Controlled Delivery of Curcumin and Vitamin K2 from Hydroxyapatite-Coated Titanium Implant for Enhanced in Vitro Chemoprevention, Osteogenesis, and in Vivo Osseointegration

Bioactive Glasses Modulate Anticancer Activity and Other Polyphenol-Related Properties of Polyphenol-Loaded PCL/Bioactive Glass Composites

In this work, bioactive glass (BG) particles obtained by three different methods (melt-quenching, sol-gel, and sol-gel-EISA) were used as modifiers of polyphenol-loaded PCL-based composites. The composites were loaded with polyphenolic compounds (PPh) extracted from sage (Salvia officinalis L.). It was hypothesized that BG particles, due to their different textural properties (porosity, surface area) and surface chemistry (content of silanol groups), would act as an agent to control the release of polyphenols from PCL/BG composite films and other significant properties associated with and affected by the presence of PPh. The polyphenols improved the hydrophilicity, apatite-forming ability, and mechanical properties of the composites and provided antioxidant and anticancer activity. As the BG particles had different polyphenol-binding capacities, they modulated the kinetics of polyphenol release from the composites and the aforementioned properties to a great extent. Importantly, the PPh-loaded materials exhibited multifaceted and selective anticancer activity, including ROS-mediated cell cycle arrest and apoptosis of osteosarcoma (OS) cells (Saos-2) via Cdk2-, GADD45G-, and caspase-3/7-dependent pathways. The materials showed a cytotoxic and antiproliferative effect on cancerous osteoblasts but not on normal human osteoblasts. These results suggest that the composites have great potential as biomaterials for treating bone defects, particularly following surgical removal of OS tumors.

Modified Titanium Surface with Nano Amorphous Calcium Phosphate@Chitosan Oligolactate as Ion Loading Platform with Multifunctional Properties for Potential Biomedical Application

Titanium (Ti) is widely used in medical and dental implants. Calcium phosphate (CPs) coatings enhance Ti implants' osteoinductive properties, and additives further improve these coatings. Recently, a nano amorphous calcium phosphate (nACP) coating decorated with chitosan oligolactate (ChOL) and selenium (Se) showed immunomodulatory effects. This study investigates the surface morphology, composition, bioactivity, mechanical properties, and Se-release mechanism of the nACP@ChOL-Se hybrid coating on Ti substrates. Amorphous calcium phosphate (ACP) was synthesized, and the nACP@ChOL-Se hybrid coating was deposited on Ti substrates using in situ anaphoretic deposition. Physico-chemical characterization was used to analyze the surface of the coating (scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier Transform Infrared Spectroscopy). The distribution of Se within the coating was examined with energy-dispersive X-ray spectroscopy (EDS). Bioactivity was evaluated in simulated body fluid (SBF), and adhesion was tested using a scratch test method. In vitro testing determined the release mechanism of Se. SEM images illustrated the surface morphology, while AFM provided a detailed analysis of surface roughness. XRD analysis revealed structural and phase composition, and EDS confirmed Se distribution within the coating. The coating exhibited bioactivity in SBF and showed good adhesion according to the scratch test. In vitro testing uncovered the release mechanism of Se from the coating. This study successfully characterized the surface morphology, composition, bioactivity, and Se-release mechanism of the nACP@ChOL-Se hybrid coating on Ti substrates, offering insights for developing immunomodulatory coatings for medical and dental applications.

Vitamin D3 Release from MgO Doped 3D Printed TCP Scaffolds for Bone Regeneration

Regenerating bone tissue in critical-sized craniofacial bone defects remains challenging and requires the implementation of innovative bone implants with early stage osteogenesis and blood vessel formation. Vitamin D3 is incorporated into MgO-doped 3D-printed scaffolds for defect-specific and patient-specific implants in low load-bearing areas. This novel bone implant also promotes early stage osteogenesis and blood vessel development. Our results show that vitamin D3-loaded MgO-doped 3D-printed scaffolds enhance osteoblast cell proliferation 1.3-fold after being cultured for 7 days. Coculture studies on osteoblasts derived from human mesenchymal stem cells (hMSCs) and osteoclasts derived from monocytes show the upregulation of genes related to osteoblastogenesis and the downregulation of RANK-L, which is essential for osteoclastogenesis. Release of vitamin D3 also inhibits osteoclast differentiation by 1.9-fold after a 21-day culture. After 6 weeks, vitamin D3 release from MgO-doped 3D-printed scaffolds enhances the new bone formation, mineralization, and angiogenic potential. The multifunctional 3D-printed scaffolds can improve early stage osteogenesis and blood vessel formation in craniofacial bone defects.

Evaluation of sustained drug release performance and osteoinduction of magnetron-sputtered tantalum-coated titanium dioxide nanotubes

Modifying the drug-release capacity of titanium implants is essential for maintaining their long-term functioning. Titanium dioxide nanotube (TNT) arrays, owing to their drug release capacity, are commonly used in the biomaterial sphere. Their unique half open structure and arrangement in rows increase the drug release capacity. However, their rapid drug release ability not only reduces drug efficiency but also produces excessive local and systemic deposition of antibiotics. In this study, we designed a tantalum-coated TNT system for drug-release optimization. A decreased nanotube size caused by the tantalum nanocoating was observed through SEM and analyzed (TNT: 110 nm, TNT-Ta1: 80 nm, TNT-Ta3: 40 nm, TNT-Ta5: 20 nm, TNT-Ta7: <5 nm). XPS analysis revealed the distribution of the chemical components, especially that of the tantalum element. In vitro experiments showed that the tantalum nanocoating enhanced cell proliferation; in particular, TNT-Ta5 possessed the best cell viability (about 1.18 of TNT groups at 7d). It also showed that the tantalum nanocoating had a positive effect on osteogenesis (especially TNT-Ta5 and TNT-Ta7). Additionally, hydrophilic/hydrophobic drug (vancomycin/raloxifene) release results indicated that the TNT-Ta5 group possessed the most desirable sustained release capacity. Moreover, in this drug release system, the hydrophobic drug showed more sustained release capacity than the hydrophilic drug (vancomycin: sustained release for more than 48 h, raloxifene: sustained release for more than 168 h). More importantly, TNT-Ta5 is proved to be an appropriate drug release system, which possesses cytocompatibility, osteogenic capacity, and sustained drug release capacity.

Natural medicine delivery from 3D printed bone substitutes

Unmet medical needs in treating critical-size bone defects have led to the development of numerous innovative bone tissue engineering implants. Although additive manufacturing allows flexible patient-specific treatments by modifying topological properties with various materials, the development of ideal bone implants that aid new tissue regeneration and reduce post-implantation bone disorders has been limited. Natural biomolecules are gaining the attention of the health industry due to their excellent safety profiles, providing equivalent or superior performances when compared to more expensive growth factors and synthetic drugs. Supplementing additive manufacturing with natural biomolecules enables the design of novel multifunctional bone implants that provide controlled biochemical delivery for bone tissue engineering applications. Controlled release of naturally derived biomolecules from a three-dimensional (3D) printed implant may improve implant-host tissue integration, new bone formation, bone healing, and blood vessel growth. The present review introduces us to the current progress and limitations of 3D printed bone implants with drug delivery capabilities, followed by an in-depth discussion on cutting-edge technologies for incorporating natural medicinal compounds embedded within the 3D printed scaffolds or on implant surfaces, highlighting their applications in several pre- and post-implantation bone-related disorders.

