Modified Sol–Gel Synthesis of Mesoporous Borate Bioactive Glasses for Potential Use in Wound Healing

Microwave-assisted fabrication of nanostructured borate bioactive glass and its bioactivity

Sol-gel bioactive glass with nanocrystalline structures has demonstrated enhanced bioactivity and acceptance by the surrounding bone tissue. In particular, borate bioactive glasses exhibit higher reactivity and apatite formation under the simulated in vitro and in vivo conditions. This study presents a microwave-assisted synthesis of borate bioactive glass (58S) and an understanding of its structural and in vitro bioactivity. By this synthesis method, the nanocrystalline structures formed within the amorphous matrix will regulate the degradation rate of the glass network during apatite formation. The calcinated borate bioactive glass features a nanorod crystalline hydroxyapatite structure embedded in the amorphous borate glass network. The formation of apatite on the surface of borate bioactive glass within 6 hours of immersion in simulated body fluid confirms the material's enhanced bioactivity and reactivity. Anti-oxidant studies, cell viability, and alkaline phosphate activity further corroborate the bioactivity of borate bioactive glass. In summary, this study highlights the significant potential of microwave-synthesized borate bioactive glass for a wide range of bone tissue engineering applications.

Investigation of Osteomyelitis Inducing Methicillin-Resistant Staphylococcus aureus Inhibition Effect by Strontium-Substituted Borate Bioactive Glasses

Borate glass transforms into hydroxycarbonate apatite more rapidly than silicate glass. This research aims to evaluate strontium's structural and biological effects on borate bioactive glass (BBG) and the influence of strontium concentrations (0%, 5%, 10%, and 15% Sr) prepared via the sol-gel method. The study reveals significant findings related to the physicochemical properties of the glass. Immersion of the glass powders in a simulated body fluid (SBF) led to the development of a hydroxyapatite (HAP) layer on the glass surfaces. This transformation was verified through X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) analyses. In particular, 5% strontium exhibited gradual degradation, resulting in particle sizes below 100 nm. The BBG-15%Sr demonstrates heightened pathogenic activity as it shows a significant inhibition zone of 14 mm at 250 μg/mL, surpassing other substituted BBGs. It effectively combats Gram-positive bacteria, completely inhibiting MRSA growth at 50 μg/mL. This underscores its robust biofilm disruption capabilities, eradicating biofilms, even at minimal concentrations after prolonged exposure. C. elegans when subjected to BBG-15%Sr shows less ROS production when compared with the others. Moreover, the results suggest that the modified glass could be a potential material for the treatment of osteomyelitis-affected bone repair.

Sol-gel derived B2O3-CaO borate bioactive glasses with hemostatic, antibacterial and pro-angiogenic activities

Sol-gel borate bioactive glasses (BGs) are promising ion-releasing biomaterials for wound healing applications. Here, we report the synthesis of a series of binary B2O3-CaO borate BGs (CaO ranging from 50 to 90 mol%) using a sol-gel-based method. The influence of CaO content in B2O3-CaO borate BG on morphology, structure and ion release behavior was investigated in detail. Reduced dissolution (ion release) and crystallization could be observed in borate BGs when CaO content increased, while the morphology was not significantly altered by increasing CaO content. Our results evidenced that the ion release behavior of borate BGs could be tailored by tuning the B2O3/CaO molar ratio. We also evaluated the in vitro cytotoxicity, hemostatic, antibacterial and angiogenic activities of borate BGs. Cytocompatibility was validated for all borate BGs. However, borate BGs exhibited composition-dependent hemostatic, antibacterial and angiogenic activities. Generally, higher contents of Ca in borate BGs facilitated hemostatic activity, while higher contents of B2O3 were beneficial for pro-angiogenic activity. The synthesized sol-gel-derived borate BGs are promising materials for developing advanced wound healing dressings, given their fast ion release behavior and favorable hemostatic, antibacterial and angiogenic activities.

A 3D-Printed Wound-Healing Material Composed of Alginate Dialdehyde-Gelatin Incorporating Astaxanthin and Borate Bioactive Glass Microparticles

In this study, a wound dressing composed of an alginate dialdehyde-gelatin (ADA-GEL) hydrogel incorporated by astaxanthin (ASX) and 70B (70:30 B₂O₃/CaO in mol %) borate bioactive glass (BBG) microparticles was developed through 3D printing. ASX and BBG particles stiffened the composite hydrogel construct and delayed its in vitro degradation compared to the pristine hydrogel construct, mainly due to their cross-linking role, likely arising from hydrogen bonding between the ASX/BBG particles and ADA-GEL chains. Additionally, the composite hydrogel construct could hold and deliver ASX steadily. The composite hydrogel constructs codelivered biologically active ions (Ca and B) and ASX, which should lead to a faster, more effective wound-healing process. As shown through in vitro tests, the ASX-containing composite hydrogel promoted fibroblast (NIH 3T3) cell adhesion, proliferation, and vascular endothelial growth factor expression, as well as keratinocyte (HaCaT) migration, thanks to the antioxidant activity of ASX, the release of cell-supportive Ca²⁺ and B³⁺ ions, and the biocompatibility of ADA-GEL. Taken together, the results show that the ADA-GEL/BBG/ASX composite is an attractive biomaterial to develop multipurposed wound-healing constructs through 3D printing.

Zinc- and Copper-Doped Mesoporous Borate Bioactive Glasses: Promising Additives for Potential Use in Skin Wound Healing Applications

In this study, zinc (Zn)- and copper (Cu)-doped 13-93B3 borate mesoporous bioactive glasses (MBGs) were successfully synthesized using nitrate precursors in the presence of Pluronic P123. We benefited from computational approaches for predicting and confirming the experimental findings. The changes in the dynamic surface tension (SFT) of simulated body fluid (SBF) were investigated using the Du Noüy ring method to shed light on the mineralization process of hydroxyapatite (HAp) on the glass surface. The obtained MBGs were in a glassy state before incubation in SBF. The formation of an apatite-like layer on the SBF-incubated borate glasses was investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The incorporation of Zn and Cu into the basic composition of 13-93B3 glass led to changes in the glass transition temperature (Tg) (773 to 556 °C), particle size (373 to 64 nm), zeta potential (−12 to −26 mV), and specific surface area (SBET) (54 to 123 m2/g). Based on the K-means algorithm and chi-square automatic interaction detection (CHAID) tree, we found that the SFT of SBF is an important factor for the prediction and confirmation of the HAp mineralization process on the glasses. Furthermore, we proposed a simple calculation, based on SFT variation, to quantify the bioactivity of MBGs. The doped and dopant-free borate MBGs could enhance the proliferation of mouse fibroblast L929 cells at a concentration of 0.5 mg/mL. These glasses also induced very low hemolysis (<5%), confirming good compatibility with red blood cells. The results of the antibacterial test revealed that all the samples could significantly decrease the viability of Pseudomonas aeruginosa. In summary, we showed that Cu-/Zn-doped borate MBGs can be fabricated using a cost-effective method and also show promise for wound healing/skin tissue engineering applications, as especially supported by the cell test with fibroblasts, good compatibility with blood, and antibacterial properties.