3D Chitosan Research Articles

Enhancement of Oxygen Reduction Performance of Biomass-Derived Carbon through Co-Doping with Early Transition Metal

We report an early transition metal co-doped carbon catalyst prepared by pyrolyzing a 3D chitosan hydrogel precursor mixed with Zr and Fe species. The catalyst exhibits high activity and pronounced long-term stability for the oxygen reduction reaction (ORR) in both acidic and alkaline media. We find that co-doping with Zr can greatly enhance the catalyst's performance, whereas doping with only Zr results in no improvement. For our optimal sample ZFNC-3-800, its current density at 0.9 V (vs. RHE) could be reach 0.64 mA/cm2, which is 1.7 times that of FNC-800. Through TEM, XRD and XPS analyses, we find that co-doping with Zr can change the microstructure of the catalyst, immobilize its iron and nitrogen components and modify the distribution of N species in the final catalyst. Importantly, co-doping with Zr leads to the creation of Zr2FeOx species, contributing to the possible structure of N4-x-Fe-Ox in our ZFNC-3-800 catalyst and enhance its performance. Fe atoms are much more electron-deficient in this structure than in FeNx species and thus favor the adsorption and activation of oxygen molecules. This work is the first to explore co-doping with early transition metals and to reveal their important role in a specific catalyst.

Chitosan-Graphene Oxide 3D scaffolds as Promising Tools for Bone Regeneration in Critical-Size Mouse Calvarial Defects

Limited self-regenerating capacity of human skeleton makes the reconstruction of critical size bone defect a significant challenge for clinical practice. Aimed for regenerating bone tissues, this study was designed to investigate osteogenic differentiation, along with bone repair capacity of 3D chitosan (CHT) scaffolds enriched with graphene oxide (GO) in critical-sized mouse calvarial defect. Histopathological/histomorphometry and scanning electron microscopy(SEM) analysis of the implants revealed larger amount of new bone in the CHT/GO-filled defects compared with CHT alone (p < 0.001). When combined with GO, CHT scaffolds synergistically promoted the increase of alkaline phosphatase activity both in vitro and in vivo experiments. This enhanced osteogenesis was corroborated with increased expression of bone morphogenetic protein (BMP) and Runx-2 up to week 4 post-implantation, which showed that GO facilitates the differentiation of osteoprogenitor cells. Meanwhile, osteogenesis was promoted by GO at the late stage as well, as indicated by the up-regulation of osteopontin and osteocalcin at week 8 and overexpressed at week 18, for both markers. Our data suggest that CHT/GO biomaterial could represent a promising tool for the reconstruction of large bone defects, without using exogenous living cells or growth factors.

