The effect of collector type on the physical, chemical, and biological properties of polycaprolactone/gelatin/nano-hydroxyapatite electrospun scaffold

Catechin as a functional additive in electrospun PCL/gelatin/nHA nanocomposite fibers for tissue engineering applications

The promise of polymeric nanocomposite fibers in the biomedical field is well‐documented due to their adjustable properties and versatility. Electrospun fiber mats, which mimic the extracellular matrix, are particularly noted for their potential in tissue regeneration and repair. In this study, we investigate the role of catechin, a flavonoid, in enhancing cellular response to electrospun nanocomposite fibers of polycaprolactone (PCL), gelatin, and nanohydroxyapatite (nHA). Nanocomposite fibers were fabricated with varying concentrations of catechin and comprehensive analyses of the composite fibers were performed to evaluate their structural and chemical properties. In vitro, assays were performed to examine cell viability and ascertain the influence of catechin on cellular responses to these nanocomposite fibers. Simultaneously, in vivo studies assessed tissue responses to these materials. The findings revealed that incorporating catechin into PCL/gelatin/nHA nanocomposite fibers improved cellular responses in vitro as demonstrated by enhanced cell viability. Furthermore, in vivo investigations displayed positive tissue responses with these fibers, indicating their capacity to enhance cell growth and accelerate tissue regeneration. This study elucidates the potential of catechin as an integral component in designing polymeric nanocomposite fibers, potentially broadening the scope of their biomedical applications.

Gelatin/Polyacrylamide-Based Antimicrobial and Self-Healing Hydrogel Film for Wound Healing Application

In this study, a self-healing, adhesive, and superabsorbent film made of gelatin, poly(acrylamide), and boric acid (GelAA) was successfully synthesized using a free radical reaction mechanism. The optimized film showed a remarkable 2865 ± 42% water absorptivity and also exhibited excellent self-healing behavior. The GelAA films were further loaded with silver nanoclusters (AgNCs) and ursodeoxycholic acid (UDC) (loading efficiency = 10%) to develop UDC/Ag/GelAA films. The loading of AgNCs in UDC/Ag/GelAA films helped in exhibiting 99.99 ± 0.01% antibacterial activity against both Gram-positive and Gram-negative bacteria, making them very effective against bacterial infections. Additionally, UDC/Ag/GelAA films had 77.19 ± 0.52% porosity and showed 90% of UDC release in 30 h, which helps in improving the cell proliferation. Our research provides an easy but highly effective process for synthesizing a hydrogel film, which is an intriguing choice for wound healing applications without the use of antibiotics.

Development and optimisation of hydroxyapatite-polyethylene glycol diacrylate hydrogel inks for 3D printing of bone tissue engineered scaffolds

In the event of excessive damage to bone tissue, the self-healing process alone is not sufficient to restore bone integrity. Three-dimensional (3D) printing, as an advanced additive manufacturing technology, can create implantable bone scaffolds with accurate geometry and internal architecture, facilitating bone regeneration. This study aims to develop and optimise hydroxyapatite-polyethylene glycol diacrylate (HA-PEGDA) hydrogel inks for extrusion 3D printing of bone tissue scaffolds. Different concentrations of HA were mixed with PEGDA, and further incorporated with pluronic F127 (PF127) as a sacrificial carrier. PF127 provided good distribution of HA nanoparticle within the scaffolds and improved the rheological requirements of HA-PEGDA inks for extrusion 3D printing without significant reduction in the HA content after its removal. Higher printing pressures and printing rates were needed to generate the same strand diameter when using a higher HA content compared to a lower HA content. Scaffolds with excellent shape fidelity up to 75-layers and high resolution (∼200 µm) with uniform strands were fabricated. Increasing the HA content enhanced the compression strength and decreased the swelling degree and degradation rate of 3D printed HA-PEGDA scaffolds. In addition, the incorporation of HA improved the adhesion and proliferation of human bone mesenchymal stem cells (hBMSCs) onto the scaffolds. 3D printed scaffolds with 2 wt% HA promoted osteogenic differentiation of hBMSCs as confirmed by the expression of alkaline phosphatase activity and calcium deposition. Altogether, the developed HA-PEGDA hydrogel ink has promising potential as a scaffold material for bone tissue regeneration, with excellent shape fidelity and the ability to promote osteogenic differentiation of hBMSCs.

