Chitosan-hybrid poss nanocomposites for bone regeneration: The effect of poss nanocage on surface, morphology, structure and in vitro bioactivity

Time-Sequential and Multi-Functional 3D Printed MgO2/PLGA Scaffold Developed as a Novel Biodegradable and Bioactive Bone Substitute for Challenging Postsurgical Osteosarcoma Treatment

Osteosarcoma (OS) is the most commonly occurring primary bone malignant tumor. The clinical postsurgical OS treatment faces big challenges for the staged therapeutic requirements of early anti-tumor, anti-bacterial, and long-lasting osteogenesis. Herein, multi-functional bioactive scaffolds with time-sequential functions of preventing tumor recurrence, inhibiting bacterial infection, and promoting bone defect repair are designed as a novel strategy. Nanocomposite scaffold magnesium peroxide (MgO2)/poly (lactide-co-glycolide) is prepared by low-temperature 3D printing for controllable releasing magnesium ions (Mg2+) and reactive oxygen species in a time-sequential manner. The scaffold with 20 wt% MgO2 (20MP) is verified with desired mechanical properties, as well as exhibits staged release behavior of bioactive elements with hydrogen peroxide (H2O2) release for the first 3 weeks, and long-lasting Mg2+ release for 12 weeks. The released H2O2 initiates chemodynamic therapy to induce apoptosis and ferroptosis in tumor cells, along with activating the anticancer immune microenvironment by M1 polarization of macrophages. The released Mg2+ subsequently enhances bone repair by activating the Wnt3a/GSK-3β/β-catenin signaling pathway to promote osteogenic differentiation of bone marrow mesenchymal stem cells and create osteopromotive immune microenvironment by M2 polarization of macrophages. In conclusion, the multi-functional 20MP scaffold demonstrates time-sequential therapeutic properties as an innovative strategy for OS-associated bone defect treatment.

Thermosensitive Polyhedral Oligomeric Silsesquioxane Hybrid Hydrogel Enhances the Antibacterial Efficiency of Erythromycin in Bacterial Keratitis

Bacterial keratitis is a serious ocular infection that can impair vision or even cause blindness. The clinical use of antibiotics is limited due to their low bioavailability and drug resistance. Hence, there is a need to develop a novel drug delivery system for this infectious disease. In this study, erythromycin (EM) was encapsulated into a bifunctional polyhedral oligomeric silsesquioxane (BPOSS) with the backbone of the poly-PEG/PPG urethane (BPEP) hydrogel with the aim of improving the drug efficiency in treating bacterial keratitis. A comprehensive characterization of the BPEP hydrogel was performed, and its biocompatibility was assessed. Furthermore, we carried out the evaluation of the antimicrobial effect of the BPEP-EM hydrogel in S. aureus keratitis using in vivo mouse model. The BPEP hydrogel exhibited self-assembling and thermogelling properties, which assisted the drug loading of drug EM and improved its water solubility. Furthermore, the BPEP hydrogel could effectively bind with mucin on the ocular surface, thereby markedly prolonging the ocular residence time of EM. In vivo testing confirmed that the BPEP-EM hydrogel exerted a potent therapeutic action in the mouse model of bacterial keratitis. In addition, the hydrogel also exhibited an excellent biocompatibility. Our findings demonstrate that the BPEP-EM hydrogel showed a superior therapeutic effect in bacterial keratitis and demonstrated its potential as an ophthalmic formulation.

Chitosan alchemy: transforming tissue engineering and wound healing

Chitosan, a biopolymer acquired from chitin, has emerged as a versatile and favorable material in the domain of tissue engineering and wound healing. Its biocompatibility, biodegradability, and antimicrobial characteristics make it a suitable candidate for these applications. In tissue engineering, chitosan-based formulations have garnered substantial attention as they have the ability to mimic the extracellular matrix, furnishing an optimal microenvironment for cell adhesion, proliferation, and differentiation. In the realm of wound healing, chitosan-based dressings have revealed exceptional characteristics. They maintain a moist wound environment, expedite wound closure, and prevent infections. These formulations provide controlled release mechanisms, assuring sustained delivery of bioactive molecules to the wound area. Chitosan's immunomodulatory properties have also been investigated to govern the inflammatory reaction during wound healing, fostering a balanced healing procedure. In summary, recent progress in chitosan-based formulations portrays a substantial stride in tissue engineering and wound healing. These innovative approaches hold great promise for enhancing patient outcomes, diminishing healing times, and minimizing complications in clinical settings. Continued research and development in this field are anticipated to lead to even more sophisticated chitosan-based formulations for tissue repair and wound management. The integration of chitosan with emergent technologies emphasizes its potential as a cornerstone in the future of regenerative medicine and wound care. Initially, this review provides an outline of sources and unique properties of chitosan, followed by recent signs of progress in chitosan-based formulations for tissue engineering and wound healing, underscoring their potential and innovative strategies.