Solvent-cast 3D printing of Chitosan hydrogel scaffolds for guided cell growth

Event Abstract Back to Event Solvent-cast 3D printing of Chitosan hydrogel scaffolds for guided cell growth Qinghua Wu1, Marion Maire2, Sophie Lerouge2, Daniel Therriault3 and Marie-Claude Heuzey1 1 École Polytechnique de Montréal, Chemical Engineering, Canada 2 École de technologie supérieure, LBeV- CHUM research center (CRCHUM) & Department of Mechanical Engineering, Canada 3 École Polytechnique de Montréal, Laboratory for Multiscale Mechanics (LM2) & Department of Mechanical Engineering, Canada Introduction: Hydrogels made of natural polymers are interesting biomaterials because they simulate the aqueous environment of extracellular matrices and present high affinity with cells.[1] In particular, chitosan, a natural polysaccharide, exhibits excellent intrinsic properties such as biodegradability, biocompatibility and physiochemical characteristics offering unique opportunities for tissue engineering.[2] However, these soft hydrogels still present important challenges with respect to their clean fabrication (i.e., without using toxic chemicals) into precise structures featuring the appropriate mechanical resistance. In this work we propose the solvent-cast 3D printing technique to obtain precise and biocompatible three-dimensional (3D) chitosan scaffolds. Materials and methods: Chitosan (degree of deacetylation = 90%, molecular weight = 207 kDa) used in this study was supplied by Biolog GmbH (Germany). 8 w/v % chitosan dissolved in mixed acids: acetic acid, lactic acid and citric acid (mole fraction: 71.1%, 27.3% and 1.6%, respectively) was prepared as the printable ink used for the fabrication. The solvent-cast 3D printing was developed to fabricate chitosan scaffolds at room temperature. The setup consists of a computer-controlled translation stage and a three-axis positioning platform. Chitosan scaffolds were produced by extruding the ink filaments on the plate in a layer–by-layer manner, which was followed by the filament solidification through solvent evaporation. Physical hydrogel scaffolds were obtained by neutralization in a sodium hydroxide solution. The tensile properties of chitosan scaffolds were examined using a MTS-Insight machine. Indirect toxicity (on extracts) of the scaffold was tested with L929 fibroblasts using the alamar blue test. The ability of cells to adhere and grow on material was also evaluated by alamar blue and live/dead assay after 1, 4 and 7 days. Results and discussion: Chitosan scaffolds with a well-controlled pore size (minimum pore size as small as ~120 µm) and interconnected multilayer microfiber networks were achieved. Printed chitosan scaffolds (Fig.1) were self-supporting and can easily be manipulated and deformed with a tweezer without breaking. Chitosan scaffolds demonstrated relatively high values of elongation at break (around 110%) and Young’s modulus (around 22 MPa), fulfilling the demands for certain targeted tissues like cardiac muscles (i.e., 500 kPa). Our cell culture study showed that extracts from chitosan scaffolds were not toxic. Moreover cells adhered and grew on the scaffolds and the chitosan microfibers were almost fully covered by cells after 7 days (Fig.2). Conclusion: We have successfully fabricated strong 3D chitosan scaffolds by solvent-cast 3D printing and observed a significant cell growth after 7 days. 3D printing truly offers a low-cost, scalable, highly flexible and efficient manufacturing technique for tissue engineering. Our strategy may also be applicable to other soft hydrogels based on self-assembling biomolecules such as collagen. Hybrid complex topologies with several soft hydrogels and tunable mechanical properties of scaffolds will be further developed to significantly advance 3D tissue-like structures. Figure 1. Optical microscopy image of 10-layer chitosan scaffolds folded using a tweezer Figure 2. Optical fluorescence microscopy image of fibroblasts grew on scaffolds during 7 days

3D Porous Chitosan-Alginate Scaffolds Promote Proliferation and Enrichment of Cancer Stem-Like Cells.

Cancer stem cells are increasingly becoming a primary target for new cancer treatment development. The ability to study their transient behavior in vitro will provide the opportunity for high-throughput testing of more effective therapies. We have previously demonstrated the use of 3D porous chitosan-alginate (CA) scaffolds to promote cancer stem-like cell (CSC) proliferation and enrichment in glioblastoma. Here we use 3D porous CA scaffolds to promote cancer stem-like cell enrichment in cell lines from prostate, liver, and breast cancers, and investigate the proliferation, morphology, and gene expressions of cells cultured in CA scaffolds as compared to 2D controls. The 3D CA scaffold cultures for all three cancer types showed reduced proliferation, formation of tumor spheroids, and increased expression of CSC associated mark genes (CD133 and NANOG), as opposed to monolayers. Additionally, we present a putative mechanism for the cancer stem-like cell enrichment on CA scaffolds. This study demonstrates that the cancer stem-like cell enrichment in CA scaffolds is a robust process that is not restricted to particular cancer types.

