Zinc substituted hydroxyapatite/silk fiber/methylcellulose nanocomposite for bone tissue engineering applications

Exploring the frontiers: The potential and challenges of bioactive scaffolds in osteosarcoma treatment and bone regeneration

The standard treatment for osteosarcoma combines surgery with chemotherapy, yet it is fraught with challenges such as postoperative tumor recurrence and chemotherapy-induced side effects. Additionally, bone defects after surgery often surpass the body's regenerative ability, affecting patient recovery. Bioengineering offers a novel approach through the use of bioactive scaffolds crafted from metals, ceramics, and hydrogels for bone defect repair. However, these scaffolds are typically devoid of antitumor properties, necessitating the integration of therapeutic agents. The development of a multifunctional therapeutic platform incorporating chemotherapeutic drugs, photothermal agents (PTAs), photosensitizers (PIs), sound sensitizers (SSs), magnetic thermotherapeutic agents (MTAs), and naturally occurring antitumor compounds addresses this limitation. This platform is engineered to target osteosarcoma cells while also facilitating bone tissue repair and regeneration. This review synthesizes recent advancements in integrated bioactive scaffolds (IBSs), underscoring their dual role in combating osteosarcoma and enhancing bone regeneration. We also examine the current limitations of IBSs and propose future research trajectories to overcome these hurdles.

Hydroxyapatite/Silk Fibroin Composite Scaffold with a Porous Structure and Mechanical Strength Similar to Cancellous Bone by Electric Field-Induced Gel Technology

Repair and regeneration of bone tissue defects is a multidimensional process that has been highly challenging to date. The artificial bone scaffold materials, which play a core role, still face the conflict that a biofriendly porous structure will reduce the mechanical performance and accelerate degradation. Herein, a multistage porous structured hydroxyapatite (HA)/silk fibroin (SF) composite scaffold (e-HA/SF) was successfully constructed by cleverly utilizing electric field-induced gel technology. The results indicated that the prepared e-HA/SF scaffolds possess biomimetic hierarchical porous structures with a suitable porosity similar to that of cancellous bone. The HA nanocrystals were uniformly encapsulated in the three-dimensional space of the composite scaffold, thus endowing the e-HA/SF composite scaffolds with an enhanced mechanical performance. Notably, the maximum compression stress and Young's modulus of e-HA/SF-2 scaffolds can reach 24.66 ± 0.88 and 28.91 ± 3.19 MPa, respectively, which are equivalent to those of cancellous bone. Such mechanical performance enhancement was previously unattainable through conventional freeze-drying strategies. Moreover, the introduction of bioactive nano-HA can trigger the optimal cell response in both static and dynamic cell culture experiments in vitro. The e-HA/SF composite scaffold developed in this study can better balance the conflict between the porous structure and mechanical and degradation properties of porous scaffolds.

The Incorporation of Zinc into Hydroxyapatite and Its Influence on the Cellular Response to Biomaterials: A Systematic Review

Zinc is known for its role in enhancing bone metabolism, cell proliferation, and tissue regeneration. Several studies proposed the incorporation of zinc into hydroxyapatite (HA) to produce biomaterials (ZnHA) that stimulate and accelerate bone healing. This systematic review aimed to understand the physicochemical characteristics of zinc-doped HA-based biomaterials and the evidence of their biological effects on osteoblastic cells. A comprehensive literature search was conducted from 2022 to 2024, covering all years of publications, in three databases (Web of Science, PUBMED, Scopus), retrieving 609 entries, with 36 articles included in the analysis according to the selection criteria. The selected studies provided data on the material's physicochemical properties, the methods of zinc incorporation, and the biological effects of ZnHA on bone cells. The production of ZnHA typically involves the wet chemical synthesis of HA and ZnHA precursors, followed by deposition on substrates using processes such as liquid precursor plasma spraying (LPPS). Characterization techniques confirmed the successful incorporation of zinc into the HA lattice. The findings indicated that zinc incorporation into HA at low concentrations is non-cytotoxic and beneficial for bone cells. ZnHA was found to stimulate cell proliferation, adhesion, and the production of osteogenic factors, thereby promoting in vitro mineralization. However, the optimal zinc concentration for the desired effects varied across studies, making it challenging to establish a standardized concentration. ZnHA materials are biocompatible and enhance osteoblast proliferation and differentiation. However, the mechanisms of zinc release and the ideal concentrations for optimal tissue regeneration require further investigation. Standardizing these parameters is essential for the effective clinical application of ZnHA.

