Cell migration and proliferation during monolayer formation and wound healing

The interaction of living cells with surfaces is important in applications of biomaterials, such as tissue engineering. Characterising and modelling the attachment, migration and proliferation of cells on materials used for tissue engineering provides valuable insight into their potential applications as well as a means of objective comparison. In this study, proliferation and migration of NIH-3T3 fibroblast cells on tissue culture plastic in vitro were quantified. The development of randomly scattered individual cells into confluent cell monolayers proceeded with cell density following a logistic growth pattern. Travelling cell wavefronts produced in a wound healing assay were modelled with a modified Fisher equation incorporating both diffusion and logistic growth. The diffusivity and growth rates thus determined could be used for comparison with cell behaviour on other surfaces or under different conditions. Cell tracking showed that the average effective velocity of cells varied inversely with cell density, supporting contact inhibition of cell movement.     

Nontoxic pH-sensitive silver nanocomposite hydrogels for potential wound healing applications

ABSTRACT

Silver nanocomposite (SNC) containing pH sensitivity with fascinating attention may be recommended for extensive utilization in eco-friendly nanomaterial applications. In the present investigation, a strategy to fabricate new biodegradable and biocompatible hydrogels based on sodium alginate/ethylene glycol/acrylic acid functionalized with silver nanocomposites, which were synthesized by a facile greener method. The swelling profile is enhanced the stimuli responsive behavior of nanocomposite hydrogels. The synthesized nanocomposite hydrogels has showed a significant pH-sensitive behavior which induced the degradation profile, cell viability, and antimicrobial activity. Hence, this kind of biomaterials has been utilized for nontoxic, degradable wound healing dressing.     

Synthesis of copper bearing borosilicate glass for soft tissue wound healing

To date, various wound dressings have been developed to increase the ability of healing and to recover the functions of wounded tissues. A complicated series of signaling pathways participate during the main phases of wound healing, i.e. hemostasis, inflammation, proliferation, and remodeling. The ions at the injury site could induce pathways either directly or indirectly; however, they must be presented slowly otherwise they would saturate the microenvironment and cause toxicity. Boron and copper ions upregulate cell recruitment, proliferation, and angiogenesis at the injury site. In this study, the synthesis of a biodegradable and slow-releasing copper-borosilicate glass via conventional melt casting and sol-gel was compared. In contrast to the melt casting-derived sample, the sol-gel glass exhibited a more regulated ion release. Thus it was selected as the optimized sample and was loaded into a gelatin-based wound dressing. In an in vivo study, after 15 days of dressing and compared to untreated models, a remarkable epidermal layer was regenerated on the wound area in the test group.     

Carbon nanotube localization at interface in cocontinuous blends of polyethylene and polycarbonate

A new technique to show good electroconductivity was proposed using carbon nanotube (CNT) localization in cocontinuous immiscible polymer blends comprising ultrahigh-molecular-weight polyethylene (UHMWPE) and polycarbonate (PC). When UHMWPE was added to PC/CNT in the molten state in an internal mixer, CNTs started moving to the UHMWPE phase. However, CNTs require a long time to diffuse into the UHMWPE phase owing to a low diffusion constant. Consequently, they remain at the interface between PC and UHMWPE. When the blends have cocontinuous structure, the localized CNTs at the phase boundary act as a conductive path, leading to a good electroconductivity. Although a similar morphology is obtained by adjusting the balance of interfacial tensions among polymers and CNT, it is difficult to find a system showing appropriate interfacial tensions. As the present method is applicable to various polymer blends, it will be an important technique to prepare a conductive nanocomposite. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 137, 48676.     

Single wall carbon nanotube dispersion and exfoliation in polymers

Dispersion and exfoliation of single wall carbon nanotubes (SWNTs) have been studied in poly(acrylonitrile) (PAN), poly(p‐phenylene benzobisoxazole) (PBO) solutions, and composite fibers using transmission electron microscopy. As a result of polymer assisted dispersion and exfoliation, the average SWNT bundle diameter in SWNT/PAN (5/95) was 11 nm, while the average diameter for the pristine SWNT bundles was about 30 nm. High resolution TEM of SWNT/PBO (10/90) composite fibers did not reveal the presence of SWNT aggregates or bundles, suggesting SWNT exfoliation as individuals. On the other hand, both oriented and unoriented nanotube bundles have been observed in SWNT/PBO samples containing 15 wt % nanotubes. Carbon nanotubes are 10⁵ times more radiation resistant than flexible polymers such as polyethylene, and 10³ times more resistant than highly radiation resistant polymers such as PBO. Therefore in the high resolution TEM study of nanotube/polymer composites, nanotubes can be observed long after the polymer has been damaged by electron radiation. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 985–989, 2005     