Hydroxyapatite coated titanium with curcumin and epigallocatechin gallate for orthopedic and dental applications

Titanium and its alloy are clinically used as an implant material for load-bearing applications to treat bone defects. However, the lack of biological interaction between bone tissue and implant and the risk of infection are still critical challenges in clinical orthopedics. In the current work, we have developed a novel approach by first 1) modifying the implant surface using hydroxyapatite (HA) coating to enhance bioactivity and 2) integrating curcumin and epigallocatechin gallate (EGCG) in the coating that would induce chemopreventive and osteogenic potential and impart antibacterial properties to the implant. The study shows that curcumin and EGCG exhibit controlled and sustained release profiles in acidic and physiological environments. Curcumin and EGCG also show in vitro cytotoxicity toward osteosarcoma cells after 11 days, and the dual system shows a ~94 % reduction in bacterial growth, indicating their in vitro chemopreventive potential and antibacterial efficacy. The release of both curcumin and EGCG was found to be compatible with osteoblast cells and further promotes their growth. It shows a 3-fold enhancement in cellular viability in the dual drug-loaded implant compared to the untreated samples. These findings suggest that multifunctional HA-coated Ti6Al4V implants integrated with curcumin and EGCG could be a promising strategy for osteosarcoma inhibition and osteoblast cell growth while preventing infection.

Garlic extract enhances bioceramic bone scaffolds through upregulating ALP & BGLAP expression in hMSC-monocyte co-culture

Bone homeostasis is predicated by osteoblast and osteoclast cell cycles where gene expressions are responsible for their differentiation from human mesenchymal stem cells (hMSC) and monocytes, respectively. The pro-osteogenic potential of an hMSC-monocyte co-culture can be measured through complementary DNA (mRNA synthesis) within the nucleus, known as quantitative polymerase chain reaction (qPCR). Through this technique, the effects of garlic extract (allicin) release from calcium phosphate bone scaffolds on gene expression of bone forming and bone remodeling cells was explored. Results show this complex biomaterial system enhances hMSC differentiation through the upregulation of bone-forming proteins. Osteoblastic gene markers alkaline phosphatase (ALP) and osteocalcin (BGLAP), are respectively upregulated by 3-fold and 1.6-fold by day 14. These mature osteoblasts then upregulate the receptor activator of nuclear factor-kB ligand (RANKL) which recruits osteoclast cells, as captured by a nearly 2-fold higher osteoclast expression of tartrate-resistance acid-phosphatase (ACP5). This also activates antagonist osteoprotegerin (OPG) expression in osteoblasts, decreasing osteoclast resorption potential and ACP5 expression by day 21. The pro-osteogenic environment with garlic extract release is further quantified by a 4× increase in phosphatase activity and visibly captured in immunofluorescent tagged confocal images. Also corroborated by enhanced collagen formation in a preliminary in vivo rat distal femur model, this work collectively reveals how garlic extract can enhance bioceramic scaffolds for bone tissue regenerative applications.

Micelle encapsulated curcumin and piperine-laden 3D printed calcium phosphate scaffolds enhance in vitro biological properties

Limitations in the current clinical management of critical-sized osseous defects have driven the need for multifunctional bone constructs. The ideal bone scaffold should possess advanced microarchitecture, well-defined pore interconnectivity, and supply biological signals, which actively guide and control tissue regeneration while simultaneously preventing post-implantation complications. Here, a natural medicine-based localized drug delivery from 3D printed scaffold is presented, which offers controlled release of curcumin, piperine from nano-sized polymeric micelles, and burst release of antibacterial carvacrol from the coating endowing the scaffold with their distinct, individual biological properties. This functionalized scaffold exhibits improved osteoblast (hFOB) cell attachment, 4-folds higher hFOB proliferation, and 73% increased hFOB differentiation while simultaneously providing cytotoxicity towards osteosarcoma cells with 61% lesser viability compared to control. In vitro, early tube formation (p < 0.001) indicates that the scaffolds can modulate the endothelial cellular network, critical for faster wound healing. The scaffold also exhibits 94% enhanced antibacterial efficacy (p < 0.001) against gram-positive Staphylococcus aureus, the main causative bacteria for osteomyelitis. Together, the multifunctional scaffolds provide controlled delivery of natural biomolecules from the nano-sized micelle-loaded 3D printed matrix for significant improvement in osteoblast proliferation, endothelial formation, osteosarcoma, and bacterial inhibition, guiding better bone regeneration for post-traumatic defect repair.

Multifunctional polydopamine - Zn2+-curcumin coated additively manufactured ceramic bone grafts with enhanced biological properties

The lack of site-specific chemotherapeutic agents after osteosarcoma surgeries often induces severe side effects. We propose the utilization of curcumin as an alternative natural chemo-preventive drug for tumor-specific delivery systems with 3D printed tricalcium phosphate (TCP) based artificial bone grafts. The poor bioavailability and hydrophobic nature of curcumin restrict its clinical use. We have used polydopamine (PDA) coating with Zn2+ functionalization to enhance the curcumin release in the biological medium. The obtained PDA-Zn2+ complex is characterized by X-ray photoelectron spectroscopy (XPS). The presence of PDA-Zn2+ coating leads to ~2 times enhancement in curcumin release. We have computationally predicted and validated the optimized surface composition by a novel multi-objective optimization method. The experimental validation of the predicted compositions indicates that the PDA-Zn2+ coated curcumin immobilized delivery system leads to a ~12 folds decrease in osteosarcoma viability on day 11 as compared to only TCP. The osteoblast viability shows ~1.4 folds enhancement. The designed surface shows the highest ~90 % antibacterial efficacy against gram-positive and gram-negative bacteria. This unique strategy of curcumin delivery with PDA-Zn2+ coating is expected to find application in low-load bearing critical-sized tumor-resection sites.

Functional anti-bone tumor biomaterial scaffold: construction and application

Bone tumors, including primary bone tumors and bone metastases, have been plagued by poor prognosis for decades. Although most tumor tissue is removed, clinicians are still confronted with the dilemma of eliminating residual cancer cells and regenerating defective bone tissue after surgery. Therefore, functional biomaterial scaffolds are considered to be the ideal candidates to bridge defective tissues and restrain cancer recurrence. Through functionalized structural modifications or coupled therapeutic agents, they provide sufficient mechanical strength and osteoinductive effects while eliminating cancer cells. Numerous novel approaches such as photodynamic, photothermal, drug-conjugated, and immune adjuvant-assisted therapies have exhibited remarkable efficacy against tumors while exhibiting low immunogenicity. This review summarizes the progress of research on biomaterial scaffolds based on different functionalization strategies in bone tumors. We also discuss the feasibility and advantages of the combined application of multiple functionalization strategies. Finally, potential obstacles to the clinical translation of anti-tumor bone bioscaffolds are highlighted. This review will provide valuable references for future advanced biomaterial scaffold design and clinical bone tumor therapy.

The Era of Biomaterials: Smart Implants?

Conditions, accidents, and aging processes have brought with them the need to develop implants with higher technology that allow not only the replacement of missing tissue but also the formation of tissue and the recovery of its function. The development of implants is due to advances in different areas such as molecular-biochemistry (which allows the understanding of the molecular/cellular processes during tissue repair), materials engineering, tissue regeneration (which has contributed advances in the knowledge of the properties of the materials used for their manufacture), and the so-called intelligent biomaterials (which promote tissue regeneration through inductive effects of cell signaling in response to stimuli from the microenvironment to generate adhesion, migration, and cell differentiation processes). The implants currently used are combinations of biopolymers with properties that allow the formation of scaffolds with the capacity to mimic the characteristics of the tissue to be repaired. This review describes the advances of intelligent biomaterials in implants applied in different dental and orthopedic problems; by means of these advances, it is expected to overcome limitations such as additional surgeries, rejections and infections in implants, implant duration, pain mitigation, and mainly, tissue regeneration.

