Strontium ranelate incorporated 3D porous sulfonated PEEK simulating MC3T3-E1 cell differentiation

Synthesis and Characterization of a Strontium-Quercetin Complex and Its In Vitro and In Vivo Potential for Application in Bone Regeneration

Progress has been made toward developing therapies to treat bone-related diseases and defects caused by trauma. However, some of these therapies, such as administering strontium ranelate to treat osteoporosis, have significant side effects. In this context, designing new and safer strontium-based materials constitutes an important current challenge. Here, we have used quercetin as a platform to synthesize a new complex based on strontium and evaluate its activity in vitro and in vivo. First, we carried out strontium complexation with quercetin. Then, we employed Fourier transform infrared spectroscopy, nuclear magnetic resonance, and thermal gravimetric analysis to determine the chemical composition of the resulting complex as [(C15H7O7)Sr2]·6(H2O), which was also supported by theoretical calculations. This complex enhanced osteogenic differentiation of a preosteoblastic cell line in vitro, which increased alkaline phosphatase activity and extracellular matrix mineralization. By using a periapical lesion model in mice, we tested whether treatment with this complex could regenerate bone defects in vivo and found that the lesions decreased after 7 days. Together, our data showed that the strontium-quercetin complex synthesized herein is a potential candidate for developing new bone regeneration therapies.

Repairing effect of magnesium oxychloride cement modified by γ-polyglutamic acid and chitosan in osteoporotic bone defect

Magnesium oxychloride cement (MOC) has the advantage of high early strength. However, it has the defect of poor water resistance. Considering this performance, we use γ-polyglutamic acid (γ-PGA) and chitosan (CS) to modify MOC. The effects of γ-PGA and CS such as strength, in vitro degradation and in vitro bioactivity of MOC were studied. Based on the preparation of γ-PGA and CS modified MOC (γ-PGA/CS-MOC) composite bone cement, the strontium ranelate (SrR) was loaded on. The results showed that the softening coefficient of γ-PGA/3 wt.% CS-MOC after soaking in SBF for 28 d reached 0.48, while that of control group (without CS and γ-PGA) was only 0.35; Cell experiments indicated that SrR could promote differentiation into osteoblasts. After the γ-PGA/CS-MOC composite bone cement containing SrR was implanted into the osteoporotic bone defect for 12 w, it was found that the material was gradually absorbed and the new bone tissue grew. The results showed that SrR/γ-PGA/CS-MOC composite bone cement had a potential application prospect in the repair of osteoporotic bone defects.

Cell-microsphere based living microhybrids for osteogenesis regulating to boosting biomineralization

Biomineralization-based cell-material living composites ex vivo showed great potential for living materials construction and cell regulation. However, cells in scaffolds with unconnected pores usually induce confined nutrient transfer and cell-cell communications, affecting the transformation of osteoblasts into osteocytes and the mineralization process. Herein, the osteoblast-materials living hybrids were constructed with porous PLLA microspheres using a rational design, in which cell-based living materials presented an improved osteoblast differentiation and mineralization model using rationally designed cell-microsphere composites. The results indicated that the microfluidic-based technique provided an efficient and highly controllable approach for producing on-demand PLLA microspheres with tiny pores (<5 μm), medium pores (5-15 μm) and large pores (>15 μm), as well as further drug delivery. Furthermore, the simvastatin (SIM)-loaded porous PLLA microsphere with ε-polylysine (ε-PL) modification was used for osteoblast (MC3T3-E1) implantation, achieving the cell-material living microhybrids, and the results demonstrated the ε-PL surface modification and SIM could improve osteoblast behavior regulation, including cell adhesion, proliferation, as well as the antibacterial effects. Both in vitro and in vivo results significantly demonstrated further cell proliferation, differentiation and cascade mineralization regulation. Then, the quantitative polymerase chain reaction or histological staining of typical markers, including collagen type I, alkaline phosphatase, runt-related transcription factor 2 and bone morphogenetic protein 2, as well as the calcium mineral deposition staining in situ, reconfirmed the transformation of osteoblasts into osteocytes. These achievements revealed a promising boost in osteogenesis toward mineralization at the microtissue level by cell-microsphere integration, suggesting an alternative strategy for materials-based ex vivo tissue construction and cell regulation, further demonstrating excellent application prospects in the field of biomineralization-based tissue regeneration.