Characterization of chitosan/citrate and chitosan/acetate films and applications for wound healing

In this work, we aimed to develop a scaffold of chitosan (CS) with a porous sponge structure for an artificial skin. The scaffolds were prepared from both CS/citric and CS/acetic solutions. In addition, the cast films were also prepared from the same solutions to compare some of their properties. They were characterized using WAXD, FTIR, DSC, tensile measurements, and SEM observation. It was found that CS/acetate had low crystallinity but CS/citrate was in an amorphous state, resulting in a large ductility with rubbery softness. Despite the different morphologies of CS/citrate and CS/acetate scaffolds, both scaffolds exhibited the wound healing effect available for tissue engineering. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Comparison of polyimide/multiwalled carbon nanotube (MWNT) nanocomposites by in situ polymerization and blending

In this research, multiwalled carbon nanotube (MWNT) was oxidized and then modified to form carboxylic groups (? COOH) on the surface and the end of the tube. After that, the MWNT was added to polyimide matrix to enhance its mechanical and electrical properties by in situ polymerization and blending. The PI/MWNT composites were obtained by spin coating and multistep thermal curing process. The comparison of in situ polymerization and blending as well as the effect of unmodified and modified MWNT were discussed in this study. The results indicate that in situ polymerization is able to make a perfect dispersion by adding modified MWNT into polyimide matrix. Thermal and mechanical properties of the composites can be improved by hydrogen bonding interaction between the modified MWNT and polyimide matrix. Electrical resistance of the composites can be decreased to meet the criterion of electrostatic charge (ESC) mitigation as the surface resistance is reduced into the range of 10⁶–10¹⁰ Ω/cm² by adding modified MWNT. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Curcumin loaded fish scale collagen-HPMC nanogel for wound healing application: Ex-vivo and In-vivo evaluation

The objective of the present investigation was to formulate curcumin loaded fish scale collagen (FSC)-hydroxypropyl methyl cellulose (HPMC K100) nanogel (CNG) for wound healing application. The curcumin nanoemulsion was prepared, characterized and loaded in FSC-HPMC nanogel. The nanogel was evaluated for ex-vivo permeation, in-vivo, skin irritation, and stability study. Ex-vivo permeation study demonstrated that CNG prolonged release and exhibited higher percent contraction value of wound compared to other formulations. In skin irritation study, formulation produced the score of less than 2 compared to control. It concluded that curcumin loaded FSC-HPMC nanogel could be prepared for wound healing applications.     

Strategies for non‐invasive imaging of polymeric biomaterial in vascular tissue engineering and regenerative medicine using ultrasound and photoacoustic techniques

The ability of new polymeric materials to provide excellent biomechanical properties expanded their potential for biomedical applications enormously. The use of non‐invasive imaging modalities could provide crucial information to monitor the efficacy/effectiveness/efficiency of the new materials employed in ‘regenerative’ approaches, including scaffolds, hydrogels, self‐assembling materials and nanosized structures. The assessment of the morpho‐functional and metabolic changes of treated or implanted tissues, the visualization of sites of drug delivery and the real‐time check of the in vivo efficacy of therapeutics could be achieved by non‐invasive micro‐ and macro‐imaging techniques. The macro‐ and nano‐requirements of these new materials and their behaviour in vivo can be investigated using standard approaches such as computed tomography, MRI and ultrasound techniques and the emerging photoacoustic imaging. This paper presents recent advancements of ultrasonography and the novel photoacoustic technique to monitor the morpho‐functional parameters of synthetic polymeric scaffolds and conduits in experimental models. © 2016 Society of Chemical Industry     

Synthesis,characterization and efficacy of chemically crosslinked PVA hydrogels for dermal wound healing in experimental animals