The H2O2 Self-Sufficient 3D Printed β-TCP Scaffolds with Synergistic Anti-Tumor Effect and Reinforced Osseointegration

Tumor recurrence and massive bone defects are two critical challenges for postoperative treatment of oral and maxillofacial tumor, posing serious threats to the health of patients. Herein, in order to eliminate residual tumor cells and promote osteogenesis simultaneously, the hydrogen peroxide (H2O2) self-sufficient TCP-PDA-CaO2-CeO2 (TPCC) scaffolds are designed by preparing CaO2 or/and CeO2 nanoparticles (NPs)/chitosan solution and modifying the NPs into polydopamine (PDA)-modified 3D printed TCP scaffolds by rotary coating method. CaO2 NPs loaded on the scaffolds can release Ca2+ and sufficient H2O2 in the acidic tumor microenvironment (TME). The generated H2O2 can further produce hydroxyl radicals (·OH) under catalysis effect by peroxidase (POD) activity of CeO2 NPs, in which the photothermal effect of the PDA coating enhances its POD catalytic effect. Overall, NPs loaded on the scaffold chemically achieve a cascade reaction of H2O2 self-sufficiency and ·OH production, while functionally achieving synergistic effects on anti-tumor and bone promotion. In vitro and in vivo studies show that the scaffolds exhibit effective osteo-inductivity, induced osteoblast differentiation and promote osseointegration. Therefore, the multifunctional composite scaffolds not only validate the concept of chemo-dynamic therapy (CDT) cascade therapy, but also provide a promising clinical strategy for postoperative treatment of oral and maxillofacial tumor.

POSS and PEG Contained Copolymer for Antibioadhesive Rigid Contact Lenses Materials Application

Myopia is a global public health issue. Rigid contact lenses (RCLs) are an effective way to correct or control myopia. However, bioadhesion issues remain one of the significant obstacles limiting its clinical application. Although enhancing hydrophilicity through various surface treatments can mitigate this problem, the duration of effectiveness is short-lived and the processing involved is complex and costly. Herein, an antiadhesive RCLs material was designed via 8-armed methacrylate-POSS (8MA-POSS), and poly(ethylene glycol) methacrylate (PEGMA) copolymerization with 3-[tris(trimethylsiloxy)silyl] propyl methacrylate (TRIS). The POSS and PEG segments incorporated P(TRIS-co-PEGMA-co-8MA-POSS) (PTPM) material was obtained and their optical transparency, refractive index, resolution, hardness, surface charge, thermal features, and wettability were tested and optimized. The antibioadhesion activities, including protein, lipid, and bacteria, were evaluated as well. In vitro and in vivo results indicated that the optimized antibioadhesive PTPM materials present good biocompatibility and biosafety. Thus, such POSS and PEG segments containing material were a potential antibioadhesive RCL material option.

Thermoplastic polyurethane/POSS nanohybrids: Synthesis, morphology, and biological properties

Recent studies show good osteoinductive properties of polyurethanes modified with polyhedral oligomeric silsesquioxanes (POSS). In this work, three types of POSS; propanediolisobutyl-POSS (PHI-POSS), disilanolisobutyl-POSS (DSI-POSS), and octahydroxybutyl-POSS (OCTA-POSS) were chemically incorporated into linear polyurethane based on an aliphatic isocyanate, hexamethylene diisocyanate (HDI), to obtain new nanohybrid PU-POSS materials. The full conversion of POSS was confirmed by Fourier transform infrared spectroscopy (FTIR-ATR) spectra of the model reactions with pure HDI. The materials obtained were investigated by FTIR, SEM-EDS, and DSC. The DSC studies showed the thermoplasticity of the obtained materials and apparently good recovery. 30-day immersion in SBF (simulated body fluid) revealed an increase in the rate of deposition of hydroxyapatite (HAp) for the highest POSS loadings, resulting in thick layers of hydroxyapatite (~60-40 μm), and the Ca/P ratio 1.67 (even 1.785). The structure and properties of the inorganic layer depend on the type of POSS, the number of hard segments, and those containing POSS, which can be tailored by changing the HDI/poly(tetramethylene glycol) (PTMG) ratio. Furthermore, the obtained composites revealed good biocompatibility, as confirmed by cytotoxicity tests conducted on two cell lines; normal human dermal fibroblasts (NHDF) and primary human osteoblasts (HOB). Adherent cells seeded on the tested materials showed viability even after a 48-h incubation. After this time, the population of viable, and proliferating cells exceeded 90%. Bioimaging studies have shown the fibroblast and osteoblast cells were well attached to the surface of the tested materials.

