Inorganic Polymers (Geopolymers) as Potential Bioactive Materials

<p>The primary aim of this project was to synthesise potassium activated geopolymer composites with bioactivity, and this was realised by adding 10wt% of calcium hydroxide, nano-structured calcium silicate or calcium phosphate to the geopolymer matrix. The synthesised samples were cured at 40'C then heated to 550'C and 600'C to reduce their alkalinity. Tensile strength was measured by diametral compression. The effect of exposure to simulated body fluid (SBF) was determined by x-ray diffractometry (XRD), 27Al, 29Si and 43Ca nuclear magnetic resonance spectroscopy with magic angle spinning (MAS NMR), pH measurements, inductively coupled plasma (ICP), scanning electron microscopy (SEM) and energy dispersive x-ray analysis (EDS). XRD, 27Al and 29Si MAS NMR confirmed that all the samples retained their structural characteristics of a true aluminosilicate geopolymer, even after heating and exposure to SBF. EDS examination of the calcium-containing geopolymer composites showed that the calcium distribution was generally homogeneous. Exposure of the geopolymer composites to SBF at body temperature, was used to simulate the behaviour of the geopolymer composites in blood plasma. XRD and SEM/ EDS analysis showed that the geopolymers containing calcium hydroxide and calcium silicate formed hydroxyl apatite (HA) and carbonate hydroxyl apatite (HCA) after their exposure to SBF, indicating a degree of bioactivity. The absorption of calcium and phosphorus from the SBF and the observation of nano crystals rich in these elements provide some evidence of bioactive phases in the composite containing calcium phosphate and the reference geopolymer. The reference and the calcium phosphate geopolymer (both heated to 600XC) produced the lowest pH (ca.8) in the SBF. ICP analysis of the SBF after exposure shows that most of the aluminium remains in the geopolymer structure. The greatest release of aluminium (< 2.7 ppm after 168 hours) was found for the calcium hydroxide geopolymer (heated to 600'C). Diametral compression testing showed that the strength of the calcium phosphate-containing geopolymer heated to 550'C (4.17 MPa) is comparable with that of Bioglass(R)(5.56 MPa), currently used as a bio-material. Although none of the composites are ideal in all respects, they show sufficient promise to suggest that with further refinement, geopolymer materials may well be become candidates as bioactive ceramics.</p>

Inorganic Polymers (Geopolymers) as Potential Bioactive Materials

<p>The primary aim of this project was to synthesise potassium activated geopolymer composites with bioactivity, and this was realised by adding 10wt% of calcium hydroxide, nano-structured calcium silicate or calcium phosphate to the geopolymer matrix. The synthesised samples were cured at 40'C then heated to 550'C and 600'C to reduce their alkalinity. Tensile strength was measured by diametral compression. The effect of exposure to simulated body fluid (SBF) was determined by x-ray diffractometry (XRD), 27Al, 29Si and 43Ca nuclear magnetic resonance spectroscopy with magic angle spinning (MAS NMR), pH measurements, inductively coupled plasma (ICP), scanning electron microscopy (SEM) and energy dispersive x-ray analysis (EDS). XRD, 27Al and 29Si MAS NMR confirmed that all the samples retained their structural characteristics of a true aluminosilicate geopolymer, even after heating and exposure to SBF. EDS examination of the calcium-containing geopolymer composites showed that the calcium distribution was generally homogeneous. Exposure of the geopolymer composites to SBF at body temperature, was used to simulate the behaviour of the geopolymer composites in blood plasma. XRD and SEM/ EDS analysis showed that the geopolymers containing calcium hydroxide and calcium silicate formed hydroxyl apatite (HA) and carbonate hydroxyl apatite (HCA) after their exposure to SBF, indicating a degree of bioactivity. The absorption of calcium and phosphorus from the SBF and the observation of nano crystals rich in these elements provide some evidence of bioactive phases in the composite containing calcium phosphate and the reference geopolymer. The reference and the calcium phosphate geopolymer (both heated to 600XC) produced the lowest pH (ca.8) in the SBF. ICP analysis of the SBF after exposure shows that most of the aluminium remains in the geopolymer structure. The greatest release of aluminium (< 2.7 ppm after 168 hours) was found for the calcium hydroxide geopolymer (heated to 600'C). Diametral compression testing showed that the strength of the calcium phosphate-containing geopolymer heated to 550'C (4.17 MPa) is comparable with that of Bioglass(R)(5.56 MPa), currently used as a bio-material. Although none of the composites are ideal in all respects, they show sufficient promise to suggest that with further refinement, geopolymer materials may well be become candidates as bioactive ceramics.</p>

COMPARISON BETWEEN STRONTIUM RANELATE AND METAL SUBSTITUTED HYDROXYAPATITE AS GRAFTING MATERIALS IN TREATMENT OF PERI-IMPLANT BONY DEFECTS WITH IMMEDIATE IMPLANTS (CLINICAL AND EXPERIMENTAL STUDY)

