Composites Based on Hydroxyapatite and Whey Protein Isolate for Applications in Bone Regeneration

Sideritis raeseri-Modified Coatings on Ti-6Al-4V as a Carrier for Controlled Delivery Systems of Active Substances

The search for the ideal metallic material for an implant is still a difficult challenge for scientists due to the phenomenon of corrosion and the consequent disruption of the implant structure. Prevention is the application of coatings that protect the implant, activate the tissues for faster regeneration, and also prevent inflammation through antibacterial and antiviral effects. The present study focuses on the selection of components for a Ti-6Al-4V alloy coating. These days, researchers are taking an intense interest in extracts of natural origin. It was decided to take a look at Sideritis raeseri, which contains vitamins and valuable elements and is rich in polyphenols, as well as antioxidants. The composition of coatings based on a PEG polymer reinforced with brushite and the S. raeseri extract with the proteins L-carnosine, fibroin, or sericin was developed. The samples were subjected to detailed physiochemical analysis, including potentiometry and electrical conductivity analysis, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis, and UV-VIS spectroscopy. The study demonstrated that polyphenols were successfully released from the coatings during incubation in vitro. The osteointegration process can be supported by a number of factors, such as the release of polyphenols from implant coatings to prevent bacterial, viral, and fungal infections. Subjecting the samples to 14 days of incubation demonstrated their interactions with the incubation fluids, an ion exchange between the medium and the materials. An analysis of the surface morphology exhibited the presence of brushite crystals and their increased number after incubation, indicating the bioactivity of the formed coatings.

Bioactive Hydrogel Based on Collagen and Hyaluronic Acid Enriched with Freeze-Dried Sheep Placenta for Wound Healing Support

In an increasingly aging society, there is a growing demand for the development of technology related to tissue regeneration. It involves the development of the appropriate biomaterials whose properties will allow the desired biological response to be obtained. Bioactivity is strongly affected by the proper selection of active ingredients. The aim of this study was to produce bioactive hydrogel materials based on hyaluronic acid and collagen modified by the addition of placenta. These materials were intended for use as dressings, and their physicochemical properties were investigated under simulated biological environmental conditions. The materials were incubated in vitro in different fluids simulating the environment of the human body (e.g., simulated body fluid) and then stored at a temperature close to body temperature. Using an FT-IR spectrophotometer, the functional groups present in the composites were identified. The materials with the added placenta showed an increase in the swelling factor of more than 300%. The results obtained confirmed the potential of using this material as an absorbent dressing. This was indicated by pH and conductometric measurements, sorption, degradation, and surface analysis under an optical microscope. The results of the in vitro biological evaluation confirmed the cytosafety of the tested biomaterials. The tested composites activate monocytes, which may indicate their beneficial properties in the first phases of wound healing. The material proved to be nontoxic and has potential for medical use.

The Enrichment of Whey Protein Isolate Hydrogels with Poly-γ-Glutamic Acid Promotes the Proliferation and Osteogenic Differentiation of Preosteoblasts

Osseous disease accounts for over half of chronic pathologies, but there is a limited supply of autografts, the gold standard; hence, there is a demand for new synthetic biomaterials. Herein, we present the use of a promising, new dairy-derived biomaterial: whey protein isolate (WPI) in the form of hydrogels, modified with the addition of different concentrations of the biotechnologically produced protein-like polymeric substance poly-γ-glutamic acid (γ-PGA) as a potential scaffold for tissue regeneration. Raman spectroscopic analysis demonstrated the successful creation of WPI-γ-PGA hydrogels. A cytotoxicity assessment using preosteoblastic cells demonstrated that the hydrogels were noncytotoxic and supported cell proliferation from day 3 to 14. All γ-PGA-containing scaffold compositions strongly promoted cell attachment and the formation of dense interconnected cell layers. Cell viability was significantly increased on γ-PGA-containing scaffolds on day 14 compared to WPI control scaffolds. Significantly, the cells showed markers of osteogenic differentiation; they synthesised increasing amounts of collagen over time, and cells showed significantly enhanced alkaline phosphatase activity at day 7 and higher levels of calcium for matrix mineralization at days 14 and 21 on the γ-PGA-containing scaffolds. These results demonstrated the potential of WPI-γ-PGA hydrogels as scaffolds for bone regeneration.