Promising Materials in the Fight against Healthcare-Associated Infections: Antibacterial Properties of Chitosan-Polyhedral Oligomeric Silsesquioxanes Hybrid Hydrogels

New technologies and materials could help in this fight against healthcare-associated infections. As the majority of these infections are caused by antibiotic-resistant bacteria, the development of materials with intrinsic antibacterial properties is a promising field of research. We combined chitosan (CS), with antibacterial properties, with polyhedral oligomeric silsesquioxanes (POSS), a biocompatible polymer with physico-chemical, mechanical, and rheological properties, creating a hydrogel using cross-linking agent genipin. The antibacterial properties of CS and CS-POSS hydrogels were investigated against nosocomial Gram-positive and Gram-negative bacteria both in terms of membrane damage and surface charge variations, and finally, the anti-biofilm property was studied through confocal microscopy. Both materials showed a good antibacterial capacity against all analyzed strains, both in suspension, with % decreases between 36.36 and 73.58 for CS and 29.86 and 66.04 for CS-POSS, and in plates with % decreases between 55.29 and 78.32 and 17.00 and 53.99 for CS and CS-POSS, respectively. The treated strains compared to the baseline condition showed an important membrane damage, which also determined a variation of surface charges, and finally, for both hydrogels, a remarkable anti-biofilm property was highlighted. Our findings showed a possible future use of these biocompatible materials in the manufacture of medical and surgical devices with intrinsic antibacterial and anti-biofilm properties.

Development of Cissus quadrangularis-Loaded POSS-Reinforced Chitosan-Based Bilayer Sponges for Wound Healing Applications: Drug Release and In Vitro Bioactivity

Nowadays, antibiotic-loaded biomaterials have been widely used in wound healing applications. However, the use of natural extracts has come into prominence as an alternative to these antimicrobial agents in the recent period. Among natural sources, Cissus quadrangularis (CQ) herbal extract is used for treatment of bone and skin diseases in ayurvedic medicine due to its antibacterial and anti-inflammatory effects. In this study, chitosan-based bilayer wound dressings were fabricated with electrospinning and freeze-drying techniques. CQ extract-loaded chitosan nanofibers were coated on chitosan/POSS nanocomposite sponges using an electrospinning method. The bilayer sponge is designed to treat exudate wounds while mimicking the layered structure of skin tissue. Bilayer wound dressings were investigated with regard to the morphology and physical and mechanical properties. In addition, CQ release from bilayer wound dressings and in vitro bioactivity studies were performed to determine the effect of POSS nanoparticles and CQ extract loading on NIH/3T3 and HS2 cells. The morphology of nanofibers was investigated with SEM analysis. Physical characteristics of bilayer wound dressings were determined with FT-IR analysis, swelling study, open porosity determination, and mechanical test. The antimicrobial activity of CQ extract released from bilayer sponges was investigated with a disc diffusion method. Bilayer wound dressings' in vitro bioactivity was examined using cytotoxicity determination, wound healing assay, proliferation, and the secretion of biomarkers for skin tissue regeneration. The nanofiber layer diameter was obtained in the range of 77.9-97.4 nm. The water vapor permeability of the bilayer dressing was obtained as 4021 to 4609 g/m2day, as it is in the ideal range for wound repair. The release of the CQ extract over 4 days reached 78-80% cumulative release. The release media were found to be antibacterial against Gram-negative and Gram-positive bacteria. In vitro studies showed that both CQ extract and POSS incorporation induced cell proliferation as well as wound healing activity and collagen deposition. As a result, CQ-loaded bilayer CHI-POSS nanocomposites were found as a potential candidate for wound healing applications.