Oxygen and nitrogen plasma etching of three-dimensional hydroxyapatite/chitosan scaffolds fabricated by additive manufacturing

Three-dimensional (3D) chitosan and hydroxyapatite (HAp)/chitosan (CH) scaffolds were fabricated by additive manufacturing, then their surfaces were etched with oxygen (O2) and nitrogen (N2) plasma. O2 and N2 plasma etching was performed to increase surface properties such as hydrophilicity, roughness, and surface chemistry on the scaffolds. After etching, hydroxyapatite was exposed on the surface of 3D HAp/CH scaffolds. The surface morphology and chemical properties were characterized by contact angle measurement, scanning electron microscopy, X-ray diffraction, and attenuated total reflection Fourier infrared spectroscopy. The cell viability of 3D chitosan scaffolds was examined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The differentiation of preosteoblast cells was evaluated by alkaline phosphatase assay. The cell viability was improved by O2 and N2 plasma etching of 3D chitosan scaffolds. The present fabrication process for 3D scaffolds might be applied to a potential tool for preparing biocompatible scaffolds.

Combined delivery of PDGF-BB and BMP-6 for enhanced osteoblastic differentiation

Natural microenvironment during bone tissue regeneration involves integration of multiple biological growth factors which regulate mitogenic activities and differentiation to induce bone repair. Among them platelet derived growth factor (PDGF-BB) and bone morphogenic protein-6 (BMP-6) are known to play a prominent role. The aim of this study was to investigate the benefits of combined delivery of PDGF-BB and BMP-6 on proliferation and osteoblastic differentiation of MC3T3-E1 preosteoblastic cells. PDGF-BB and BMP-6 were loaded in gelatin and poly (3-hydroxybutyric acid-co-3-hydroxyvaleric acid) particles, respectively. The carrier particles were then loaded into 3D chitosan matrix fabricated by freeze drying. The fast release of PDGF-BB during 7 days was accompanied by slower and prolonged release of BMP-6. The premising release of mitogenic factor PDGF-BB resulted in an increased MC3T3-E1 cell population seeded on chitosan scaffolds. Osteogenic markers of RunX2, Col 1, OPN were higher on chitosan scaffolds loaded with growth factors either individually or in combination. However, OCN expression and bone mineral formation were prominent on chitosan scaffolds incorporating PDGF-BB and BMP-6 as a combination.

3D Porous Chitosan-Alginate Scaffolds as an In Vitro Model for Evaluating Nanoparticle-Mediated Tumor Targeting and Gene Delivery to Prostate Cancer.

Cationic nanoparticles (NPs) for targeted gene delivery are conventionally evaluated using 2D in vitro cultures. However, this does not translate well to corresponding in vivo studies because of the marked difference in NP behavior in the presence of the tumor microenvironment. In this study, we investigated whether prostate cancer (PCa) cells cultured in three-dimensional (3D) chitosan-alginate (CA) porous scaffolds could model cationic NP-mediated gene targeted delivery to tumors in vitro. We assessed in vitro tumor cell proliferation, formation of tumor spheroids, and expression of marker genes that promote tumor malignancy in CA scaffolds. The efficacy of NP-targeted gene delivery was evaluated in PCa cells in 2D cultures, PCa tumor spheroids grown in CA scaffolds, and PCa tumors in a mouse TRAMP-C2 flank tumor model. PCa cells cultured in CA scaffolds grew into tumor spheroids and displayed characteristics of higher malignancy as compared to those in 2D cultures. Significantly, targeted gene delivery was only observed in cells cultured in CA scaffolds, whereas cells cultured on 2D plates showed no difference in gene delivery between targeted and nontarget control NPs. In vivo NP evaluation confirmed targeted gene delivery, indicating that only CA scaffolds correctly modeled NP-mediated targeted delivery in vivo. These findings suggest that CA scaffolds serve as a better in vitro platform than 2D cultures for evaluation of NP-mediated targeted gene delivery to PCa.

