Antibacterial and Osteogenic Doxycycline Imprinted Bioglass Microspheres to Combat Bone Infection

Currently, postoperative infection is a significant challenge in bone and dental surgical procedures, demanding the exploration of innovative approaches due to the prevalence of antibiotic-resistant bacteria. This study aims to develop a strategy for controlled and smart antibiotic release while accelerating osteogenesis to expedite bone healing. In this regard, temperature-responsive doxycycline (DOX) imprinted bioglass microspheres (BGMs) were synthesized. Following the formation of chitosan-modified BGMs, poly N-isopropylacrylamide (pNIPAm) was used for surface imprinting of DOX. The temperature-responsive molecularly imprinted polymers (MIPs) exhibited pH and temperature dual-responsive adsorption and controlled-release properties for DOX. The temperature-responsive MIP was optimized by investigating the molar ratio of N,N'-methylene bis(acrylamide) (MBA, the cross-linker) to NIPAm. Our results demonstrated that the MIPs showed superior adsorption capacity (96.85 mg/g at 35 °C, pH = 7) than nonimprinted polymers (NIPs) and manifested a favorable selectivity toward DOX. The adsorption behavior of DOX on the MIPs fit well with the Langmuir model and the pseudo-second-order kinetic model. Drug release studies demonstrated a controlled release of DOX due to imprinted cavities, which were fitted with the Korsmeyer-Peppas kinetic model. DOX-imprinted BGMs also revealed comparable antibacterial effects against Staphylococcus aureus and Escherichia coli to the DOX (control). In addition, MIPs promoted viability and osteogenic differentiation of MG63 osteoblast-like cells. Overall, the findings demonstrate the significant potential of DOX-imprinted BGMs for use in bone defects. Nonetheless, further in vitro investigations and subsequent in vivo experiments are warranted to advance this research.

Nanodevices based on mesoporous glass nanoparticles enhanced with zinc and curcumin to fight infection and regenerate bone

Nanotechnology-based approaches are emerging as promising strategies to treat different bone pathologies such as infection, osteoporosis or cancer. To this end, several types of nanoparticles are being investigated, including those based on mesoporous bioactive glasses (MGN) which exhibit exceptional structural and textural properties and whose biological behaviour can be improved by including therapeutic ions in their composition and loading them with biologically active substances. In this study, the bone regeneration capacity and antibacterial properties of MGNs in the SiO2-CaO-P2O5 system were evaluated before and after being supplemented with 2.5% or 4% ZnO and loaded with curcumin. in vitro studies with preosteoblastic cells and mesenchymal stem cells allowed determining the biocompatible MGNs concentrations range. Moreover, the bactericidal effect of MGNs with zinc and curcumin against S. aureus was demonstrated, as a significant reduction of bacterial growth was detected in both planktonic and sessile states and the degradation of a pre-formed bacterial biofilm in the presence of the nanoparticles also occurred. Finally, MC3T3-E1 preosteoblastic cells and S. aureus were co-cultured to investigate competitive colonisation between bacteria and cells in the presence of the MGNs. Preferential colonisation and survival of osteoblasts and effective inhibition of both bacterial adhesion and biofilm formation of S. aureus in the co-culture system were detected. Our study demonstrated the synergistic antibacterial effect of zinc ions combined with curcumin and the enhancement of the bone regeneration characteristics of MGNs containing zinc and curcumin to obtain systems capable of simultaneously promoting bone regeneration and controlling infection. STATEMENT OF SIGNIFICANCE: In search of a new approach to regenerate bone and fight infections, a nanodevice based on mesoporous SiO2-CaO-P2O5 glass nanoparticles enriched with Zn2+ ions and loaded with curcumin was designed. This study demonstrates the synergistic effect of the simultaneous presence of zinc ions and curcumin in the nanoparticles that significantly reduces the bacterial growth in planktonic state and is capable to degrade pre-formed S. aureus biofilms whereas the nanosystem exhibits a cytocompatible behaviour in the presence of preosteoblasts and mesenchymal stem cells. Based on these results, the designed nanocarrier represents a promising alternative for the treatment of acute and chronic infections in bone tissues, while avoiding the significant current problem of bacterial resistance to antibiotics.