Multifaceted Materials for Enhanced Osteogenesis and Antimicrobial Properties on Bioplastic Polyetheretherketone Surfaces: A Review

Implant-associated infections and the increasing number of bone implants loosening and falling off after implantation have become urgent global challenges, hence the need for intelligent alternative solutions to combat implant loosening and falling off. The application of polyetheretherketone (PEEK) in biomedical and medical therapy has aroused great interest, especially because its elastic modulus close to bone provides an effective alternative to titanium implants, thereby preventing the possibility of bone implants loosening and falling off due to the mismatch of elastic modulus. In this Review, we provide a comprehensive overview of recent advances in surface modifications to prevent bone binding deficiency and bacterial infection after implantation of bone implants, starting with inorganics for surface modification, followed by organics that can effectively promote bone integration and antimicrobial action. In addition, surface modifications derived from cells and related products of biological activity have been proposed, and there is increasing evidence of clinical potential. Finally, the advantages and future challenges of surface strategies against medical associated poor osseointegration and infection are discussed, with promising prospects for developing novel osseointegration and antimicrobial PEEK materials.

Conducting biointerface of spider-net-like chitosan-adorned polyurethane/SPIONs@SrO2-fMWCNTs for bone tissue engineering and antibacterial efficacy

In pursuit of enhancing bone cell proliferation, this study delves into the fabrication of porous scaffolds through the integration of nanomaterials. Specifically, we present the development of highly conductive chitosan (CS) nanonets on fibro-porous polyurethane (PU) bio-membranes. These nanofibers comprise functionalized multiwall carbon nanotubes (fMWCNTs), well-dispersed superparamagnetic iron oxide (SPIONs), and strontium oxide (SrO2) nanoparticles. The resulting porous scaffold exhibits remarkable interfacial biocompatibility, antibacterial properties, and load-bearing capability. Through meticulous in vitro investigations, the CS-PU/SPIONs/SrO2-fMWCNTs nanofibrous scaffolds have demonstrated a propensity to promote bone cell regeneration. Notably, the integration of these nanomaterials has been found to upregulate crucial bone-related markers, including ALP, ARS, COL-I, RUNX2, and SPP-I. The evaluation of these markers, conducted through quantitative real-time polymerase chain reaction (qRT-PCR) and immunocytochemistry, substantiates the improved cell survival and enhanced osteogenic differentiation facilitated by the integrated nanomaterials. This comprehensive analysis underscores the efficacy of CS-PU/SPIONs/SrO2-fMWCNTs bioscaffolds in promoting MC3T3-E1 cell regeneration within, thereby holding promise for advancements in bone tissue engineering and regenerative medicine.

Synergistic Effect of Nano Strontium Titanate Coating and Ultraviolet C Photofunctionalization on Osteogenic Performance and Soft Tissue Sealing of poly(ether-ether-ketone)

This study aimed to evaluate the bioactivity of poly(ether ether ketone) (PEEK) after surface modification by persistent photoconductive strontium titanate (SrTiO3) magnetron sputtering and ultraviolet (UV) C irradiation. According to the different modifications, the PEEK specimens were randomly divided into five groups (n = 38/group): PEEK, Sr100-PEEK, Sr200-PEEK, UV/PEEK, and UV/Sr200-PEEK. Then, the specimens of Sr100-PEEK and Sr200-PEEK groups were, respectively, coated with 100 and 200 nm thickness photocatalyst SrTiO3 on the PEEK surface by magnetron sputtering. Subsequently, UV-C light photofunctionalized the specimens of PEEK and Sr200-PEEK groups to form UV/PEEK and UV/Sr200-PEEK groups. The specimens were characterized by a step meter, scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive X-ray spectroscopy (EDX), and a water contact angle meter. The release test of the Sr ion was performed by inductively coupled plasma mass spectrometry (ICP-MS). In vitro study, osteogenic activity (MC3T3-E1 osteoblast-like cells) and epithelial and connective tissue attachment (gingival epithelial cells GE1 and fibroblasts NIH3T3) were analyzed in five groups. Surface morphology of the specimens was changed after coating, and the Sr content on the Sr-PEEK surface was increased with increasing coating thickness. In addition, the contact angle was increased significantly after magnetron sputtering. After UV-C photofunctionalization, the content of surface elements changed and the contact angle was decreased. The release of Sr ion was sustained, and the final cumulative release amount did not exceed the safety limit. In vitro experiments showed that SrTiO3 improved the cell activity of MC3T3-E1 and UV-C irradiation further enhanced the osteogenic performance of PEEK. Besides, UV-C irradiation also significantly promoted the cell viability, development, and expression of adhesion proteins of GE1 and NIH3T3 on PEEK. The present investigation demonstrated that nano SrTiO3 coating with UV-C photofunctionalization synergistically enhanced the osteogenic properties and soft tissue sealing function of PEEK in vitro.