Natural Compounds and Biopolymers-Based Hydrogels Join Forces to Promote Wound Healing

Rapid and complete wound healing is a clinical emergency, mainly in pathological conditions such as Type 2 Diabetes mellitus. Many therapeutic tools are not resolutive, and the research for a more efficient remedial remains a challenge. Wound dressings play an essential role in diabetic wound healing. In particular, biocompatible hydrogels represent the most attractive wound dressings due to their ability to retain moisture as well as ability to act as a barrier against bacteria. In the last years, different functionalized hydrogels have been proposed as wound dressing materials, showing encouraging outcomes with great benefits in the healing of the diabetic wounds. Specifically, because of their excellent biocompatibility and biodegradability, natural bioactive compounds, as well as biomacromolecules such as polysaccharides and protein, are usually employed in the biomedical field. In this review, readers can find the main discoveries regarding the employment of naturally occurring compounds and biopolymers as wound healing promoters with antibacterial activity. The emerging approaches and engineered devices for effective wound care in diabetic patients are reported and deeply investigated.

Recent progress on electrospun nanofibrous polymer membranes for water and air purification: A review

Developing new polymer membranes with excellent thermal, mechanical, and chemical stability has shown great potential for various environmental remediation applications such as wastewater treatment and air filtration. Polymer membranes have been widely investigated over the past years and utilized to overcome severe ecological issues. Membrane-based technologies play a critical role in water purification and air filtration with the ability to act efficiently and sustainably. Electrospun nanofiber membranes have displayed excellent performance in removing various contaminants from water, such as bacteria, dyes, heavy metals, and oil. These nanofibrous membranes have shown good potential to filter the air from tiny particles, volatile organic compounds, and toxic gases. The performance of polymer membranes can be enhanced by fine-tuning polymer structure, varying surface properties, and strengthening overall membrane porosity. In this review, we discuss the involvement of electrospun nanofibrous membranes in different environmental remediation applications. It further reviews the recent progress of polymer membrane development by utilizing nanoparticles and naturally occurring polymers.

Extracellular matrix mechanobiology in cancer cell migration

The extracellular matrix (ECM) is pivotal in modulating tumor progression. Besides chemically stimulating tumor cells, it also offers physical support that orchestrates the sequence of events in the metastatic cascade upon dynamically modulating cell mechanosensation. Understanding this translation between matrix biophysical cues and intracellular signaling has led to rapid growth in the interdisciplinary field of cancer mechanobiology in the last decade. Substantial efforts have been made to develop novel in vitro tumor mimicking platforms to visualize and quantify the mechanical forces within the tissue that dictate tumor cell invasion and metastatic growth. This review highlights recent findings on tumor matrix biophysical cues such as fibrillar arrangement, crosslinking density, confinement, rigidity, topography, and non-linear mechanics and their implications on tumor cell behavior. We also emphasize how perturbations in these cues alter cellular mechanisms of mechanotransduction, consequently enhancing malignancy. Finally, we elucidate engineering techniques to individually emulate the mechanical properties of tumors that could help serve as toolkits for developing and testing ECM-targeted therapeutics on novel bioengineered tumor platforms. STATEMENT OF SIGNIFICANCE: Disrupted ECM mechanics is a driving force for transitioning incipient cells to life-threatening malignant variants. Understanding these ECM changes can be crucial as they may aid in developing several efficacious drugs that not only focus on inducing cytotoxic effects but also target specific matrix mechanical cues that support and enhance tumor invasiveness. Designing and implementing an optimal tumor mimic can allow us to predictively map biophysical cue-modulated cell behaviors and facilitate the design of improved lab-grown tumor models with accurately controlled structural features. This review focuses on the abnormal changes within the ECM during tumorigenesis and its implications on tumor cell-matrix mechanoreciprocity. Additionally, it accentuates engineering approaches to produce ECM features of varying levels of complexity which is critical for improving the efficiency of current engineered tumor tissue models.

