Synthesis of novel nanostructured bredigite-amoxicillin scaffolds for bone defect treatment: cytocompatibility and antibacterial activity

Bone infections in human beings are an essentially destructive problem with crucial clinical and economic effects; thus, incorporation of antibiotics such as amoxicillin (AMX) into the scaffold was developed as an effective treatment for bone infections. In this respect, we develop new nanostructured bredigite (Bre; Ca7MgSi4O16)–amoxicillin (AMX; α-amino-hydroxybenzyl-penicillin) scaffolds containing different concentrations of amoxicillin (0, 3, 5, and 10%) by using space holder method to assure bactericidal properties. The result depicted that the Bre–AMX scaffolds possess porosity of 80–82% with high compressive strength of 1.2–1.4 MPa and controlled antibiotic release for prevention of infection. Bre–(3–10%)AMX scaffolds were able to destroy Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) bacteria, as well as effectively inhibit the growth of bacterial cells; in addition, the antibacterial activity of the AMX-loaded scaffolds augmented with the increase of the AMX concentration. Sustained drug release was detected from Bre–AMX scaffolds accompanied by initial burst release of 20% for 8 h, followed by a sustained release, which is favorable for bone infection treatment. These new Bre–(3–5%)AMX scaffolds possess excellent mechanical properties and antibacterial activity with no cytotoxicity suggested as an appropriate alternative for bone infection treatment

Fabrication, degradation behavior and cytotoxicity of nanostructured hardystonite and titania/hardystonite coatings on Mg alloys

In this study, nanostructured hardystonite (HT) and titania (TiO2)/hardystonite (HT) dual-layered coatings were deposited on biodegradable Mg-Ca-Zn alloy via physical vapor deposition (PVD) combined with electrophoretic deposition (EPD). Although a single layer nano-HT coating can decrease the corrosion rate from 1.68 to 1.02 mm/year, due to the presence of porosities and microcracks, the nano-HT layer cannot sufficiently protect the Mg substrate. In contrast, the corrosion resistance of nano-HT coating is further improved by using nano-TiO2 underlayer since it was a smooth, very uniform and compact layer with higher contact angle (52.30°). In addition, the MTT assay showed the viability of MC3T3-E1 on the nano-HT and nano-TiO2/HT coatings. The results demonstrated that the two-step surface modification improved both corrosion resistance and the cytocompatibility of the Mg alloy, hence making it feasible for orthopedic applications

Novel nanostructured baghdadite-vancomycin scaffolds: in-vitro drug release, antibacterial activity and biocompatibility

One of the most important therapeutic and economic concerns regarding surgery, is the occurrence of post-operative infections which leads to an increase in premature failure rate. Therefore, novel nanostructured baghdadite-vancomycin (Ba-Vac) scaffolds were prepared using the space holder method with good mechanical properties and controlled drug release to inhibit post-surgery infections. The results showed that the (Ba-Vac) scaffolds were attained with the pore size of 300–400 µm and total porosity of 80–82% with compressive strength of 0.86–0.88 MPa. In drug release profiles, a burst release was observed for 6 h, followed by a sustained release. Ba-Vac scaffolds presented good antibacterial activity toward Staphylococcus aureus (S. aureus). More attachment and spreading of MG-63 osteoblast cells on the Ba and Ba-(1-3 wt%)Vac scaffolds was also observed in comparison with the Ba-5 wt%Vac scaffold. Therefore, the Ba-(1–3 wt%)Vac scaffold is a good candidate for inhibiting post-surgery infections, as well as for bone tissue engineering

A new multifunctional monticellite-ciprofloxacin scaffold: preparation, bioactivity, biocompatibility, and antibacterial properties

This work prepared novel monticellite-ciprofloxacin (Mon-CPFX) scaffolds with different concentrations of CPFX (0, 1, 3, and 6%) via the space holder method. The Mon-CPFX scaffolds had a compressive strength of 1 ± 0.1 MPa, porosity of 81–83%, and pore size of 300–420 μm. The formation of hydroxyapatite on the Mon-CPFX scaffold surfaces was observed after soaking in simulated body fluid (SBF) solution for 28 d, with a Ca/P atomic ratio of 1.62 indicating high apatite formation ability. Antibacterial tests indicated the antibacterial effect of Mon-CPFX scaffolds is strongly related to the CPFX concentration; the greatest bacterial inhibition was observed for the scaffold containing 6% CPFX. Furthermore, an MTT assay illustrated that Mon scaffold loading with up to 3% CPFX resulted in higher cell viability, cell proliferation, and attachment than for scaffolds containing 6% CPFX. This particular novel type of multifunctional Mon-CPFX scaffold could be considered for bone infection treatment owing to its suitable compressive strength along with excellent bioactivity, antibacterial performance, and biocompatibility

Synthesis of a novel nanostructured zinc oxide/baghdadite coating on Mg alloy for biomedical application: In-vitro degradation behavior and antibacterial activities

