Antibacterial, drug delivery, and osteoinduction abilities of bioglass/chitosan scaffolds for dental applications

Porous Poly(2-hydroxyethyl methacrylate) Hydrogel Scaffolds for Tissue Engineering: Influence of Crosslinking Systems and Silk Sericin Concentration on Scaffold Properties

Tailored porous structures of poly(2-hydroxyethyl methacrylate) (PHEMA) and silk sericin (SS) were used to create porous hydrogel scaffolds using two distinct crosslinking systems. These structures were designed to closely mimic the porous nature of the native extracellular matrix. Conventional free radical polymerization of 2-hydroxyethyl methacrylate (HEMA) was performed in the presence of different concentrations of SS (1.25, 2.50, 5.00% w/v) with two crosslinking systems. A chemical crosslinking system with N'N-methylene bisacrylamide (MBAAm) and a physical crosslinking system with dimethylurea (DMU) were used: C-PHEMA/SS (crosslinked using MBAAm) and C-PHEMA/pC-SS (crosslinked using MBAAm and DMU). The focus of this study was on investigating the impact of these crosslinking methods on various properties of the scaffolds, including pore size, pore characteristics, polymerization time, morphology, molecular interaction, in vitro degradation, thermal properties, and in vitro cytotoxicity. The various crosslinked networks were found to appreciably influence the properties of the scaffolds, especially the pore sizes, in which smaller sizes and higher numbers of pores with high regularity were seen in C-PHEMA/1.25 pC-SS (17 ± 2 μm) than in C-PHEMA/1.25 SS (34 ± 3 μm). Semi-interpenetrating networks were created by crosslinking PHEMA-MBAAm-PHEMA while incorporating free protein molecules of SS within the networks. The additional crosslinking step involving DMU occurred through hydrogen bonding of the -C=O and -N-H groups with the SS, resulting in the simultaneous incorporation of DMU and SS within the PHEMA networks. As a consequence of this process, the scaffold C-PHEMA/pC-SS exhibited smaller pore sizes compared to scaffolds without DMU crosslinking. Moreover, the incorporation of higher loadings of SS led to even smaller pore sizes. Additionally, the gelation time of C-PHEMA/pC-SS was delayed due to the presence of DMU in the crosslinking system. Both porous hydrogel scaffolds, C-PHEMA/pC-SS and PHEMA, were found to be non-cytotoxic to the normal human skin dermal fibroblast cell line (NHDF cells). This promising result indicates that these hydrogel scaffolds have potential for use in tissue engineering applications.

Sol-gel silicate glass doped with silver for bone regeneration: Antibacterial activity, intermediate water, and cell death mode

The hydration state of bioactive glass materials and its relationship with their biocompatibility have been receiving attention. In this research, silver-containing bioactive glasses (BGAgs) (Ag contents of 0.25, 0.5, and 1.0% in the glass system) were developed using the sol-gel method. Their physicochemical properties, size, morphology, and surface area were characterized by conducting X-rays diffraction (XRD), Fourier transform infrared (FTIR), Transmission electron microscopy (TEM), and Brunauer-Emmett-Teller (BET) surface area analyses. The surface charges of the developed BGAgs were evaluated using the Nano Zetasizer. Moreover, the antibacterial activities and intermediate water (IW) contents of hydrated BGAgs were determined. Finally, BGAgs disks were tested against osteosarcoma (MG63) cell line to evaluate their death modes. The physicochemical characteristics of the BGAgs revealed no modifications after Ag doping. In comparison, relative changes were recorded in the particle size (20-33 to 16-29 nm), surface area (4.3 to 3.7 m²/g), and particle charge (-24 to -14.6 mV). Doping the current glass system with silver produced impressive amounts of IW, consistent with recorded proliferation rates of the cells when treated with BGAgs. The determined hydration states correlated with other findings in this research might be helpful in predicting and assessing the biological behaviors of BGAgs.

Development of Bioactive Glass-Collagen-Hyaluronic Acid-Polycaprolactone Scaffolds for Tissue Engineering Applications

In this work, bioactive glass (BG) particles synthesized by a sol-gel method, hyaluronic acid (HYA) and collagen (COL) extracted from chicken eggshell membrane (ESM), and as-purchased polycaprolactone (PCL) were used to obtain a novel bioactive scaffold using the gel-pressing technique. Two composite mixtures in weight percent were obtained and identified as SCF-1 and SCF-2, and were characterized by using FTIR, XRD, and SEM techniques. Subsequently, the composite materials applied as coatings were evaluated in simulated body fluid solutions using electrochemical techniques. The results of bioactivity and biodegradability evaluations, carried out by immersing in simulated body fluid and phosphate-buffered saline solution, showed that the SCF-1 sample presented the best biocompatibility. In accordance with the potentiodynamic results, the 316L-SS and the SCF-1-coated SS showed a very similar corrosion potential (Ecorr), around −228 mV, and current density (icorr) values in close proximity, while the SCF-2-coated SS showed more positive Ecorr around −68 mV and lower icorr value in one order of magnitude. These results agree with those obtained by electrochemical impedance spectroscopy, which show a corrosion mechanism governed by activation and finite diffusion through the porous layer. In addition, results were complemented by dynamic compression testing under oscillating forces to identify the developed scaffolds’ response under external forces, where the SCF-1 scaffold presented a maximum compression. The degradation resistance, bioactivity, and mechanically obtained measurements provided interesting results for potential further studies in tissue engineering.

