Sara Pourshahrestani

Bioactive glass reinforced elastomer composites for skeletal regeneration: A review.

Biodegradable elastomers have clinical applicability due to their biocompatibility, tunable degradation and elasticity. The addition of bioactive glasses to these elastomers can impart mechanical properties sufficient for hard tissue replacement. Hence, a composite with a biodegradable polymer matrix and a bioglass filler can offer a method of augmenting existing tissue. This article reviews the applications of such composites for skeletal augmentation.

Inorganic hemostats: The state-of-the-art and recent advances.

Hemorrhage is the most common cause of death both in hospitals and on the battlefield. The need for an effective hemostatic agent remains, since all injuries are not amenable to tourniquet use. There are many topical hemostatic agents and dressings available to control severe bleeding. This article reviews the most commonly used inorganic hemostats, subcategorized as zeolite and clay-based hemostats. Their hemostatic functions as well as their structural properties that are believed to induce hemostasis are discussed. The most important findings from in vitro and in vivo experiments are also covered.

Gallium-containing mesoporous bioactive glass with potent hemostatic activity and antibacterial efficacy

Haemorrhage remains the leading cause of potentially survivable death in both military and civilian populations. Although a large variety of hemostatic agents have been developed, many of them have an inadequate capacity to induce hemostasis and are not effective in killing bacteria. In recent years, mesoporous bioactive glasses (MBGs) were found to be effective in inducing hemostasis. However, the materials may not be considered as ideal hemostats since they do not offer antimicrobial activity. The gallium ion (Ga+3) not only exhibits antibacterial properties but also accelerates the blood coagulation cascade. The aim of this study was to develop MBGs containing various concentrations of Ga2O3 (1, 2 & 3 mol%) via the evaporation-induced self-assembly (EISA) process and investigate whether the addition of Ga3+ would induce both hemostatic and antibacterial effects. The results indicated that the incorporation of lower Ga2O3 content (1 mol%) into the MBG system improved structural properties including the specific surface area, mesopore size and pore volume as well as the release of silicon and calcium ions. The bioactive glass was found to stimulate blood coagulation, platelet adhesion and thrombus generation and exerted an antibacterial effect against both Escherichia coli and Staphylococcus aureus. Likewise, Ga-doped MBGs showed excellent cytocompatibility even after 3 days, with the 1% Ga2O3-containing MBG attaining the best biocompatibility that render them safe hemostatic agents for stopping bleeding. This study demonstrated that the lowest Ga2O3-substituted MBG can be a potent candidate for controlling haemorrhage and wound infection.

Potency and Cytotoxicity of a Novel Gallium-Containing Mesoporous Bioactive Glass/Chitosan Composite Scaffold as Hemostatic Agents

Chitosan-based hemostats are promising candidates for immediate hemorrhage control. However, they have some disadvantages and require further improvement to achieve the desired hemostatic efficiency. Here, a series of 1% Ga2O3-containing mesoporous bioactive glass-chitosan composite scaffolds (Ga-MBG/CHT) were constructed by the lyophilization process and the effect of various concentrations of Ga-MBG (10, 30, and 50 wt %) on the hemostatic function of the CHT scaffold was assessed as compared to that of Celox Rapid gauze (CXR), a current commercially available chitosan-coated hemostatic gauze. The prepared scaffolds exhibited >79% porosity and showed increased water uptake compared to that in CXR. The results of coagulation studies showed that pure CHT and composite scaffolds exhibited increased hemostatic performance with respect to CXR. Furthermore, the composite scaffold with the highest Ga-MBG content (50 wt %) had increased capability to enhancing thrombus generation, blood clotting, and platelet adhesion and aggregation than that of the scaffold made of pure CHT. The antibacterial efficacy and biocompatibility of the prepared scaffolds were also assessed by a time-killing assay and an Alamar Blue assay, respectively. Our results show that the antibacterial effect of 50% Ga-MBG/CHT was more pronounced than that of CHT and CXR. The cell viability results also demonstrated that Ga-MBG/CHT composite scaffolds had good biocompatibility, which facilitates the spreading and proliferation of human dermal fibroblast cells even with 50 wt % Ga-MBG loading. These results suggest that Ga-MBG/CHT scaffolds could be a promising hemostatic candidate for improving hemostasis in critical situations.