In this study, we have investigated the efficacy of crosslinked polyvinyl alcohol (PVA) hydrogel as a wound dressing material, using rat as the animal model. The hydrogel was synthesized by chemical crosslinking of PVA with potassium persulphate and the crosslinking reaction parameters were optimized. The developed hydrogel was found to possess excellent mechanical properties, high water absorption capacity, gel content, and optimum water vapor transmission rate, indicating its ability to act as an effective wound dressing material. The inherent nontoxic characteristics of PVA remained unaltered after crosslinking. The in vitro diffusion studies of bovine serum albumin (BSA) as model protein, indicated a relatively slow release of protein resulting from its microencapsulation in the polymeric matrix. For in vivo studies, full‐thickness excision wounds (2 × 2 cm²) were made on the dorsal surface of rats. The hydrogel was applied on the wound and changed at regular intervals. For comparison of wound healing ability, a radiation crosslinked PVA‐based hydrogel, “HiZel” was used as a reference control. The wounds treated with PVA hydrogel healed faster as indicated by an increased rate of wound contraction (16.5 days versus 22.0 in control group). Treatment with “Hizel” led to increase in hydroxyproline in the wound tissue, whereas treatment with PVA hydrogel led to increase in both hydroxyproline as well as hexosamine. This probably provides added strength to the tissue, thereby indicating that PVA hydrogel had higher efficacy than “Hizel”. The results suggest that chemically crosslinked PVA hydrogel could be used as an effective wound dressing material. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Unleashing the potential of supercritical fluids for polymer processing in tissue engineering and regenerative medicine

One of the major scientific challenges that tissue engineering and regenerative medicine (TERM) faces to move from benchtop to bedside regards biomaterials development, despite the latest advances in polymer processing technologies.A variety of scaffolds processing techniques have been developed and include solvent casting and particles leaching, compression molding and particle leaching, thermally induced phase separation, rapid prototyping, among others. Supercritical fluids appear as an interesting alternative to the conventional methods for processing biopolymers as they do not require the use of large amounts of organic solvents and the processes can be conducted at mild temperatures. However, this processing technique has only recently started to receive more attention from researchers. Different processing methods based on the use of supercritical carbon dioxide have been proposed for the creation of novel architectures based on natural and synthetic polymers and these will be unleashed in this paper.     

Development and characterization of niobium-releasing silicate bioactive glasses for tissue engineering applications

Novel niobium-containing bioactive glass formulations (Nb-BGs) were designed, produced and used to fabricate sintered glass-ceramic granules to examine their in vitro bioactivity and angiogenic potential. Nb-BGs were prepared by melting and quenching. Afterwards, the glasses were crushed and milled into fine powders. These powders were used to make aqueous slurries which were poured into molds, dried and sintered to produce pellets, from which granules of 0.5–0.85 mm in size were obtained. In vitro bioactivity was tested by immersing the granules in simulated body fluid for up to 14 days. Cell biology tests were carried out by indirect culture of bone marrow stromal cells (ST-2) with supernatants resulting from incubation of BG granules in cell culture medium. The effect of dissolution products from Nb-BGs on the secretion of vascular endothelial growth factor (VEGF) was assessed to characterize the angiogenic potential of the new Nb-containing BG compositions.     

Fabrication and characterization of silk/forsterite composites for tissue engineering applications

In this research, novel composite scaffolds consisting of silk fibroin and forsterite powder were prepared by a freeze-drying method. In addition, the effects of forsterite powder contents on the structure of the scaffolds were investigated to provide an appropriate composite for bone tissue engineering applications. The morphology studies using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques showed that the forsterite ceramic was well distributed throughout the structures of SF/forsterite scaffolds. Furthermore, the forsterite powder (up to 40 wt%) was homogenously distributed within the silk fibroin as a matrix.     

聚天冬氨酸衍生物的研究进展及其在药物控释和组织工程领域中的应用

聚天冬氨酸衍生物是一种具有良好生物相容性、生物降解性的新材料.作者综述了聚天冬氨酸衍生物的研究进展,介绍了共聚法、一般开环法、开环交联法制备聚天冬氨酸衍生物,以及近几年聚天冬氨酸衍生物作为共价大分子复合体、胶束药物载体、水凝胶药物载体在药物控释方面的研究进展,及其在组织工程支架上的应用.     

Membranes for the life sciences and their future roles in medicine

Since the global outbreak of COVID-19, membrane technology for clinical treatments, including extracorporeal membrane oxygenation(ECMO) and protective masks and clothing, has attracted intense research attention for its irreplaceable abilities. Membrane research and applications are now playing an increasingly important role in various fields of life science. In addition to intrinsic properties such as size sieving,dissolution and diffusion, membranes are often endowed with additional functions ...     