Development of a three-dimensional in vitro blood-brain barrier using the chitosan-alginate polyelectrolyte complex as the extracellular matrix

Polyelectrolyte complexes (PECs) consist of a spontaneous assembly of oppositely charged polysaccharides. PECs can be used to obtain a hydrogel tissue scaffold in tissue culture. In this study, it is aimed to use PEC as a blood-brain barrier (BBB) model scaffold. By mixing polycationic chitosan and polyanionic alginate solutions at a certain ratio it was obtained a 3D hydrogel scaffold and mimicked in vivo environment of the tissue. The PEC hydrogel scaffold’s chemical, physical, and mechanical characterizations were performed with FTIR, DSC, DMA, and Micro-CT analyses. In order to develop an in vitro BBB model, the human neuroblastoma cell line (SH-SY5Y) and mouse astrocyte cell line (C8-D1A) were mixed into a hydrogel, which is the abluminal side of the BBB. Human microvascular endothelial cells (HBEC-5i) were seeded on the hydrogel, and it was aimed to mimic the luminal side of the BBB. The characterization of the BBB model was determined by measuring the TEER, observation of the cell morphology with SEM, performing the permeability of Lucifer Yellow, and observation of tight junction proteins with immunofluorescence staining. As a result, HBEC-5i cells expressed tight junction proteins (ZO-1 and Claudin-5), showed TEER of 340 ± 22 Ω.cm2, and the Lucifer Yellow permeability of 7.4 × 10−7 ± 2.7 × 10−7 cm/s, which was suitable for use as an in vitro BBB model. Using a hydrogel PEC composed of chitosan and alginate as an extracellular matrix increased the direct interaction of endothelial cells, astrocytes, and neurons with each other and thus obtained a much less permeable model compared to other standard transwell models.

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POSS and SSQ Materials in Dental Applications: Recent Advances and Future Outlooks

Recently, silsesquioxanes (SSQ) and polyhedral oligomeric silsesquioxanes (POSS) have gained much interest in the area of biomaterials, mainly due to their intrinsic properties such as biocompatibility, complete non-toxicity, the ability to self-assemble and to form a porous structure, facilitating cell proliferation, creating a superhydrophobic surface, osteoinductivity, and ability to bind hydroxyapatite. All the above has resulted in new developments in medicine. However, the application of POSS-containing materials in dentistry is still at initial stage and deserves a systematic description to ensure future development. Significant problems, such as reduction of polymerization shrinkage, water absorption, hydrolysis rate, poor adhesion and strength, unsatisfactory biocompatibility, and corrosion resistance of dental alloys, can be addressed by the design of multifunctional POSS-containing materials. Because of the presence of silsesquioxanes, it is possible to obtain smart materials that allow the stimulation of phosphates deposition and repairing of micro-cracks in dental fillings. Hybrid composites result in materials exhibiting shape memory, as well as antibacterial, self-cleaning, and self-healing properties. Moreover, introducing POSS into polymer matrix allows for materials for bone reconstruction, and wound healing. This review covers the recent developments in the field of POSS application in dental materials and gives the future perspectives within a promising field of biomedical material science and chemical engineering.

Recent Developments in Polymer Nanocomposites for Bone Regeneration

Most people who suffer acute injuries in accidents have fractured bones. Many of the basic processes that take place during embryonic skeletal development are replicated throughout the regeneration process that occurs during this time. Bruises and bone fractures, for example, serve as excellent examples. It almost always results in a successful recovery and restoration of the structural integrity and strength of the broken bone. After a fracture, the body begins to regenerate bone. Bone formation is a complex physiological process that requires meticulous planning and execution. A normal healing procedure for a fracture might reveal how the bone is constantly rebuilding as an adult. Bone regeneration is becoming more dependent on polymer nanocomposites, which are composites made up of a polymer matrix and a nanomaterial. This study will review polymer nanocomposites that are employed in bone regeneration to stimulate bone regeneration. As a result, we will introduce the role of bone regeneration nanocomposite scaffolds, and the nanocomposite ceramics and biomaterials that play a role in bone regeneration. Aside from that, recent advances in polymer nanocomposites might be used in a variety of industrial processes to help people with bone defects overcome their challenges will be discussed.