Radiological evaluations of low cost wollastonite nano-ceramics graft doped with iron oxide in the treatment of induced defects in canine mandible

Wollastonite with/without maghemite [(Fe2O3), 0, 3 and 10 wt%] was prepared by facile wet precipitation method. Effect of Fe2O3 presence in the obtained nano-ceramics on physical structure, morphology, size and the mechanical features was evaluated using X-ray diffraction, transmission electron microscope, and universal testing machine. Moreover, the in vitro biomineralization was examined using simulated body fluid (SBF) by means of scanning electron microscope/energy dispersive X-ray, Fourier transform infrared, and inductively coupled plasma. An in vivo study was conducted on 24 adult male mongrel dogs to test the biosafety of fabricated samples in the reconstruction of experimentally induced mandibular bone defects. Bone density was measured through cone beam computed tomography analysis conducted at 1 and 3 months following surgery. Wollastonite was the main phase in all the prepared samples however little maghemite was developed in Fe-containing samples. No remarkable changes were recognized for physical structure of obtained microcrystalline structures, however, a decrease in particle size was noted in the existence of Fe2O3 (10-15 nm) when compared to the pure wollastonite (30-50 nm). Mechanical features were dependent on the included Fe2O3 concentration within the wollastonite ceramic matrix. The degree of biomineralization of the samples immersed in SBF was elevated with the increase in Fe2O3 percentage. Clinically, the reconstruction of bone defects was uneventful without any adverse toxic effect. Bone density was significantly increased at 1 and 3 months (p < .001) in grafted defects compared to control ones. Increasing the doping concentrations of iron oxide was associated with significant increase (p < .001) of bone density in all induced defects. Due to the impressive healing effect of current fabricated nano-ceramics, they are recommended to be utilized as low cost bone graft alternatives.

Multifunctional magnetite nanoparticles for drug delivery: Preparation, characterisation, antibacterial properties and drug release kinetics

Multifunctional nanoparticles (NPs) with magnetic (M) and antibacterial properties were prepared for drug delivery purposes by a method involving co-precipitation synthesis. Partial and complete substitutions of ferrous ions (Fe²⁺) by copper ions (Cu²⁺) were carried out for the preparation of the magnetite NPs, which are designated as Cu_0.5M and CuM, respectively, in this work. In addition, chitosan and ciprofloxacin were hybridized with the NPs from the previous step to achieve multifunctional properties. XRD, TEM, SEM/EDAX, VSM and FTIR were subsequently employed to characterize various properties of the prepared NPs, namely, crystallinity, nanostructure (size), particle morphology, elemental mapping, magnetic strength and chemical composition. Antibacterial properties of the NPs were tested against Bacillus cereus (Gram-positive bacteria), Escherichia coli (Gram-negative bacteria) and Candida albicans (yeast). Efficiency of the ciprofloxacin release was also studied for the drug-loaded NPs. It is demonstrated that the obtained NPs possess mixed phases with crystalline structures that are affected by the degree of Cu ion substitution (5-10 nm (M), 2.5-3.5 nm (Cu_0.5M) and 11-16 nm (CuM)). Saturation magnetization values of the NPs were recorded as 38.7, 3.5 and 1.3 emu/g, respectively. It was also found that the introduction of Cu ions in the NP samples improved the significance of their antibacterial activity, especially against Escherichia coli. Chitosan and ciprofloxacin were found to have stronger effects against Bacillus cereus and Escherichia coli and lesser effects against Candida albicans. However, the samples containing chitosan, ciprofloxacin and the higher Cu ion concentration exhibited strong influence against Candida albicans. During a study period of 30-days, the amounts of released drug from the tested NPs were 85, 26 and 20% of the originally loaded amount, respectively. Owing to the findings in this paper, the developed NPs are considered to have good potential for drug delivery applications and to study them further such as in pre-clinical studies.

Recent advances and future perspectives of sol–gel derived porous bioactive glasses: a review

Sol–gel derived bioactive glasses have been extensively explored as a promising and highly porous scaffold materials for bone tissue regeneration applications owing to their exceptional osteoconductivity, osteostimulation and degradation rates.