A Comparative Study on Physicochemical Properties and In Vitro Biocompatibility of Sr-Substituted and Sr Ranelate-Loaded Hydroxyapatite Nanoparticles

Synthetic hydroxyapatite nanoparticles (nHAp) possess compositional and structural similarities to those of bone minerals and play a key role in bone regenerative medicine. Functionalization of calcium phosphate biomaterials with Sr, i.e., bone extracellular matrix trace element, has been proven to be an effective biomaterial-based strategy for promoting osteogenesis in vitro and in vivo. Functionalizing nHAp with Sr2+ ions or strontium ranelate (SrRAN) can provide favorable bone tissue regeneration by locally delivering bioactive molecules to the bone defect microenvironment. Moreover, administering an antiosteoporotic drug, SrRAN, directly into site-specific bone defects could significantly reduce the necessary drug dosage and the risk of possible side effects. Our study evaluated the impact of the Sr source (Sr2+ ions and SrRAN) used to functionalize nHAp by wet precipitation on its in vitro cellular activities. The systematic comparison of physicochemical properties, in vitro Sr2+ and Ca2+ ion release, and their effect on in vitro cellular activities of the developed Sr-functionalized nHAp was performed. The ion release tests in TRIS-HCl demonstrated a 21-day slow and continuous release of the Sr2+ and Ca2+ ions from both Sr-substituted nHAp and SrRAN-loaded HAp. Also, SrRAN and Sr2+ ion release kinetics were evaluated in DMEM to understand their correlation with in vitro cellular effects in the same time frame. Relatively low concentration (up to 2 wt %) of Sr in the nHAp led to an increase in the alkaline phosphatase activity in preosteoblasts and expression of collagen I and osteocalcin in osteoblasts, demonstrating their ability to boost bone formation.

Drug Delivery and Therapy Strategies for Osteoporosis Intervention

With the advent of the aging society, osteoporosis (OP) risk increases yearly. Currently, the clinical usage of anti-OP drugs is challenged by recurrent side effects and poor patient compliance, regardless of oral, intravenous, or subcutaneous administration. Properly using a drug delivery system or formulation strategy can achieve targeted drug delivery to the bone, diminish side effects, improve bioavailability, and prolong the in vivo residence time, thus effectively curing osteoporosis. This review expounds on the pathogenesis of OP and the clinical medicaments used for OP intervention, proposes the design approach for anti-OP drug delivery, emphatically discusses emerging novel anti-OP drug delivery systems, and enumerates anti-OP preparations under clinical investigation. Our findings may contribute to engineering anti-OP drug delivery and OP-targeting therapy.

Enhancing cell adhesive and antibacterial activities of glass-fibre-reinforced polyetherketoneketone through Mg and Ag PIII

Glass-fibre-reinforced polyetherketoneketone (PEKK-GF) shows great potential for application as a dental implant restoration material; however, its surface bioinertness and poor antibacterial properties limit its integration with peri-implant soft tissue, which is critical in the long-term success of implant restoration. Herein, functional magnesium (Mg) and silver (Ag) ions were introduced into PEKK-GF by plasma immersion ion implantation (PIII). Surface characterization confirmed that the surface morphology of PEKK-GF was not visibly affected by PIII treatment. Further tests revealed that PIII changed the wettability and electrochemical environment of the PEKK-GF surface and enabled the release of Mg²⁺ and Ag⁺ modulated by Giavanni effect. In vitro experiments showed that Mg/Ag PIII-treated PEKK-GF promoted the proliferation and adhesion of human gingival fibroblasts and upregulated the expression of adhesion-related genes and proteins. In addition, the treated samples inhibited the metabolic viability and adhesion of Streptococcus mutans and Porphyromonas gingivalis on their surfaces, distorting bacterial morphology. Mg/Ag PIII surface treatment improved the soft tissue integration and antibacterial activities of PEKK-GF, which will further support and broaden its adoption in dentistry.