In vivo and In vitro properties evaluation of curcumin loaded MgO doped 3D printed TCP scaffolds

The lack of site-specific chemotherapeutic agents to treat bone malignancy throws a significant challenge in the design of a delivery vehicle. The major scientific question posed in this study is, can we utilize curcumin-loaded magnesium oxide (MgO) doped 3D printed tricalcium phosphate (TCP) bone grafts as a localized delivery system that improves early stage in vivo osseointegration and in vitro chemoprevention, antibacterial properties? We have utilized curcumin as an alternative natural chemopreventive agent for bone cancer-specific delivery after direct incorporation on the 3D printed tricalcium phosphate (TCP) bone grafts. The addition of MgO as a dopant to TCP leads to ∼1.3 times enhancement in compressive strength. The designed drug delivery system shows up to ∼22% curcumin release in a physiological pH of 7.4 after 30 days. The presence of curcumin leads to up to ∼8.5 times reduction in osteosarcoma viability. In vitro results indicate that these scaffolds significantly enhance bone-forming osteoblast cells while reducing the bone-resorbing osteoclast cells. The in vivo rat distal femur model surgery followed by histological assessment with H&E, vWF, and Movat pentachrome staining results show that the designed scaffolds lead to new bone formation (up to ∼2.5 times higher than the control) after successful implantation. The presence of MgO and curcumin results in up to ∼71% antibacterial efficacy against osteomyelitis causing S. aureus. These 3D printed osteogenic and chemopreventive scaffolds can be utilized in patient-specific low load-bearing defect sites.

In situ titanium phosphate formation on a titanium implant as ultrahigh bonding with nano-hydroxyapatite coating for rapid osseointegration

Titanium (Ti) has been widely used as a dental implant material due to its excellent mechanical property and good biocompatibility. However, its poor biological activity severely limits its ability to bond with bony tissues. To ameliorate this situation, a preparation method of ultra-high bonding nano-hydroxyapatite (n-HA) coating on the Ti surface is urgently needed. Here, Ti phosphate/n-HA (TiP-Ca) composite coatings with ultra-high bonding were prepared by a two-step hydrothermal treatment. The TiP coating was first formed in situ on the pure Ti substrate and then n-HA crystals further grew on the TiP surface. The formation mechanism of composite coating and reasons for increased bonding strength were systematically investigated. The results show that the TiP-Ca coating remains stable and exhibits an ultra-high bonding strength with the Ti implant (up to 783.30 ± 207.46 N). An effective solution was designed to address the problems of easy peel off. Cell experiments showed that TiP-Ca could promote the adhesion of MC3T3-E1 and expression of OCN, Runx2, and ALP. In vivo evaluation further confirmed that the TiP-Ca composite coating significantly enhanced osseointegration. The designed coating shows great potential in clinical application of implants.

Localized Nanoindentation Paradigm for Revealing Sutured Tissue Interface Mechanics and Integrity

This study investigates the nanoindentation technique to elucidate the quasi-static and dynamic stress response at the wounded and sutured tissue interface. In vitro modeling and wound healing analysis enable an understanding of sutured tissue interface integrity, modulus, and stability using an artificial abdominal wall model. Sutured tissues with simple interrupted suturing (SIS) demonstrated a 35-40% higher modulus than simple continuous suturing (SCS). High-density suturing with a suture space of 2.5 mm exhibited a 2-fold higher modulus than low-density suturing with a suture space of 5 mm. The elastic modulus of the sutured pad immersed in deionized water was ∼70-95% of the dry condition. The dynamic stress data indicate that long-term body motions-triggered stress instability at the wound interface was affected by suturing style and density. The pivotal factors determining wound healing are quasi-static and dynamic modulus at the sutured interface, which is intimately associated with patient pain, wound complications, healing speed, and blood flow. The proposed method and data are an original approach to addressing wound healing, contributing to patient well-being and identifying, interpreting, and breaking the drawn-out debates in the suturing field.

Recent Trends in Hydroxyapatite Supplementation for Osteoregenerative Purposes

Bone regeneration has gained attention in the biomedical field, which has led to the development of materials and synthesis methods meant to improve osseointegration and cellular bone activity. The properties of hydroxyapatite, a type of calcium phosphate, have been researched to determine its advantages for bone tissue engineering, particularly its biocompatibility and ability to interact with bone cells. Recently, the advantages of utilizing nanomolecules of hydroxyapatite, combined with various substances, in order to enhance and combine their characteristics, have been reported in the literature. This review will outline the cellular and molecular roles of hydroxypatite, its interactions with bone cells, and its nano-combinations with various ions and natural products and their effects on bone growth, development, and bone repair.

Curcumin in human osteosarcoma: From analogs to carriers

Osteosarcoma (osteogenic sarcoma), the most prevalent primary malignant bone tumor in adolescents, confers low survival rates in patients with metastatic disease. Dietary curcumin has a number of anticancer properties but has poor bioavailability. To improve the clinical applications of curcumin, several potential curcumin analogs and nanobased curcumin delivery systems have been developed. In this critical review, we address the biological and pharmacological characteristics of curcumin and its analogs, with an emphasis on strategies to improve the bioactivity and bioavailability of curcumin analogs that may increase their application in the treatment of potent human metastatic osteosarcoma. We highlight promising current multifunctional nanoformulations and three-dimensional printed scaffold systems utilized for the targeting and delivery of curcumin in human osteosarcoma cells. Our purpose is to drive further research on curcumin analogs and carriers to improve their bioavailability and anti-osteosarcoma bioactivity.

Additively manufactured Bi-functionalized bioceramics for reconstruction of bone tumor defects

Bone tissue exhibits critical factors for metastatic cancer cells and represents an extremely pleasant spot for further growth of tumors. The number of metastatic bone lesions and primary tumors that arise directly from cells comprised in the bone milieu is constantly increasing. Bioceramics have recently received significant attention in bone tissue engineering and local drug delivery applications. Additionally, additive manufacturing of bioceramics offers unprecedented advantages including the possibilities to fill irregular voids after the resection and fabricate patient-specific implants. Herein, we investigated the recent advances in additively manufactured bioceramics and ceramic-based composites that were used in the local bone tumor treatment and reconstruction of bone tumor defects. Furthermore, it has been extensively explained how to bi-functionalize ceramics-based biomaterials and what current limitations impede their clinical application. We have also discussed the importance of further development into ceramic-based biomaterials and molecular biology of bone tumors to: (1) discover new potential therapeutic targets to enhance conventional therapies, (2) local delivering of bio-molecular agents in a customized and "smart" way, and (3) accomplish a complete elimination of tumor cells in order to prevent tumor recurrence formation. We emphasized that by developing the research focus on the introduction of novel 3D-printed bioceramics with unique properties such as stimuli responsiveness, it will be possible to fabricate smart bioceramics that promote bone regeneration while minimizing the side-effects and effectively eradicate bone tumors while promoting bone regeneration. In fact, by combining all these therapeutic strategies and additive manufacturing, it is likely to provide personalized tumor-targeting therapies for cancer patients in the foreseeable future. STATEMENT OF SIGNIFICANCE: To increase the survival rates of cancer patients, different strategies such as surgery, reconstruction, chemotherapy, radiotherapy, etc have proven to be essential. Nonetheless, these therapeutic protocols have reached a plateau in their effectiveness due to limitations including drug resistance, tumor recurrence after surgery, toxic side-effects, and impaired bone regeneration following tumor resection. Hence, novel approaches to specifically and locally attack cancer cells, while also regenerating the damaged bony tissue, have being developed in the past years. This review sheds light to the novel approaches that enhance local bone tumor therapy and reconstruction procedures by combining additive manufacturing of ceramic biomaterials and other polymers, bioactive molecules, nanoparticles to affect bone tumor functions, metabolism, and microenvironment.

