Novel, cost-effective, Cu-doped calcium silicate nanoparticles for bone fracture intervention: Inherent bioactivity and in vivo performance

Copper-doped magnesium phosphate nanopowders for critical size calvarial bone defect intervention

Calvarial defects of bone present difficult clinical situations, and their restoration using biocompatible materials requires special treatments that enable bone regeneration. Magnesium phosphate (MgP) is known as an osteoinductive biomaterial because it contains Mg2+ ions and P ions that enhance the activity of osteoplast cells and help in bone regeneration. In this study, MgP and CuO-doped MgP were fabricated and characterized for their physicomechanical properties, particle size, morphology, surface area, antibacterial test, and in vitro bioactivity evaluation using the following techniques: X-rays diffraction, Fourier-transformer infrared, TEM, and Brunauer, Emmett and Teller (BET) surface area, X-rays photoelectron spectroscopy (XPS), and Scanning electron microscopy (SEM). Furthermore, these nanopowders were implanted in adult inbred male Wistar rats and studied after two periods (28 and 56 days). The results demonstrated that the obtained semiamorphous powders are in nanoscale (≤ 50 nm). XPS analysis ensured the preparation of MgP as mono MgP and CuO were incorporated in the structure as Cu2+ . The bioactivity was supported by the observation of calcium phosphate layer on the nanopowders' surface. The in vivo study demonstrated success of MgP nanopowders especially those doped with CuO in restoration of calvarial defect bone. Therefore, fabricated biomaterials are of great potential in restoration of bone calvarial defects.

Influence of the addition of different metal oxides on physicochemical and biological properties of calcium fluorosilicate/PCL bone cement

Calcium silicate cements have been greatly developed in the last decades through different approaches. Among these approaches, the inclusion of antibacterial agents or addition of metal oxides. Herein, calcium silicate cement containing fluorine (CFS) was developed from sodium fluorosilicate precursor for the first time using chemical perception method. Afterwards, metal oxide Bi2O3 or MgO or ZrO2 was individually mixed with CFS powder and blended together using Polycaprolactone polymer (PCL). The cement mixtures were characterized using DSC, XRD, FTIR and SEM/EDX to determine the effect of metal oxide on the pure CFS. Furthermore, mechanical, antibacterial and cell viability properties were evaluated for the developed CFS mixture cements. Moreover, these CFS mixture cements were implanted in male Wistar rats to determine the effect of metal oxides on the rate of bone reformation. The findings of physicochemical and morphological characterization showed no remarkable effects on the pure CFS after mixing with each metal oxide. However, enhanced compressive strengths (up to 104.07N/cm2), antibacterial activity and cell viability (up to 96%) were achieved for the CFS cement mixtures. Finally, the in vivo studies confirmed the biocompatibility of the CFS cement mixtures and especially those mixed with Bi2O3 or ZrO2. Therefore, this study supports that CFS blends with Bi2O3 or ZrO2 can be novel promising cementing materials for bone restoration.

Chitosan nanoparticles for sustained release of metformin and its derived synthetic biopolymer for bone regeneration

