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Self-gelling/setting injectable biomaterials hold great promise for the delivery of bioactive molecules and cells useful for tissue engineering and regenerative medicine. In the biopolymeric regime, a broad compositional spectrum has been developed, yet very limited compositional options have been developed for inorganic injectables. For example, calcium phosphate (CaP)-based injectables are considered to be one of the most promising classes of materials for bone repair and reconstruction. Here we present an update on the recent advancements in CaP-injectables, where significant efforts have been undertaken to improve the regenerative capacity by tailoring the chemical compositions and increasing the drug delivery potential.

This paper presents the structural characterisation and degradation behavior of the glass system 20Na 2 O–(30 − X )CaO– X MgO–50P 2 O 5 ( X = 0, 5, 10, 15, 20, 25 and 30 mol%) wherein magnesium oxide is introduced as a partial calcium oxide substitute. This system is of interest from the viewpoint of investigating the subtle effects on structure and degradation that arise from the substitution of divalent ions (Mg 2 + for Ca 2 + ) in these glass systems. Studies such as differential thermal analysis (DTA), Fourier transform infrared (FTIR) spectroscopy and 31 P nuclear magnetic resonance (NMR) reveal little change in the glass structure. However, degradation and ion release measurements for glass discs immersed in deionised water at 37 °C over a 21 day period highlight an inverse exponential effect between glass degradation rate and MgO content. Thus, the investigated glass systems provide interesting insights into the effects of parameters such as ionic radius, atomic weight and bond length on the glass properties. From an applications perspective, these glasses offer a selective range of degradation rates from highly degradable to relatively stable systems and can potentially serve as vehicles for the delivery of magnesium ions in the clinical realm.

Kinetic data for solvolyses of α-methylthioacetyl chloride, phenylthioacetyl chloride and thiophene-2-acetyl chloride in at least 33 aqueous solvent systems including 2,2,2-trifluoroethanol–ethanol solvent were determined at 10 °C by a conductimetric method, and their rates of solvolyses were correlated using Grunwald–Winstein type equations with the ionizing power parameter (YCl: based on the solvolyses of 1-adamantyl chloride) and the nucleophilicity parameter (NT). Kinetic solvent isotope effects (KSIEs) in water and methanol were investigated for the above compounds and in methanol also for phenyl, diphenyl, and trimethylacetyl and isobutyryl chlorides. The results show similar absolute rate constants, similar large amounts of nucleophilic solvent assistance, but different KSIE values (explained by general base catalysis).

Background The objective of this study was to investigate the effects of bioactive calcium phosphate cements (CPC, α-tricalcium phosphate-based) incorporating zinc-bioglass (ZnBG) on the odontogenic differentiation and angiogenesis of human dental pulp cells (HDPCs). Methods BGs with varying concentrations of Zn (0, 2.5 and 5%) were produced via a sol-gel process. The proliferation of HDPCs on CPC/BGs was determined by MTS assay. Alizarin red staining, RT-PCR, and ALP activity were used to assess odontogenic differentiation, and western blot analysis was used to asses signaling pathways. In vitro angiogenesis was examined via mRNA expression of angiogenic genes and tubule formation. Results All cement formulations showed no cytotoxicity. The CPCs with ZnBG showed increased ALP activity, enhanced formation of mineralized nodules, and upregulated mRNA expression of DMP-1, DSPP, Runx2, and osterix in a time- and dose-dependent manner, relative to CPCs without Zn. ZnBG upregulated integrins α1, α2, β1, and β3 and activated integrin downstream signal pathways, such as p-FAK, p-Akt, p-paxillin, RhoA, MAPK, and NF-κB, as well as canonical and non-canonical Wnt signaling. In addition, ZnBG upregulated VEGF mRNA in HDPCs and increased the tubular structure in endothelial cells. Conclusions Our results demonstrate that ZnBG incorporated within CPCs activates odontogenic differentiation and promotes angiogenesis in vitro through integrin, Wnt, MAPK, and NF-κB pathways. Thus, CPCs incorporating ZnBG are promising matrices in tissue engineering to stimulate endodontic regeneration.

Nanofibrous structures developed by electrospinning technology provide attractive extracellular matrix conditions for the anchorage, migration, and differentiation of tissue cells, including those responsible for the regeneration of hard tissues. Together with the ease of set up and cost-effectiveness, the possibility to produce nanofibers with a wide range of compositions and morphologies is the merit of electrospinning. Significant efforts have exploited the development of bone regenerative nanofibers, which includes tailoring of composite/hybrid compositions that are bone mimicking and the surface functionalization such as mineralization. Moreover, by utilizing bioactive molecules such as adhesive proteins, growth factors, and chemical drugs, in concert with the nanofibrous matrices, it is possible to provide artificial materials with improved cellular responses and therapeutic efficacy. These studies have mainly focused on the regulation of stem cell behaviors for use in regenerative medicine and tissue engineering. While there are some challenges in achieving controllable delivery of bioactive molecules and complex-shaped three-dimensional scaffolds for tissue engineering, the electrospun nanofibrous matrices can still have a beneficial impact in the area of hard-tissue regeneration.