Nano-Hydroxyapatite Composite Scaffolds Loaded with Bioactive Factors and Drugs for Bone Tissue Engineering

Nano-hydroxyapatite (n-HAp) is similar to human bone mineral in structure and biochemistry and is, therefore, widely used as bone biomaterial and a drug carrier. Further, n-HAp composite scaffolds have a great potential role in bone regeneration. Loading bioactive factors and drugs onto n-HAp composites has emerged as a promising strategy for bone defect repair in bone tissue engineering. With local delivery of bioactive agents and drugs, biological materials may be provided with the biological activity they lack to improve bone regeneration. This review summarizes classification of n-HAp composites, application of n-HAp composite scaffolds loaded with bioactive factors and drugs in bone tissue engineering and the drug loading methods of n-HAp composite scaffolds, and the research direction of n-HAp composite scaffolds in the future is prospected.

Poly(pro-curcumin) Materials Exhibit Dual Release Rates and Prolonged Antioxidant Activity as Thin Films and Self-Assembled Particles

Curcumin is a natural polyphenol that exhibits remarkable antioxidant and anti-inflammatory activities; however, its clinical application is limited in part by its physiological instability. Here, we report the synthesis of curcumin-derived polyesters that release curcumin upon hydrolytic degradation to improve curcumin stability and solubility in physiological conditions. Curcumin was incorporated in the polymer backbone by a one-pot condensation polymerization in the presence of sebacoyl chloride and polyethylene glycol (PEG, M_n = 1 kDa). The thermal and mechanical properties, surface wettability, self-assembly behavior, and drug-release kinetics all depend sensitively on the mole percentage of curcumin incorporated in these statistical copolymers. Curcumin release was triggered by the hydrolysis of phenolic esters on the polymer backbone, which was confirmed using a PEGylated curcumin model compound, which represented a putative repeating unit within the polymer. The release rate of curcumin was controlled by the hydrophilicity of the polymers. Burst release (2 days) and extended release (>8 weeks) can be achieved from the same polymer depending on curcumin content in the copolymer. The materials can quench free radicals for at least 8 weeks and protect primary neurons from oxidative stress in vitro. Further, these copolymer materials could be processed into both thin films and self-assembled particles, depending on the solvent-based casting conditions. Finally, we envision that these materials may have potential for neural tissue engineering application, where antioxidant release can mitigate oxidative stress and the inflammatory response following neural injury.

Multifunctional 3D-printed bioceramic scaffolds: Recent strategies for osteosarcoma treatment

Osteosarcoma is the most prevalent bone malignant tumor in children and teenagers. The bone defect, recurrence, and metastasis after surgery severely affect the life quality of patients. Clinically, bone grafts are implanted. Primary bioceramic scaffolds show a monomodal osteogenesis function. With the advances in three-dimensional printing technology and materials science, while maintaining the osteogenesis ability, scaffolds become more patient-specific and obtain additional anti-tumor ability with functional agents being loaded. Anti-tumor therapies include photothermal, magnetothermal, old and novel chemo-, gas, and photodynamic therapy. These strategies kill tumors through novel mechanisms to treat refractory osteosarcoma due to drug resistance, and some have shown the potential to reverse drug resistance and inhibit metastasis. Therefore, multifunctional three-dimensional printed bioceramic scaffolds hold excellent promise for osteosarcoma treatments. To better understand, we review the background of osteosarcoma, primary 3D-printed bioceramic scaffolds, and different therapies and have a prospect for the future.

Curcumin and its Analogs and Carriers: Potential Therapeutic Strategies for Human Osteosarcoma

Curcumin is a natural polyphenol phytochemical derived from turmeric with antioxidant, anti-inflammatory, and anticancer properties but is concerned about poor solubility in water, absorption, and metabolic stability. Potent metastatic osteosarcoma is the most common primary bone cancer in children, adolescents, and young adults. It is responsible for low survival rates because of its high rate of metastasis to the lungs. To improve poor bioavailability, numerous curcumin analogs were developed to possess anticancer characteristics through a variety of biological pathways involved in cytotoxicity, proliferation, autophagy, sensitizing chemotherapy, and metastases. This review provides an overview of their various pharmacological functions, molecular mechanisms, and therapeutic potential as a remedy for human osteosarcoma. To enhance therapeutic efficacy, several liposomal nanoparticles, nanocarriers, multifunctional micelles, and three-dimensional printed scaffolds have also been developed for the controlled delivery of curcumin targeting human osteosarcoma cells. Consequently, curcumin and several potential analogs and delivery formulations are optimistic candidates to improve the currently available strategy for human osteosarcoma. However, further insight into the mechanism of action of promising curcumin analogs and the development of carriers in clinical trials of osteosarcoma needs to be investigated to improve their overall potency and clinical utility, in particular the anti-metastatic effect.

Vitamin K: A novel cancer chemosensitizer

Cancer incidences are growing rapidly and causing millions of deaths globally. Cancer treatment is one of the most exigent challenges. Drug resistance is a natural phenomenon and is considered one of the major obstacles in the successful treatment of cancer by chemotherapy. Combination therapy by the amalgamation of various anticancer drugs has suggested modulating tumor response by targeting various signaling pathways in a synergistic or additive manner. Vitamin K is an essential nutrient and has recently been investigated as a potential anticancer agent. The combination of vitamin K analogs, such as vitamins K1, K2, K3, and K5, with other chemotherapeutic drugs have demonstrated a safe, cost-effective, and most efficient way to overcome drug resistance and improved the outcomes of prevailing chemotherapy. Published reports have shown that vitamin K in combination therapy improved the efficacy of clinical drugs by promoting apoptosis and cell cycle arrest and overcoming drug resistance by inhibiting P-glycoprotein. In this review, we discuss the mechanism, cellular targets, and possible ways to develop vitamin K subtypes into effective cancer chemosensitizers. Finally, this review will provide a scientific basis for exploiting vitamin K as a potential agent to improve the efficacy of chemotherapeutic drugs.

Combination Therapy Using Polyphenols: An Efficient Way to Improve Antitumoral Activity and Reduce Resistance

Polyphenols represent a structural class of mainly natural organic chemicals that contain multiple phenol structural units. The beneficial properties of polyphenols have been extensively studied for their antitumor, anti-inflammatory, and antibacterial effects, but nowadays, their medical applications are starting to be extended to many other applications due to their prebiotic role and their impact on the microbiota. This review focused on the use of polyphenols in cancer treatment. Their antineoplastic effects have been demonstrated in various studies when they were tested on numerous cancer lines and some in in vivo models. A431 and SCC13 human skin cancer cell lines treated with EGCG presented a reduced cell viability and enhanced cell death due to the inactivation of β-catenin signaling. Additionally, resveratrol showed a great potential against breast cancer mainly due to its ability to exert both anti-estrogenic and estrogenic effects (based on the concentration) and because it has a high affinity for estrogen receptors ERα and Erβ. Polyphenols can be combined with different classical cytostatic agents to enhance their therapeutic effects on cancer cells and to also protect healthy cells from the aggressiveness of antitumor drugs due to their anti-inflammatory properties. For instance, curcumin has been reported to reduce the gastrointestinal toxicity associated with chemotherapy. In the case of 5-FU-induced, it reduced the gastrointestinal toxicity by increasing the intestinal permeability and inhibiting mucosal damage. Co-administration of EGCG and doxorubicin induced the death of liver cancer cells. EGCG has the ability to inhibit autophagic activity and stop hepatoma Hep3B cell proliferation This symbiotic approach is well-known in medical practice including in multiple chemotherapy.