Background: There are considerable socioeconomic costs associated with bone defects, making regenerative medicine an increasingly attractive option for treating them. Chitosan is a natural biopolymer; it is used in approaches for sustained slow release and osteogenesis, and metformin has osteoinductivity. Our study aimed to synthesize chitosan and human serum albumin (HSA) with a metformin nanoformulation to evaluate the therapeutic effects of this nanoformulation on bone defects in vitro. Methods: A pluripotent differentiation assay was performed in vitro on mouse bone marrow mesenchymal stem cells (BMSCs). Cell Counting Kit-8 was used to detect whether metformin was toxic to BMSCs. The osteogenesis-related gene expression of osteocalcin (OCN) and osteoprotegerin (OPG) from BMSCs was tested by real-time polymerase chain reaction (PCR). HSA, metformin hydrochloride, and chitosan mixtures were magnetically stirred to finish the assembly of metformin/HSA/chitosan nanoparticles (MHC NPs). The MHC NPs were characterized using transmission electron microscopy (TEM), dynamic light scattering (DLS), and Fourier transform infrared spectroscopy (FT-IR). To test the expression of OCN and OPG, western blot were used. MHC NPs were evaluated in vitro for their osteoinductivity using alkaline phosphatase (ALP). Results: BMSCs successfully differentiated into osteogenic and adipogenic lineages in vitro. According to real-time PCR, a 50 µM concentration of metformin promoted osteogenesis in BMSCs most effectively by upregulating the osteogenic markers OCN and OPG. The microstructure of MHC NPs was spherical with an average nanosize of 20 ± 4.7 nm and zeta potential of -8.3 mV. A blueshift and redshift were observed in MHC NPs following exposure to wavelengths of 1,600-1,900 and 2,000-3,700 nm, respectively. The encapsulation (%) of metformin was more than 90%. The simulation study showed that MHC NPs have good stability and it could release metformin slowly in vitro at room temperature. Upon treatment with the studied MHC NPs for 3 days, ALP was significantly elevated in BMSCs. In addition, the MHC NPs-treated BMSCs upregulated the expression of OPG and OCN, as shown by real-time PCR and western blot. Conclusion: MHC NPs have a stable metformin release effect and osteogenic ability. Therefore, as a derived synthetic biopolymer, it is expected to play a role in bone tissue regeneration.

Trends of calcium silicate biomaterials in medical research and applications: A bibliometric analysis from 1990 to 2020

Background: Calcium silicate biomaterials (CSB) have witnessed rapid development in the past 30 years. This study aimed to accomplish a comprehensive bibliometric analysis of the published research literature on CSB for biomedical applications and explore the research hotspot and current status.

Methods: Articles related to CSB published in the last three decades (1990–2020) were retrieved from Web of Science Core Collection. The R bibliometrix package and VOSviewer were used to construct publication outputs and collaborative networking among authors, their institutes, countries, journals’ matrices and keywords plus.

Results: A total of 872 publications fulfilling the search criteria were included. CSB is mainly reported for bone tissues and dental applications. Among researchers, Chang J from Chinese Academy of Sciences and Gandolfi MG from the University of Bologna are the most productive author in these two fields, respectively. China was the leading contributor to the research on CSB in the medical field. A total of 130 keywords appeared more ten or more times were identified. The term “mineral trioxide aggregate” ranked first with 268 occurrences. The co-occurrence analysis identified three major clusters: CSB in dentistry, bone tissue and vitro bioactivity.

Conclusion: Calcium silicate biomaterials have a promising scope for various biomedical applications ranging from regeneration of hard tissues (bone and teeth) to skin, tumor, cardiac muscle and other soft tissues. This study may help researchers further understand the frontiers of the field.

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.

Osteogenic potential of calcium silicate-doped iron oxide nanoparticles versus calcium silicate for reconstruction of critical-sized mandibular defects: An experimental study in dog model

Objective

To evaluate bioactivity and osteogenic potential of calcium silicate (CS)-doped iron oxide (Fe₂O₃) nanoparticles versus pure CS in the reconstruction of induced critical-sized mandibular defects.

Design

CS-doped Fe₂O₃ was prepared; morphological and microstructure identification of nanoparticles were made. An in vivo randomised design was developed on 24 adult male dogs where four critical-sized mandibular defects were created in each dog. Bone defects were allocated into control, CS, CS-3% Fe₂O₃ and CS-10% Fe₂O₃ group. Dogs were euthanized at 1 and 3 months (12 dog/time) for histopathologic and histomorphometric evaluation.

Results

At three months, bone formation and maturation were evident where mean ± SD percent of mature bone was 2.66 ± 1.8, 9.9 ± 2.5, 22.9 ± 4.9, and 38.6 ± 8.1 in control, CS, CS-3% Fe₂O₃, and CS-10% Fe₂O₃ groups respectively. A high significant (P < 0.001) increase in area percent of mature bone was recorded in CS, CS-3% Fe₂O₃, and CS- 10% Fe₂O₃ groups compared to control group (73%, 88% and 93.3% respectively). Significant increase (P < 0.001) in area of mature bone was recorded in CS-3% Fe₂O₃ and CS-10% Fe₂O₃ groups compared to CS group. A significant increase (P < 0.001) in area of mature bone formation was detected in CS-10% Fe₂O₃ group compared to other groups.