Preparation and properties of nano silica-based bioactive glass/apatite/sodium alginate composite hydrogel

In this paper, given the lack of osteogenic activity of sodium alginate (SA) hydrogel and to simulate the composition of natural bone, ionic-crosslinking NBG/n-HA/SA hydrogel scaffolds were prepared by using nano bioactive glass (NBG) and nano hydroxyapatite (n-HA) with high bioactivity as composite calcium sources and reinforcement phases, and D-gluconic acid δ-lactone (GDL) as the coagulant. The results showed that the mixture of the precursor forming the network had good injectability and plasticity. When the dosage of GDL was 0.75 g, the gelling time of the composite hydrogel could be regulated within 4-8 min, and the hydrogel had high compressive strength (170-220 kPa), as well. When the mass ratio of calcium source to SA was 1:1, the crosslinking network was relatively uniform with a considerable number of large pores around 40 μm in the structure. In the immersion experiment in vitro, it was found that the composite hydrogel could promote the deposition of bone-like apatite on the material's surface. Meanwhile, the cell experiments in vitro verified that the NBG/n-HA/SA composite hydrogel had good cytocompatibility without cytotoxicity. Moreover, the composite hydrogel could enhance the activity of ALP of mouse bone marrow mesenchymal stem cells, and thus, it had good osteogenic activity.

Ceramic Nanofiber Materials for Wound Healing and Bone Regeneration: A Brief Review

Ceramic nanofibers have been shown to be a new horizon of research in the biomedical area, due to their differentiated morphology, nanoroughness, nanotopography, wettability, bioactivity, and chemical functionalization properties. Therefore, considering the impact caused by the use of these nanofibers, and the fact that there are still limited data available in the literature addressing the ceramic nanofiber application in regenerative medicine, this review article aims to gather the state-of-the-art research concerning these materials, for potential use as a biomaterial for wound healing and bone regeneration, and to analyze their characteristics when considering their application.

A nano approach towards the creation of a biointerface as stimulator of osteogenic differentiation

There is a great need for tissue engineering constructs with the ability to modulate stem cell behavior. The initial adhesion, growth and differentiation of stem cell are a key strategy in bone tissue engineering and it can be controlled through biomaterial-cell interface. Here we engineered a polycaprolactone/gelatin/bioactive glass (PCL/GT/BG) nanocomposite scaffold coated with Fibronectin (FN) as a potential candidate to aid the bone regeneration process by giving cells a temporary template to grow into. For this purpose, initially BG nanoparticles (nBG) of 70 ± 15 nm were synthesized, characterized and then impregnated into PCL/GT matrix to create a nanocomposite fibrous mesh. An optimized structure was selected based on fiber uniformity, diameter, and the mechanical properties. Cell adhesion, growth, and the expression of osteogenic-related genes as a result of FN tethering, through specific surface interactions, was evaluated. Furthermore, the potential of optimized nanofiberous structure as a drug delivery vehicle for the local release of therapeutic agents was studied by using amoxicillin as a model drug. The release profile revealed that around 70% of drug was released in an hour for non-crosslinked fibers (burst release) followed by a gradual release up to 72 h. The release profile was steadier for crosslinked fibers. The scaffold also showed an antibacterial effect against ubiquitous gram-positive Staphylococcus aureus. The current study provides an insight for future researchers who aim to create nanocomposite materials as multifunctional scaffolds for bone tissue engineering applications.

[Effect of bioactive glass pretreatment on the durability of dentin bonding interface]

OBJECTIVE

To study the effect of bioactive glass (BG) on the dentin bond strength and the microleakage of hybrid layer.

