Surface modification of PLGA/β-TCP scaffold for bone tissue engineering: Hybridization with collagen and apatite

The objective of this experiment is to produce a novel scaffold composed of poly (lactic-co-glycolic acid) (PLGA)/β-tricalciumphosphate (β-TCP) skeleton covered with apatite/collagen sponge. BMSCs were used to evaluate the cell behavior on the hybrid scaffold. Cell morphology on the surfaces of PLGA/β-TCP skeleton and PLGA/β-TCP skeleton with apatite/collagen sponge composite coating was studied by scanning electron microscopy (SEM). Cell proliferation was assessed by cell number counting. Differentiated BMSCs function was monitored by measuring alkaline phosphates activity of the cells. These results demonstrated that the apatite/collagen sponge composite coating could improve cell proliferation and ALP activity of the hybrid scaffolds and increase its hydrophilicity after hybridization. The experiment suggested that the PLGA/β-TCP skeleton with apatite/collagen sponge composite coating is promising as a candidate 3D substrate for bone tissue engineering.     

Nanostructured bioactive glass coating on porous hydroxyapatite scaffold for strength enhancement

Many attempts have been focused on preparing highly porous scaffolds with appropriate mechanical strength. This paper has developed a new route to enhance the compressive strength of porous HA (hydroxyapatite) scaffold (porosity: ∼ 83%, mean pore size:∼ 800 μm). Briefly this route included nanostructure coating of bioactive glass on struts of porous HA. Coating microstructure consisted of the grains with the range between 91 and 320 nm and micron size pores that could be detected by SEM observation. This simple method improved the compressive strength of highly porous HA from 0.22 to 1.49 MPa. The obtained scaffolds provided good mechanical support while maintaining bioactivity so they could be used as tissue engineering scaffolds for low-load bearing applications.     

Highly interconnected macroporous MBG/PLGA scaffolds with enhanced mechanical and biological properties via green foaming strategy

In this study, mesoporous bioactive glass particles (MBGs) are incorporated into poly(lactic-co-glycolic acid) (PLGA) to fabricate highly interconnected macroporous composite scaffolds with enhanced mechanical and biological properties via a developed supercritical carbon dioxide (scCO₂) foaming method. Scaffolds show favorable highly interconnected and macroporous structure through a high foaming pressure and long venting time foaming strategy. Specifically, scaffolds with porosity from 73% to 85%, pore size from 120 μm to 320 μm and interconnectivity of over 95% are controllably fabricated at MBG content from 0 wt% to 20 wt%. In comparison with neat PLGA scaffolds, composite scaffolds perform improved strength (up to 1.5 folds) and Young's modulus (up to 3 folds). The interconnected macroporous structure is beneficial to the ingrowth of cells. More importantly, composite scaffolds also provide a more promising microenvironment for cellular proliferation and adhesion with the release of bioactive ions. Hopefully, MBG/PLGA scaffolds developed by the green foaming strategy in this work show promising morphological, mechanical and biological features for tissue regeneration.     

Cyclic Dipeptide: A Privileged Molecular Scaffold to Derive Structural Diversity and Functional Utility

Cyclic dipeptides (CDPs) are the simplest form of cyclic peptides with a wide range of applications from therapeutics to biomaterials. CDP is a versatile molecular platform endowed with unique properties such as conformational rigidity, intermolecular interactions, structural diversification through chemical synthesis, bioavailability and biocompatibility. A variety of natural products with the CDP core exhibit anticancer, antifungal, antibacterial, and antiviral activities. The inherent bioactivities have inspired the development of synthetic analogues as drug candidates and drug delivery systems. CDP plays a crucial role as conformation and molecular assembly directing core in the design of molecular receptors, peptidomimetics and fabrication of functional material architectures. In recent years, CDP has rapidly become a privileged scaffold for the design of advanced drug candidates, drug delivery agents, bioimaging, and biomaterials to mitigate numerous disease conditions. This review describes the structural diversification and multifarious biomedical applications of the CDP scaffold, discusses challenges, and provides future directions for the emerging field.     