Fabricating a robust POSS-PCL nanofiber scaffold for nesting of mesenchymal stem cells: potential application in bone tissue regeneration

BACKGROUND

According to recent studies, electrospun Poly (Ɛ-caprolactone) (PCL) is an absorbing candidate for the formulation of biocompatible scaffolds used in tissue engineering. Tissue engineering is a set of techniques for producing or reconstructing tissue, whose primary purpose is to restore or improve the function of tissues in the human body. Tissue engineering combines the principles of materials and cell transplantation to develop alternative tissues or promote endogenous regeneration. However, this electrospun scaffold, consisting of PCL, has disadvantages such as low cell adhesion, inactivity of the surface, osteoinduction, and acidic destruction of the scaffold that causes inflammation at the implant site, often making it unsuitable implant. This study aimed to improve PCL base cellular scaffolds with the formulation of polyhedral oligomeric silsesquioxane - Polycaprolactone (POSS-PCL) nanofiber scaffolds. The present research focuses on the synthesis of nanofibers for their cell interaction features, and application in bone tissue engineering and regeneration.

RESULTS

POSS/ PCL Nanocomposites with 2, 5, and 10 wt.% of POSS were synthesized in the Trichloromethane, then POSS - PCL Nanofibers were prepared by the electrospinning technique. In this study, the structures of nanohybrids and nanofibers have been evaluated by FTIR, HNMR, XRD, SEM, EDX, and DSC. The biocompatibility of formulated POSS-PCL scaffolds was detected using mesenchymal stem cells (MSCs). Then several parameters were examined, involving DCFH ROS detection system, gene expression (cell viability/apoptosis, osteogenesis potentiality, and redox molecular homeostasis.

CONCLUSIONS

Based on our results, POSS-PCL nano-scaffolds in comparison with PCL have shown a robust potentiality in homing, growth, and differentiation of stem cells. Synthesis of POSS-PCL Nanofibers and their potential application in Bone Regeneration.

Chitosan/POSS Hybrid Hydrogels for Bone Tissue Engineering

Hybrid hydrogels composed of chitosan (CS) have shown great potential in bone tissue engineering and regeneration. The introduction of polyhedral oligomeric silsesquioxanes (POSS) in the biopolymeric matrix has been demonstrated to improve the rheological and biological properties of the hybrid composites. In this work, we have integrated the favourable features of chitosan (CS) and POSS nanoparticles to design new nanocomposites for bone tissue regeneration, focusing our attention on the effect of POSS concentration within the CS matrix (0.5, 1, and 1.5 equivalents in weight of POSS with respect to CS) on the chemical, physical, rheological, and in vitro biological properties of the final composites. The drug release ability of the synthesized hydrogel scaffolds were also investigated using, as the model drug, ketoprofen, that was included in the scaffold during the gelling procedure, showing a more controlled release for the hybrids with respect to CS (86-91% of drug released after two weeks). The results of the in vitro biological tests performed on human fetal osteoblastic cells (hFOB 1.19) culture demonstrated the great biocompatibility of the hybrid materials. The hybrids, at the different POSS concentrations, showed values of cell mortality superimposable with control cells (11.1 vs. 9.8%), thus revealing the CS/POSS hydrogels as possible candidates for bone tissue engineering applications.

Biomimetic chitosan with biocomposite nanomaterials for bone tissue repair and regeneration

Biomimetic materials for better bone graft substitutes are a thrust area of research among researchers and clinicians. Autografts, allografts, and synthetic grafts are often utilized to repair and regenerate bone defects. Autografts are still considered the gold-standard method/material to treat bone-related issues with satisfactory outcomes. It is important that the material used for bone tissue repair is simultaneously osteoconductive, osteoinductive, and osteogenic. To overcome this problem, researchers have tried several ways to develop different materials using chitosan-based nanocomposites of silver, copper, gold, zinc oxide, titanium oxide, carbon nanotubes, graphene oxide, and biosilica. The combination of materials helps in the expression of ideal bone formation genes of alkaline phosphatase, bone morphogenic protein, runt-related transcription factor-2, bone sialoprotein, and osteocalcin. In vitro and in vivo studies highlight the scientific findings of antibacterial activity, tissue integration, stiffness, mechanical strength, and degradation behaviour of composite materials for tissue engineering applications.