Plasma sprayed fluoride and zinc doped hydroxyapatite coated titanium for load-bearing implants

Titanium (Ti) alloys show excellent fatigue and corrosion resistance, high strength to weight ratio, and no toxicity; however, poor osseointegration ability of Ti may lead to implant loosening in vivo. Plasma spraying of hydroxyapatite [HA, Ca₁₀ (PO₄)₆ (OH)₂] coating on Ti surfaces is commercially used to enhance osseointegration and the long-term stability of these implants. The biological properties of HA can be improved with the addition of both cationic and anionic dopants, such as zinc ions (Zn²⁺) and fluoride (F^-). However, the hygroscopic nature of fluoride restricts its utilization in the radiofrequency (RF) plasma spray process. In addition, the amount of doping needs to be optimized to ensure cytocompatibility. We have fabricated zinc and fluoride doped HA-coated Ti6Al4V (Ti64) to mitigate these challenges using compositional and parametric optimizations. The RF induction plasma spraying method is utilized to prepare the coatings. Multiple parametric optimizations with amplitude and frequency during the processing result in coating thicknesses between 80 and 145 μm. No adverse effects on the adhesion properties of the coating are noticed because of doping. The antibacterial efficacy of each composition is tested against S. aureus for 24, 48, and 72 h, and showed that the addition of zinc oxide and calcium fluoride to HA leads to nearly 70 % higher antibacterial efficacy than pure HA-coated samples. The addition of osteogenic Zn²⁺and F^- leads to 1.5 times higher osteoblast viability for the doped samples than pure HA-coated samples after 7-days of cell culture. Zn²⁺ and F^- doped HA-coated Ti64 with simultaneous improvements in anti-bacterial efficacy and in vitro biocompatibility can find application in load-bearing implants, particularly in revision surgeries and immune-compromised patients.

Zinc curcumin complex on fluoride doped hydroxyapatite with enhanced biological properties for dental and orthopedic applications

Since antiquity, curcumin, from turmeric is utilized in traditional Indian medicine (Ayurveda) to treat bone disorders. However, the hydrophobic nature and poor absorption of curcumin limit its clinical applications. There is a need to develop a novel strategy that can significantly enhance curcumin's biological properties. The current work reports the utilization of Zn²⁺-curcumin complex from a fluoride doped hydroxyapatite matrix for osteosarcoma inhibition, osteoblast growth, and anti-bacterial properties. The interaction between Zn²⁺ and curcumin increases curcumin release by ~ 2.5 folds. The fabricated drug delivery system shows up to ~ 1.6 times enhancement in osteoblast cell viability. The presence of curcumin results in ~ 4 times more osteosarcoma inhibition compared to control. The antibacterial efficacy of this system is confirmed against Staphylococcus aureus, due to the presence of antibacterial fluoride, zinc, and curcumin. This multifunctional drug delivery system can be utilized for various bone-tissue engineering and dental applications.

Construction of Local Drug Delivery System on Titanium-Based Implants to Improve Osseointegration

Titanium and its alloys are the most widely applied orthopedic and dental implant materials due to their high biocompatibility, superior corrosion resistance, and outstanding mechanical properties. However, the lack of superior osseointegration remains the main obstacle to successful implantation. Previous traditional surface modification methods of titanium-based implants cannot fully meet the clinical needs of osseointegration. The construction of local drug delivery systems (e.g., antimicrobial drug delivery systems, anti-bone resorption drug delivery systems, etc.) on titanium-based implants has been proved to be an effective strategy to improve osseointegration. Meanwhile, these drug delivery systems can also be combined with traditional surface modification methods, such as anodic oxidation, acid etching, surface coating technology, etc., to achieve desirable and enhanced osseointegration. In this paper, we review the research progress of different local drug delivery systems using titanium-based implants and provide a theoretical basis for further research on drug delivery systems to promote bone–implant integration in the future.

Effects of Vitamin A (Retinol) Release from Calcium Phosphate Matrices and Porous 3D Printed Scaffolds on Bone Cell Proliferation and Maturation

Vitamin A is a fat-soluble compound widely known for vision health. Highly variable reports on its effects on bone health have necessitated further research to truly understand its role on bone cell proliferation. Retinol, one bioactive form of vitamin A, is incorporated into synthetic bone graft scaffolds for low load-bearing clinical bone treatment. The objective of this work is to understand the effects of retinol on osteoblast and osteoclast cells when embedded within calcium phosphate matrices, including interconnected porous 3D printed tricalcium phosphate scaffolds. Results show that hydrophobic retinol can be released from bone scaffolds when a combination of biodegradable polymers, polycaprolactone and polyethylene glycol, are employed as drug carriers. The release of retinol in vitro can support a 20 ± 1% increase in osteoblast (bone-forming) cell proliferation with proper cell adhesion and filopodial extensions. Osteoclast cell morphology is necrosed and torn with a reduction in proliferation at approximately 6 ± 1% when retinol is present. In addition, inhibition of osteoclastic resorption pit bays is noted using scanning electron microscopy. With the scaffolds' round pore interconnectivity facilitating retinol release, this system can provide an alternative to traditional bone grafts while additionally supporting bone healing through enhanced osteoblast cell proliferation and inhibition of osteoclast resorption activity.

Traditional Chinese Medicine Compound-Loaded Materials in Bone Regeneration

Bone is a dynamic organ that has the ability to repair minor injuries via regeneration. However, large bone defects with limited regeneration are debilitating conditions in patients and cause a substantial clinical burden. Bone tissue engineering (BTE) is an alternative method that mainly involves three factors: scaffolds, biologically active factors, and cells with osteogenic potential. However, active factors such as bone morphogenetic protein-2 (BMP-2) are costly and show an unstable release. Previous studies have shown that compounds of traditional Chinese medicines (TCMs) can effectively promote regeneration of bone defects when administered locally and systemically. However, due to the low bioavailability of these compounds, many recent studies have combined TCM compounds with materials to enhance drug bioavailability and bone regeneration. Hence, the article comprehensively reviewed the local application of TCM compounds to the materials in the bone regeneration in vitro and in vivo. The compounds included icariin, naringin, quercetin, curcumin, berberine, resveratrol, ginsenosides, and salvianolic acids. These findings will contribute to the potential use of TCM compound-loaded materials in BTE.

Combining Coaxial Electrospinning and 3D Printing: Design of Biodegradable Bilayered Membranes with Dual Drug Delivery Capability for Periodontitis Treatment

Periodontitis is a chronic inflammatory disease that can lead to significant destruction of tooth-supporting tissues, compromising dental function and patient's health. Although the currently employed treatment approaches can limit the advance of the disease, the development of multifunctional and hierarchically structured materials is still in demand for achieving successful tissue regeneration. Here, we combine coaxial electrospinning and 3D printing techniques to prepare bilayered zein-based membranes as a potential dual drug delivery platform for periodontal tissue regeneration. A layer of core-sheath electrospun nanofibers consisting of poly(ethylene oxide) (PEO)/curcumin (Curc)/tetracycline hydrochloride (TH) as the core and zein/poly(ε-caprolactone)(PCL)/β-glycerolphosphate (β-GP) as the sheath was deposited over a 3D printed honeycomb PLA/zein/Curc platform in order to render a bilayered structure that can mimic the architecture of periodontal tissue. The physicochemical properties of engineered constructs as well as the release profiles of distinct drugs were mainly controlled by varying the concentration of zein (10, 20, 30%, w/w relative to dry PCL) on the sheath layer of nanofibers, which displayed average diameters ranging from 150 to 400 nm. In vitro experiments demonstrated that the bilayered constructs provided sustained release of distinct drugs over 8 days and exhibited biocompatibility toward human oral keratinocytes (Nok-si) (cell viability >80%) as well as antibacterial activity against distinct bacterial strains including those of the red complex such as Porphyromonas gingivalis and Treponema denticola, which are recognized to elicit aggressive and chronic periodontitis. Our study reveals the potential of zein-based bilayered membranes as a dual drug delivery platform for periodontal tissue regeneration.