选择性激光烧结方法加工仿生支架的工艺研究

在利用选择性激光烧结技术加工仿生支架过程中，加工参数（包括激光功率、扫描速度、扫描间距）是影响成形质量的重要因素，通过调整加工参数可以使成形零件内部保持一定的孔隙，从而产生支架内部微孔结构。正交试验方法可以科学地安排和分析多种因素的影响，从而优化加工参数，最终获得具有较高孔隙率的仿生支架。     

面向骨组织工程的三维仿生支架的微观结构研究

骨缺损修复是当今国际组织工程领域的一个难题，而细胞载体支架的制取是骨缺损问题研究的重点。探讨了支架结构制取的几种方法并进行了比较，采用数模相结合的方法进行微观结构的设计，获得了参数(孔的形状、尺寸，孔隙率等)可控的骨支架模型。     

Fabrication and toughening behavior of carbon nanotube (CNT) scaffold reinforced SiBCN ceramic composites with high CNT loading

Uniform dispersion, high loading and three-dimensional (3D) continuous network of carbon nanotube (CNT) are desired for high-performance nanocomposites to fully utilize the superior strength and toughness of CNTs. In this work, monolithic CNTs/SiBCN composites with high CNT loading (10 wt% and 20 wt%) were prepared from 3D scaffold-like CNT cottons and a liquid polyborosilazane (PBSZ) precursor through precursor infiltration and pyrolysis process. The 3D CNT scaffold in the nanocomposite can function as passive filler and gas path to ensure formation of monolithic bulks. Moreover, direct infiltration of PBSZ into the pores among CNT cotton can hinder agglomeration of CNTs and localize CNTs at the original sites, guarantee good alignment and high CNT concentration in the final nanocomposite. This highly concentrated 3D CNT reinforcement in the nanocomposite shows unique resistance to cracking under external stress related to the complex fracture behavior of CNT bundles during the cracking formation and extension process (including CNT bridging, aligning, pulling out and then breaking), which more favors for absorbing energies and enhance toughness of the ceramic composites.     

Subtractive manufacturing of customized hydroxyapatite scaffolds for bone regeneration

An approach to the preparation of customized hydroxyapatite scaffolds for bone regeneration based on subtractive manufacturing has been developed. The developed method is intended as a simple alternative to rapid prototyping based on additive manufacturing methods. The method for the preparation of customized scaffolds consists in computer numerical controlled (CNC) milling of porous hydroxyapatite foam. The machinable foam for customized scaffolds was prepared by direct foaming of a colloidal hydroxyapatite suspension and the foam structure was consolidated by the gelcasting method. The optimal foam after sintering reached a high porosity of 83.3% and the cellular-like structure contained spherical pores with an average diameter of 613 µm, which were connected through windows with an average diameter of 161 µm. The compressive strength of the sintered foam reached an average value of 2 MPa. CNC milling was tested at different stages of the production cycle of the porous foam and after the reinforcing of the foam by impregnation. The best results were obtained by milling the foam presintered at 1100 °C. The milling process was demonstrated and scaffold examples were successfully manufactured.     

Novel method to produce β-TCP scaffolds

The production of ceramic scaffolds by a novel method was reported in this work. The method comprised the mixture of colloidal silica and β-tricalcium phosphate (β-TCP) powder, where paraffin microspheres were further added to provide the porosity in the scaffold after firing. Thermo-gravimetric analysis showed that the paraffin was completely degraded before 550 °C, where the heat treatment at 1100 °C was enough to remove the paraffin and provide porosity and mechanical strength. The scaffold had an open porosity, but with poor pore interconnection. The density of the scaffold was 1.11 ± 0.03 g/cm³ with a porosity of 64.98 ± 1.1%, and the compression strength was 5.02 ± 1.2 MPa.     

钢管脚手架扣件力学性能试验夹具

针对目前对钢管脚手架扣件的检验无专用夹具，设计了一套脚手架扣件力学性能试验夹具。该夹具能满足GBl5831-1995钢管脚手架扣件中力学性能检验的要求，且实用、准确、高效。