Crystalline selenite substituted carbonated hydroxyapatite nanorods: Synthesis, characterization, evaluation of bioactivity and cytotoxicity

Abstract

Synthesis of pure and selenite substituted hydroxyapatites (HAP and Se-HAP with 0.02-0.10Se) by sol-gel method and evaluation of their morphological features, nature of functional groups, phase purity, in vitro bioactivity and cytotoxicity are addressed. Spectral studies confirm the incorporation of selenite into the HAP lattice, accompanied by an increase in CO 3 2-content to maintain the charge imbalance following replacement of P 5+ with Se 4+, thus making the formation of selenite substituted carbonated HAP. Selenite substitution in the HAP lattice has led to a higher crystallinity and increased the crystallite size. The morphology of HAP is changed from sphere to rod-like structure upon substitution by selenite and the size of the rod is increased with an increase in the selenite content.Among the Se-HAP's, a better in vitro bioactivity and cell viability are observed for 0.02Se-HAP and 0.04Se-HAP while the trend is reversed when the extent of selenite substitution becomes higher. role in improving the biological activity of the apatites and, the eventual bone formation and regeneration. Selenium is a vital micro-nutrient and one of the most essential elements required for many biological metabolisms. It plays an important role in the protein functions, induction of cancer cell apoptosis, proliferation, and differentiation of bone cells to improve bone health. It also exhibits good antibacterial property. [16][17][18][19][20] Thus, substitution of selenite in the HAP matrix is likely to improve biological functions. However, studies on selenite incorporated HAPs are rather limited. The biological influence of selenium on human system is dose dependant and hence the use of selenium beyond the tolerance level could lead to selenosis and toxicity to cellular environment. [21][22][23] Hence, it is imperative to optimize the concentration of selenite in HAP. In earlier reports, selenite-substituted HAP (Se-HAP) was synthesized by precipitation method. 16,17,24,25 Nevertheless, this method led to a decrease in crystallinity of Se-HAP and promoted agglomeration of crystals even at lower concentrations of selenite. Crystalline HAP's are known to improve biomineralization process (the bone like apatite formation) and hence, they serve as exceptional biomaterials. Moreover, orthopedic implant applications warrant the use of highly crystalline apatites due to their stability during the early stages of resorption process and their ability to increase the longevity of the coating. 26Among the various methods available for the synthesis of HAP, 27-33 the sol-gel method has received much attention owing to its inherent advantages such as high product purity, improved crystallinity, homogenous molecular mixing and, its ability to synthesize HAP's at relatively low temperatures. 34,35 The sol-gel method, which has not been attempted previously for the synthesis of Se-HAP is an ideal choice to prepare high pure crystalline apatites. 36-38The present study aims to synthesize Se-HAP's with varying precursor selenite co...

Improving the Bioactivity of Hydroxyapatite Through Strontium Substitution and Forming a Composite with Graphitic Carbon Nitride

“…The interaction of negatively charged PO 4 3and OHions with the positively charged Ca 2+ ions in the SBF solution enables the formation of the apatite layer. Sr 2+ ions have the ability to promote the bioactivity as well as to stimulate the new bone formation (24,25).…”

The Effect of Peat Swamp Water on Tooth Demineralization of Copper and Selenium Ion

“…Artificial saliva does not have selenium ions, which means that adsorption by hydroxyapatite crystals cannot occur compared to the other 2 groups. 17,22 Theoretically, selenium ions in teeth can increase tooth vulnerability to demineralization process. However, peat water with a lot of organic substances that can stabilized the bond between selenium ions and hydroxyapatite crystals, thus may decrease demineralization process.…”