Comparison of three different lactic acid bacteria-fermented proteins on RAW 264.7 osteoclast and MC3T3-E1 osteoblast differentiation

Osteoporosis is a state of bone weakening caused by an imbalance in osteoblast and osteoclast activity. In this study, the anti-osteoporotic effects of three proteins fermented by lactic acid bacteria (LAB) were assessed. Commercial proteins sodium caseinate (SC), whey protein isolate (WPI), and soy protein isolate (SPI) were fermented by LAB strains for 48 h. The fermented products (F-SC, F-WPI, and F-SPI, respectively) were used in an in vitro osteoclast and osteoblast-like cell model to assess their effects on bone health. Despite no difference in the results of TRAP staining of RANKL-induced osteoclastogenesis, F-WPI and F-SPI were effective in normalizing the altered gene expression of osteoclastogenesis markers such as TRAP, Nfatc1, RANK, and ATP6v0d. F-SPI was also effective in modulating osteoblasts by enhancing the expression of the osteoblastogenesis markers T1Col, Col2a, and OSX to levels higher than those in the SPI group, indicating that protein characteristics could be enhanced through bacterial fermentation. Moreover, these boosted effects of F-SPI may be involved with isoflavone-related metabolism during LAB-fermentation of SPI. These results demonstrate the potential of LAB-fermented proteins as dietary supplements to prevent bone loss. However, further understanding of its effects on balancing osteoblasts and osteoclasts and the underlying mechanisms is needed.

Whey Protein Isolate/Calcium Silicate Hydrogels for Bone Tissue Engineering Applications-Preliminary In Vitro Evaluation

Whey protein isolate (WPI) hydrogels are attractive biomaterials for application in bone repair and regeneration. However, their main limitation is low mechanical strength. Therefore, to improve these properties, the incorporation of ceramic phases into hydrogel matrices is currently being performed. In this study, novel whey protein isolate/calcium silicate (WPI/CaSiO3) hydrogel biomaterials were prepared with varying concentrations of a ceramic phase (CaSiO3). The aim of this study was to investigate the effect of the introduction of CaSiO3 to a WPI hydrogel matrix on its physicochemical, mechanical, and biological properties. Our Fourier Transform Infrared Spectroscopy results showed that CaSiO3 was successfully incorporated into the WPI hydrogel matrix to create composite biomaterials. Swelling tests indicated that the addition of 5% (w/v) CaSiO3 caused greater swelling compared to biomaterials without CaSiO3 and ultimate compressive strength and strain at break. Cell culture experiments demonstrated that WPI hydrogel biomaterials enriched with CaSiO3 demonstrated superior cytocompatibility in vitro compared to the control hydrogel biomaterials without CaSiO3. Thus, this study revealed that the addition of CaSiO3 to WPI-based hydrogel biomaterials renders them more promising for bone tissue engineering applications.

Influence of Drying Technique on Physicochemical Properties of Synthetic Hydroxyapatite and Its Potential Use as a Drug Carrier

Naturally occurring hydroxyapatite (HA) is the mineral phase of bone tissue. It is characterized by its bioactivity toward stimulating bone cells to proliferate and thus form new apatite layers. For this reason, it is a material commonly used in implantology for filling defects or covering implants (such as endoprostheses). There are several methods to obtain synthetic HA, and by controlling parameters such as temperature, pressure or the drying process, physicochemical parameters of the final powder can be affected. In the present study, HA was obtained by wet precipitation technique and subjected to two different drying methods, determining whether this parameter significantly affects the properties of the final material obtained. Analyzed Fourier-transform infrared spectroscopy (FT-IR) confirmed the presence of functional groups typical for HA. X-ray diffraction analysis (XRD) demonstrated that the materials are partially amorphous; however, the only phase was identified in HA. Scanning electron microscopy (SEM) was used to evaluate the surface morphology and the density, and average grain diameter was measured. Furthermore, HA powders were subjected to modification with the antibiotic clindamycin to determine the potential for use as a carrier for the active substance. The release rate of the drug was determined by high-performance liquid chromatography (HPLC). The differences in the characteristics of the powders were relatively small; however, they affected the rate of drug release from the material as well as the shape of the grains. The method of drying the powders was shown to affect the shape of the grains, as well as the porosity of the sinters prepared from it. A higher amount of clindamycin released into PBS was observed in material with more pores. The materials have demonstrated the potential to be used as a carrier for the active substance; however, further biological, as well as physicochemical, analysis is required.

