Brushite (Ca,M)HPO4, 2H2O doping with bioactive ions (M = Mg2+, Sr2+, Zn2+, Cu2+, and Ag+): a new path to functional biomaterials?

Dicalcium phosphate dihydrate, DCPD (CaHPO₄·2H₂O), brushite, is an important calcium phosphate compound encountered in mineralized tissues and used in medicine, especially in bone cement formulations. However, the use of DCPD as direct implantable biomaterial has not received dedicated attention. In addition, the possibility to dope DCPD with biologically active ions to modulate its performances was not systematically explored. We have investigated in depth the doping of DCPD with Mg²⁺, Sr²⁺, Zn²⁺, Cu²⁺, and Ag⁺ ions. Clear modifications in terms of chemical composition, particle size, pore distribution, crystal morphology, and affinity for water were pointed out. Then, the samples were cultured with human adipose-derived stem cells to explore cytotoxicity and proliferation. Various behaviors were noticed dependent on the incorporated metal ions. Such DCPD compounds associated with bioactive metal ions, and particularly Ag⁺ and Zn²⁺, appear promising as a new family of reactive materials for use, as such or in combination, in bone-related applications.     

Development of Poor Cell Adhesive Immersion Precipitation Membranes Based on Supramolecular Bis‐Urea Polymers

A variety of biomedical applications requires tailored membranes; fabrication through a mix‐and‐match approach is simple and desired. Polymers based on supramolecular bis‐urea (BU) moieties are capable of modular integration through directed non‐covalent stacking. Here, it is proposed that non‐cell adhesive properties can be introduced in polycaprolactone‐BU‐based membranes by the addition of poly(ethylene glycol) (PEG)‐BU during immersion precipitation membrane fabrication, while unmodified PEG is not retained in the membrane. PEG‐BU addition results in denser membranes with a similar pore size compared to pristine membranes, while PEG addition induces defect formation. Infrared spectroscopy and surface hydrophobicity measurements indicate that PEG‐BU is retained during membrane processing. Additionally, PEG‐BU incorporation successfully leads to poor cell adhesive surfaces. No evidence is observed to indicate PEG retention. The results obtained indicate that the BU system enables intimate mixing of BU‐modified polymers after processing. Collectively, the results provide the first steps toward BU‐based immersion precipitated supramolecular membranes for biomedical applications.     

生物介质萃取技术研究进展

生物介质萃取技术,即以生物(或仿生)材料如细胞、细菌和蛋白质等为萃取吸附固定相的样品制备技术。近年来该技术在多个领域得到了较为广泛的应用,例如利用生物材料对金属的吸附性质用于分析环境样品中微量金属元素;利用生物材料(免疫蛋白)的抗原–抗体结合性质用于食品和药品中毒素的检测等。主要针对近年来生物材料作为样品预处理介质用于微量重金属离子富集及霉菌毒素纯化富集两个方面的应用进行概述,为生物介质萃取技术的进一步推广应用提供参考。     

组织工程用水凝胶材料

综述了目前用于组织工程支架材料的水凝胶,包括胶原和明胶、透明质酸盐、海藻酸盐,琼脂糖和壳聚糖等天然水凝胶,聚丙烯酸及其衍生物、聚氧化乙烯及其衍生共聚物、聚乙烯醇、聚磷腈和合成多肽等合成水凝胶,并介绍了可注射性组织工程水凝胶。     

Interfacial Compatibilization into PLA/Mg Composites for Improved In Vitro Bioactivity and Stem Cell Adhesion

The present work highlights the crucial role of the interfacial compatibilization on the design of polylactic acid (PLA)/Magnesium (Mg) composites for bone regeneration applications. In this regard, an amphiphilic poly(ethylene oxide-b-L,L-lactide) diblock copolymer with predefined composition was synthesised and used as a new interface to provide physical interactions between the metallic filler and the biopolymer matrix. This strategy allowed (i) overcoming the PLA/Mg interfacial adhesion weakness and (ii) modulating the composite hydrophilicity, bioactivity and biological behaviour. First, a full study of the influence of the copolymer incorporation on the morphological, wettability, thermal, thermo-mechanical and mechanical properties of PLA/Mg was investigated. Subsequently, the bioactivity was assessed during an in vitro degradation in simulated body fluid (SBF). Finally, biological studies with stem cells were carried out. The results showed an increase of the interfacial adhesion by the formation of a new interphase between the hydrophobic PLA matrix and the hydrophilic Mg filler. This interface stabilization was confirmed by a decrease in the damping factor (tanδ) following the copolymer addition. The latter also proves the beneficial effect of the composite hydrophilicity by selective surface localization of the hydrophilic PEO leading to a significant increase in the protein adsorption. Furthermore, hydroxyapatite was formed in bulk after 8 weeks of immersion in the SBF, suggesting that the bioactivity will be noticeably improved by the addition of the diblock copolymer. This ceramic could react as a natural bonding junction between the designed implant and the fractured bone during osteoregeneration. On the other hand, a slight decrease of the composite mechanical performances was noted.     

Interpenetrating polymer networks of polyurethane and maleimide-terminated polyurethane for biomedical applications

Interpenetrating polymer networks (IPNs) of polyurethane (PU) and maleimide-terminated polyurethane (UBMI) were prepared by using a simultaneous polymerization technique. The effects of the UBMI molecular weight and amounts of the UBMI in the IPNs on the mechanical properties, dynamic mechanical properties, degree of compatibility, water absorption, surface properties and dynamic thrombosis were investigated. Bulk structure and surface properties were analyzed in order to correlate their blood compatibility. The IPNs exhibited a higher ultimate tensile strength especially when the UBMI with short soft chains was introduced. The heterogeneous characteristics were found for the IPNs when longer soft segment chains were incorporated in the PU component polymer. The presence of hydrophilic/hydrophobic alternative microdomains on the IPN surface was proposed to be the reason for good blood compatibility. The degree of compatibility, compositions of each domain and content of each domain in the matrix were calculated and correlated with the blood compatibility.     

Medical applications of radiation formed hydrogels

Polyvinylpyrrolidone was used as a main component of two new biomaterials: hydrogels wound dressings and therapeutic system for induction of labour. Ionizing radiation was applied as a tool for initiation of crosslinking and sterilization of these materials. Both products successfully passed clinical tests and have been commercialized. Draft of technology and some properties are shortly reviewed in this report.