dicalcium phosphate dihydrate (DCPD) for use in non-invasive surgery in this work. The effect of the conserving time on the viscosity, yield stress and injectability of the calcium phosphate cement (CPC) pastes were studied. The results showed that as the conserving time of the pastes prolonged, the viscosity and the yield stress of the pastes increased exponentially, and the injectability of the pastes decreased. This resulted from the transformation of DCPD and ACP into hydroxyapatite via hydration reaction. The results also indicated that the pastes still exhibited good injectability in even 15 min after preparation of the CPC pastes.

Rheological Properties of an Injectable Calcium Phosphate Bone Cement and their Relationship with the Phase Evolution


 Unintentional nitrogen incorporation has been observed in a set of microwave plasma chemical vapor deposition (MPCVD)-grown samples. No abnormality has been detected on the apparatus especially the base pressure and feeding gas purity. By a comprehensive investigation including the analysis of the plasma composition, we have found that a minor leakage of the system could be significantly magnified by the thermal effect, resulting in a considerable residual nitrogen in the diamond material. Moreover, the doping mechanism of leaked air is different to pure nitrogen doping. The dosage of several ppm of pure nitrogen can lead to efficient nitrogen incorporation in diamond, while at least thousands ppm of leaked air is required for detecting obvious residual nitrogen. The difference of the dosage has been ascribed to the suppression effect of oxygen that consumes nitrogen. As the unintentional impurity is basically detrimental to the controllable fabrication of diamond for electronic application, we have provided an effective way to suppress the residual nitrogen in a slightly leaked system by modifying the susceptor geometry. This study indicates that even if a normal base pressure can be reached, the nitrogen residing in the chamber can be “activated” by the thermal effect and thus be incorporated in diamond material grown by a MPCVD reactor.

The origin, characteristics, and suppression of residual nitrogen in a MPCVD diamond growth reactor

The anti-washout ability of calcium phosphate cement (CPC) determines the effectiveness of CPC in clinical application. The γ-ray irradiation method often used in the sterilization process of CPC products is easy to degrade some commonly polymer anti-washout agent, which greatly reduces its anti-washout performance. Artemisia sphaerocephala Krasch gum (ASKG) has the potential of radiation resistance and anti-washout, but no one has considered its performance as anti-washout agent of CPC and mechanism of radiation resistance and anti-washout so far. In this study, we report the effect of γ-ray on ASKG and the effectiveness of ASKG for enhancing of radiation resistance and anti-washout ability of CPC, the physical, chemical properties and in vitro cell behaviors of ASKG-CPCs were also investigated. The results showed that addition of ASKG before and after irradiation could significantly enhanced the anti-washout performance of CPC, which is differ from conventional anti-washout agents. Meanwhile, ASKG-CPCs had an excellent injectable property and biocompatibility, and low content of irradiated ASKG could promote bone differentiation well. We anticipate that the radiation-resistant and anti-washout ASKG-CPCs have potential application prospect in orthopaedic surgery.

Physicochemical Properties and Cytocompatibility of Radiation-resistant and Anti-washout Calcium Phosphate Cement by Introducing Artemisia Sphaerocephala Krasch Gum.

Jiandong Ye

Papers

多尺度研究铜/金刚石界面电子及热传输特性

A novel anti-washout curing solution of calcium phosphate cement prepared via irradiation polymerization.

Rheological Properties of an Injectable Calcium Phosphate Bone Cement and their Relationship with the Phase Evolution

The origin, characteristics, and suppression of residual nitrogen in a MPCVD diamond growth reactor

Physicochemical Properties and Cytocompatibility of Radiation-resistant and Anti-washout Calcium Phosphate Cement by Introducing Artemisia Sphaerocephala Krasch Gum.