3D and 4D printing hydroxyapatite-based scaffolds for bone tissue engineering and regeneration

The osseous tissue can be classified as a nanocomposite that encompasses a complex interweaving of organic and inorganic matrices. This intricate amalgamation consists of a collagen component and a mineral phase that are intricately arranged to form elaborate and perforated configurations. Hydroxyapatite, whether synthesized artificially or obtained from natural sources, has garnered considerable attention as a composite material in the field of bone tissue engineering due to its striking resemblance to bone in terms of structure and characteristics. Hydroxyapatite (HA) constitutes the predominant ceramic biomaterial for biomedical applications due to its ability to replicate the mineral composition of vertebrate bone. Nonetheless, it is noteworthy that the present biomimetic substance exhibits unfavorable mechanical characteristics, characterized by insufficient tensile and compressive strength, thus rendering it unsuitable for effective employment in the field of bone tissue engineering. Due to its beneficial attributes, hydroxyapatite (HA) is frequently employed in conjunction with various polymers and crosslinkers as composites to enhance mechanical properties and overall efficacy of implantable biomaterials engineered. The restoration of skeletal defects through the use of customized replacements is an effective way to replace damaged or lost bone structures. This method not only restores the bones' original functions but also reinstates their initial aesthetic appearance. The utilization of hydroxyapatite-polymer composites within 3D-printed grafts necessitates meticulous optimization of both mechanical and biological properties, in order to ensure their suitability for employment in medical devices. The utilization of 3D-printing technology represents an innovative approach in the manufacturing of HA-based scaffolds, which offers advantageous prospects for personalized bone regeneration. The expeditious prototyping method, with emphasis on the application of 3D printing, presents a viable approach in the development of bespoke prosthetic implants, grounded on healthcare data sets. 4D printing approach is an evolved form of 3D printing that utilizes programmable materials capable of altering the intended shape of printed structures, contingent upon single or dual stimulating factors. These factors include aspects such as pH level, temperature, humidity, crosslinking degree, and leaching factors.

Screw Osteointegration-Increasing Biomechanical Resistance to Pull-Out Effect

Spinal disorders cover a broad spectrum of pathologies and are among the most prevalent medical conditions. The management of these health issues was noted to be increasingly based on surgical interventions. Spinal fixation devices are often employed to improve surgery outcomes, increasing spinal stability, restoring structural integrity, and ensuring functionality. However, most of the currently used fixation tools are fabricated from materials with very different mechanical properties to native bone that are prone to pull-out effects or fail over time, requiring revision procedures. Solutions to these problems presently exploited in practice include the optimal selection of screw shape and size, modification of insertion trajectory, and utilization of bone cement to reinforce fixation constructs. Nevertheless, none of these methods are without risks and limitations. An alternative option to increasing biomechanical resistance to the pull-out effect is to tackle bone regenerative capacity and focus on screw osteointegration properties. Osteointegration was reportedly enhanced through various optimization strategies, including use of novel materials, surface modification techniques (e.g., application of coatings and topological optimization), and utilization of composites that allow synergistic effects between constituents. In this context, this paper takes a comprehensive path, starting with a brief presentation of spinal fixation devices, moving further to observations on how the pull-out strength can be enhanced with existing methods, and further focusing on techniques for implant osteointegration improvement.

Characterization of a Graphene Oxide-Reinforced Whey Hydrogel as an Eco-Friendly Absorbent for Food Packaging

This study presents a structural analysis of a whey and gelatin-based hydrogel reinforced with graphene oxide (GO) by ultraviolet and visible (UV-VIS) spectroscopy, Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD). The results revealed barrier properties in the UV range for the reference sample (containing no graphene oxide) and the samples with minimal GO content of 0.66×10−3% and 3.33×10−3%, respectively, in the UV-VIS and near-IR range; for the samples with higher GO content, this was 6.67×10−3% and 33.33×10−3% as an effect of the introduction of GO into the hydrogel composite. The changes in the position of diffraction angles 2θ from the X-ray diffraction patterns of GO-reinforced hydrogels indicated a decrease in the distances between the turns of the protein helix structure due to the GO cross-linking effect. Transmission electron spectroscopy (TEM) was used for GO, whilst scanning electron microscopy (SEM) was used for the composite characterization. A novel technique for investigating the swelling rate was presented by performing electrical conductivity measurements, the results of which led to the identification of a potential hydrogel with sensor properties.