MP19-02 HUMAN RENAL PROXIMAL TUBULE CELLS EXPRESSING FUNCTIONAL CHARACTERISTICS WITH MEMBRANOUS AND 3D TUBULAR CHITOSAN SCAFFOLD

You have accessJournal of UrologyStem Cell Research1 Apr 2015MP19-02 HUMAN RENAL PROXIMAL TUBULE CELLS EXPRESSING FUNCTIONAL CHARACTERISTICS WITH MEMBRANOUS AND 3D TUBULAR CHITOSAN SCAFFOLD Ini Chiang Ini ChiangIni Chiang More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2015.02.994AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Human renal proximal tubule cells (HRPTCs) are responsible for reabsorption of glomerular filtrations and maintenance of water/electrolytes internal balance. Primary culture of HRPTCs is a promising target for applications in bioengineering, reconstructive medicine, nephrotoxicity assay, physiological studies, and even bioartificial kidney. In this study, we chose chitosan to fabricate membranous and tubular scaffolds for HRPTCs cultivation due to biocompatibility, biodegradability, antibacterial and wound-healing activity. METHODS First, primary HRPTCs digested and retrieved from nephrectomy/nephroureterectomy specimen were seeded on chitosan membrane, collagen-coated well, and blank petri dish (TCPS). Cell viability, dome quantitation, immunofluorescence characterization, western blot assay and transepithelial electrical resistance (TEER) were compared. RESULTS HRPTCs could be maintained on chitosan membrane with good viability and differentiation characteristics for at least six months in serum-free condition. Dome formation is a specific marker of renal proximal tubule cell differentiation. HRPTCs on chitosan membrane showed higher dome numbers than cells on collagen and TCPS. HRPTCs also showed highest expression of Na+-K+ ATPase £∖-1 subunit and lowest expression of Vimentin on chitosan membrane, which indicated that HRPTCs would be functional and of specific differentiation characteristics on this biomaterial. Then, HRPTCs were further cultivated on a 3D chitosan tubular scaffold successfully with cell full confluence and dome formation. Graph 1 (A) Cross-sectional view of the tubular chitosan scaffold (B) Longitudinal incision of the tube was done and the inner side of the tube was noted with confluent PTCs. (C) Dome formation was noted under x50 SEM field. Arrow: Dome (D) Dome formation under x500 SEM Graph 2 Human renal proximal convoluted tubule cell dome formation on chitosan membrane demonstrated by confocal microscopy with horizontal and vertical view CONCLUSIONS Human renal proximal tubule cells could be maintained with good viability and functional characteristics on chitosan membranous and tubular scaffold © 2015 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 193Issue 4SApril 2015Page: e215-e216 Advertisement Copyright & Permissions© 2015 by American Urological Association Education and Research, Inc.MetricsAuthor Information Ini Chiang More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Development of an immunomodulatory biomaterial: Using resolvin D1 to modulate inflammation

In our search for immunomodulatory biomaterials capable of modulating the inflammatory response through M2 macrophage polarization, we report here on a new strategy that resulted from the incorporation of resolvin D1 (RvD1), a pro-resolution lipid mediator in porous 3D chitosan (Ch) scaffolds, followed by its lyophilisation. We have investigated the inflammatory response caused by this biomaterial in vivo using a mouse air-pouch model of inflammation. We found that this developed material caused a decrease in inflammatory cells recruited to the implant site, together with higher numbers of F4/80+/CD206+ cells (M2 macrophages) and lower numbers of F4/80+/CCR7+ cells (M1 macrophages). It also induced a general decrease in pro-inflammatory cytokines, and caused a decrease in the inflammatory cells observed around and within the implanted scaffolds, when compared with Ch alone or Ch not submitted to lyophilisation after RvD1 incorporation. Our results demonstrate that we were able to develop an immunomodulating biomaterial that triggers a shift in the macrophage response towards a M2 reparative response that will be advantageous for the host.