Well-ordered mesoporous silica and bioactive glasses: Promises for improved hemostasis

Immediate control of uncontrolled bleeding and infection are essential for saving lives in both combat and civilian arenas. Inorganic well-ordered mesoporous silica and bioactive glasses have recently shown great promise for accelerating hemostasis and infection control. However, to date, there has been no comprehensive report assessing their specific mechanism of action in accelerating the hemostasis process and exerting an antibacterial effect. After providing a brief overview of the hemostasis process, this review presents a critical overview of the recently developed inorganic mesoporous silica and bioactive glass-based materials proposed for hemostatic clinical applications and specifically investigates their unique characteristics that render them applicable for hemostatic applications and preventing infections. This article also identifies promising new research directions that should be undertaken to ascertain the effectiveness of these materials for hemostatic applications.

Development of poly (1, 8-octanediol citrate)/chitosan blend films for tissue engineering applications

Blends of poly (1, 8-octanediol citrate) (POC) and chitosan (CS) were prepared through solution casting technique. Films with different component fractions (POC/CS: 100/0, 90/10, 80/20, 70/30, 60/40, and 0/100) were successfully prepared and characterized for their mechanical, thermal, structural and morphological properties as well as biocompatibility. The incorporation of CS to POC significantly increased tensile strength and elastic modulus and presented limited influences on pH variation which is important to the biocompatibility of biomaterial implants. The assessment of surface topography indicated that blending could enhance and control the surface roughness of the pure films. POC/CS blends well-supported human dermal fibroblast cells attachment and proliferation, and thus can be used for a range of tissue engineering applications.

Comparative efficacy of hemorrhage control of a novel mesoporous bioactive glass versus two commercial hemostats

Mesoporous bioactive glass containing 1% Ga2O3 (1%Ga-MBG) is attractive for hemorrhage control because of its surface chemistry which can promote blood-clotting. The present study compares this proprietary inorganic coagulation accelerator with two commercial hemostats, CeloxTM (CX) and QuikClot Advanced Clotting Sponge PlusTM (ACS+). The results indicate that the number of adherent platelets were higher on the 1%Ga-MBG and CX surfaces than ACS+ whereas a greater contact activation was seen on 1%Ga-MBG and ACS+ surfaces than CX. 1%Ga-MBG not only resulted in larger platelet aggregates and more extensive platelet pseudopodia compared to CX and ACS+ but also significantly accelerated the intrinsic pathways of the clotting cascade. In vitro thrombin generation assays also showed that CX and ACS+ induced low levels of thrombin formation while 1%Ga-MBG had significantly higher values. 1%Ga-MBG formed a larger red blood cell aggregate than both CX and ACS+. Direct exposure of 1%Ga-MBG to fibroblast cells increased cell viability after 3 days relative to CX and ACS+, inferring excellent cytocompatibility. The results of this study promote 1%Ga-MBG as a promising hemostat compared to the commercially available products as it possesses essential factors required for coagulation activation.

Synthesis and Characterization of Supramolecular Elastomers from Polyacids Composed of Vegetable Oils

Supramolecular elastomers were synthesized using vegetable oil materials namely palm acid oil (PAO) and sunflower oil (SFO). The oils were first epoxidized using formic acid and hydrogen peroxide. The epoxidized oils and adipic acid were then reacted to make polyacids, mainly triacid. Finally, diethylenetriamine (DETA) was added to polyacid to yield fatty amide and a polycondensation with urea performed to achieve the desired elastomers. The synthesized materials were characterized by using Fourier Transform Infrared (FTIR), Nuclear Magnetic Resonance (NMR) and Thermogravimetric Analyzer (TGA) in order to determine structure, type of bonding and thermal stability. The spectrums revealed that the synthesized fatty amides are contained amide groups that correctly formed from reaction of amine groups of DETA and acid functionality of polyacids. Moreover, the resulted structures showed the formation of multiple hydrogen-bonding in the elastomers. TGA thermograms clearly indicated good thermal stability of the elastomers to 500 °C.