Green Synthesis of Bioactive Hydroxyapatite/Cellulose Composites from Food Industrial Wastes

This work aimed at conversion of worthless indurtial wastes to valuable product. Herein, bioactive composites based on bacterial cellulose (BC) and eggshell or eggshell-derived hydroxyapatite (HAp) were prepared by a green method using Gluconacetobacter xylinum bacteria. The effect of addition of eggshell (BC/Eg) and eggshell-derived HAp (BC/HAp-Eg) on the bacterial cellulose yield, biodegradation and biocompatibility was studied. For comparison, HAp derived from chemical precursors was synthesized (BC/HAp-ch). The resultant composites were characterized by XRD, FTIR, and SEM/EDX. Furthermore, the biodegradation and bioactivity were assessed in SBF, and the cell viability was studied against oral normal cells. The results showed that the productivity of BC applied HAp-derived eggshell (1.83 g/L) was higher than that of using (1.37 g/L). Interestingly, the eggshell was converted to Ca3(PO4)2 during incubation in the bacterial culture medium, while Ca3(PO4)2 was formed as a secondary phase when using either eggshell-derived HAp or chemically-derived. The in vitro bioactivity test in SBF showed that all composites were induced the formation of a bone-like apatite layer on their surface with Ca/P ratio, 1.49, 1.35, and 1.41 for BC/Eg, BC/HAp-ch, and BC/HAp-Eg, respectively, near to the ratio in the natural HAp. Finally, the in vitro cell viability test was confirmed good biocompatibility against the composites. However, at high sample concentration (250 µg/mL), BC/HA-Eg showed the higher cell viability (95.2%) than that of BC/Eg (80.5%) and BC/HA-ch (86.2%). In conclusion, eggshell waste could be used directly with bacterial cellulose to produce bioactive composites without the need to convert it to HAp which reduced the cost of production and thus has a higher economic return. Obiviously, eggshell waste can act as calcium, organic matter source, pH preservation, nuterilizing agent along with potential instead of costly buffering agent in the BC culture medium and further for increased the BC production.

Role of alkali metal oxide type on the degradation and in vivo biocompatibility of soda-lime-borate bioactive glass

In this work, it is the first time to study the effect of replacing of Na₂ O by a fixed amount of Li₂ O or K₂ O in soda-lime-borate glass on its in vivo biocompatibility. The glass composition was based on xM₂ O-20x Na₂ O20 CaO60 B₂ O₃ , (wt %), where, M₂ OLi₂ O and K₂ O, and consequently, samples encoded BN100, BK50, and BL50. The degradation test was carried out in 0.25 M K₂ HPO₄ solution. The in vivo test was performed in the femoral bone defect of Sprague-Dawley adult male rat. Following up bone formation was conducted by the histological analyses and bone formation markers (alkaline phosphatase [ALP] and osteocalcin [OCN]). Furthermore, the glass effect on the liver and kidney functions was addressed in this study using (alanine transaminase [ALT] and aspartate transaminase [AST]) and (urea and creatinine), respectively. The results of the degradation test showed that the glass dissolution rate was increased by incorporating of K₂ O, and its ion release was occurred by a diffusion-controlled process. Moreover, in vivo bioactivity test showed that serum activity of ALP, OCN level, and the newly formed bone was higher in BL50-implanted group than that of BN100 andBK50at 3 w and 6 w post-surgery. As well as, implantation of all glass samples in the femoral bone defect did not alter the liver and kidney functions. In conclusion, the synthesized borate glass was well served as a controlled delivery system for Li⁺ ion release, which enhanced bone formation as shown from the bone formation markers (ALP and OCN).

In vitro drug release behavior of Ce-doped nano-bioactive glass carriers under oxidative stress

Ce-containing bioactive glasses are known to decrease reactive oxygen activities inside the body. That is because of their excellent catalytic activities which come from the fast interchange of Ce³⁺/Ce⁴⁺ oxidation states. This research was mainly aimed at preparing new Ce-doped nano-bioactive glasses based on 60SiO₂-(10-x)B₂O₃-25CaO-5P₂O₅-xCeO₂, in mole% (x = 0 and 5 mol%) as multifunctional bone fillings. Moreover, the glasses were used as a delivery system for ciprofloxacin to intensely solve the bone infection complications. Nevertheless, there were no previous works studied of the nature immersing solution effect on the drug release behavior from Ce-doped nano-bioactive glass carriers. Therefore, phosphate-free and phosphate-containing buffer solutions with/without superoxide species (H₂O₂) were used to investigate the efficacy of this drug delivery system in different environment. The results showed that Ce addition enhanced the formation of apatite layer and cell viability. Moreover, the percentage of released drug was apparently affected by the glass composition and nature of soaking fluid, specifically, in the media containing superoxide species (H₂O₂). In conclusion, the prepared Ce-doped glass nanoparticles illustrated multifunctional bone filling material, but when it intended to be utilized as a drug delivery system, the nature of surrounding medium have to be taken into consideration.