No abstract
A family of hydroxyapatite (HAP)-filled chitosan (CHI)-poly(acrylic acid) (PAA) polyelectrolyte complexes was prepared for the development of a degradable biocompatible organic matrix with nascent HAP that will degrade in vivo over a period of time. The effects of complexation on the degradation profile of the composites as well as the interaction between the CHI-PAA matrix and HAP in the composite system were evaluated by studying the swelling behavior of these composites in phosphatebuffered saline (PBS) by varying their CHI-PAA ratio and HAP content. All composite systems showed a general trend of three stages of swelling with the variation in the degree of equilibrium swelling. The percentage weight gain initially decreased in a linear way with increases in the HAP weight percentages, leading to a first equilibrium swelling, represented by the plateau; further increased to a greater extent; and finally stabilized. The CHI/PAA/HAP composites were stable in PBS up to a period of more than 45 days whereas the 50/50 CHI/PAA control sample showed a single equilibrium attained after a period of 288 h. Further exposure of the specimen to the medium led to its disintegration. It was also observed that, even though CHI and PAA were capable of binding HAP, because of the lack of efficient binding, the integrity of the CHI-HAP and PAA-HAP composites were lost within 48 h. The 50/50/80 CHI/PAA/HAP composition showed the minimum amount of swelling in the series.
The suitability of calcium phosphate crystals for thermoluminescence dosimetry (TLD) applications is investigated, owing to their equivalence to bone mineral. The α and β phases of tricalcium phosphate (TCP) were synthesized through wet precipitation and high temperature solid state routes and doped with Dy and Eu. The photoluminescence and thermoluminescence studies of the phosphors have been carried out.The TL properties were found to be highly dependent on the method of preparation of the material. Eu doping gave good PL emission, whereas Dy doping was more efficient in TL emission. β-TCP was found to be less TL sensitive than α-TCP, yet it was identified as a better phosphor material owing to its better fading characteristics.The dependence of TL of β-TCP : Dy on the energy and dose of radiation, and on the doping concentration were studied. The TL intensity was observed to fade exponentially during a storage period of 20 days, but it stabilized at 70% of the initial value after 30 days. The optimum doping concentration was found to be 0⋅5 mol%.
Hyperthermia is a promising cancer therapy due to its minimally-invasive procedure, and the cancer therapeutic efficacy can be improved by magnetic hyperthermia combined with pharamacotherapy. Iron oxide (IO) nanoparticle is a popular medium for hyperthermia treatment, and hydroxyapatite (HA) has been widely used for bone filling and augmentation. IO nanoparticle embedded on hydroxyapatite (HAIO) was synthesized through co-precipitation method, and chitosan or poly (N-isopropylacrylamide) (PNIPAAM) were coated on the HAIO with calcium alginate to form the spheres (Chitosan coated HAIO and PNIPAAM coated HAIO). HAIO, Chitosan coated HAIO and PNIPAAM coated HAIO were used as carriers of 5-fluorouracil (5-FU), one of the drugs for cancer chemical therapy, and the 5-FU release behavior in PBS solution was investigate at ambient and elevated temperatures. The amount of the released 5-FU from the HAIO, Chitosan coated HAIO and PNIPAAM coated HAIO are almost the same at ambient temperature. But at elevated temperature, that from Chitosan coated HAIO was reduced while that from the PNIPAAM coated HAIO was increased.
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