Conclusion

CS-doped Fe₂O₃ has good osteoconductive, biocompatible properties with promoted bone regeneration. Fe₂O₃ has synergistic effect in combination with CS to promote bone formation. Increasing concentration of Fe₂O₃ nanoparticles resulted in improved osteogenesis and maturation. Results suggests that the novel CS-Fe₂O₃ alloplasts could be used for reconstruction of critical-sized bone defects.

Strategies for Enhancing Vascularization of Biomaterial-Based Scaffold in Bone Regeneration

Despite the recent advances in reconstructive orthopedics; fracture union is a challenge to bone regeneration. Concurrent angiogenesis is a complex process governed by events, delicately entwined with osteogenesis. However, poorly perfused scaffolds have lower success rates; necessitating the need for a better vascular component, which is important for the delivery of nutrients, oxygen, waste elimination, recruitment of cells for optimal bone repair. This review highlights the latest strategies to promote biomaterial-based scaffold vascularization by incorporation of cells, growth factors, inorganic ions, etc. into natural or synthetic polymers, ceramic materials, or composites of organic and inorganic compounds. Furthermore, it emphasizes structural modifications, biophysical stimuli, and natural molecules to fabricate scaffolds aiding the genesis of dense vascularization following their implantation to manifest a compatible regenerative microenvironment without graft rejection.

A Novel Treatment of Schistosomiasis: Nano-Calcium Silicate Incorporating 5% Copper Oxide

Purpose: Praziquantel (PZQ) is a well-known drug accredited by the World Health Organization (WHO) for the treatment of schistosomiasis. It shows poor efficiency in patients during the earliest infection phases. Therefore, the search for new alternative drugs was the intention of many researchers. Methods: In the current study, the effect of different concentrations (ranging from 0.07-10 μg∕mL) of calcium silicate (CS) containing 5% copper oxide [CS-5%CuO] on golden hamster infected by Schistosoma mansoni and Schistosoma haematobium (Egyptian strains) was evaluated in both in vitro and in vivo. To the best of our knowledge, this is a novel study in investigating the efficiency of CS-5%CuO against both strains of schistosomes. The worms of S. mansoni and S. haematobium were tested in RPMI-1640 medium in vitro. Results: The results declare that CS-5% CuO exhibited excellent anti-schistosomal activities on both in vitro and in vivo experiments for both Egyptians Schistosoma strains. The most potential effect of the CS-5% CuO was exhibited after 6 h by 10 μg∕mL with significant activity of (P value = 0.001). Conclusion: Therefore, CS-5%CuO may become an innovative treatment for the schistosomiasis.

Nanomaterials for Biomedical Applications: Production, Characterisations, Recent Trends and Difficulties

Designing of nanomaterials has now become a top-priority research goal with a view to developing specific applications in the biomedical fields. In fact, the recent trends in the literature show that there is a lack of in-depth reviews that specifically highlight the current knowledge based on the design and production of nanomaterials. Considerations of size, shape, surface charge and microstructures are important factors in this regard as they affect the performance of nanoparticles (NPs). These parameters are also found to be dependent on their synthesis methods. The characterisation techniques that have been used for the investigation of these nanomaterials are relatively different in their concepts, sample preparation methods and obtained results. Consequently, this review article aims to carry out an in-depth discussion on the recent trends on nanomaterials for biomedical engineering, with a particular emphasis on the choices of the nanomaterials, preparation methods/instruments and characterisations techniques used for designing of nanomaterials. Key applications of these nanomaterials, such as tissue regeneration, medication delivery and wound healing, are also discussed briefly. Covering this knowledge gap will result in a better understanding of the role of nanomaterial design and subsequent larger-scale applications in terms of both its potential and difficulties.

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.

