Well-Ordered Mesoporous Silica and Bioactive Glasses: Promise 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

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

A systematic review on peripheral blood-derived mesenchymal stem cells as a therapy for cartilage repair

Comprehensive analysis showed that the popularity of research peripheral blood-derived mesenchymal stem cells for knee cartilage repair is still lacking, as they peripherally exist at a very low level. Despite its small cell number, peripheral blood is yet one of the most convenient sources of mesenchymal stem cells due to its less invasive method to harvest. This study aimed to systematically review the current evidence of peripheral blood-derived mesenchymal stem cells towards the repair of articular cartilage defect. A comprehensive literature search was performed to identify all in vivo studies reporting the structural outcome of articular cartilage repair in the knee following electronic databases: PubMed, WOS and SCOPUS. The in vitro characterizations of peripheral blood-derived mesenchymal stem cells were evaluated to enable quality assessment. Literature from 1934 to 2019 showed 4822 of total articles with only three findings related to pre-clinical studies were included in the analysis. The selection of animal model, type of transplantation, mobilization of the peripheral blood, in vitro culture condition, type of scaffold, assessments on the cartilage defect, and the outcome measures were heterogeneous. Evidence showed that mobilized peripheral blood-derived mesenchymal stem cells were more superior in repairing articular cartilage compared to those that were non-mobilized. These cells also showed a comparable capability in repairing articular cartilage than the commonly used bone marrow mesenchymal stem cells. Overall, more progress is needed to expand the usage of peripheral blood-derived mesenchymal stem cells from basic biological science to the translational studies in clinical practice

Hydrothermal Synthesis and Characterisation of Bioactive Glass-Ceramic Nanorods

In this study fabrication of rod-like bioactive glass-ceramics (BGCs) using hydrothermal treatment based on a sol-gel precursor is reported for the first time. BGCs with composition 58 wt% SiO2, 33 wt% CaO and 9 wt% P2O5 were synthesized in different thermal conditions (200 and 220 °C) and characterised with regard to morphology, chemical composition and crystallinity. The bioactivity of the materials was assessed by immersion in simulated body fluid for up to 7 days. The results revealed that as the reaction temperature increased from 200 to 220 °C, the diameter of rods was reduced from microscale to nanoscale and the crystallinity was enhanced. It was also found that the BGC nanorods have higher surface area and consequently enhanced bioactivity than BGC microrods. This technique provides a facile method for rapid production of BGC nanorods at relatively low temperature which may have the potential to be used as bioactive composite reinforcement or for bone grafting applications

Linear and nonlinear analysis of normal and CAD-affected heart rate signals

Coronary Artery Disease (CAD) is one of the dangerous cardiac disease, often may lead to sudden cardiac death. It is difficult to diagnose CAD by manual inspection of electrocardiogram (ECG) signals. To automate this detection task, in this study, we extracted the Heart Rate (HR) from the ECG signals and used them as base signal for further analysis. We then analyzed the HR signals of both normal and CAD subjects using (i) time domain, (ii) frequency domain and (iii) nonlinear techniques. The following are the nonlinear methods that were used in this work: Poincare plots, Recurrence Quantification Analysis (RQA) parameters, Shannon entropy, Approximate Entropy (ApEn), Sample Entropy (SampEn), Higher Order Spectra (HOS) methods, Detrended Fluctuation Analysis (DFA), Empirical Mode Decomposition (EMD), Cumulants, and Correlation Dimension. As a result of the analysis, we present unique recurrence, Poincare and HOS plots for normal and CAD subjects. We have also observed significant variations in the range of these features with respect to normal and CAD classes, and have presented the same in this paper. We found that the RQA parameters were higher for CAD subjects indicating more rhythm. Since the activity of CAD subjects is less, similar signal patterns repeat more frequently compared to the normal subjects. The entropy based parameters, ApEn and SampEn, are lower for CAD subjects indicating lower entropy (less activity due to impairment) for CAD. Almost all HOS parameters showed higher values for the CAD group, indicating the presence of higher frequency content in the CAD signals. Thus, our study provides a deep insight into how such nonlinear features could be exploited to effectively and reliably detect the presence of CAD

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

Fabrication and Characterization of Poly(Octanediol Citrate)/gallium-Containing Bioglass Microcomposite Scaffolds

Bone can be affected by osteosarcomae requiring surgical excision of the tumor as part of the treatment regime. Complete removal of cancerous cells is difficult and conventionally requires the removal of a margin of safety around the tumor to offer improved patient prognosis. This work considers a novel series of composite scaffolds based on poly (octanediol citrate) (POC) impregnated with gallium-based bioglass microparticles for possible incorporation into bone following tumor removal. The objective of this research was to fabricate and characterize these scaffolds and subsequently report on their mechanical and biological properties. The porous micro composite scaffolds with various concentrations of bio glass (10, 20, 30 wt%) incorporated were fabricated using a salt leaching technique. The scaffolds exhibited compression modulus in the range of 0.3–7 MPa. The addition of bio glass increased the mechanical properties even though porosity increased. Furthermore, increasing the concentration of bio glass had a significant influence on glass transition temperature from 2.5 °C for the pure polymer to around 25 °C for 30 % bio glass-containing composite. The ion release study revealed that composites containing 10 % bio glass had the highest ion release ratio after 28 days of soaking in phosphate buffered saline. The interaction of bio glass phase with POC led to the formation of additional ionic crosslinks aside from covalent crosslinks which further resulted in increased stiffness and decreased weight loss. The osteoblast cells were well attached and growth on composites and collagen synthesis increased particularly with the 10 % bio glass concentration

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 \u3e79% 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