Titanium Implants and Local Drug Delivery Systems Become Mutual Promoters in Orthopedic Clinics

Titanium implants have always been regarded as one of the gold standard treatments for orthopedic applications, but they still face challenges such as pain, bacterial infections, insufficient osseointegration, immune rejection, and difficulty in personalizing treatment in the clinic. These challenges may lead to the patients having to undergo a painful second operation, along with increased economic burden, but the use of drugs is actively solving these problems. The use of systemic drug delivery systems through oral, intravenous, and intramuscular injection of various drugs with different pharmacological properties has effectively reduced the levels of inflammation, lowered the risk of endophytic bacterial infection, and regulated the progress of bone tumor cells, processing and regulating the balance of bone metabolism around the titanium implants. However, due to the limitations of systemic drug delivery systems-such as pharmacokinetics, and the characteristics of bone tissue in the event of different forms of trauma or disease-sometimes the expected effect cannot be achieved. Meanwhile, titanium implants loaded with drugs for local administration have gradually attracted the attention of many researchers. This article reviews the latest developments in local drug delivery systems in recent years, detailing how various types of drugs cooperate with titanium implants to enhance antibacterial, antitumor, and osseointegration effects. Additionally, we summarize the improved technology of titanium implants for drug loading and the control of drug release, along with molecular mechanisms of bone regeneration and vascularization. Finally, we lay out some future prospects in this field.

Research progress on the biological modifications of implant materials in 3D printed intervertebral fusion cages

Anterior spine decompression and reconstruction with bone grafts and fusion is a routine spinal surgery. The intervertebral fusion cage can maintain intervertebral height and provide a bone graft window. Titanium fusion cages are the most widely used metal material in spinal clinical applications. However, there is a certain incidence of complications in clinical follow-ups, such as pseudoarticulation formation and implant displacement due to nonfusion of bone grafts in the cage. With the deepening research on metal materials, the properties of these materials have been developed from being biologically inert to having biological activity and biological functionalization, promoting adhesion, cell differentiation, and bone fusion. In addition, 3D printing, thin-film, active biological material, and 4D bioprinting technology are also being used in the biofunctionalization and intelligent advanced manufacturing processes of implant devices in the spine. This review focuses on the biofunctionalization of implant materials in 3D printed intervertebral fusion cages. The surface modifications of implant materials in metal endoscopy, material biocompatibility, and bioactive functionalizationare summarized. Furthermore, the prospects and challenges of the biofunctionalization of implant materials in spinal surgery are discussed. Fig.a.b.c.d.e.f.g As a pre-selected image for the cover, I really look forward to being selected. Special thanks to you for your comments.

Potential of natural products in osteosarcoma treatment: Focus on molecular mechanisms

Osteosarcoma is the most frequent type of bone cancer found in children and adolescents, and commonly arises in the metaphyseal region of tubular long bones. Standard therapeutic approaches, such as surgery, chemotherapy, and radiation therapy, are used in the management of osteosarcoma. In recent years, the mortality rate of osteosarcoma has decreased due to advances in treatment methods. Today, the scientific community is investigating the use of different naturally derived active principles against various types of cancer. Natural bioactive compounds can function against cancer cells in two ways. Firstly they can act as classical cytotoxic compounds by non-specifically affecting macromolecules, such as DNA, enzymes, and microtubules, which are also expressed in normal proliferating cells, but to a greater extent by cancer cells. Secondly, they can act against oncogenic signal transduction pathways, many of which are activated in cancer cells. Some bioactive plant-derived agents are gaining increasing attention because of their anti-cancer properties. Moreover, some naturally-derived compounds can significantly promote the effectiveness of standard chemotherapy drugs, and in certain cases are able to ameliorate drug-induced adverse effects caused by chemotherapy. In the present review we summarize the effects of various naturally-occurring bioactive compounds against osteosarcoma.

Chimeric Peptides Quickly Modify the Surface of Personalized 3D Printing Titanium Implants to Promote Osseointegration

Titanium (Ti) and titanium alloys have been widely used in the field of biomedicine. However, the unmatched biomechanics and poor bioactivities of conventional Ti implants usually lead to insufficient osseointegration. To tackle these challenges, it is critical to develop a novel Ti implant that meets the bioadaptive requirements for load-bearing critical bone defects. Notably, three-dimensional (3D)-printed Ti implants mimic the microstructure and mechanical properties of natural bones. Additionally, eco-friendly techniques based on inorganic-binding peptides have been applied to modify Ti surfaces. Herein, in our study, Ti surfaces were modified to reinforce osseointegration using chimeric peptides constructed by connecting W9, RP1P, and minTBP-1 directly or via (GP)4, respectively. PR1P is derived from the extracellular VEGF-binding domain of prominin-1, which increases the expression of VEGF and promotes the binding of VEGF to endothelial cells, thereby accelerating angiogenesis. W9 induces osteoblast differentiation in bone marrow mesenchymal stem cells and human mesenchymal stem cells to promote bone formation. Overall, chimeric peptides promote osseointegration by promoting angiogenesis and osteogenesis. Additionally, chimeric peptides with P3&4 were more effective than those with P1&2 in improving osseointegration, which might be ascribed to the capacity of P3&4 to provide a greater range for chimeric peptides to express their activity. This work successfully used chimeric peptides to modify 3D-Ti implant surfaces to improve osseointegration on the implant-bone surface.

Curcumin-Microsphere/IR820 Hybrid Bifunctional Hydrogels for In Situ Osteosarcoma Chemo-co-Thermal Therapy and Bone Reconstruction

Conventional biomaterial-mediated osteosarcoma therapy mainly focuses on its antitumor effect yet often fails to overcome the problem of post-treatment bone tissue defect repair. Simultaneously, minimally invasive drug delivery methods are becoming spotlights for normal tissue preservation. Herein, an injectable curcumin-microsphere/IR820 coloaded hybrid methylcellulose hydrogel (Cur-MP/IR820 gel) platform was designed for osteosarcoma therapy and bone regeneration. In vitro, the K7M2wt osteosarcoma cells were eradicated by hyperthermia and curcumin. Later, the sustained release of curcumin promoted alkaline phosphatase expression and calcium deposition of bone mesenchymal stem cells. In vivo, this hybrid hydrogel could reach tumor site via injection and turned into hydrogel due to heat sensitivity. Under the irradiation of an 808 nm laser, localized hyperthermia (∼51 °C) generated in 5 min to ablate the tumor. Meanwhile, the thermal-accelerated curcumin release and thermal-increased cell membrane permeability led to tumor cell apoptosis. Tumors in photothermal-co-chemotherapy group were successfully restrained from day 2 after treatment. After that, bone reconstruction was promoted because of sustained released curcumin. The chemo-co-thermal efficacy and osteogenic capacity of Cur-MP/IR820 hydrogel suggest a promising approach to the treatment of osteosarcoma and provide provoking inspiration for treating bone tumors and repairing bone tissue.

In situ functionalizing calcium phosphate biomaterials with curcumin for the prevention of bacterial biofilm infections

This study developed a novel bioactive bone substitute (hydroxyapatite, HA) with improved anti-biofilm activity by functionalizing with curcumin (anti-biofilm compound) which provide sufficient flux of curcumin concentration for 14 days. The released curcumin acts to inhibit biofilm formation and control the number of viable planktonic cells simultaneously. To prepare curcumin-functionalized HA, different concentrations of curcumin (up to 3% w/v) were added simultaneously during the precipitation process of HA. The highest loading (50 mg/g HA) of curcumin onto HA was achieved with 2% w/v of curcumin. Physicochemical characterizations of curcumin-functionalized HA composites revealed that curcumin was successfully incorporated onto HA. Curcumin was sustainably released over 14 days, while higher curcumin release was observed in acidic condition (pH 4.4) compared to physiological (pH 7.4). The cytotoxicity assays revealed that no significant difference on bone cells growth on curcumin-functionalized HA and non-functionalized HA. Curcumin-functionalized HA was effective to inhibit bacterial cell attachment and subsequent biofilm maturation stages. The anti-biofilm effect was stronger against Staphylococcus aureus compared to Pseudomonas aeruginosa. The curcumin-functionalized HA composite significantly delayed the maturation of S. aureus compared to non-functionalized HA in which microcolonies of cells only begin to appear at 96 h. Up to 3.0 log reduction in colony forming unit (CFU)/mL of planktonic cells was noted at 24 h of incubation for both microorganisms. Thus, in this study we have suggested that curcumin loaded HA could be an alternative antimicrobial agent to control the risk of infections in post-surgical implants.