Pellet-Based Fused Filament Fabrication (FFF)-Derived Process for the Development of Polylactic Acid/Hydroxyapatite Scaffolds Dedicated to Bone Regeneration

Scaffolds can be defined as 3D architectures with specific features (surface properties, porosity, rigidity, biodegradability, etc.) that help cells to attach, proliferate, and to differentiate into specific lineage. For bone regeneration, rather high mechanical properties are required. That is why polylactic acid (PLA) and PLA/hydroxyapatite (HA) scaffolds (10 wt.%) were produced by a peculiar fused filament fabrication (FFF)-derived process. The effect of the addition of HA particles in the scaffolds was investigated in terms of morphology, biological properties, and biodegradation behavior. It was found that the scaffolds were biocompatible and that cells managed to attach and proliferate. Biodegradability was assessed over a 5-month period (according to the ISO 13781-Biodegradability norm) through gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and compression tests. The results revealed that the presence of HA in the scaffolds induced a faster and more complete polymer biodegradation, with a gradual decrease in the molar mass (Mn) and compressive mechanical properties over time. In contrast, the Mn of PLA only decreased during the processing steps to obtain scaffolds (extrusion + 3D-printing) but PLA scaffolds did not degrade during conditioning, which was highlighted by a high retention of the mechanical properties of the scaffolds after conditioning.

Antibacterial adhesive self-healing hydrogels to promote diabetic wound healing

The development of compressible, stretchable and self-healing hydrogel dressings with good adhesive, antibacterial and angiogenesis properties is needed to promote the regeneration of diabetic wounds in clinical applications. In this work, a series of self-healing, adhesive and antibacterial hydrogels based on gelatin methacrylate (GelMA), adenine acrylate (AA), and CuCl₂ were designed through covalent bonding, coordination complexation of Cu²⁺ and carboxyl groups and hydrogen bonding to promote diabetic wound healing. These hydrogels exhibit efficient self-healing properties, remarkable fatigue resistance, and good adhesive properties due to the hydrogen bond and the metal-ligand coordination provided by the Cu²⁺ and the carboxyl group. The GelMA/AA/Cu1.0 hydrogel (containing 1.0 mg/mL Cu²⁺) with well-balanced biocompatibility and antibacterial properties exhibited efficient hemostatic performance in a mouse liver trauma model and significantly promoted the healing process in a full-thickness skin diabetic wound model. The immunohistochemistry results showed that the GelMA/AA/Cu1.0 hydrogel can promote regular epithelialization and collagen deposition when compared to the Tegaderm^TM Film, GelMA hydrogel, and GelMA/AA/Cu0 hydrogel. The immunofluorescence results confirmed that the GelMA/AA/Cu1.0 hydrogel can reduce the expression of proinflammatory factors and promote angiogenesis. In conclusion, the GelMA/AA/Cu hydrogel is an effective wound dressing to promote the healing process of diabetic skin wounds. STATEMENT OF SIGNIFICANCE: Diabetic wounds exhibit an extremely high risk of bacterial infection and poor angiogenesis in a high-sugar environment, hindering their healing process. Hydrogel wound dressings are a promising wound care material that need to have stable and long-lasting adhesive properties, avoid shedding, provide lasting protection to wounds, antibacterial properties and promote angiogenesis. In this study, a series of self-healing, adhesive, and antibacterial hydrogels based on gelatin methacrylate (GelMA), acrylated adenine (AA), and CuCl₂ were designed and synthesized via free radical polymerization, hydrogen bond, and ionic bond to promote diabetic wound healing. Overall, GelMA/AA/Cu hydrogels are promising materials to promote diabetic wound healing.

Electrospun fiber-based strategies for controlling early innate immune cell responses: Towards immunomodulatory mesh designs that facilitate robust tissue repair

Electrospun fibrous meshes are widely used for tissue repair due to their ability to guide a host of cell responses including phenotypic differentiation and tissue maturation. A critical factor determining the eventual biological outcomes of mesh-based regeneration strategies is the early innate immune response following implantation. The natural healing process involves a sequence of tightly regulated, temporally varying and delicately balanced pro-/anti-inflammatory events which together promote mesh integration with host tissue. Matrix designs that do not account for the immune milieu can result in dysregulation, chronic inflammation and fibrous capsule formation, thus obliterating potential therapeutic outcomes. In this review, we provide systematic insights into the effects of specific fiber/mesh properties and mechanical stimulation on the responses of early innate immune modulators viz., neutrophils, monocytes and macrophages. We identify matrix characteristics that promote anti-inflammatory immune phenotypes, and we correlate such responses with pro-regenerative in vivo outcomes. We also discuss recent advances in 3D fabrication technologies, bioactive functionalization approaches and biomimetic/bioinspired immunomodulatory mesh design strategies for tissue repair and wound healing. The mechanobiological insights and immunoregulatory strategies discussed herein can help improve the translational outcomes of fiber-based regeneration and may also be leveraged for intervention in degenerative diseases associated with dysfunctional immune responses. STATEMENT OF SIGNIFICANCE: The crucial role played by immune cells in promoting biomaterial-based tissue regeneration is being increasingly recognized. In this review focusing on the interactions of innate immune cells (primarily neutrophils, monocytes and macrophages) with electrospun fibrous meshes, we systematically elucidate the effects of the fiber microenvironment and mechanical stimulation on biological responses, and build upon these insights to inform the rational design of immunomodulatory meshes for effective tissue repair. We discuss state-of-the-art fabrication methods and mechanobiological advances that permit the orchestration of temporally controlled phenotypic switches in immune cells during different phases of healing. The design strategies discussed herein can also be leveraged to target several complex autoimmune and inflammatory diseases.