METHODS

In the study, 30 dentin planes were prepared from the third molars with no caries and equally assigned to the control group, BG group, and sodium trimetaphosphate (STMP)-polyacrylic acid (PAA)-BG group (S-P-BG group), randomly. After etched with 35% phosphoric acid, the dentin planes of BG group were pretreated with 0.5 g/L BG, and the dentin planes of S-P-BG group were pretreated with 5% STMP, 5% PAA and 0.5 g/L BG. No additional pretreatment was done to the dentin planes of control group. Then the dentin planes were bonded using 3M Single Bond 2 adhesive to 3M Z350XT composite resin, and cut into 0.9 mm×0.9 mm column samples, which were stored at 37 ℃ artificial saliva (AS). After 24 hours, 1 month, and 3 months, the microtensile bond strength test was performed. The data were analyzed using one-way ANOVA and LSD method. The morphology of the bond fracture interface was observed with scanning electron microscope. Other 27 teeth were collected and the enamel layer and roots cut off, with the pulp chamber exposed. 0.1% rhodamine B was added to the 3M Single Bond 2 adhesive, and then the adhesive was applied to complete the bonding procedures as above. The teeth were stored in 37 ℃ AS for 24 hours, 1 month, 3 months, and then 0.1% sodium fluorescein solution was placed in the chambers and stained for 1 hour. Confocal laser scanning microscopy was used to observe the interface morphology and microleakage of the hybrid layer.

RESULTS

At the end of 24 hours and 1 month, there was no significant difference in the microtensile bond strength among the three groups (P>0.05). After 3 months of soaking, the S-P-BG group [(36.91±7.07) MPa] had significantly higher microtensile bond strength than the control group [(32.73±8.06) MPa] (P=0.026); For the control group and the BG group, the microtensile bond strength significantly decreased at the end of 3 months compared with 24 hours (control group: P=0.017, BG group: P=0.01); The microtensile bond strength of S-P-BG group af the end of 3 months had no significant difference in compared with 24 hours [(37.99±7.98) MPa] (P>0.05). Observation of the fracture surface at the 24 hours showed no obvious mineralization in all the three groups. After 1 and 3 months, mineral formation was observed in BG group and S-P-BG group, and no obvious collagen exposure was observed in S-P-BG group. Confocal laser scanning microscopy revealed no obvious differences in the morphology and quantity of the resin tag in the control group, BG group and S-P-BG group. At the end of 24 hours, leakage was found in all the three groups. The microleakage of the control group increased at the end of 3 months, while the microleakage of the BG and S-P-BG groups decreased.

CONCLUSION

BG pretreatment of dentin bonding interface can induce mineralization at the bonding interface and reduce the microleakage of the hybrid layer; pretreating the dentin bonding interface with STMP, PAA and BG may enhance the maintaining of the dentin bonding durability.

Comprehensive Survey on Nanobiomaterials for Bone Tissue Engineering Applications

One of the most important ideas ever produced by the application of materials science to the medical field is the notion of biomaterials. The nanostructured biomaterials play a crucial role in the development of new treatment strategies including not only the replacement of tissues and organs, but also repair and regeneration. They are designed to interact with damaged or injured tissues to induce regeneration, or as a forest for the production of laboratory tissues, so they must be micro-environmentally sensitive. The existing materials have many limitations, including impaired cell attachment, proliferation, and toxicity. Nanotechnology may open new avenues to bone tissue engineering by forming new assemblies similar in size and shape to the existing hierarchical bone structure. Organic and inorganic nanobiomaterials are increasingly used for bone tissue engineering applications because they may allow to overcome some of the current restrictions entailed by bone regeneration methods. This review covers the applications of different organic and inorganic nanobiomaterials in the field of hard tissue engineering.