Water-soluble photopolymerizable chitosan hydrogels for biofabrication via two-photon polymerization

Fabrication of three-dimensional (3D) hydrogel microenvironments with predefined geometry and porosity can facilitate important requirements in tissue engineering and regenerative medicine. Chitosan (CH) is well known as a biocompatible hydrogel with prospective biological properties for biomedical aims. So far, microstructuring of this soft material presents a great limitation for its application as functional supporting material for guided tissue formation. Enabling photopolymerization, chemically modified CH can be applied for the biofabrication of reproducible 3D scaffolds using rapid prototyping techniques like two-photon polymerization (2PP) or others. The application of this technique allows precise serial fabrication of computer-designed microstructure geometries by scanning a femtosecond laser beam within a photosensitive material. This work explores a new synthesis of water-soluble photosensitive chitosan and the fabrication of well-defined microstructures from the generated materials. To modulate the mechanical and biochemical properties of the material, CH was combined and cross-linked with synthetic poly(ethylene glycol) diacrylate. For a biological adaption to the in vivo situation, CH was covalently crosslinked with a photosensitive modified vascular endothelial growth factor (VEGF). Performed in vitro studies reveal that modified CH is biocompatible. VEGF enhances CH bioactivity. Furthermore, a 3D CH scaffold can be successfully seeded with cells. Therefore, the established CH holds great promise for future applications in tissue engineering.

Processing and Characterization of 3D Dense Chitosan Pieces, for Orthopedic Applications, by Adding Plasticizers

In this work, plasticizer agents were incorporated in a chitosan based formulation, as a strategy to improve the fragile structure of chitosan based-materials. Three different plasticizers: ethylene glycol, glycerol and sorbitol, were blended with chitosan to prepare 3D dense chitosan specimens. The properties of the obtained structures were assessed for mechanical, microstructural, physical and biocompatibility behavior. The results obtained revealed that from the different specimens prepared, the blend of chitosan with glycerol has superior mechanical properties and good biological behavior, making this chitosan based formulation a good candidate to improve robust chitosan structures for the construction of bioabsorbable orthopedic implants.

Effects of flow configuration on bone tissue engineering using human mesenchymal stem cells in 3D chitosan composite scaffolds.

Perfusion bioreactor plays important role in supporting 3D bone construct development. Scaffolds of chitosan composites have been studied to support bone tissue regeneration from osteogenic progenitor cells including human mesenchymal stem cells (hMSC). In this study, porous scaffolds of hydroxyapatite (H), chitosan (C), and gelatin (G) were fabricated by phase-separation and press-fitted in the perfusion bioreactor system where media flow is configured either parallel or transverse with respect to the scaffolds to investigate the impact of flow configuration on hMSC proliferation and osteogenic differentiation. The in vitro results showed that the interstitial flow in the transverse flow (TF) constructs reduced cell growth during the first week of culture but improved spatial cell distribution and early onset of osteogenic differentiation measured by alkaline phosphatase and expression of osteogenic genes. After 14 days of bioreactor culture, the TF constructs have comparable cell number but higher expression of bone markers genes and proteins compared to the parallel flow constructs. To evaluate ectopic bone formation, the HCG constructs seeded with hMSCs pre-cultured under two flow configurations for 7 days were implanted in CD-1 nude mice. While Masson's Trichrom staining revealed bone formation in both constructs, the TF constructs have improved spatial cell and osteoid distribution throughout the 2.0 mm constructs. The results highlight the divergent effects of media flow over the course of construct development and suggest that the flow configuration is an important parameter regulating the cellular events leading to bone construct formation in the HCG scaffolds.

Preparation and Properties of 3D Chitosan Microtubes

The preparation of 3D chitosan microtubes from polymer solutions in citric and lactic acids by the wet and dry molding methods is described. The mechanism of formation of the insoluble polymeric layer constructing the walls of these microtubes is characterized. The microtubes obtained from chitosan solutions in citric acid are found to have a fragile porous inner layer. For those obtained from chitosan solutions in lactic acid the morphology, elastic-deformation properties, physicomechanical properties, and biocompatibility were assessed. These samples have smooth outer and inner surfaces with no visible defects and high values of elongation at break. The strength of the microtubes obtained by the dry method is much higher than in the case of the wet one. A high adhesion and high proliferative activity of the epithelial-like MA-104 cellular culture on the surface of our microtubular substrates in model in vitro experiments were revealed. Prospects of using chitosan microtubes as vascular prostheses are suggested.