Curcumin in Osteosarcoma Therapy: Combining With Immunotherapy, Chemotherapeutics, Bone Tissue Engineering Materials and Potential Synergism With Photodynamic Therapy

Osteosarcoma is a dominating malignant bone tumor with high mortality due to pulmonary metastases. Furthermore, because of the cancer cell erosion and surgery resection, osteosarcoma always causes bone defects, which means dysfunction and disfigurement are seldom inevitable. Although various advanced treatments (e.g. chemotherapy, immunotherapy, radiotherapy) are coming up, the 5-year survival rate for osteosarcoma with metastases is still dismal. In line with this, the more potent treatments for osteosarcoma are in high demand. Curcumin, a perennial herb, has been reportedly applied in the therapy of various types of tumors via different mechanisms. In vitro, it has also been reported that curcumin can inhibit the proliferation of osteosarcoma cell lines and can be used to repair bone defects. This seems curcumin is a promising candidate in osteosarcoma treatment. However, due to its congenital property like hydrophobicity, and low bioavailability, affecting its anticancer effect, clinical applications of curcumin are highly limited. To enhance its performance in cancer therapies, some synergist approaches with curcumin have emerged. The present review presents some prospective ones (i.e. combinations with immunotherapy, chemotherapeutics, bone tissue engineering, and biomaterials) applied in osteosarcoma treatment. Additionally, with the advancements of photodynamic therapy in cancer therapy, this review also prospects the combination of curcumin with photodynamic therapy in osteosarcoma treatment.

Practical strategy to construct anti-osteosarcoma bone substitutes by loading cisplatin into 3D-printed titanium alloy implants using a thermosensitive hydrogel

Surgical resection and perioperative adjuvant chemotherapy-based therapies have improved the prognosis of patients with osteosarcoma; however, intraoperative bone defects, local tumour recurrence, and chemotherapy-induced adverse effects still affect the quality of life of patients. Emerging 3D-printed titanium alloy (Ti₆Al₄V) implants have advantages over traditional implants in bone repair, including lower elastic modulus, lower stiffness, better bone conduction, more bone in-growth, stronger mechanical interlocking, and lager drug-loading capacity by their inherent porous structure. Here, cisplatin, a clinical first-line anti-osteosarcoma drug, was loaded into Ti₆Al₄V implants, within a PLGA-PEG-PLGA thermo-sensitive hydrogel, to construct bone substitutes with both anti-osteosarcoma and bone-repair functions. The optimal concentrations of cisplatin (0.8 and 1.6 mg/mL) were first determined in vitro. Thereafter, the anti-tumour effect and biosafety of the cisplatin/hydrogel-loaded implants, as well as their bone-repair potential were evaluated in vivo in tumour-bearing mouse, and bone defect rabbit models, respectively. The loading of cisplatin reduced tumour volume by more than two-thirds (from 641.1 to 201.4 mm³) with negligible organ damage, achieving better anti-tumour effects while avoiding the adverse effects of systemic cisplatin delivery. Although bone repair was hindered by cisplatin loading at 4 weeks, no difference was observed at 8 weeks in the context of implants with versus without cisplatin, indicating acceptable long-term stability of all implants (with 8.48%–10.04% bone in-growth and 16.94%–20.53% osseointegration). Overall, cisplatin/hydrogel-loaded 3D-printed Ti₆Al₄V implants are safe and effective for treating osteosarcoma-caused bone defects, and should be considered for clinical use.

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Vehiculated within PLGA-PEG-PLGA hydrogel, cisplatin can be conveniently loaded into 3D-printed Ti₆Al₄V implants.

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The cisplatin/hydrogel-loaded implants are safe and show a good anti-tumour potential both in vitro and in vivo.

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This strategy has better anti-osteosarcoma effects and fewer side effects than the conventional cisplatin delivery method.

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Cisplatin loading does not decrease the bone repair effect of 3D-printed Ti₆Al₄V implants 8 weeks after surgery.

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As the components of the implants are non-toxic, this strategy has great potential for clinical translation.

Natural medicine delivery from biomedical devices to treat bone disorders: A review

With an increasing life expectancy and aging population, orthopedic defects and bone graft surgeries are increasing in global prevalence. Research to date has advanced the understanding of bone biology and defect repair mechanism, leading to a marked success in the development of synthetic bone substitutes. Yet, the quest for functionalized bone grafts prompted the researchers to find a viable alternative that regulates cellular activity and supports bone regeneration and healing process without causing serious side-effects. Recently, researchers have introduced natural medicinal compounds (NMCs) in bone scaffold that enables them to release at a desirable rate, maintains a sustained release allowing sufficient time for tissue in-growth, and guides bone regeneration process with minimized risk of tissue toxicity. According to World Health Organization (WHO), NMCs are gaining popularity in western countries for the last two decades and are being used by 80% of the population worldwide. Compared to synthetic drugs, NMCs have a broader range of safety window and thus suitable for prolonged localized delivery for bone regeneration. There is limited literature focusing on the integration of bone grafts and natural medicines that provides detailed scientific evidences on NMCs, their toxic limits and particular application in bone tissue engineering, which could guide the researchers to develop functionalized implants for various bone disorders. This review will discuss the emerging trend of NMC delivery from bone grafts, including 3D-printed structures and surface-modified implants, highlighting the significance and potential of NMCs for bone health, guiding future paths toward the development of an ideal bone tissue engineering scaffold. STATEMENT OF SIGNIFICANCE: To date, additive manufacturing technology provids us with many advanced patient specific or defect specific bone constructs exhibiting three-dimensional, well-defined microstructure with interconnected porous networks for defect-repair applications. However, an ideal scaffold should also be able to supply biological signals that actively guide tissue regeneration while simultaneously preventing post-implantation complications. Natural biomolecules are gaining popularity in tissue engineering since they possess a safer, effective approach compared to synthetic drugs. The integration of bone scaffolds and natural biomolecules exploits the advantages of customized, multi-functional bone implants to provide localized delivery of biochemical signals in a controlled manner. This review presents an overview of bone scaffolds as delivery systems for natural biomolecules, which may provide prominent advancement in bone development and improve defect-healing caused by various musculoskeletal disorders.

Surface engineering of biomaterials in orthopedic and dental implants: Strategies to improve osteointegration, bacteriostatic and bactericidal activities

BACKGROUND

The success of biomedical implants in orthopedic and dental applications is usually limited due to insufficient bone-implant integration, and implant-related infections. Biointerfaces are critical in regulating their interactions and the desirable performance of biomaterials in biological environment. Surface engineering has been widely studied to realize better control of the interface interaction to further enhance the desired behavior of biomaterials.

PURPOSE AND SCOPE

This review aims to investigate surface coating strategies in hard tissue applications to address insufficient osteointegration and implant-related infection problems.

SUMMARY

We first focused on surface coatings to enhance the osteointegration and biocompatibility of implants by emphasizing calcium phosphate-related, nanoscale TiO₂ -related, bioactive tantalum-based and biomolecules incorporated coatings. Different coating strategies such as plasma spraying, biomimetic deposition, electrochemical anodization and LENS are discussed. We then discussed techniques to construct anti-adhesive and bactericidal surface while emphasizing multifunctional surface coating techniques that combine potential osteointegration and antibacterial activities. The effects of nanotopography via TiO₂ coatings on antibacterial performance are interesting and included. A smart bacteria-responsive titanium dioxide nanotubes coating is also attractive and elaborated.

