Papers by Keyword: Tissue Engineering

Abstract: Poly (N-isopropylacrylamide) (PNIPAm) has been one of the most widely studied thermal responsive polymer in tissue engineering owing to its reversible hydrophilic-hydrophobic phase transition across its lower critical solution temperature (~32°C) that is close to human physiological temperatures. Among tissue engineering constructs, nanofibrous scaffolds offer an added advantage in mimicking the morphology of the native extracellular matrix (ECM). Electrospinning has been reported as one of the most facile method to produce PNIPAm nanofibres and neat electrospun nanofibres scaffold is known to possess poor aqueous stability, limiting its use in tissue engineering applications. In contrast, numerous studies on PNIPAm hydrogels have shown relatively good aqueous stability owing to the hydrophilic 3D crosslinked structure of the hydrogel which resist instant dissolution but rather swell to a greater or lesser extent. However, the presence of crosslinkages in PNIPAm hydrogels causes it to be hardly electrospinnable into nanofibres. In the present work, crosslinker free PNIPAm was radical polymerized to a high molecular weight of 385 kDa. To produce nanofibers, electrospinning was carried out on a dedicated %wt of PNIPAm solution containing octaglycidyl polyhedral oligomeric silsesquioxane (OpePOSS) and 2-ethyl-4-methylimidazole (EMI). Resulting PNIPAm nanofibrous network was found to strongly resemble the ECM morphology with fiber diameter of 436.35 ± 187.04 nm, pore size 1.24 ± 1.27 μm and 63.6% total porosity. Aqueous stability was studied in cell culture media over the course of 28 days. The current result shows significant improvement with a gradual mass loss up to a maximum of 35% instead of the near immediate dissolution observed in the case of electrospun neat PNIPAm scaffold without crosslinks.

Abstract: Utilization of natural biopolymers has shown potential in generating innovations for tissue engineering applications. This study aims to fabricate scaffolds from cellulose acetate derived from kapok fiber. Cellulose is extracted from raw kapok fibers by alkali treatment and delignification then synthesized into cellulose acetate. Kapok cellulose acetate (KCA) is dissolved in dimethyl sulfoxide to fabricate the scaffold. Materials were characterized using Attenuated Total Reflectance – Fourier Transform Infrared (ATR-FTIR) spectrometer, X-ray diffractometer (XRD) and Differential Scanning Calorimeter (DSC). FTIR analysis has shown that cellulose was extracted from kapok and cellulose acetate was successfully synthesized. XRD analysis also confirmed the presence of cellulose acetate. Results have also shown that synthesized KCA seems to have higher crystallinity than commercially available cellulose acetate (CCA). The degree of substitution (DS) of KCA was found to be 2.85 which is close to the DS value of tri-substituted cellulose acetate. DSC analysis has shown lower glass transition temperature of 52.15°C but higher degradation temperature of 300.43°C than the CCA. Moreover, the values for the enthalpy of fusion for two endotherms of KCA (44.0556 J/g and 18.6946 J/g) are higher than the values for CCA by 344% and 261%, respectively; thus, indicating the higher degree of crystallinity for synthesized KCA samples.

Abstract: The aim of this research is to synthesis biopolymeric materials from hydroxyethyl cellulose (HEC) (5 wt. %) blended with sodium alginate (SA) (10 wt. %) at 1:1 ratio fabricated by using freeze-drying technique. The HES/SA was treated with simulated body fluid (SBF) by immersion technique through the depositing of calcium phosphate on the scaffold’s surfaces. All scaffolds were characterizing by using field emission electron microscope (FESEM), attenuated total reflectance-Fourier infrared transform (ATR-FTIR), and thermogravimetric analysis (TGA). The FESEM images results displayed interconnected porous structure with diameter ranging from 40 to 400 μm with average apatite diameter in range of 95 nm – 148 nm. The ATR-FTIR results exhibit possible interactions between hydroxyl groups of HEC, SA and apatite groups of the scaffolds. The TGA results showed four different regions of mass losses, represents the amorphous transition temperature and water disposal, side-chain bond breaking, pyrolysis of SA and dihydroxylation behaviour of calcium phosphate, respectively. Cell-scaffolds interaction demonstrated that human fetal osteoblast (hFOB) cells differentiated and spread well on scaffolds with better cell proliferation and attachment was more prominent on HEC/SA treated with SBF. Since these biocompatible and biodegradable scaffolds showed promising results, these scaffolds could be adopted for the design of next-generation tissue-engineered bone grafts.

Abstract: One of the largest fields of application of electrospun materials is the biomedical field, including development of scaffolds for tissue engineering, drug delivery and wound healing. Electrospinning appears as a promising technique in terms of scaffolds composition and architecture, which is the main aspect of this review paper, with a special attention to natural polymers including collagen, fibrinogen, silk fibroin, chitosan, chitin etc. Thanks to the adaptability of the electrospinning process, versatile hybrid, custom tailored structure scaffolds have been reported. The same is achieved due to the vast biomaterials’ processability as well as modifications of the basic electrospinning set-up and its combination with other techniques, simultaneously or by post-processing.