Chitosan hydrogel loaded with Aloe vera gel and tetrasodium ethylenediaminetetraacetic acid (EDTA) as the wound healing material: in vitro and in vivo study

The main aim of the current study was to develop a chitosan hydrogel containing Aloe vera gel and Ethylenediaminetetraacetic acid (EDTA) as the wound healing materials. Chitosan with the concentration of (2% w/v) was prepared in AA (0.5%, v/v) and Tetrasodium EDTA (0.01% w/w) and AV (0.5% v/v) were added to the prepared polymer solution. As prepared solution was cross-linked by β-GP with the weight ratio of 1/6 w/w (1 chitosan and 6 β-GP). The characterization of the hydrogels showed that the hydrogels have porous structures and interconnected pores with the pores size range from 41.5 ± 14 to 48.3 ± 11 μm. The swelling and weight loss measurements of the hydrogels showed that the hydrogels could swell up to 240% of their initial weight during 8 h and loss 79.7 ± 3.5% of the initial weight during 14 days. The antibacterial studies depicted that the prepared Cs/tEDTA/AV hydrogel inhibited the growth of Staphylococcus aureus (the minimum inhibition concentration, MIC of 73 ± 4.8) and Pseudomonas aeruginosa (the MIC of 40 ± 7.9). Moreover, the prepared hydrogels were hemocompatible (Cs/tEDTA/AV: OD of 0.24 ± 0.30) and biocompatible (Cs/tEDTA/AV: OD of 0.38 ± 0.01). At the final stage, the wound healing assessments in the animal model revealed that the application of the prepared hydrogels effectively enhanced the wound healing process. In conclusion, the results confirmed the efficacy of the prepared hydrogels as the wound healing materials.     

Preparation and characterization of porous scaffold composite films by blending chitosan and gelatin solutions for skin tissue engineering

Biodegradable polymers have significant potential in biotechnology and bioengineering. However, for some applications, they are limited by their inferior mechanical properties and unsatisfactory compatibility with cells and tissues. In the present investigation blends of chitosan and gelatin with various compositions were produced as candidate materials for biomedical applications. Fourier transform infrared spectral analysis showed good compatibility between these two biodegradable polymers. The composite films showed improved tensile properties, highly porous structure, antimicrobial activities, low water dissolution, low water uptake and high buffer uptake compared to pure chitosan or gelatin films. These enhanced properties could be explained by the introduction of free ? OH, ? NH₂ and ? NHOCOCH₃ groups of the amorphous chitosan in the blends and a network structure through electrostatic interactions between the ammonium ions (? NH³⁺) of the chitosan and the carboxylate ions (? COO^?) of the gelatin. Scanning electron microscopy images of the blend composite films showed homogeneous and smooth surfaces which indicate good miscibility between gelatin and chitosan. The leafy morphologies of the scaffolds indicate a large and homogeneous porous structure, which would cause increased ion diffusion into the gel that could lead to an increase in stability in aqueous solution, buffer and temperature compared to the gelatin/chitosan system. In vivo testing was done in a Wistar rat (Rattus norvegicus) model and the healing efficiencies of the scaffolds containing various compositions of chitosan were measured. The healing efficiencies in Wistar rat of composites with gelatin to chitosan ratios of 10:3 and 10:4 were compared with that of a commercially available scaffold (Eco‐plast). It was observed that, after 5 days of application, the scaffold with a gelatin to chitosan ratio of 10:3 showed 100% healing in the Wistar rat; however, the commercial Eco‐plast showed only a little above 40% healing of the dissected rat wound. Copyright © 2012 Society of Chemical Industry     

Autonomous crack healing ability of SiC dispersed Yb2Si2O7 by oxidations in air and water vapor

Yb₂Si₂O₇ is a popular environmental barrier coating; however, it decomposes into Yb₂SiO₅ in high-temperature steam environments. The thermal mismatch between Yb₂Si₂O₇ and Yb₂SiO₅ leads to the cracking and failure of the disilicate coating via oxidation. Dispersing SiC nanofillers into the Yb₂Si₂O₇ matrix is suggested to maintain the Yb₂Si₂O₇ matrix and promote crack self-healing. This study is aimed at clarifying the effect of water vapor on the self-healing ability of such composites. X-ray diffraction analysis and scanning electron microscopy were used to monitor the surface composition and the crack formation, respectively, in 10 vol% SiC-dispersed Yb₂Si₂O₇ composites. Annealing at temperatures higher than 750 °C in air or in a water vapor rich atmosphere led to strength recovery and the self-healing of indentation-induced surface cracks owing to volume expansion during the oxidation of SiC. The self-healing effect was influenced by the oxidation time and temperature. Rapid diffusion of H₂O as an oxidizer into the SiO₂ layer promoted self-healing in a water vapor rich atmosphere. However, accelerated oxidation at temperatures higher than 1150 °C formed bubbles on the surface. Fabricating composites with a small amount of Yb₂SiO₅ will be a solution to these problems.