Novel nanofibrous electrically conductive scaffolds based on poly(ethylene glycol)s-modified polythiophene and poly(ε-caprolactone) for tissue engineering applications

Biomimetic alginate-based electroconductive nanofibrous scaffolds for bone tissue engineering application

Novel electrically conductive nanofibrous scaffolds were designed and fabricated through the grafting of aniline monomer onto a phenylamine-functionalized alginate (Alg-NH2) followed by electrospinning with poly(vinyl alcohol) (PVA). Performance of the prepared scaffolds in bone tissue engineering (TE) were studied in terms of physicochemical (e.g., conductivity, electroactivity, morphology, hydrophilicity, water uptake, and mechanical) and biological (cytocompatibility, in vitro biodegradability, cells attachment and proliferation, hemolysis, and protein adsorption) properties. The contact angles of the scaffolds with water drop were obtained about 50 to 60° that confirmed their excellent hydrophilicities for TE applications. Three dimensional (3D), inter-connected and uniform porous structures of the scaffolds without any bead formation was confirmed by scanning electron microscopy (SEM). Electrical conductivities of the fabricated scaffolds were obtained as 1.5 × 10-3 and 2.7 × 10-3 Scm-1. MTT assay results revealed that the scaffolds have acceptable cytocompatibilities and can enhance the cells adhesion as well as proliferation, which approved their potential for TE applications. Hemolysis rate of the developed scaffolds were quantified <2 % even at high concentration (200 μgmL-1) of samples that approved their hemocompatibilities. The scaffolds were also exhibited acceptable protein adsorption capacities (65 and 68 μgmg-1). As numerous experimental results, the developed scaffolds have acceptable potential for bone TE.

Electrically conductive carbon-based (bio)-nanomaterials for cardiac tissue engineering

A proper self-regenerating capability is lacking in human cardiac tissue which along with the alarming rate of deaths associated with cardiovascular disorders makes tissue engineering critical. Novel approaches are now being investigated in order to speedily overcome the challenges in this path. Tissue engineering has been revolutionized by the advent of nanomaterials, and later by the application of carbon-based nanomaterials because of their exceptional variable functionality, conductivity, and mechanical properties. Electrically conductive biomaterials used as cell bearers provide the tissue with an appropriate microenvironment for the specific seeded cells as substrates for the sake of protecting cells in biological media against attacking mechanisms. Nevertheless, their advantages and shortcoming in view of cellular behavior, toxicity, and targeted delivery depend on the tissue in which they are implanted or being used as a scaffold. This review seeks to address, summarize, classify, conceptualize, and discuss the use of carbon-based nanoparticles in cardiac tissue engineering emphasizing their conductivity. We considered electrical conductivity as a key affecting the regeneration of cells. Correspondingly, we reviewed conductive polymers used in tissue engineering and specifically in cardiac repair as key biomaterials with high efficiency. We comprehensively classified and discussed the advantages of using conductive biomaterials in cardiac tissue engineering. An overall review of the open literature on electroactive substrates including carbon-based biomaterials over the last decade was provided, tabulated, and thoroughly discussed. The most commonly used conductive substrates comprising graphene, graphene oxide, carbon nanotubes, and carbon nanofibers in cardiac repair were studied.

Bacterial cellulose-based composites for nerve tissue engineering

Nerve injuries and neurodegenerative disorders are very serious and costly medical challenges. Damaged nerve tissue may not be able to heal and regain its function, and scar tissue may restrict nerve cell regeneration. In recent years, new electroactive biomaterials have attracted widespread attention in the neural tissue engineering field. Bacterial cellulose (BC) due to its unique properties such as good mechanical properties, high water retention, biocompatibility, high crystallinity, large surface area, high purity, very fine network, and inability to absorb in the human body due to cellulase deficiency, can be considered a promising treatment for neurological injuries and disorders that require long-term support. However, BC lacks electrical activity, but can significantly improve the nerve regeneration rate by combining with conductive structures. Electrical stimulation has been shown to be an effective means of increasing the rate and accuracy of nerve regeneration. Many factors, such as the intensity and pattern of electrical current, have positive effects on cellular activity, including cell adhesion, proliferation, migration and differentiation, and cell-cell/tissue/molecule/drug interaction. This study discusses the importance and essential role of BC-based biomaterials in neural tissue regeneration and the effects of electrical stimulation on cellular behaviors.