Preparation of macroporous chitosan patch using co-solvent as a transdermal drug-delivery system

As a simple method, bio-patches of band type have been widely used in various medical areas for more than 70 years. Despite their numerous advantages, drawbacks such as a lack of adhesive strength and low efficiency of transdermal drug delivery have limited their application. To improve the convenience of use, a 3D porous chitosan patch was prepared simply by phase separation of a solvent (acidic water)/co-solvent [dimethyl carbonate (DMC)]. As a tackifier of low cytotoxicity, allyl 2-cyanoacrylate bio-glue was prepolymerized and coated onto the porous chitosan patch. Various properties were examined, such as mechanical strength, efficiency of drug-delivery, morphology, cytotoxicity and degradability. We ascertained that the optimal ratio of co-solvent for achieving a highly porous chitosan patch was DMC at a ratio of 5 %. The resultant drug release by the optimal highly porous chitosan patch was approximately twofold faster than that of the untreated control. The porous patch showed improved efficiency of cell adhesion after culturing in cells for 4 h. After 72 h, the cultured cells showed increased cell proliferation on the porous patches. These results strongly suggest that the chitosan-based porous patches covered with modified cyanoacrylate can be widely used as good adhesive patches in various incidents.

3D porous chitosan scaffolds suit survival and neural differentiation of dental pulp stem cells.

A key aspect of cell replacement therapy in brain injury treatment is construction of a suitable biomaterial scaffold that can effectively carry and transport the therapeutic cells to the target area. In the present study, we created small 3D porous chitosan scaffolds through freeze-drying, and showed that these can support and enhance the differentiation of dental pulp stem cells (DPSCs) to nerve cells in vitro. The DPSCs were collected from the dental pulp of adult human third molars. At a swelling rate of ~84.33 ± 10.92 %, the scaffold displayed high porosity and interconnectivity of pores, as revealed by SEM. Cell counting kit-8 assay established the biocompatibility of the chitosan scaffold, supporting the growth and survival of DPSCs. The successful neural differentiation of DPSCs was assayed by RT-PCR, western blotting, and immunofluorescence. We found that the scaffold-attached DPSCs showed high expression of Nestin that decreased sharply following induction of differentiation. Exposure to the differentiation media also increased the expression of neural molecular markers Microtubule-associated protein 2, glial fibrillary acidic protein, and 2',3'-cyclic nucleotide phosphodiesterase. This study demonstrates that the granular 3D chitosan scaffolds are non-cytotoxic, biocompatible, and provide a conducive and favorable micro-environment for attachment, survival, and neural differentiation of DPSCs. These scaffolds have enormous potential to facilitate future advances in treatment of brain injury.

A Multicompartment Holder for Spinner Flasks Improves Expansion and Osteogenic Differentiation of Mesenchymal Stem Cells in Three-Dimensional Scaffolds

In the tissue engineering field dynamic culture systems, such as spinner flasks, are widely used due to their ability to improve mass transfer in suspension cell cultures. However, this culture system is often unsuitable to culture cells in three-dimensional (3D) scaffolds. To address this drawback, we designed a multicompartment holder for 3D cell culture, easily adaptable to spinner flasks. Here, the device was tested with human mesenchymal stem cells (MSCs) seeded in 3D porous chitosan scaffolds that were maintained in spinner flasks under dynamic conditions (50 rpm). Standard static culture conditions were used as control. The dynamic conditions were shown to significantly increase MSCs proliferation over 1 week (approximately 6-fold) and to improve cell distribution within the scaffold. Moreover, they also promoted osteogenic differentiation of MSCs, inducing an earlier peak in alkaline phosphatase (ALP) activity, and a more homogenous ALP staining and matrix mineralization in the whole scaffolds, but particularly in the center. Overall, this study shows a new multicompartment holder to culture 3D scaffolds that can broaden the application of spinner flasks.

Outer electrospun polycaprolactone shell induces massive foreign body reaction and impairs axonal regeneration through 3D multichannel chitosan nerve guides.