Simultaneous toughness and stiffness of 3D printed nano-reinforced polylactide matrix with complete stereo-complexation via hierarchical crystallinity and reactivity

A novel strategy adaptive to 3D printing of stereo-complexed polylactide matrix for simultaneous toughness and stiffness was designed. Stereo-complexation is a potent way to enhance both aqueous stability and heat resistance of polylactide, but also aggravates brittleness problem of polylactide. Though poly(butyleneadipate-co-terephthalate) elastomer with epoxidized compatibilizer improved stiffness and toughness of common polylactide, their effectiveness on mechanical and crystallization properties of stereo-complexed polylactide remained unknown. More importantly, incorporation of above techniques into 3D printing kept a fundamental challenge. Both stereo-complexation of polylactide and covalent coupling of polylactide and poly(butyleneadipate-co-terephthalate) by epoxidized compatibilizer are easy to occur when preparing the filaments for printing, impeding the following 3D printing procedure. The hypothesis for this research is that controlled hierarchical crystallization and reaction in three thermal processes could ensure simultaneous toughness and stiffness, and complete stereo-complexation in polylactide matrices. Reinforcing effects of a selected epoxidized compatibilizer, POSS_(epoxy)8, on crystallinities, thermal properties, mechanical properties and morphologies were systematically studied. Such a strategy not only removed the obstacles in incorporating stereo-complexation and coupling techniques of polylactide into 3D printing, but also revealed the mechanism to produce high-performance 3D printed polylactide matrix via hierarchical crystallization and reaction.

Effectiveness of an ocular adhesive polyhedral oligomeric silsesquioxane hybrid thermo-responsive FK506 hydrogel in a murine model of dry eye

Dry eye is a common ocular disease that results in discomfort and impaired vision, impacting an individual's quality of life. A great number of drugs administered in eye drops to treat dry eye are poorly soluble in water and are rapidly eliminated from the ocular surface, which limits their therapeutic effects. Therefore, it is imperative to design a novel drug delivery system that not only improves the water solubility of the drug but also prolongs its retention time on the ocular surface. Herein, we develop a copolymer from mono-functional POSS, PEG, and PPG (MPOSS-PEG-PPG, MPEP) that exhibits temperature-sensitive sol-gel transition behavior. This thermo-responsive hydrogel improves the water solubility of FK506 and simultaneously provides a mucoadhesive, long-acting ocular delivery system. In addition, the FK506-loaded POSS hydrogel possesses good biocompatibility and significantly improves adhesion to the ocular surface. In comparison with other FK506 formulations and the PEG-PPG-FK506 (F127-FK506) hydrogel, this novel MPOSS-PEG-PPG-FK506 (MPEP-FK506) hydrogel is a more effective treatment of dry eye in the murine dry eye model. Therefore, delivery of FK506 in this POSS hydrogel has the potential to prolong drug retention time on the ocular surface, which will improve its therapeutic efficacy in the management of dry eye.

Stability Efficiencies of POSS and Microalgae Extracts on the Durability of Ethylene-Propylene-Diene Monomer Based Hybrids

The EPDM (ethylene-propylene-diene monomer) hybrids with improved thermal and radiation strengths containing 1 and 5 phr of polyhedral oligomeric silsesquioxane (vinyl-POSS, Ov-POSS) and/or 2 phr of microalgae (Chlorella vulgaris (CV) and Spirulinaplatensis (SP)) powders were investigated in respect to their thermal stability after γ-irradiation. The material durability under accelerated degradation was qualified by chemiluminescence and gelation, which prove the contribution of inorganic filler and microalgae extracts on the increase of hybrid thermal stability, as well as the interaction between added components (POSS and CV or SP). The activation energies and the durabilities under accelerated degradation were calculated, indicating their suitable usage as appropriate materials in various applications. The reported results indicate the improvement effect of both microalgal powders on the oxidation strength, but the contribution of Spirulinaplatensis grabs attention on its efficient effects upon the prevention of degradation under accelerated aging conditions. The thermal performances of the tested EPDM based hybrids are remarkably ameliorated, if the certain formulation includes Ov-POSS (5 phr) and Spirulinaplatensis (2 phr), certifying its suitability for the pertinent applications.

Fabrication of nano-decorated ZnO-fibrillar chitosan exhibiting a superior performance as a promising replacement for conventional ZnO

In this research, bioactive nano-hybrids based on the nano-fibrillar chitosan-ZnO (NF-CS-ZnO) were synthesized to diminish the toxicity of ZnO-NPs. The successful formation of nano-hybrids was confirmed by FT-IR, UV-Vis, and FE-SEM analyses, showing a uniform spherical ZnO-NPs with an average diameter of 20-30 nm, homogeneously dispersed on NF-CS. The obtained results demonstrated a remarkable antibacterial activity of NF-CS-ZnO-0.6 nano-hybrid against E. coli and S. aureus and, interestingly, no cytotoxic on normal cells (even at a high concentration of 100 μg/mL). Furthermore, NF-CS hybridization efficiently decreased the up-regulation in Cas3, Cas9, and Il6 of inspected fishes compared to the ZnO-NPs. Histopathological examination revealed hepatocyte necrosis in the fish exposed to ZnO-NPs and hyperemia exposed to NF-CS-ZnO-0.6 nano-hybrid. Finally, NF-CS efficiently improved the bio-safety and bactericidal activity of ZnO-NPs; therefore, NF-CS-ZnO nano-hybrid is prominently recommended as a talented low-toxicity antibacterial agent replacement of conventional ZnO-NPs for use in different applications.