Scaffolds the backbone of tissue engineering: Advancements in use of polyhydroxyalkanoates (PHA)

Our body is built to heal from inside out naturally but wide-ranging medical conditions necessitate the need for artificial assistance, and therefore, something that can assist the body to heal wounds and damaged tissues quickly and efficiently is of utmost importance. Tissue engineering technology helps to regenerate new tissue to replace the diseased or injured one. The technology uses biodegradable porous three-dimensional scaffolds for mimicking the structure and functions of the natural extracellular matrix. The material and design of scaffolds are critical areas of biomaterial research. Biomaterial-based three-dimensional structures have been the most promising material to serve as scaffolds for seeding cells, both in vivo and in vitro. One such material is polyhydroxyalkanoates (PHAs) which are thermoplastic biopolyesters that are highly suitable for this purpose due to their enhanced biocompatibility, biodegradability, thermo-processability, diverse mechanical properties, non-toxicity and natural origin. Moreover, they have tremendous possibilities of customization through biological physical and chemical modification as well as blending with other materials. They are being used for several tissue engineering applications such as bone graft substitute, cardiovascular patches, stents, for nerve repair and in implantology as valves and sutures. The present review overviews usage of a multitude of PHA-based biomaterials for a wide range of tissue engineering applications, based on their properties suitable for the specific applications.

Mussel-inspired ultra-stretchable, universally sticky, and highly conductive nanocomposite hydrogels

Developing ultra-stretchable, universally sticky, and highly conductive nanocomposite hydrogels without doping agents and nanoparticle-aggregation is still a challenge. Herein, doping-free and nanoparticle-aggregation-inhibited hydrogels composed of Fe3+, dopamine (DA), pyrrole (Py) and polyacrylic acid (PAA) were prepared. Polypyrrole-polydopamine (PPy-PDA)/PAA hydrogels were quickly formed due to the abundant ionic bonds and physical cross-linking under the addition of Fe3+. Moreover, the H+ ions of the carboxylic acid groups on the PAA polymer chain helped to improve the conductivity of the hydrogels. Surprisingly, the multi-functional hydrogels received a high stretchability of 1900%, a tissue-like elastic modulus of 22 kPa, an adhesive strength of 2125.9 J m-2, and a high conductivity of 0.39 S m-1. Besides, the PPy-PDA/PAA hydrogels showed good antioxidant activity, biocompatibility and tissue repairing behavior. In short, the prepared multi-functional hydrogels have potential to address the human clinical problem of tissue repair and regeneration.

Smooth Muscle Cell Responses to Poly(ε-Caprolactone) Triacrylate Networks with Different Crosslinking Time

Poly(ε-caprolactone) triacrylate (PCLTA) is attractive in tissue engineering because of its good biocompatibility and processability. The crosslinking time strongly influences PCLTAs cellular behaviors. To investigate these influences, PCLTAs with different molecular weights were crosslinked under UV light for times ranging from 1 to 20 min. The crosslinking efficiency of PCLTA increased with decreasing the molecular weight and increasing crosslinking time which could increase the gel fraction and network stiffness and decrease the swelling ratio. Then, the PCLTA networks crosslinked for different time were used as substrates for culturing rat aortic smooth muscle cells (SMCs). SMC attachment and proliferation all increased when the PCLTA molecular weight increased from 8k to 10k and then to 20k at the same crosslinking time. For the same PCLTA, SMC attachment, proliferation, and focal adhesions increased with increasing the crosslinking time, in particular, between the substrates crosslinked for less than 3 min and longer than 5 min. This work will provide a good experimental basis for the application of PCLTA.

Scaffolding polymeric biomaterials: Are naturally occurring biological macromolecules more appropriate for tissue engineering?

Nowadays, tissue and organ failures resulted from injury, aging accounts, diseases or other type of damages is one of the most important health problems with an increasing incidence worldwide. Current treatments have limitations including, low graft efficiency, shortage of donor organs, as well as immunological problems. In this context, tissue engineering (TE) was introduced as a novel and versatile approach for restoring tissue/organ function using living cells, scaffold and bioactive (macro-)molecules. Among these, scaffold as a three-dimensional (3D) support material, provide physical and chemical cues for seeding cells and has an essential role in cell missions. Among the wide verity of scaffolding materials, natural or synthetic biopolymers are the most commonly biomaterials mainly due to their unique physicochemical and biological features. In this context, naturally occurring biological macromolecules are particular of interest owing to their low immunogenicity, excellent biocompatibility and cytocompatibility, as well as antigenicity that qualified them as popular choices for scaffolding applications. In this review, we highlighted the potentials of natural and synthetic polymers as scaffolding materials. The properties, advantages, and disadvantages of both polymer types as well as the current status, challenges, and recent progresses regarding the application of them as scaffolding biomaterials are also discussed.

A novel gold-based stimuli-responsive theranostic nanomedicine for chemo-photothermal therapy of solid tumors

The chemo-photothermal therapy performance of a novel theranostic nanoparticles that fabricated through the conjugation of HS-poly(ε-caprolactone)-block-poly(N-isopropylacrylamide)-block-poly(acrylic acid) (HS-PCL-b-PNIPAAm-b-PAA) and gold nanoparticles (GNPs) was extensively investigated. The GNPs@polymer conjugate theranostic NPs was loaded with doxorubicin hydrochloride (DOX) as an anticancer drug through electrostatic interactions to afford GNPs@polymer-DOX theranostic nanomedicine. Temperature and pH-triggered in vitro drug release behavior of the developed theranostic nanomedicine were also examined. The biocompatibility of the synthesized GNPs@polymer theranostic NPs was confirmed through the assessing survival rate of breast cancer cell line (MCF7) using MTT assay. In vitro cytotoxic effects of the GNPs@polymer-DOX theranostic nanomedicine was also evaluated against MCF7 cells in both with or without laser irradiation (532 nm, 145 mJ per pulse, 5 min) conditions, and the results obtained were compared with free DOX as the reference. As the results, the developed GNPs@polymer-DOX can be considered as theranostic nanomedicine for chemo-photothermal therapy of solid tumors.