Metal-based nanoparticles for bone tissue engineering

Tissue is vital to the organization of multicellular organisms, because it creates the different organs and provides the main scaffold for body shape. The quest for effective methods to allow tissue regeneration and create scaffolds for new tissue growth has intensified in recent years. Tissue engineering has recently used some promising alternatives to existing conventional scaffold materials, many of which have been derived from nanotechnology. One important example of these is metal nanoparticles. The purpose of this review is to cover novel tissue engineering methods, paying special attention to those based on the use of metal-based nanoparticles. The unique physiochemical properties of metal nanoparticles, such as antibacterial effects, shape memory phenomenon, low cytotoxicity, stimulation of the proliferation process, good mechanical and tensile strength, acceptable biocompatibility, significant osteogenic potential, and ability to regulate cell growth pathways, suggest that they can perform as novel types of scaffolds for bone tissue engineering. The basic principles of various nanoparticle-based composites and scaffolds are discussed in this review. The merits and demerits of these particles are critically discussed, and their importance in bone tissue engineering is highlighted.

Physiochemical properties of copper doped calcium sulfate in vitro and angiogenesis in vivo

Bone cements were prepared by mixing calcium sulfate and copper sulfate in various proportions. We examined physical and physicochemical properties of the copper doped calcium sulfates and the effects of the cements on angiogenesis in vivo. Rod shaped calcium sulfate crystals were visible by scanning electron microscopy in the cement that contained no copper sulfate, whereas plate-like crystals covered the surface of the cement with high copper content. After immersion of the cements in simulated body fluid (SBF) for 1 day, X-ray diffractometric analysis showed that gypsum precipitates had formed in the copper doped calcium sulfate. The compressive strength of the cements increased from 3.3 MPa for pure calcium sulfate to 6.4 MPa for samples with copper sulfate added. Calcium ion release was greatest from pure calcium sulfate, and the rate of copper ion release was higher for cements containing the most copper. We found that 6 weeks after implantation, more blood vessels had formed around the high copper cement than for the copper-free cement. Copper doped calcium sulfate appears to be useful for application to regenerative medicine including wound healing and bone tissue engineering.

Toward Highly Dispersed Mesoporous Bioactive Glass Nanoparticles With High Cu Concentration Using Cu/Ascorbic Acid Complex as Precursor

Copper (Cu) ions have a variety of advantageous biological functionalities, such as proangiogenic and bactericidal activities. Given the intrinsic biodegradability and biocompatibility, silicate-based mesoporous bioactive glass nanoparticles (MBGNs) are considered as promising platforms for the delivery of Cu ions. However, effective incorporation of Cu into MBGNs still faces challenges, e.g., particle aggregation, the formation of insoluble crystalline Cu-based nanoparticles, and a low loading amount of Cu. We report a novel method to synthesize chemically homogenous and highly dispersed Cu-containing MBGNs (Cu-MBGNs) with tunable Cu concentration by using ascorbic acid/Cu complexes as the precursor of Cu in a microemulsion-assisted sol-gel approach. Cu-MBGNs exhibited a sphere-like shape with a particle size between 100 and 300 nm while their pore size varied from 2 to 10 nm. The inclusion of Cu, regardless of the incorporated concentration, did not significantly affect the morphology of particles. ICP-AES results indicated that the concentration of Cu in the particles could be conveniently tuned from 0 to ~6 mol% by controlling the amount of ascorbic acid/Cu complexes added, while the formation of crystalline Cu-based nanoparticles was avoided. The amorphous feature of Cu-MBGNs was proved by XRD, while the predominant oxidation state of Cu was evidenced to be Cu2+ by XPS. The incorporation of Cu did not inhibit the apatite-forming ability (bioactivity) of the particles in contact with simulated body fluid. Cu-MBGNs exhibited the capability of releasing Cu, Si, and Ca ions over time in the physiological fluid. The concentration of released Cu ions could be controlled by selecting specific Cu-MBGNs of different Cu contents. The dissolution products of most Cu-MBGNs at the dosage of 1, 0.1, and 0.01 mg/mL did not exhibit cytotoxicity, while only 7Cu-MBGN was cytotoxic at the dosage of 1 mg/mL. This study provided a feasible strategy to synthesize highly dispersed amorphous Cu-MBGNs with high Cu concentrations for biomedical applications. The particles exhibit great potential as building blocks for developing composite 3D scaffolds, coatings, and drug carriers, particularly when a large amount of particles incorporated may compromise the properties of (polymer) matrix materials while a relatively high concentration of released Cu ions is still required.