Gelatin-based electrospun and lyophilized scaffolds with nano scale feature for bone tissue engineering application: review

The rebuilding of the normal functioning of the damaged human body bone tissue is one of the main objectives of bone tissue engineering (BTE). Fabricated scaffolds are mostly treated as artificial supports and as materials for regeneration of neo bone tissues and must closely biomimetic the native extracellular matrix of bone. The materials used for developing scaffolds should be biodegradable, nontoxic, and biocompatible. For the resurrection of bone disorder, specifically natural and synthetic polymers such as chitosan, PCL, gelatin, PGA, PLA, PLGA, etc. meet the requirements for serving their functions as artificial bone substitute materials. Gelatin is one of the potential candidates which could be blended with other polymers or composites to improve its physicochemical, mechanical, and biological performances as a bone graft. Scaffolds are produced by several methods including electrospinning, self-assembly, freeze-drying, phase separation, fiber drawing, template synthesis, etc. Among them, freeze-drying and electrospinning are among the popular, simplest, versatile, and cost-effective techniques. The design and preparation of freeze-dried and electrospun scaffolds are of intense research over the last two decades. Freeze-dried and electrospun scaffolds offer a distinctive architecture at the micro to nano range with desired porosity and pore interconnectivity for selective movement of small biomolecules and play its role as an appropriate matrix very similar to the natural bone extracellular matrix. This review focuses on the properties and functionalization of gelatin-based polymer and its composite in the form of bone scaffolds fabricated primarily using lyophilization and electrospinning technique and their applications in BTE.

A novel porous granular scaffold for the promotion of trabecular bone repair by time-dependent alteration of morphology

Granular scaffolds have been extensively used in the clinic to repair irregular maxillofacial defects. There remain some challenges for the repair of trabecular structures in cancellous bone due to the reticular lamella-like morphology. In this study, we fabricated a novel granular scaffold by rational design of components with different degradation rates so that the morphology of the novel scaffold can evolve to match the growth period of bone cells. Here, polycaprolactone (PCL) was used to fabricate porous microspheres as a skeleton with slow degradation. The macropores were filled with quick degraded gelatin to form complete microspheres. Asynchronous degradation of the two components altered the morphology of the evolutive scaffold from compact to porous, gradually exposing the ridge-like skeletons. This scaffold reversed the decline of cellular adhesion to simple porous skeletons during the initial adhesion. Furthermore, the cells were able to grow into the pores and adhere onto the skeletons with an elongated cellular morphology, facilitating osteogenic differentiation. This novel scaffold was experimentally proven to promote the regeneration of alveolar bone along with a good percentage of bone volume and the formation of trabecular structures. We believe this morphology-evolved scaffold is highly promising for regenerative applications in the clinic.

Effects of Electrospinning Parameter Adjustment on the Mechanical Behavior of Poly-ε-caprolactone Vascular Scaffolds

Electrospinning is a perspective method widely suggested for use in bioengineering applications, but the variability in currently available data and equipment necessitates additional research to ascertain the desirable methodology. In this study, we aimed to describe the effects of electrospinning technique alterations on the structural and mechanical properties of (1,7)-polyoxepan-2-one (poly-ε-caprolactone, PCL) scaffolds, such as circumferential and longitudinal stress/strain curves, in comparison with corresponding properties of fresh rat aorta samples. Scaffolds manufactured under different electrospinning modes were analyzed and evaluated using scanning electronic microscopy as well as uniaxial longitudinal and circumferential tensile tests. Fiber diameter was shown to be the most crucial characteristic of the scaffold, correlating with its mechanical properties.