We report on the performance of composite nerve grafts with an inner 3D multichannel porous chitosan core and an outer electrospun polycaprolactone shell. The inner chitosan core provided multiple guidance channels for regrowing axons. To analyze the in vivo properties of the bare chitosan cores, we separately implanted them into an epineural sheath. The effects of both graft types on structural and functional regeneration across a 10 mm rat sciatic nerve gap were compared to autologous nerve transplantation (ANT). The mechanical biomaterial properties and the immunological impact of the grafts were assessed with histological techniques before and after transplantation in vivo. Furthermore during a 13-week examination period functional tests and electrophysiological recordings were performed and supplemented by nerve morphometry. The sheathing of the chitosan core with a polycaprolactone shell induced massive foreign body reaction and impairment of nerve regeneration. Although the isolated novel chitosan core did allow regeneration of axons in a similar size distribution as the ANT, the ANT was superior in terms of functional regeneration. We conclude that an outer polycaprolactone shell should not be used for the purpose of bioartificial nerve grafting, while 3D multichannel porous chitosan cores could be candidate scaffolds for structured nerve grafts.

In vitro cytocompatibility evaluation of chitosan/graphene oxide 3D scaffold composites designed for bone tissue engineering.

Extensively studied nowadays, graphene oxide (GO) has a benefic effect on cell proliferation and differentiation, thus holding promise for bone tissue engineering (BTE) approaches. The aim of this study was not only to design a chitosan 3D scaffold improved with GO for optimal BTE, but also to analyze its physicochemical properties and to evaluate its cytocompatibility and ability to support cell metabolic activity and proliferation. Overall results show that the addition of GO in the scaffold's composition improved mechanical properties and pore formation and enhanced the bioactivity of the scaffold material for tissue engineering. The new developed CHT/GO 3 wt% scaffold could be a potential candidate for further in vitro and in vivo osteogenesis studies and BTE approaches.

Biotin‐conjugated anti‐CD44 antibody–avidin binding system for the improvement of chondrocyte adhesion to scaffolds

The clinical need for improved treatment options for patients with cartilage injuries has motivated tissue-engineering studies aimed at the in vitro generation of cell-based implants with functional properties. The success of tissue-engineered repair of cartilage may depend on the rapid and efficient adhesion of transplanted cells to the scaffold. In the present study, chondrocyte-scaffold constructs were engineered by planting porcine chondrocytes into nonporous chitosan membranes and 3D porous chitosan scaffolds that were treated with or without biotin-conjugated anti-CD44 antibody-avidin binding system and avidin-biotin binding system. The spreading area, cell exfoliation rates, cell proliferation rates, histological analysis, DNA and glycosaminoglycan (GAG) content, and mRNA expression were investigated to evaluate the efficiency of biotin-conjugated anti-CD44 antibody-avidin binding system for the improvement of cell adhesion to scaffolds in the cartilage tissue. The results showed that the biotin-conjugated anti-CD44 antibody-avidin binding system improved cell adhesion to scaffolds effectively. These studies suggest that this binding system has the potential to provide improved tissue-engineered cartilage for clinical applications.

Fabrication of chitosan-silver nanoparticle hybrid 3D porous structure as a SERS substrate for biomedical applications

We propose a simple, low-cost, large-area, and functional surface enhanced Raman scattering (SERS) substrate for biomedical applications. The SERS substrate with chitosan-silver nanoparticles (chitosan-Ag NPs) hybrid 3D porous structure was fabricated simply by a one-step method. The chitosan was used as a template for the Ag NPs deposition. SERS enhancement by the chitosan-Ag NPs substrate was experimentally verified using rhodamine B as an analyte. Thiolated single stranded DNA was also measured for atopic dermatitis genetic markers (chemokines CCL17) at a low concentration of 5pM. We successfully designed a novel SERS substrate with silver nanoparticle hybridized 3D porous chitosan that has the potential to become a highly sensitive and selective tool for biomedical applications.