Influence of varying thermal treatment on bioactive material with equal Ca/P ratio: A local drug delivery system for bone regeneration

Abstract

Designing a biomaterial with excellent bioactivity, biocompatibility, mechanical strength, porosity, and osteogenic properties is essential to incorporate therapeutic agents in order to promote efficient bone regeneration. The work intended to prepare bioactive glass with tailor-made equal Ca/P (CP) ratio to obtain clinophosinaite (Cpt) as dominant phase. Clinophosinaite (Na 3 CaPSiO 7 ) is one of the rarest phases of bioactive glass (BG), which is supposed to play key role in bioactivity. The novelty of this work is to track the required sintering temperature to attain equimolar calcium phosphate-containing clinophosinaite phase and its behavior. Further, its consequent physicochemical and biological properties were analyzed. Phase transition from Rhenanite to Cpt, and later the Cpt emerged as dominant phase with increase of calcination temperature from 700 to 1000 C was studied. The quantifying evolution of Cpt with Rhenanite over increasing annealing temperature also results with the major morphological modifications. BET analysis confirmed the surface area and porosity (Type-IV mesoporous) were gradually elevated upto 900 C, which had contrary effect on mechanical strength. Formation of hydroxyl carbonate apatite (HCA) layer confirmed the bioactivity of the prepared samples at varying time intervals. The CP samples demonstrated better hemocompatibility in post-immersion (i.e., less than 1% of lysis) when compared with pre-immersion. Enhanced protein adsorption and cumulative release (85%) of Simvastatin (SIM) drug was attained at 900 C treatment.

Devitrite (Na2Ca3Si6O16) phase dominated nanostructured 45S5 bioactive glass: exploring its structural and biological properties

“…The variations in sintering conditions appear to impact both the structural and surface properties of the bioglass nanostructured material. Krishnamoorthy et al [28] have discussed an interesting phenomenon observed in the context of BG, which is similar to what occurs in other vitreous systems. This phenomenon is related to changes in the material's surface area during the sintering process at higher temperatures.…”

“…In relation to cell viability and proliferation, the increased cell viability can be attributed to compressive strain and BG stabilization at lower sintering temperatures. Thus, a comprehensive mechanical analysis would provide valuable insights into the interplay between enhancing material properties, sintering conditions, and cellular behaviour [30].…”

“…It states that, the material is hemocompatible, if the hemolysis percentage in the presence of a biomaterial is less than 5%. Additionally, nonhemolysis is known by its hemolysis per cent from 0 to 2%, while slight hemolysis is occurred from 2% to 5% [28,31]. The compatibility of 45S5 BGs at 900 BG, 1000 BG-1, 2, and 3 with erythrocytes was examined.…”

“…The emergence of the HCA layer which began on the 3rd day as a result of calcium and phosphate ions release. Krishnamoorthy et al specified that, the peak intensity for the formation of amorphous calcium phosphate increased steadily with longer hours of incubation and calcination temperature [28]. HCA exhibits characteristics peaks due to the carbonate ions into the apatite crystal lattice.…”

“…The 45S5 BG can be loaded with drugs to provide localized drug delivery to the site of implantation, which can improve the efficacy of the therapy and reduce the side effects associated with systemic drug administration [36]. SIM is a commonly used drug for treating hypercholesterolemia, and it has been shown to have beneficial effects on bone regeneration [28]. Figure 15 shows, the drug release of SIM loaded 900 BG, 1000BG-1, 2 and 3 BGs were monitored using UV-Vis spectroscopy in PBS at 37 • C. The release profile for all BGs determines the rate of drug release remains constant throughout the release period with zero order release kinetics.…”