Tunable Spun Fiber Constructs in Biomedicine: Influence of Processing Parameters in the Fibers' Architecture

Electrospinning and wet-spinning have been recognized as two of the most efficient and promising techniques for producing polymeric fibrous constructs for a wide range of applications, including optics, electronics, food industry and biomedical applications. They have gained considerable attention in the past few decades because of their unique features and tunable architectures that can mimic desirable biological features, responding more effectively to local demands. In this review, various fiber architectures and configurations, varying from monolayer and core-shell fibers to tri-axial, porous, multilayer, side-by-side and helical fibers, are discussed, highlighting the influence of processing parameters in the final constructs. Additionally, the envisaged biomedical purposes for the examined fiber architectures, mainly focused on drug delivery and tissue engineering applications, are explored at great length.

Conductive photothermal non-swelling nanocomposite hydrogel patch accelerating bone defect repair

Bone defect repair is one of the most common issue in clinic. Developmental multifunctional scaffolds have become a promising strategy to effectively promote bone defect repair. Here, a series of...

Recent advances in polymer scaffolds for biomedical applications

The review provides insights into current advancements in electrospinning-assisted manufacturing for optimally designing biomedical devices for their prospective applications in tissue engineering, wound healing, drug delivery, sensing, and enzyme immobilization, and others. Further, the evolution of electrospinning-based hybrid biomedical devices using a combined approach of 3 D printing and/or film casting/molding, to design dimensionally stable membranes/micro-nanofibrous assemblies/patches/porous surfaces, etc. is reported. The influence of various electrospinning parameters, polymeric material, testing environment, and other allied factors on the morphological and physico-mechanical properties of electrospun (nano-/micro-fibrous) mats (EMs) and fibrous assemblies have been compiled and critically discussed. The spectrum of operational research and statistical approaches that are now being adopted for efficient optimization of electrospinning process parameters so as to obtain the desired response (physical and structural attributes) has prospectively been looked into. Further, the present review summarizes some current limitations and future perspectives for modeling architecturally novel hybrid 3 D/selectively textured structural assemblies, such as biocompatible, non-toxic, and bioresorbable mats/scaffolds/membranes/patches with apt mechanical stability, as biological substrates for various regenerative and non-regenerative therapeutic devices.

Conditions adjustment of polycaprolactone nanofibers scaffolds encapsulated with core shells of Au@Se via laser ablation for wound healing applications

Au@Se core-shell nanoparticles were obtained via laser ablation technique to be incorporated into polycaprolactone (PCL) nanofibrous scaffolds for wound healing applications at different contributions of Se nanoparticles (SeNPs). The synthesized layers were inspected via X-ray diffraction (XRD) and Fourier transformed infrared (FTIR). Additionally, microstructural and surface morphology were followed with different SeNPs contributions before and after fibroblast culturing. Moreover, Selenium dopant is affected Maximum roughness valley depth while it starts from 0.31 µm at Au@0.0Se@PCL reaching 0.457 µm at Au@12Se@PCL; however, after culturing starts from 0.3833 µm reaching 0.41 µm. Besides, the antibacterial activity was screened, showing the absence of inhibition zones in free selenium composition; however, it grows up reaching 8.3 ± 0.8, and 8.0 ± 0.8 for E. coli and S. aureus, respectively at the maximum contribution of selenium. SeNPs contributed composites show higher cell viability than Selenium free composite that it reaches its max in Au@8.0Se@PCL, recording 95.3 ± 2.3%. Composites show an excellent Wound dressing capability that its performance is directly proportional to selenium content. This significant enrichment of antibacterial activity and cell viability could recommend these composites for additional research in medical applications.

Pharmaceutical electrospinning and 3D printing scaffold design for bone regeneration

Bone regenerative engineering provides a great platform for bone tissue regeneration covering cells, growth factors and other dynamic forces for fabricating scaffolds. Diversified biomaterials and their fabrication methods have emerged for fabricating patient specific bioactive scaffolds with controlled microstructures for bridging complex bone defects. The goal of this review is to summarize the points of scaffold design as well as applications for bone regeneration based on both electrospinning and 3D bioprinting. It first briefly introduces biological characteristics of bone regeneration and summarizes the applications of different types of material and the considerations for bone regeneration including polymers, ceramics, metals and composites. We then discuss electrospinning nanofibrous scaffold applied for the bone regenerative engineering with various properties, components and structures. Meanwhile, diverse design in the 3D bioprinting scaffolds for osteogenesis especially in the role of drug and bioactive factors delivery are assembled. Finally, we discuss challenges and future prospects in the development of electrospinning and 3D bioprinting for osteogenesis and prominent strategies and directions in future.