Abstract: Background: Hydroxyapatite (HAP), as a common biomaterial in bone tissue engineering, can be fabricated in combination with other osteogenic agents. Pentoxifylline (PTX) is demonstrated to have positive roles in bone defect healing. Since local administration can diminish the systemic side effects of the drug, the objectives of the current in vitro study were to find the effects of PTX on the osteoblast functions for tissue engineering applications. Methods: a HAP scaffold was fabricated by casting the HAP slurry within polyurethane foam. The scaffold was enriched with 5 mg/mL PTX. Alginate (Alg) was used as drug carrier to regulate the PTX releasing rate. MG-63 osteosarcoma cells were cultured on 3D scaffolds and 2D Alg films in the presence or absence of PTX. Results: PTX did not affect the cell viability, attachment and phenotype. Also, the ultrastructure of the scaffolds was not modified by PTX enrichment. Alizarin red S staining showed that PTX has no effect on calcium deposition. Besides, Raman confocal microscopy demonstrated an increase in the organic matrix formation including proline, valine and phenylalanine deposition (represented collagen). Although PTX increased the total protein secretion, it led to a decrease in the alkaline phosphatase activity and vascular endothelial growth factor (VEGF) content. PTX reduced the hydration and degradation rates and it was released mainly at the first 24 hours of incubation. Conclusion: Based on our in vitro study, application of engineered PTX-loaded HAP scaffold in bone regeneration can act on behalf of organic matrix production, but not angiogenesis and mineralization.

Abstract: Patients suffering from cardiovascular disease lack suitable stent. In this study, a new polymeric composite material was prepared by incorporating various concentrations of gamma-glycidoxypropyltrimethoxysilane (GPTMS) into silk fibroin (SF), aiming at achieving a novel composite film with superior mechanical and biological properties, in order to match the requirement of cardiovascular tissue engineering stents. Fourier transform infrared spectroscopy (FTIR) analysis showed that GPTM could promote SF to transform from the original alpha helix and random coil/extension chain conformation to the beta-folded conformation. Tensile experiment indicated tensile strength and breaking elongation of SF/GPTMS hybrid film reach the maximum with 20% GPTMS content. Within a certain range, the water drop contact angle of SF/GPTMS hybrid film is positively correlated with the content of GPTMS. Endothelial cells (ECs) are best grown on hybrid SF/GPTMS hybrid film with 20% GPTMS content.

Abstract: Bovine bone is a considerable source for the production of hydroxyapatite. The recent study reported a novel method to extract hydroxyapatite from bovine bone without producing hazardous residue. The bovine bones were cut and boiled in the opened chamber followed by boiling in pressurized tank. The bones were then soaked into 95% ethanol. Calcination was then conducted in 800°C, 900°C and 1,000°C, for 2 hours. The result was then grinded and sieved. The powder then was characterized using Fourier transform infrared (FT-IR), Scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD) to measure the purity of hydroxyapatite. It is concluded that the hydroxyapatite derived from this process showed 100% purity, resulting 35.34 ± 0.39% w/w from the wet bone weight and 72.3% w/w from the dried weight. The present extraction method has been proven to yield high amount of pure hydroxyapatite as well as reducing the use of hazardous reagent.

Abstract: In this study, biodegradable scaffolds based on hydroxyethyl cellulose (HEC) (5 wt%) and poly (vinyl alcohol) (PVA) (15 wt%) with different percentages of celullose nanocrystal (CNC) (1 and 7 wt%) were fabricated by lyophilization method to get highly porous scaffolds. These scaffolds were made water insoluble by cross-linking via heat treatment. The morphology and thermal properties of HEC/PVA/CNCs scaffolds were characterized by using Scanning Electron Microscope (SEM) and Thermogravimetric Analysis (TGA). The morphological study showed that both prepared scaffold have highly porous structures with good pore interconnected structure. It was observed that thermal properties of scaffolds increased significantly as the concentration of CNCs increased. Cytotoxicity studies on scaffolds were carried out by utilizing human fetal osteoblast (hFOB) cells using DAPI nuclear stain and then confirmed using SEM. hFOB cells were able to attach and spread on all scaffolds. Incorporated CNCs as reinforcing nanofiller on scaffolds promising a superior functionality in bone tissue engineering.

Abstract: Bioactivity is an important aspect in biomaterial science ensuring materials used are safe for clinical application. The study describes fabrication of composites containing polylactic acid (PLA) – polyethylene glycol (PEG) with incorporation of sol-gel derived 45S5 bioactive glass (BG). Thermal analysis via Differential Thermal Analysis shows a favorable point over degree of crystallization that influence cells attachment, although non-significant difference in values indicates BG has homogenously dispersed. This correlates to X-ray diffraction analysis where non-significant difference is seen in intensities of the diffraction peaks, which confirms low impact of BG brittleness properties over the fabricated composite. Composites’ pH and degradation study in Simulated Body Fluid shows a steady increment profile over time and lower degradation rate for the composite after incorporation of BG. In vitro cell proliferation study also showed that HDF cells seeded on composite film of P/BG2.5 exhibit highest cell viability with steady increment of proliferation throughout the observation period.

Abstract: A novel method to obtain porous three-dimensional chitosan-based matrices has been developed. The structure is characterized by an interconnected system of pores, with controlled diameter by varying the concentration of chitosan and the nature of the solvent. The material is biodegradable, biocompatible, with high adhesion to fibroblasts and promotes its proliferation.