Biomineralized Composite Liquid Crystal Fiber Scaffold Promotes Bone Regeneration by Enhancement of Osteogenesis and Angiogenesis

Liquid crystals (LCs) are appealing biomaterials for applications in bone regenerative medicine due to their tunable physical properties and anisotropic viscoelastic behavior. This study reports a novel composite poly (L-lactide) (PLLA) scaffold that is manufactured by a simple electrospinning and biomineralization technique that precisely controls the fibrous structure in liquid LC phase. The enriched-LC composites have superior mineralization ability than neat PLLA; furthermore BMSC cells were inoculated onto the HAP-PLLA/LC with hydroxyapatite (HAP) composite scaffold to test the capability for osteogenesis in vitro. The results show that the PLLA/LC with HAP produced by mineralization leads to better cell compatibility, which is beneficial to cell proliferation, osteogenic differentiation, and expression of the angiogenic CD31 gene. Moreover, in vivo studies showed that the HAP-PLLA/LC scaffold with a bone-like environment significantly accelerates new and mature lamellar bone formation by development of a microenvironment for vascularized bone regeneration. Thus, this bionic composite scaffold in an LC state combining osteogenesis with vascularized activities is a promising biomaterial for bone regeneration in defective areas.

Application of nanoparticles in bone tissue engineering; a review on the molecular mechanisms driving osteogenesis

The introduction of nanoparticles into bone tissue engineering strategies is beneficial to govern cell fate into osteogenesis and the regeneration of large bone defects. The present study explored the role of nanoparticles to advance osteogenesis with a focus on the cellular and molecular pathways involved. Pubmed, Pubmed Central, Embase, Scopus, and Science Direct databases were explored for those published articles relevant to the involvement of nanoparticles in osteogenic cellular pathways. As multifunctional compounds, nanoparticles contribute to scaffold-free and scaffold-based tissue engineering strategies to progress osteogenesis and bone regeneration. They regulate inflammatory responses and osteo/angio/osteoclastic signaling pathways to generate an osteogenic niche. Besides, nanoparticles interact with biomolecules, enhance their half-life and bioavailability. Nanoparticles are promising candidates to promote osteogenesis. However, the interaction of nanoparticles with the biological milieu is somewhat complicated, and more considerations are recommended on the employment of nanoparticles in clinical applications because of NP-induced toxicities.

Kinetic Analysis on the Stabilization Effects of Substituted POSS Powders Embedded in γ-Radiolyzed Polypropylene

The present paper proposes a reliable alternative for the increasing stability of polypropylene (PP) by modified polyhedral oligomeric silsesquioxanes (POSS). The chemiluminescence measurements and FTIR records point complementarily out the determinant influence of substituents on the progress of oxidation during the accelerated degradation caused by γ-irradiation. The main kinetic approach of oxidation acting in radiation-induced aging recommends some of the studied structures of modified POSS as appropriate compounds for improving stability of polypropylene at low additive concentration. The analysis of the present results is based on the implication of substituted POSS, whose contribution to the limitation of oxidation is conditioned by the influence of substituents. The delay of the oxidative degradation in studied γ-irradiated polypropylene is the consequence of the interaction between molecular PP fragments and the silanol moieties generated during radiolysis, which are the most vulnerable points of POSS structure.

Effect of crosslinking processing on the chemical structure and biocompatibility of a chitosan-based hydrogel

Chitosan (CS)-based hydrogels with different structures were prepared to ensure the bioavailability of bioactive components. With the electrostatic interaction between CS and anionic crosslinkers, the structure of the CS-based hydrogel changed and influenced the swelling ability, which was beneficial for maintaining bioactive ingredients in the hydrogel. Compared with sodium hexametaphosphate, hydrogels crosslinked by sodium tripolyphosphate (STPP) had a higher swelling capacity and more stable release profile (no more than 10% BSA in the upper gastrointestinal tract), which could deliver bioactive ingredients to the colon. Moreover, due to electrostatic interactions, the surface of the CS-based hydrogel became hydrophilic, which helped Caco2 cells to grow on it. 118.86%-147.22% cell viability was found on the CS-based hydrogel. Furthermore, with different crosslinkers and concentrations in the crosslinking process, the release properties and safety of the hydrogels were varied, but the STPP-crosslinked CS hydrogel presented good cell adhesivity for bioactive components to the colon.