Preparation and Characterization of Nanofibrous Scaffolds of Ag/Vanadate Hydroxyapatite Encapsulated into Polycaprolactone: Morphology, Mechanical, and In Vitro Cells Adhesion

Series of nanofibrous composites of polycaprolactone (PCL) were fabricated in different compositions of modified hydroxyapatite (HAP). The encapsulated HAP was co-doped with Ag/vanadate ions at different Ag contributions. XRD and FTIR techniques confirmed the powder and fibrous phase formation. Further, the morphological and mechanical behaviors of the electrospun nanofibrous scaffolds containing hydroxyapatite were investigated. The nanofibrous phases were biologically evaluated via studying contact angle, antibacterial, cell viability, and in vitro growth of human fibroblasts cell line (HFB4). It is obvious that silver ions cause gradual deviation in powder grains from wafer-like to cloudy grains. The maximum height of the roughness (Rt) ranged from 902.0 to 956.9 nm, while the valley depth of the roughness (Rv) ranged from 308.3 to 442.8 nm, for the lowest and the highest additional Ag ions for powdered phases. Moreover, the highest contribution of silver through the nanofibrous phases leads to the formation of lowest filaments size ranged from 0.07 to 0.53 µm. Further, the fracture strength was increased exponentially from 2.51 ± 0.35 MPa at zero concentration of silver ions up to 4.23 ± 0.64 MPa at 0.6 Ag/V-HAP@PCL. The fibrous phases were biologically evaluated in terms of antibacterial, cell viability, and in vitro growth of human fibroblasts cell line (HFB4). The nanofibrous composition of 0.8 Ag/V-HAP@PCL reached the maximum potential against E. coli and S. aureus and recorded 20.3 ± 1.1 and 19.8 ± 1.2 mm, respectively. This significant performance of the antibacterial activity and cell viability of co-doped HAP distributed through PCL could recommend these compositions for more research in biological applications, including wound healing.

Radially patterned transplantable biodegradable scaffolds as topographically defined contact guidance platforms for accelerating bone regeneration

BACKGROUND

The healing of large critical-sized bone defects remains a clinical challenge in modern orthopedic medicine. The current gold standard for treating critical-sized bone defects is autologous bone graft; however, it has critical limitations. Bone tissue engineering has been proposed as a viable alternative, not only for replacing the current standard treatment, but also for producing complete regeneration of bone tissue without complex surgical treatments or tissue transplantation. In this study, we proposed a transplantable radially patterned scaffold for bone regeneration that was defined by capillary force lithography technology using biodegradable polycaprolactone polymer.

RESULTS

The radially patterned transplantable biodegradable scaffolds had a radial structure aligned in a central direction. The radially aligned pattern significantly promoted the recruitment of host cells and migration of osteoblasts into the defect site. Furthermore, the transplantable scaffolds promoted regeneration of critical-sized bone defects by inducing cell migration and differentiation.

CONCLUSIONS

Our findings demonstrated that topographically defined radially patterned transplantable biodegradable scaffolds may have great potential for clinical application of bone tissue regeneration.

Synergistic effects of gelatin and nanotopographical patterns on biomedical PCL patches for enhanced mechanical and adhesion properties

Biomedical patches have been known as important biomaterial-based medical devices for the clinical treatment of tissue and organ diseases. Inspired by the extracellular matrix-like aligned nanotopographical pattern as well as the unique physical and biocompatible properties of gelatin, we developed strength-enhanced biomedical patches by coating gelatin onto the nanopatterned surface of polycaprolactone (PCL). The relative contributions of the nanotopographical pattern (physical factor) and gelatin coating (chemical factor) in enhancing the mechanical and adhesive properties of PCL were quantitatively investigated. The nanotopographical pattern increased the surface area of PCL, allowing more gelatin to be coated on its surface. The biomedical patch made from gelatin-coated nanopatterned PCL showed strong mechanical and adhesive properties (tensile strength: ~14.5 MPa; Young's modulus: ~60.2 MPa; and normal and shear adhesive forces: ~1.81 N/cm² and ~352.3 kPa) as well as good biocompatibility. Although the nanotopographical pattern or gelatin coating alone could enhance these physical properties of PCL in both dry and wet environmental conditions, both factors in combination further strengthened the properties, indicating the importance of synergistic cues in driving the mechanical behavior of biomedical materials. This strength-enhanced biomedical patch will be especially useful for the treatment of tissues such as cartilage, tendon, and bone.