In this research, zinc oxide (ZnO) and zinc oxide/baghdadite (ZnO/Ca3ZrSi2O9) were prepared on the surface of Mg alloy using physical vapor deposition (PVD) coupled with electrophoretic deposition (EPD). For this purpose, the nanostructured ZnO was prepared with a thickness of 900 nm and crystallite sizes of 64 nm as under layer while nanostructured baghdadite with a thickness of 10 µm was deposited on the Mg alloy substrate as an over-layer. Electrochemical measurement exhibited that the ZnO/Ca3ZrSi2O9-coated specimen has a higher corrosion resistance and superior stability in simulated body fluid (SBF) solution in comparison with the ZnO-coated and bare Mg alloy samples. Antibacterial activities of the uncoated and coated specimens were evaluated against various pathogenic species (Escherichia coli, Klebsiella pneumoniae, and Shigella dysenteriae) via disc diffusion method. The obtained results showed that ZnO and ZnO/Ca3ZrSi2O9 coatings have great zones of inhibition (ZOI) against E. coli, Klebsiella, and Shigella. However, less ZOI was found around the bare Mg alloy. Therefore, ZnO/Ca3ZrSi2O9 is a promising coating for orthopedic applications of biodegradable Mg alloys considering its excellent antibacterial activities and high corrosion resistance

Graphene oxide encapsulated forsterite scaffolds to improve mechanical properties and antibacterial behavior

It is very desirable to have good antibacterial properties and mechanical properties at the same time for bone scaffolds. Graphene oxide (GO) can increase the mechanical properties and antibacterial performance, while forsterite (Mg2SiO4) as the matrix can increase forsterite/GO scaffolds' biological activity for bone tissue engineering. Interconnected porous forsterite scaffolds were developed by space holder processes for bone tissue engineering in this research. The forsterite/GO scaffolds had a porosity of 76%-78% with pore size of 300-450 µm. The mechanism of the mechanical strengthening, antibacterial activity, and cellular function of the forsterite/GO scaffold was evaluated. The findings show that the compressive strength of forsterite/1 wt.% GO scaffold (2.4 ± 0.1 MPa) was significantly increased, in comparison to forsterite scaffolds without GO (1.4 ± 0.1 MPa). Validation of the samples' bioactivity was attained by forming a hydroxyapatite layer on the forsterite/GO surface within in vitro immersion test. The results of cell viability demonstrated that synthesized forsterite scaffolds with low GO did not show cytotoxicity and enhanced cell proliferation. Antibacterial tests showed that the antibacterial influence of forsterite/GO scaffold was strongly correlated with GO concentration from 0.5 to 2 wt.%. The scaffold encapsulated with 2 wt.% GO had the great antibacterial performance with bacterial inhibition rate around 90%. As results show, the produced forsterite/1 wt.% GO can be an attractive option for bone tissue engineering

Antibacterial Activity and Cell Responses of Vancomycin-Loaded Alginate Coating on ZSM-5 Scaffold for Bone Tissue Engineering Applications

Despite the significant advancement in bone tissue engineering, it is still challenging to find a desired scaffold with suitable mechanical and biological properties, efficient bone formation in the defect area, and antibacterial resistivity. In this study, the zeolite (ZSM-5) scaffold was developed using the space holder method, and a novel vancomycin-loaded alginate coating was developed on it to promote their characteristics. Our results demonstrated the importance of alginate coating on the microstructure, mechanical, and cellular properties of the ZSM-5 scaffold. For instance, a three-fold increase in the compressive strength of coated scaffolds was observed compared to the uncoated ZSM-5. After the incorporation of vancomycin into the alginate coating, the scaffold revealed significant antibacterial activity against Staphylococcus aureus (S. aureus). The inhibition zone increased to 35 mm. Resets also demonstrated 74 ± 2.5% porosity, 4.3 ± 0.07 MPa strength in compressive conditions, acceptable cellular properties (72.3 ± 0.2 (%control) cell viability) after 7 days, good cell attachment, and calcium deposition. Overall, the results revealed that this scaffold could be a great candidate for bone tissue engineering

Characterization and biological properties of nanostructured clinoenstatite scaffolds for bone tissue engineering applications

With the enhancement of bone-tissue regeneration technologies, there is an increment request for perfect bio-ceramic scaffolds with multifunctional properties, including high mechanical strength as well as biological and controlled drug-release potential. In the present work, extremely porous clinoenstatite (CLEN; MgSiO3) scaffolds with different micropore sizes and great interconnectivity were fabricated for the first time via the space holder method and subsequent sintering. The NaCl particle size escalation as spacer results in an increase of the pore size and interconnectivity and reduction of the compressive strength. According to the results, nanostructured CLEN scaffolds contain pore sizes in the range of ~450–650 µm and porosity more than ~77–81%, which offered greater compressive strength (0.9 MPa) in comparison with the other CLEN scaffolds. Favorable burst release was noticed throughout the first 8 h, and right after the early burst, the dose was progressively reduced until 35 h, and subsequently, a sustained release was noticed. In vitro examinations verified the antimicrobial performance of the metronidazole (MTZ)-embedded CLEN scaffolds towards the Fusobacterium nucleatum (Fn) and Aggregatibacter actinomycetemcomitans (Aa) bacteria. In this context, the antibacterial performance is enhanced with escalating MTZ loading into scaffolds, which is directly linked with the increase of MTZ concentration. The results exhibited that both CLEN and MTZ-embedded CLEN scaffolds presented apatite formation capability in SBF. The biological test showed that the MG63 cell adhesion and proliferation on the CLEN scaffold were comparable with their counterpart loaded with low MTZ concentration. Also, the scaffold's ALP activity with low MTZ concentration was considerably greater than that of the scaffold with high MTZ concentration. The results presented here demonstrate that the fabricated CLEN scaffold with 1–3 wt% MTZ concentration has a great potential to be utilized as a bone repair material for tissue engineering applications