Progress and Prospects of Polymer-Based Drug Delivery Systems for Bone Tissue Regeneration

Despite the high regenerative capacity of bone tissue, there are some cases where bone repair is insufficient for a complete functional and structural recovery after damage. Current surgical techniques utilize natural and synthetic bone grafts for bone healing, as well as collagen sponges loaded with drugs. However, there are certain disadvantages associated with these techniques in clinical usage. To improve the therapeutic efficacy of bone tissue regeneration, a number of drug delivery systems based on biodegradable natural and synthetic polymers were developed and examined in in vitro and in vivo studies. Recent studies have demonstrated that biodegradable polymers play a key role in the development of innovative drug delivery systems and tissue engineered constructs, which improve the treatment and regeneration of damaged bone tissue. In this review, we discuss the most recent advances in the field of polymer-based drug delivery systems for the promotion of bone tissue regeneration and the physical-chemical modifications of polymers for controlled and sustained release of one or more drugs. In addition, special attention is given to recent developments on polymer nano- and microparticle-based drug delivery systems for bone regeneration.

Smurf1-targeting miR-19b-3p-modified BMSCs combined PLLA composite scaffold to enhance osteogenic activity and treat critical-sized bone defects

Over the past few years, tissue-engineering technology provided a new direction for bone defects therapy, which involved developing applicable biological materials composite with seed cells to repair bone defects tissue. However, as one of the commonest seed cells for tissue engineering, BMSCs (bone marrow mesenchymal stem cells), are still lacking an efficient and accurate differentiation ability into functional osteoblast. Given these facts, the development of a novel tissue engineering technology integrated BMSCs and scaffold materials have become an urgent need for bone defects repair. In this work, we found that miR-19b-3p could suppress the expression of Smurf1 which is a negative regulator of osteogenesis. By employing lentivirus pLVTHM-miR-19b-3p transfected BMSCs, we verified that miR-19b-3p could promote BMSCs osteogenic differentiation via suppressing Smurf1 expression. Furthermore, we designed a new porous PLLA/POSS scaffold combined with BMSCs for tissue engineering. In vitro experiment showed that miR-19b-3p modified BMSCs facilitated the expansion and proliferation of BMSCs when culturing with the PLLA/POSS scaffold. We established rats calvarial critical-sized defect model, after transplanting the BMSCs/PLLA/POSS for 3 month, the pathology, immunohistochemical and Micro-CT results showed that miR-19b-BMSCs/PLLA/POSS significantly facilitated the osteogenesis differentiation, enhanced the bone density of defect area and accelerated the repair of bone defect. We elucidated the mechanism that miR-19b-3p suppressed the expression of Smurf1 and provided a novel tissue engineering strategy for using microRNA gene-modified BMSCs combined with PLLA/POSS scaffold in bone tissue engineering.

Osseointegration of Antimicrobial Acrylic Bone Cements Modified with Graphene Oxide and Chitosan

Acrylic bone cement (ABC) is one of the most used materials in orthopedic surgery, mainly for the fixation of orthopedic implants to the bone. However, ABCs usually present lack of biological activity and osseointegration capacity that leads to loosening of the prosthesis. This work reports the effect of introducing graphene oxide (GO) and chitosan (CS), separately or together, in the ABC formulation on setting performance, mechanical behavior, and biological properties. Introduction of both CS and GO to the ABC decreased the maximum temperature by 21% and increased the antibacterial activity against Escherichia coli by 87%, while introduction of only CS decreased bending strength by 32%. The results of cell viability and cell adhesion tests showed in vitro biocompatibility. The in vivo response was investigated using both subdermal and bone parietal implantations in Wistar rats. Modified ABCs showed absence of immune response, as confirmed by a normal inflammatory response in Wistar rat subdermal implantation. The results of the parietal bone implantation showed that the addition of CS and GO together allowed a near total healing bone–cement interface, as observed in the micrographic analysis. The overall results support the great potential of the modified ABCs for application in orthopedic surgery mainly in those cases where osseointegration is required.