CONCLUSION

Developing multifunctional surface coatings combining osteogenesis and antimicrobial activity is the current trend. Surface engineering methods are usually combined to obtain hierarchical multiscale surface structures with better biofunctionalization outcomes.

An alternative ex vivo method to evaluate the osseointegration of Ti-6Al-4V alloy also combined with collagen

Due to the increasing number of orthopedic implantation surgery and advancements in biomaterial manufacturing, chemistry and topography, there is an increasing need of reliable and rapid methods for the preclinical investigation of osseointegration and bone ingrowth. Implant surface composition and topography increase osteogenicity, osteoinductivity, osteoconductivity and osseointegration of a prosthesis. Among the biomaterials used to manufacture an orthopedic prosthesis, titanium alloy (Ti-6Al-4V) is the most used. Type I collagen (COLL I) induces cell function, adhesion, differentiation and bone extracellular matrix component secretion and it is reported to improve osseointegration if immobilized on the alloy surface. The aim of the present study was to evaluate the feasibility of an alternative ex vivo model, developed by culturing rabbit cortical bone segments with Ti-6Al-4V alloy cylinders (Ti-POR), fabricated through the process of electron beam melting (EBM), to evaluate osseointegration. In addition, a comparison was made with Ti-POR coated with COLL I (Ti-POR-COLL) to evaluate osseointegration in terms of bone-to-implant contact (BIC) and new bone formation (nBAr/TAr) at 30, 60 and 90 d of culture. After 30 and 60 d of culture, BIC and nBAr/TAr resulted significantly higher in Ti-POR-COLL implants than in Ti-POR. No differences have been found at 90 d of culture. With the developed model it was possible to distinguish the biomaterial properties and behavior. This study defined and confirmed for the first time the validity of the alternative ex vivo method to evaluate osseointegration and that COLL I improves osseointegration and bone growth of Ti-6Al-4V fabricated through EBM.

Polyphenols as a versatile component in tissue engineering

The fabrication of functional tissue or organs substitutes has always been the pursuit of goals in the field of tissue engineering. But even biocompatible tissue-engineered scaffolds still suffer from immune rejection, subsequent long-term oxidative stress and inflammation, which can delay normal tissue repair and regeneration. As a well-known natural antioxidant, polyphenols have been widely used in tissue engineering in recent years. The introduced polyphenols not only reduce the damage of oxidative stress to normal tissues, but show specific affinity to functional molecules, such as receptors, enzyme, transcription and transduction factors, etc. Therefore, polyphenols can promote the recovery process of damaged tissues by both regulating tissue microenvironment and participating in cell events, which embody specifically in antioxidant, anti-inflammatory, antibacterial and growth-promoting properties. In addition, based on its hydrophilic and hydrophobic moieties, polyphenols have been widely used to improve the mechanical properties and anti-degradation properties of tissue engineering scaffolds. In this review, the research advances of tissue engineering scaffolds containing polyphenols is discussed systematically from the aspects of action mechanism, introduction method and regulation effect of polyphenols, in order to provide references for the rational design of polyphenol-related functional scaffolds.

Bio-surface coated titanium scaffolds with cancellous bone-like biomimetic structure for enhanced bone tissue regeneration

In view of the fact that titanium (Ti)-based implants still face the problem of loosening and failure of the implants caused by the slow biological response, the low osseointegration rate and the implant bacterial infection in clinical application, we designed a cancellous bone-like biomimetic Ti scaffold using the template accumulated by sugar spheres as a pore-forming agent. And based on a modified surface mineralization process and mussel-like adhesion mechanism, a silicon-doped calcium phosphate composite coating (Van-pBNPs/pep@pSiCaP) with Vancomycin (Van)-loaded polydopamine (pDA)-modified albumin nanoparticles (Van-pBNPs) and cell adhesion peptides (GFOGER) was constructed on the surface of Ti scaffold for mimicking the extracellular matrix (ECM) microenvironment of natural bone matrix to induce greater tissue regeneration. The in vitro study demonstrated that this porous Ti scaffold with functional bio-surface could distinctly facilitate cell early adhesion and spreading, and activate the expression of α2β1 integrin receptor on the cell membrane through promoting the formation of focal adhesions (FAs) in bone marrow stromal cells (BMSCs), thus mediating greater osteogenic cell differentiation. And it could also effectively inhibit the adhesion and growth of Staphylococcus epidermidis, exhibiting good antibacterial properties. Moreover, the Van-pBNPs/pep@pSiCaP-Ti scaffolds showed enhanced in vivo bone-forming ability due to the contributions of bioactive chemical components and the natural cancellous bone-like macrostructure. This work offers a promising structural and functional bio-inspired strategy for designing metal implants with desirable ability of osteoinduction synergistically with antibacterial efficacy for promoting bone regeneration and infection prevention simultaneously. STATEMENT OF SIGNIFICANCE: This manuscript describes a new method for making porous Ti scaffolds with a natural cancellous bone-like structure. Besides, a functional bio-surface was constructed on the bionic structure, mimicking some of the functions of the collagen-rich organic matrix and inorganic CaP nanocrystallites of native ECM of bone in chemical components and biological activities. This interconnected inter-pore opening structure encouraged the migration of cells among open macro-pores within the scaffold. In addition, the functionalized surface not only improved early cell adhesion, spreading, stimulated greater osteogenic differentiation of bone-forming cells, but also endowed the scaffold with excellent antibacterial effect. The biomimetic metal implant with multiple biomedical functions designed in this study has a great clinical application potential. This study represents a feasible method for the preparation of biomimetic structure of metal implants and the improvement of their surface biological activity.

Effects of vitamin C on osteoblast proliferation and osteosarcoma inhibition using plasma coated hydroxyapatite on titanium implants

Plasma-sprayed hydroxyapatite (HAp) coated titanium (Ti) implants are being extensively used in orthopedic surgeries and post-tumor resection to repair load-bearing segmental bone defects. In this study, vitamin C, an abundantly available natural biomolecule, is loaded onto plasma-sprayed HAp-coated commercially pure titanium (cpTi) surface to evaluate its chemopreventive and osteogenic properties, suggesting its clinical significance as an alternative or adjunct therapy in the treatment for osteosarcoma bone resection. Controlled release of vitamin C from HAp coated cpTi implant is assessed by in vitro drug release study, where Korsmeyer-Peppas model was applied to understand the release kinetics. After 21 days, the implants loaded with 400 and 800 μg of vitamin C showed a cumulative release of 62.7 and 74.1% in acidic microenvironment, whereas, 50.9% and 53.1% of total vitamin C release were observed by the implants loaded with 400 and 800 μg of vitamin C in physiological pH, respectively. To observe the effects of in vitro vitamin C release on osteosarcoma and osteoblast cellular activity, MG-63 (human osteosarcoma) and hFOB (human fetal osteoblast) cells were cultured on the surface of the implant and MTT cell viability assay and FESEM were carried out at 3 and 7 days of culture. Presence of high dosages 25 mM vitamin C shows a statistically significant (p≤0.05) decrease in osteosarcoma cell viability after 3 days, while both 5 mM and 25mM vitamin C reduced cellular viability by 2.5 folds (p≤0.05) compared to the control after 7 days. Interestingly, the presence of vitamin C showed no obvious signs of cytotoxicity towards osteoblast cell-line at day 3 and day 7, as confirmed by the MTT assay. Additionally, the FESEM images depict layers of hFOB cellular morphology on the surface of the implants, suggesting excellent cytocompatibility towards the osteoblast cells. These results suggest that vitamin C loaded HAp coated cpTi implant with improved osteogenic and chemopreventive properties can be considered as a promising reconstructive option to repair the post-tumor resection defects in osteosarcoma.