Structural, Spectroscopic, and Biological Characterization of Novel Rubidium(I) and Europium(III) Co-Doped Nano-Hydroxyapatite Materials and Their Potential Use in Regenerative Medicine

This research investigates hydrothermally synthesized hydroxyapatite nanoparticles doped with rubidium(I) and europium(III) ions. Investigation focused on establishing the influence of co-doped Eu³⁺ and Rb⁺ ions on hydroxyapatite lattice. Therefore, structural, and morphological properties were characterized via using X-ray powder diffraction (XRPD), infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM), as well as transmission electron microscopy (TEM) techniques. Furthermore, this investigation evaluates the impact of various Rb⁺ ion doping concentrations on the distinct red emission of co-doped Eu³⁺ ions. Hence, luminescence properties of the obtained materials were evaluated by measuring emission excitation, emission spectra, and luminescence decays. As established by numerous studies, synthetic hydroxyapatite has excellent application in biomedical field, as it is fully biocompatible. Its biocompatible makes it highly useful in the biomedical field as a bone fracture filler or hydroxyapatite coated dental implant. By the incorporation of Eu³⁺ ions and Rb⁺ ions we established the impact these co-doped ions have on the biocompatibility of hydroxyapatite powders. Therefore, biocompatibility toward a ram's red blood cells was evaluated to exclude potential cytotoxic features of the synthesized compounds. Additionally, experimental in vitro bioactive properties of hydroxyapatite nanoparticles doped with Rb⁺ and Eu³⁺ ions were established using a mouse osteoblast model. These properties are discussed in detail as they contribute to a novel method in regenerative medicine.

Effects of Sterilization and Hydrolytic Degradation on the Structure, Morphology and Compressive Strength of Polylactide-Hydroxyapatite Composites

Composites based on polylactide (PLA) and hydroxyapatite (HA) were prepared using a thermally induced phase separation method. In the experimental design, the PLA with low weight-average molar mass (M_w) and high M_w were tested with the inclusion of HA synthesized as whiskers or hexagonal rods. In addition, the structure of HA whiskers was doped with Zn, whereas hexagonal rods were mixed with Sr salt. The composites were sterilized and then incubated in phosphate-buffered saline for 12 weeks at 37 °C, followed by characterization of pore size distribution, molecular properties, density and mechanical strength. Results showed a substantial reduction of PLA M_w for both polymers due to the preparation of composites, their sterilization and incubation. The distribution of pore size effectively increased after the degradation process, whereas the sterilization, furthermore, had an impact on pore size distribution depending on HA added. The inclusion of HA reduced to some extent the degradation of PLA quantitatively in the weight loss in vitro compared to the control without HA. All produced materials showed no cytotoxicity when validated against L929 mouse skin fibroblasts and hFOB 1.19 human osteoblasts. The lack of cytotoxicity was accompanied by the immunocompatibility with human monocytic cells that were able to detect pyrogenic contaminants.

Fabrication and Characterization of Submicron-Scale Bovine Hydroxyapatite: A Top-Down Approach for a Natural Biomaterial

Submicron hydroxyapatite has been reported to have beneficial effects in bone tissue engineering. This study aimed to fabricate submicron-scale bovine hydroxyapatite (BHA) using the high-energy dry ball milling method. Bovine cortical bone was pretreated and calcined to produce BHA powder scaled in microns. BHA was used to fabricate submicron BHA with milling treatment for 3, 6, and 9 h and was characterized by using dynamic light scattering, scanning electron microscope connected with energy dispersive X-Ray spectroscopy, Fourier-transform infrared spectroscopy, and X-ray diffractometry to obtain its particle size, calcium-to-phosphorus (Ca/P) ratio, functional chemical group, and XRD peaks and crystallinity. Results showed that the particle size of BHA had a wide distribution range, with peaks from ~5 to ~10 µm. Milling treatment for 3, 6, and 9 h successfully gradually reduced the particle size of BHA to a submicron scale. The milled BHA's hydrodynamic size was significantly smaller compared to unmilled BHA. Milling treatment reduced the crystallinity of BHA. However, the treatment did not affect other characteristics; unmilled and milled BHA was shaped hexagonally, had carbonate and phosphate substitution groups, and the Ca/P ratio ranged from 1.48 to 1.68. In conclusion, the fabrication of submicron-scale BHA was successfully conducted using a high-energy dry ball milling method. The milling treatment did not affect the natural characteristics of BHA. Thus, the submicron-scale BHA may be potentially useful as a biomaterial for bone grafts.

