ABSTRACT
Biomineralization is the process by which organisms form mineralized tissues with hierarchical structures and excellent properties, including the bones and teeth in vertebrates. The underlying mechanisms and pathways of biomineralization provide inspiration for designing and constructing materials to repair hard tissues. In particular, the formation processes of minerals can be partly replicated by utilizing bioinspired artificial materials to mimic the functions of biomolecules or stabilize intermediate mineral phases involved in biomineralization. Here, we review recent advances in biomineralization-inspired materials developed for hard tissue repair. Biomineralization-inspired materials are categorized into different types based on their specific applications, which include bone repair, dentin remineralization, and enamel remineralization. Finally, the advantages and limitations of these materials are summarized, and several perspectives on future directions are discussed.
Subject(s)
BiomineralizationABSTRACT
Tooth enamel is prone to be attacked by injurious factors, leading to a de/remineralization imbalance. To repair demineralized enamel and prevent pulp inflammation caused by biofilm accumulation, measures are needed to promote remineralization and inhibit bacterial adhesion on the tooth surface. An innovative material, poly (aspartic acid)-polyethylene glycol (PASP-PEG), was designed and synthesized to construct a mineralizing and anti-adhesive surface that could be applied to repair demineralized enamel. A cytotoxicity assay revealed the low cytotoxicity of synthesized PASP-PEG. Adsorption results demonstrated that PASP-PEG possesses a high binding affinity to the hydroxyapatite (HA)/tooth surface. In vitro experiments and scanning electron microscopy (SEM) demonstrated a strong capacity of PASP-PEG to induce in situ remineralization and direct the oriented growth of apatite nanocrystals. Energy dispersive X-ray spectroscopy (EDS), X-ray diffraction analysis (XRD) and Vickers hardness tests demonstrated that minerals induced by PASP-PEG were consistent with healthy enamel in Ca/P ratio, crystal form and surface micro-hardness. Contact angle tests and bacterial adhesion experiments demonstrated that PASP-PEG yielded a strong anti-adhesive effect. In summary, PASP-PEG could achieve dual effects for enamel repair and anti-adhesion of bacteria, thereby widening its application in enamel repair.
ABSTRACT
BACKGROUND: Protein drugs such as insulin are usually used in the form of injection due to its low oral administration bioavailability. For the purpose of higher bioavailability, the common method is to encapsulate the drug into algitnate/chitosan microspheres, which introduced polysaccharides to accelerate biological absorption or reduce demolition of protease. OBJECTIVE: To construct alginate/chitosan microspheres containing cationic?-cyclodextrin polymer (CP?CD) /insulin complex for insulin oral delivery system, in addition, to inspect the influence of the charge density of cationic ?-cyclodextrin polymers on insulin release performance in vitro. DESIGN, TIME AND SETTING: The contrast observation experiment was performed at the Laboratory of Department of Polymer Science and Engineering, Sichuan University from November 2006 to July 2008. MATERIALS: ?-cyclodextrin, epichlorohydrin was supplied by Tianjin Bodi Chemical Industry Co., Ltd. Choline chloride and alginate was provided by Kelong Reagent Company, chitosan was purchased from Golden-shell Biochemical Co., Ltd. And insulin was produced by Wanbang Biochemical Pharmaceutical Company. METHODS: Cationic ?-cyclodextrin polymer was synthesized through a one-step polymerization of ?-cyclodextrin, epichlorohydrin and choline chloride. It was combined with insulin and then encapsulated into alginate/chitosan microspheres. In vitro insulin release behavior of the microsphere was studied in simulative gastrointestinal fluid. MAIN OUTCOME MEASURES: The entrapment efficiency, as well as insulin release in simulative gastrointestinal fluid. RESULTS: The charge density of CP?CD had a great impact on the insulin association efficiency of microspheres. The maximum association efficiency could reach (76.3?1.5)%. It showed that cumulative insulin release of microspheres containing CP?CD was less than that of the control group in simulated gastric fluid. The insulin released was 5.8 IU in simulated intestinal fluid, which was higher than the control group. CONCLUSION: Alginate/chitosan microsphere containing CP?CD/insulin complex is a promising system for improving insulin oral delivery efficiency.
ABSTRACT
The one-step method was adopted in this study to synthesize aliphatic polyurethane with 4,4-methylene dicyclohexyl diisocyanate(HMDI), 1,4-butanediol (BDO) and poly (tetrahydrofuran) (PTMG). The tests conducted on this material were: FIR spectrum, mechanical properties test, water contact angles test, hemolysis test and platelet adhesion test. Results showed that this material has a good tensile strength up to 30 Mpa, similar to aromaphatic polyurethane. But its tensile elongation, tensile permanent change, hydrophility are better than those of aromaphatic polyurethane. The hemolysis test and platelet adhesion test showed that it has good blood compatibility.