Vancomycin-loaded methylcellulose aerogel scaffolds for advanced bone tissue engineering

Scaffolds grafting combined with local delivery of antibiotics at the injury site may promote bone regeneration along with prevention of infections. In this work, a processing strategy combining the 3D-printing of polysaccharide-based inks with supercritical (sc)CO2 technology was employed to manufacture drug-loaded, nanostructured, and personalized-to-patient aerogels for the first time. Methylcellulose (MC) was employed as graft matrix endowed with nanohydroxyapatite (nHA) to confer bioactivity as required in bone tissue engineering (BTE). MC-nHA aerogels were obtained through the 3D-printing of hydrogel-based scaffolds followed by scCO2 drying. Aerogels were loaded with vancomycin (VAN), an antibiotic employed in the management of bone infections. Textural properties and printing fidelity of scaffolds were studied as well as VAN release, long-term bioactivity, and pre-osteoblasts mineralization. In vitro cell studies and in vivo Artemia salina tests were carried out to evaluate the potential toxicity of the antibiotic-loaded aerogels. Aerogels efficacy in inhibiting bacterial growth was assessed by antimicrobial tests with Staphylococcus aureus. Textural stability of the aerogels after 7 months of storage was also evaluated. Obtained results showed that the scaffolds promoted the intended two-in-one effect (bone repair and infection management simultaneously) in a personalized way, regulating formulation design, drug dose, and porosity.

Mechanical, biocompatibility and antibacterial studies of gelatin/polyvinyl alcohol/silkfibre polymeric scaffold for bone tissue engineering

The current study focuses on the incorporation of natural polymers (gelatin, silk fibre) and synthetic (polyvinyl alcohol) polymer towards the fabrication of a novel composite for bone tissue engineering. The Electrospinning method was used to fabricate the novel gelatin/polyvinyl alcohol/silk fibre scaffold. XRD, FTIR and SEM-EDAX analysis was performed to characterize the composite. The characterized composite was investigated for its physical properties (porosity and mechanical studies) and biological studies (antimicrobial activity, hemocompatibility, bioactivity). The fabricated composite showed high porosity and the highest tensile strength of 34 MPa, with elongation at a break of 35.82 for the composite. The antimicrobial activity of the composite was studied and the zone of inhibition was measured around 51 ± 0.54 for E. coli, 48 ± 0.48 for S. aureus and 50 ± 0.26 for C. albicans. The hemolytic % was noted around 1.36 for the composite and the bioactivity assay revealed the formation of apatite on composite surfaces.

Zn-doped Mono- and Biphasic Calcium Phosphate Materials Derived from Agriculture Waste and Their Potential Biomedical Applications: Part I

In this study, calcium phosphate materials were obtained via a simple, eco-friendly wet synthesis method using hen eggshells as a calcium source. It was shown that Zn ions were successfully incorporated into hydroxyapatite (HA). The obtained ceramic composition depends on the zinc content. When doped with 10 mol % of Zn, in addition to HA and Zn-doped HA, DCPD (dicalcium phosphate dihydrate) appeared and its content increased with the increase in Zn concentration. All doped HA materials exhibited antimicrobial activity against S. aureus and E. coli. Nevertheless, fabricated samples significantly decreased preosteoblast (MC3T3-E1 Subclone 4) viability in vitro, exerting a cytotoxic effect which probably resulted from their high ionic reactivity.

Fabrication and characterization of novel polyhydroxybutyrate-keratin/nanohydroxyapatite electrospun fibers for bone tissue engineering applications

The role of scaffolds in bone regeneration is of great importance. Here, the electrospun scaffolds of poly (3-hydroxybutyrate)-keratin (PHB-K)/nanohydroxyapatite (nHA) with different morphologies (long nanorods (HAR) and very short nanorods (HAP)) and weight percentages (up to 10 w/w%) of nHA were fabricated and characterized. The fibers integrity, the porosity of above 80%, and increase in pore size up to 16 μm were observed by adding nHA. The nanofibers crystallinity increased by 13.5 and 22.8% after the addition of HAR and HAP, respectively. The scaffolds contact angle decreased by almost 20° and 40° after adding 2.5 w/w% HAR and HAP, respectively. The tensile strength of the scaffolds increased from 2.99 ± 0.3 MPa for PHB-K to 6.44 ± 0.16 and 9.27 ± 0.04 MPa for the scaffolds containing 2.5 w/w% HAR and HAP, respectively. After immersing the scaffolds into simulated body fluid (SBF), the Ca concentration decreased by 55% for HAR- and 73% for HAP-containing scaffolds, showing the bioactivity of nHA-containing scaffolds. The results of cell attachment, proliferation, and viability of MG-63 cells cultured on the nanocomposites showed the positive effects of nHA. The results indicate that the nanocomposite scaffolds, especially HAP-containing ones, can be suitable for bone tissue engineering applications.