Calcium Phosphate Nanoparticles Cytocompatibility Versus Cytotoxicity: A Serendipitous Paradox.

Due to efficacious characteristics of calcium phosphate nanoparticles (CPNs), they have numerously been employed in nanomedicine, particularly as carrier for therapeutic and diagnostic agents, and also in tissue engineering. Although calcium phosphate minerals are noted for their cytocompatibility, there are outstanding findings from various studies that question whether they are still compatible with cells in nanoscale ranges or not and it leads to the controversial issue of CPNs cytocompatibility versus cytotoxicity. In this regard, it is necessary to know how CPNs could result in cytotoxicity for future studies. Interestingly, most of the researchers have attributed the cytotoxicity to triggering of apoptosis in CPNs-exposed cells. Furthermore, it is reported that CPNs could result in cancer cell demise through induction of apoptosis. According to the findings, not only CPNs are promising for cancer cell drug delivery, but also they have the potential to be employed as therapeutic agents. In this review, firstly the physical and chemical properties of CPNs and their application in medicine are reviewed. Moreover, the interaction between CPNs and different kind of cells are covered. Lastly, employment of CPNs as a therapeutic agent is discussed.

Physicochemical properties and bioactivity of freeze-cast chitosan nanocomposite scaffolds reinforced with bioactive glass.

Chitosan based nanocomposite scaffolds were prepared by freeze casting method through blending constant chitosan concentration with different portions of synthesized bioactive glass nanoparticles (BGNPs). Transmission Electron Microscopy (TEM) image showed that the particles size of bioactive glass (64SiO2.28CaO.8P2O5) prepared by sol-gel method was approximately less than 20 nm. Fourier Transform Infrared Spectroscopy (FT-IR) and X-ray Diffraction (XRD) analysis showed proper interfacial bonding between BGNPs and chitosan polymers. Scanning Electron Microscopy (SEM) images depicted a unidirectional structure with homogenous distribution of BGNPs among chitosan matrix associated with the absence of pure chitosan scaffold's wall pores after addition of only 10 wt.% BGNPs. As the BGNP content increased from 0 to 50 wt.%, the compressive strength and compressive module values increased from 0.034 to 0.419 MPa and 0.41 to 10.77 MPa, respectively. Biodegradation study showed that increase in BGNP content leads to growth of weight loss amount. The in vitro biomineralization studies confirmed the bioactive nature of all nanocomposites. Amount of 30 wt.% BGNPs represented the best concentration for absorption capacity and bioactivity behaviors.