Objective:The aim of this study is to compare between both of strontium ranelate and metallic substitute of hydroxyapatite as grafting materials in the treatment of peri-implant bony defects with immediate placement of dental implant in type I extraction sites within maxillary esthetic zone among clinical and experimental levels. This assessment was based on clinical, radiographic and histological studies. Subjects and Methods: The present study was carried on two types of population among both experimental levels on experimental white albinus rabbits and on clinical level among human patients for replacement of non-restorable maxillaryanterior and/or premolar teeth within esthetic zone by immediate implant. A written informed consent was obtained from all patients before their participation in this study.Patients were classified into two groups: the first one was with five patients with non-restorable maxillary anterior or premolar tooth that was treated by an immediately placed implant in conjunction with metallic substituted hydroxyapatite while the second one was treated by an immediately placed implant in conjunction with strontium ranelate as grafting material.The second sample population of study was carried out among ten male white (newzland) experimental rabbits with average body weight between 2.5 and 3 KG and within suitable environmental conditions in Medical Experimental Research Center (MERC) in faculty of medicine, Mansoura University. All rabbits sample was also divided equally and randomly in two groups with five rabbits within each one by the same criteria as mentioned where the first group was composed of five rabbits that received dental implant within intentionally made defect in tibia by trephine bur in conjunction with metallic substituted hydroxyl apatite as grafting material within gap between implant and defect and the second group was with the same criteria and procedures with strontium ranelategafting material within the defect. Pre-oparative photographs and cone beam computed topography (CBCT) were taken for study sample population. Within clinical patients, immediately paced dental implant have been placed in anterior esthetic zone with bone grafting around dental implant according to each group, Immediate CBCT and implant stability measurements has been taken after surgery followed by six months follow-up period to evaluate marginal bone loss, bone density, papillary esthetic score, implant stability and probing depth around dental implants. While within experimental animals trephine bur was used to intentionally create the bony defect that will simulate defect around immediate dental implant with grafting material around according to each group with six months follow-up to evaluate marginal bone loss, implant stability,bone density and for histological examination around implant within grafted area. All data were collected and statistically analyzed. Results:Generally among both clinical and experimental levels within both of clinical patients and experimental rabbits, metal substituted hydroxyl apatite (MSHAP) showed better results with significant difference than that presented in other group that has received Strontium ranelate (Sr) as a grafting material to fill the bony marginal gap around immediate dental implant during six months follow-up study period. Results presented high difference of significance between two groups in experimental and clinical levels in concern with both implant stability, marginal bone loss and even in bone quality and denisty when measured after six months follow-up. On the other hand there was no significant difference in concern with soft tissue response after six months in relation with peri-implant probing depth and MSHAP showed slight better results than that of Sr in records of papillary esthetic scores among clinical patients. Histological results showed better response of surrounding bony tissues towards MSHAP than that of Sr with more affinity of osteoblasts and osteocytes to the site of the grafted area. Conclusions:Metallic substituted hydroxyl-apatite (MSHAP) with its additive magnetic molecules within hydroxyapatite structure has better bony response from surrounding bony tissues than that provided by Strontium Ranelate (Sr) according to bone filling and preservation with less marginal loss, more affinity of new osteoblasts and mature osteocytes, long term implant stability after grafting and better bone density and quality at the grafted area around immediate dental implants in anterior maxillary area.

Exploration of gum ghatti-modified porous scaffolds for bone tissue engineering applications

Taking advantage of the tissue engineering principles, the formed hydroxyl apatite-modified gum ghatti biomaterial with its porous nature, biocompatibility, and efficient mechanical properties can be potential for the bone repair and regeneration.

The Study of Vietnamese Bonechar Synthesis and its Applications in Removal Organic Color

Biochar was synthesized from two material sources such as animal waste or plant waste. In this work, biochar was synthesized going from bovine bone waste at Vietnam country, called as Vietnamese bone char (VNBC). Many steps of process to VNBC synthesis, and its surface characteristics were investigated, respectively. The applications of VNBC being as adsorbents were examined then. The results of synthesis process were obtained the VNBC product sample with optimal condition to be at temperature of 650 oC, corresponding to 120 minutes. The analysis on surface properties of VNBC indicated that the specific surface area were 120.315 m2/g, with pore diameter as 87.48 Å measured by BJH (Barrett, Joyner and Halenda) method. The surface morphology with the particle size measured by SEM (Scanning Electronic Spectroscopy) method was 70 nm. The composition compounds of VNBC contained calcium carbonate-hydroxyl apatite with the formula was Ca10(PO4)5.65(CO3)0.64(OH)3.45 measured by FT-IR (Fourier Transform Infrared Spectroscopy) and XRD (X-Ray Diffraction Spectroscopy) methods, respectively. In application, VNBC uses at optimal condition as an adsorbent to remove the organic color solutions for instance KMnO4 and methylene blue (MB) were considered. The results of VNBC adsorbent to remove the colored solutions measured by UV/VIS (Ultraviolet Visible spectroscopy) method are obtained with adsorption capacity of KMnO4 as from 33.51 to 46.22 mg color/g BC, and MB from 12.1 to 15.04 mg color/g BC, respectively. These results shown that VNBC were able to use making a potential adsorbent in the treatment of wastewater contained organic color in industry.

Production of composite membrane from waste Kappa-Carrageenan and Tilapia (Oreochromis niloticus) fishbone

Kappa-Carrageenan has been widely used as a gelling agent and stabilizer in the food industry. This research is an application of Kappa Carrageenan as polymer membrane with the combination of Hydroxyl Apatite obtained from the fishbone. Different weight percentages of K-Carrageenan and Fishbone were mixed to make a filtering media with the use of Glutaraldehyde as a crosslinking agent. Before the crosslinking, K carrageenan were pretreated with monochloroacetic acid, ethanol and sodium hydroxide to become an alkali-based solution that will be readily mixed with the hydroxyl apatite. Fishbone were converted to hydroxyl apatite through subjection in a high temperature dryer. Polymer membrane were characterized by evaluating its mechanical and physical properties such as elastic resistance, water permeability and mean pore size diameter with the use of force gauge, filtration due to gravity and scanned electron microscopy respectively. Based from the evaluation, composite with 60% KCarrageenan-40% Fishbone displayed the most feasible characteristic of a filtering media such as its mechanical strength and water permeability. Composite with 80% KCarrageenan-20% Fishbone has the smallest pore size in which a good characteristic also of a filtering media.