Coating of manganese functional polyetheretherketone implants for osseous interface integration

Polyetheretherketone (PEEK) has been used extensively in biomedical engineering and it is highly desirable for PEEK implant to possess the ability to promote cell growth and significant osteogenic properties and consequently stimulate bone regeneration. In this study, a manganese modified PEEK implant (PEEK-PDA-Mn) was fabricated via polydopamine chemical treatment. The results showed that manganese was successfully immobilized on PEEK surface, and the surface roughness and hydrophilicity significantly improved after surface modification. Cell experiments in vitro demonstrated that the PEEK-PDA-Mn possesses superior cytocompatibility in cell adhesion and spread. Moreover, the osteogenic properties of PEEK-PDA-Mn were proved by the increased expression of osteogenic genes, alkaline phosphatase (ALP), and mineralization in vitro. Further rat femoral condyle defect model was utilized to assess bone formation ability of different PEEK implants in vivo. The results revealed that the PEEK-PDA-Mn group promoted bone tissue regeneration in defect area. Taken together, the simple immersing method can modify the surface of PEEK, giving outstanding biocompatibility and enhanced bone tissue regeneration ability to the modified PEEK, which could be applied as an orthopedic implant in clinical.

Recent advances in regenerative biomaterials

Nowadays, biomaterials have evolved from the inert supports or functional substitutes to the bioactive materials able to trigger or promote the regenerative potential of tissues. The interdisciplinary progress has broadened the definition of 'biomaterials', and a typical new insight is the concept of tissue induction biomaterials. The term 'regenerative biomaterials' and thus the contents of this article are relevant to yet beyond tissue induction biomaterials. This review summarizes the recent progress of medical materials including metals, ceramics, hydrogels, other polymers and bio-derived materials. As the application aspects are concerned, this article introduces regenerative biomaterials for bone and cartilage regeneration, cardiovascular repair, 3D bioprinting, wound healing and medical cosmetology. Cell-biomaterial interactions are highlighted. Since the global pandemic of coronavirus disease 2019, the review particularly mentions biomaterials for public health emergency. In the last section, perspectives are suggested: (i) creation of new materials is the source of innovation; (ii) modification of existing materials is an effective strategy for performance improvement; (iii) biomaterial degradation and tissue regeneration are required to be harmonious with each other; (iv) host responses can significantly influence the clinical outcomes; (v) the long-term outcomes should be paid more attention to; (vi) the noninvasive approaches for monitoring in vivo dynamic evolution are required to be developed; (vii) public health emergencies call for more research and development of biomaterials; and (viii) clinical translation needs to be pushed forward in a full-chain way. In the future, more new insights are expected to be shed into the brilliant field-regenerative biomaterials.

Polymer–Metal Composite Healthcare Materials: From Nano to Device Scale

Metals have been investigated as biomaterials for a wide range of medical applications. At nanoscale, some metals, such as gold nanoparticles, exhibit plasmonics, which have motivated researchers’ focus on biosensor development. At the device level, some metals, such as titanium, exhibit good physical properties, which could allow them to act as biomedical implants for physical support. Despite these attractive features, the non-specific delivery of metallic nanoparticles and poor tissue–device compatibility have greatly limited their performance. This review aims to illustrate the interplay between polymers and metals, and to highlight the pivotal role of polymer–metal composite/nanocomposite healthcare materials in different biomedical applications. Here, we revisit the recent plasmonic engineered platforms for biomolecules detection in cell-free samples and highlight updated nanocomposite design for (1) intracellular RNA detection, (2) photothermal therapy, and (3) nanomedicine for neurodegenerative diseases, as selected significant live cell–interactive biomedical applications. At the device scale, the rational design of polymer–metallic medical devices is of importance for dental and cardiovascular implantation to overcome the poor physical load transfer between tissues and devices, as well as implant compatibility under a dynamic fluidic environment, respectively. Finally, we conclude the treatment of these innovative polymer–metal biomedical composite designs and provide a future perspective on the aforementioned research areas.