The Ability and Mechanism of nHAC/CGF in Promoting Osteogenesis and Repairing Mandibular Defects

Nano-hydroxyapatite/collagen (nHAC) is a new type of bone tissue engineering scaffold material. To speed up the new bone formation of nHAC, this study used concentrated growth factor (CGF) and nHAC in combination to repair rabbit mandibular defects. nHAC/CGF and nHAC were implanted into rabbit mandibles, and X-ray, Micro-CT, HE and Masson staining, immunohistochemical staining and biomechanical testing were performed at 8, 16 and 24 weeks after surgery. The results showed that as the material degraded, the rate of new bone formation in the nHAC/CGF group was better than that in the nHAC group. The results of the HE and Masson staining showed that the bone continuity or maturity of the nHAC/CGF group was better than that of the nHAC group. Immunohistochemical staining showed that OCN expression gradually increased with time. The nHAC/CGF group showed significantly higher BMP2 than the nHAC group at 8 weeks and the difference gradually decreased with time. The biomechanical test showed that the compressive strength and elastic modulus of the nHAC/CGF group were higher than those of the nHAC group. The results suggest that nHAC/CGF materials can promote new bone formation, providing new ideas for the application of bone tissue engineering scaffold materials in oral clinics.

Preparation, Characterization, and Biocompatibility Assessment of Polymer-Ceramic Composites Loaded with Salvia officinalis Extract

In the present work, hydroxyapatite-polymer materials were developed. The preparation, as well as characterization of the ceramic-polymer composites based on polyvinylpyrrolidone, sodium alginate, and gelatin were described. The system was enriched with the addition of common sage extract (Salvia officinalis). The antioxidant potential of sage aqueous extract and total polyphenol content was determined. The antioxidant capacity and total phenolic content of extract were equal to 86.06 ± 0.49% and 16.21 ± 0.58 mg gallic acid equivalents per gram of dry weight, respectively. Incubation studies in selected biological liquids were carried out to determine the biomineralization capacity on the surface of the composites and to examine the kinetics of release of the active substances from within the material. As a result of the incubation, a gradual release of the extract over time from the polymer matrix was observed; moreover, the appearance of new apatite layers on the composite surface was recorded as early as after 14 days, which was also confirmed by energy-dispersive X-ray spectroscopy (EDS) microanalysis. The composites were analyzed with Fourier transform infrared spectroscopy (FTIR) spectroscopy, and the morphology was recorded by scanning electron microscope (SEM) imaging. The in vitro biological studies allowed their cytotoxic effect on the reference L929 fibroblasts to be excluded. Further analysis of the biomaterials showed that enrichment with polyphenols does not support the adhesion of L929 cells to the surface of the material. However, the addition of these natural components stimulates human monocytes that constitute the first step of tissue regeneration.

Recent Advances in the Treatment of Bone Metastases and Primary Bone Tumors: An Up-to-Date Review

In the last decades, the treatment of primary and secondary bone tumors has faced a slow-down in its development, being mainly based on chemotherapy, radiotherapy, and surgical interventions. However, these conventional therapeutic strategies present a series of disadvantages (e.g., multidrug resistance, tumor recurrence, severe side effects, formation of large bone defects), which limit their application and efficacy. In recent years, these procedures were combined with several adjuvant therapies, with different degrees of success. To overcome the drawbacks of current therapies and improve treatment outcomes, other strategies started being investigated, like carrier-mediated drug delivery, bone substitutes for repairing bone defects, and multifunctional scaffolds with bone tissue regeneration and antitumor properties. Thus, this paper aims to present the types of bone tumors and their current treatment approaches, further focusing on the recent advances in new therapeutic alternatives.

Various Simulated Body Fluids Lead to Significant Differences in Collagen Tissue Engineering Scaffolds

This study aims to point out the main drawback with respect to the design of simulated body environments. Three media commonly used for the simulation of the identical body environment were selected, i.e., Kokubo’s simulated body fluid that simulates the inorganic component of human blood plasma, human blood plasma, and phosphate buffer saline. A comparison was performed of the effects of the media on collagen scaffolds. The mechanical and structural effects of the media were determined via the application of compression mechanical tests, the determination of mass loss, and image and micro-CT analyses. The adsorption of various components from the media was characterized employing energy-dispersive spectrometry. The phase composition of the materials before and after exposure was determined using X-ray diffraction. Infrared spectroscopy was employed for the interpretation of changes in the collagen secondary structure. Major differences in terms of the mechanical properties and mass loss were observed between the three media. Conversely, only minor structural changes were detected. Since no general recommendation exists for selecting the simulated body environment, it is necessary to avoid the simplification of the results and, ideally, to utilize alternative methods to describe the various aspects of degradation processes that occur in the media.