Strontium-substituted sub-micron bioactive glasses inhibit ostoclastogenesis through suppression of RANKL-induced signaling pathway

Strontium-substituted bioactive glass (Sr-BG) has shown superior performance in bone regeneration. Sr-BG-induced osteogenesis has been extensively studied; however, Sr-BG-mediated osteoclastogenesis and the underlying molecular mechanism remain unclear. It is recognized that the balance of osteogenesis and osteoclastogenesis is closely related to bone repair, and the receptor activators of nuclear factor kappaB ligand (RANKL) signaling pathway plays a key role of in the regulation of osteoclastogenesis. Herein, we studied the potential impact and underling mechanism of strontium-substituted sub-micron bioactive glass (Sr-SBG) on RANKL-induced osteoclast activation and differentiation in vitro. As expected, Sr-SBG inhibited RANKL-mediated osteoclastogenesis significantly with the experimental performance of decreased mature osteoclasts formation and downregulation of osteoclastogenesis-related gene expression. Furthermore, it was found that Sr-SBG might suppress osteoclastogenesis by the combined effect of strontium and silicon released through inhibition of RANKL-induced activation of p38 and NF-κB pathway. These results elaborated the effect of Sr-SBG-based materials on osteoclastogenesis through RANKL-induced downstream pathway and might represent a significant guidance for designing better bone repair materials.

Biomedical applications of natural-based polymers combined with bioactive glass nanoparticles

The combination of natural polymers with nanoparticles allowed the development of functional bioinspired constructs. This review discusses the composition, design, and applications of bioinspired nanocomposite constructs based on bioactive glass nanoparticles (BGNPs).

Strontium-Substituted Submicrometer Bioactive Glasses Modulate Macrophage Responses for Improved Bone Regeneration

Host immune response induced by foreign bone biomaterials plays an important role in determining their fate after implantation. Hence, it is well worth designing advanced bone substitute materials with beneficial immunomodulatory properties to modulate the host-material interactions. Bioactive glasses (BG), with excellent osteoconductivity and osteoinductivity, are regarded as important biomaterials in the field of bone regeneration. In order to explore a novel BG-based osteoimmunomodulatory implant with the capacity of potentially enhancing bone regeneration, it is a possible way to regulate the local immune microenvironment through manipulating macrophage polarization. In this study, strontium-substituted submicrometer bioactive glass (Sr-SBG) was prepared as an osteoimmunomodulatory bone repair material. To investigate whether the incorporation of Sr into SBG could synergistically improve osteogenesis by altering macrophage response, we systematically evaluated the interaction between Sr-SBG and macrophage during the process of bone regeneration by in vitro biological evaluation and in vivo histological assessment. It was found that the Sr-SBG modulates proper inflammatory status, leading to enhanced osteogenesis of mouse mesenchymal stem cells (mMSCs) and suppressed osteoclastogenesis of RAW 264.7 cells compared to SBG without strontium substitution. In vivo study confirmed that Sr-SBG initiated a less severe immune response and had an improved effect on bone regeneration than SBG, which corresponded with the in vitro evaluation. In conclusion, these findings suggested that Sr-SBG could be a promising immunomodulatory bone repair material designed for improved bone regeneration.

Bioactive Glass Nanoparticles: From Synthesis to Materials Design for Biomedical Applications

Thanks to their high biocompatibility and bioactivity, bioactive glasses are very promising materials for soft and hard tissue repair and engineering. Because bioactivity and specific surface area intrinsically linked, the last decade has seen a focus on the development of highly porous and/or nano-sized materials. This review emphasizes the synthesis of bioactive glass nanoparticles and materials design strategies. The first part comprehensively covers mainly soft chemistry processes, which aim to obtain dispersible and monodispersed nanoparticles. The second part discusses the use of bioactive glass nanoparticles for medical applications, highlighting the design of materials. Mesoporous nanoparticles for drug delivery, injectable systems and scaffolds consisting of bioactive glass nanoparticles dispersed in a polymer, implant coatings and particle dispersions will be presented.

Thermal-based regulation on biomineralization and biological properties of bioglass nanoparticles decorated PAN-based carbon nanofibers

The mechanism and model for biomineralization behavior and cell culture of CNF/BG sintered at various temperatures.

High mechanical strength bioactive wollastonite bioceramics sintered from nanofibers

The high mechanical strength bioactive wollastonite bioceramics were successfully fabricated via pressureless sintering using nanofibers as raw materials.