Gelatin-polycaprolactone-nanohydroxyapatite electrospun nanocomposite scaffold for bone tissue engineering

Bone injuries and fractures generally take a long period to heal itself. To address this problem, bone tissue engineering (BTE) has gained significant research impetus. Among the several techniques used for scaffold fabrication, electrospinning ought to be the most promising technique for the development of the nanostructured scaffolds. The present study was carried out to fabricate an electrospun nanocomposite scaffold for BTE by using gelatin, polycaprolactone (PCL), and nanohydroxyapatite (nHAp). To prepare Gelatin-PCL-nHAp nanocomposite scaffold: Gelatin-PCL blend was electrospun and then treated with nHAp (1 wt%) for different time periods. The fabricated nanocomposite scaffold was analysed by field emission scanning electron microscopy (FESEM) to determine the fiber diameter and evaluate the fiber morphology. The Gelatin-PCL-nHAp nanocomposite scaffold-20 min exhibited the average fiber diameter of 615±269 nm and average pore size 4.7±1.04 μm, and also revealed the presence of nHAp particles over the Gelatin-PCL scaffold surface. Further, X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy and thermogravimetric (TG) analysis also indicated the deposition of nHAp over the Gelatin-PCL scaffold surface. MTT assay and DNA quantification showed good viability and significant proliferation of human osteoblasts on Gelatin-PCL-nHAp nanocomposite scaffold. Moreover, cell-scaffold constructs illustrated efficient cellular attachment and adequately spread cells, and it also depicts characteristic polygonal morphology of osteoblasts over the Gelatin-PCL-nHAp nanocomposite scaffold. Thus, the results of in-vitro analysis of electrospun nanocomposite scaffold suggest that the Gelatin-PCL-nHAp scaffold can be a potential candidate for BTE applications.

Effect of zirconia-mullite incorporated biphasic calcium phosphate/biopolymer composite scaffolds for bone tissue engineering

New bioactive scaffolds with improved mechanical properties, biocompatibility and providing structural support for bone tissue are being developed for use in the treatment of bone defects. In this study, we have synthesized bioactive scaffolds consisting of biphasic calcium phosphate (BCP) and zirconia-Mullite (2ZrO₂·[3Al₂O₃ ·2 SiO₂] (ZAS)) (BCPZAS) combined with polymers matrix of polycaprolactone (PCL)-alginate (Alg)-chitosan (Chi) (Chi/Alg-PCL) (BCPZAS@Chi/Alg-PCL). The composite material scaffolds were prepared by a blending technique. The microstructure, mechanical, bioactivity and in vitro biological properties with different ratios of BCP to ZAS of 1:0, 3:1, 1:1, 1:3 and 0:1 wt% in polymer matrix were analyzed. Microstructure analysis showed a successful incorporation of the BCPZAS particles with an even distribution of them within the polymer matrix. The mechanical properties were found to gradually decrease with increasing the ratio of ZAS particles in the scaffolds. The highest compressive strength was 42.96 ± 1.01MPa for the 3:1 wt% BCP to ZAS mixing. Bioactivity test, the BCPZAS@Chi/Alg-PCL composite could induce apatite formation in simulate body fluid (SBF). In-vitro experiment using UMR-106 osteoblast-like cells on BCPZAS@Chi/Alg-PCL composite scaffold showed that there is cell attachment to the scaffolds with proliferation. These experimental results demonstrate that the BCPZAS@Chi/Alg-PCL composite especially for the BCP:ZAS at 3:1 wt% could be utilized as a scaffold for bone tissue engineering applications.

Physical, electrochemical and biological evaluations of spin-coated ε-polycaprolactone thin films containing alumina/graphene/carbonated hydroxyapatite/titania for tissue engineering applications