Conducting Polymer Scaffolds Based on Poly(3,4-ethylenedioxythiophene) and Xanthan Gum for Live-Cell Monitoring

Conducting polymer scaffolds can promote cell growth by electrical stimulation, which is advantageous for some specific type of cells such as neurons, muscle, or cardiac cells. As an additional feature, the measure of their impedance has been demonstrated as a tool to monitor cell growth within the scaffold. In this work, we present innovative conducting polymer porous scaffolds based on poly(3,4-ethylenedioxythiophene) (PEDOT):xanthan gum instead of the well-known PEDOT:polystyrene sulfonate scaffolds. These novel scaffolds combine the conductivity of PEDOT and the mechanical support and biocompatibility provided by a polysaccharide, xanthan gum. For this purpose, first, the oxidative chemical polymerization of 3,4-ethylenedioxythiophene was carried out in the presence of polysaccharides leading to stable PEDOT:xanthan gum aqueous dispersions. Then, by a simple freeze-drying process, porous scaffolds were prepared from these dispersions. Our results indicated that the porosity of the scaffolds and mechanical properties are tuned by the solid content and formulation of the initial PEDOT:polysaccharide dispersion. Scaffolds showed interconnected pore structure with tunable sizes ranging between 10 and 150 μm and Young's moduli between 10 and 45 kPa. These scaffolds successfully support three-dimensional cell cultures of MDCK II eGFP and MDCK II LifeAct epithelial cells, achieving good cell attachment with very high degree of pore coverage. Interestingly, by measuring the impedance of the synthesized PEDOT scaffolds, the growth of the cells could be monitored.

Intelligent anticancer drug delivery performances of two poly(N-isopropylacrylamide)-based magnetite nanohydrogels

This article evaluates the anticancer drug delivery performances of two nanohydrogels composed of poly(N-isopropylacrylamide-co-itaconic anhydride) [P(NIPAAm-co-IA)], poly(ethylene glycol) (PEG), and Fe₃O₄ nanoparticles. For this purpose, the magnetite nanohydrogels (MNHGs) were loaded with doxorubicin hydrochloride (DOX) as a universal anticancer drug. The morphologies and magnetic properties of the DOX-loaded MNHGs were investigated using transmission electron microscopy (TEM) and vibrating-sample magnetometer (VSM), respectively. The sizes and zeta potentials (ξ) of the MNHGs and their corresponding DOX-loaded nanosystems were also investigated. The DOX-loaded MNHGs showed the highest drug release values at condition of 41 °C and pH 5.3. The drug-loaded MNHGs at physiological condition (pH 7.4 and 37 °C) exhibited negligible drug release values. In vitro cytotoxic effects of the DOX-loaded MNHGs were extensively evaluated through the assessing survival rate of HeLa cells using the MTT assay, and there in vitro cellular uptake into the mentioned cell line were examined using fluorescent microscopy and fluorescence-activated cell sorting (FACS) flow cytometry analyses. As the results, the DOX-loaded MNHG1 exhibited higher anticancer drug delivery performance in the terms of cytotoxic effect and in vitro cellular uptake. Thus, the developed MNHG1 can be considered as a promising de novo drug delivery system, in part due to its pH and thermal responsive drug release behavior as well as proper magnetite character toward targeted drug delivery.

Integration of Emerging Biomedical Technologies in Meat Processing to Improve Meat Safety and Quality

Modern-day processing of meat products involves a series of complex procedures designed to ensure the quality and safety of the meat for consumers. As the size of abattoirs increases, the logistical problems associated with large-capacity animal processing can affect the sanitation of the facility and the meat products, potentially increasing transmission of infectious diseases. Additionally, spoilage of food from improper processing and storage increases the global economic and ecological burden of meat production. Advances in biomedical and materials science have allowed for the development of innovative new antibacterial technologies that have broad applications in the medical industry. Additionally, new approaches in tissue engineering and nondestructive cooling of biological specimens could significantly improve organ transplantation and tissue grafting. These same strategies may be even more effective in the preservation and protection of meat as animal carcasses are easier to manipulate and do not have the same stringent requirements of care as living patients. This review presents potential applications of emerging biomedical technologies in the food industry to improve meat safety and quality. Future research directions investigating these new technologies and their usefulness in the meat processing chain along with regulatory, logistical, and consumer perception issues will also be discussed.