Composite structures are at the frontier of materials science and engineering and polymeric/ceramic composites present one of their most prospective subsets. Prior studies have shown both improvements and deteriorations of properties of polymers upon the addition of ceramic phases to them, but not many studies have dealt with the direct comparison of chemically distinct inorganic additives. The goal of this study was to compare the properties of ε-polycaprolactone (PCL) thin films supplemented with alumina, graphene, carbonated hydroxyapatite or titania particles, individually, in identical amounts (12 wt%). The composite films were analyzed for their phase composition, grain size, morphology, surface roughness, porosity, cell response, mechanical properties and electrochemical performance. Each additive imparted one or more physical or biological properties onto PCL better than others. Thus, alumina increased the microhardness of the films better than any other additive, with the resulting values exceeding 10 MPa. It also led to the formation of a composite with the least porosity and the greatest stability to degradation in simulated body fluid based on open circuit potential (OCP) measurements and electrochemical impedance spectroscopy (EIS). Titania made the surface of PCL roughest, which in combination with its high porosity explained why it was the most conducive to the growth of human fibroblasts, alongside being most prone to degradation in wet, corrosive environments and having the highest Poisson's ratio. Graphene, in contrast, made the surface of PCL smoothest and the bulk structure most porous, but also most conductive, with the OCP of -37 mV. The OCP of PCL supplemented with carbonated hydroxyapatite had the highest OCP of -134 mV and also the highest mechanical moduli, including the longitudinal (781 MPa), the shear (106 MPa), the bulk (639 MPa), and the elastic (300 MPa). The only benefit of the deposition of multilayered PCL films supplemented with all four inorganic additives was to enable a relatively high resistance to degradation. This study demonstrates that the properties of thin PCL films could be effectively optimized through the simple choice of appropriate inorganic additives dispersed in them. There is no single additive that proves ideal for improving all the properties of interest in PCL thin films, but their choice should be adjusted to the actual application. One such method of compositional optimization could prove crucial in the effort to develop biocomposites for superior performance in tissue engineering applications.

In vitro and in vivo assessment of glucose cross-linked gelatin/zein nanofibrous scaffolds for cranial bone defects regeneration

The purpose of this study was to evaluate the glucose cross-linked gelatin/zein scaffolds for bone regeneration in vitro and in vivo. The nanofibrous scaffolds exhibited fast mineralization in the concentrated simulated body fluid with the deposited octacalcium phosphate and dicalcium phosphate dehydrate. The nanofibrous scaffolds exhibited no cytotoxic effect on MC3T3e1 cells in a CCK-8 test. Additionally, scanning electron microscope and confocal laser scanning microscopy images revealed that all the scaffolds were biocompatible and showed excellent support for MC3T3e1 cells. In the osteogenesis characterizations, Alizarin Red staining experiments indicated the improved calcium deposits on the cross-linked scaffolds, while the alkaline phosphatase activity showed no difference. Furthermore, the in vivo cranial bone regeneration results suggested that the cross-linked gelatin/zein scaffolds presented a strong positive effect on the cranial bone regeneration with the increased new bone volume and connective tissue formation, but the incorporation of zein in the gelatin scaffolds did not favor the bone regeneration. Moreover, the cross-linked gelatin scaffold retarded the bone resorption as indicated by the higher levels of IFN-γ and lower levels of IL-6, which restricted the differentiation of osteoclasts.

Electrophoretically deposited mesoporous magnesium silicate with ordered nanopores as an antibiotic-loaded coating on surface-modified titanium

Infection is quite usual for implants after surgery and a systemic administration of antibiotics causes problems before the eradication of bacteria. Localized drug delivery from implants is an effective way by which the mentioned target can be met. In the current work, ordered mesoporous magnesium silicate (OMMS) is coated on plasma electrolytic oxidation (PEO)-modified titanium (Ti) substrate through electrophoretic deposition (EPD) and rifampin as an antibiotic is loaded on OMMS coating to be applied as an antibacterial coating. The immersion test into simulated body fluid and also potentiodynamic polarization assay are adopted to assess the in vitro bioactivity up to 7 days and corrosion resistance of the specimens, respectively. The double surface coatings of PEO and EPD are achieved on Ti substrate and the thickness for each one is found to be 4 and 25 μm, respectively. Regarding to drug delivery capability of OMMS as the EPD coating, the loading capacity is 25% and release trend sustains up to 96 h. The antibacterial activity and also cell viability of OMMS coating are significantly increased with rifampin loading. The results of our study exhibit that OMMS as a multifunctional coating deposited on the PEO-modified Ti substrate improves corrosion resistance, in vitro bioactivity, alkaline phosphatase activity, and mineralization of the substrate. Moreover, rifampin-loaded OMMS coating is not only able to prevent infection, but it also increases the osteogenesis cells viability. Therefore, rifampin-loaded OMMS coating on Ti is potentially regarded appropriate for orthopedic applications.