Wireless electrostimulation for cancer treatment: An integrated nanoparticle/coaxial fiber mesh platform

Cancer, namely breast and prostate cancers, is the leading cause of death in many developed countries. Controlled drug delivery systems are key for the development of new cancer treatment strategies, to improve the effectiveness of chemotherapy and tackle off-target effects. In here, we developed a biomaterials-based wireless electrostimulation system with the potential for controlled and on-demand release of anti-cancer drugs. The system is composed of curcumin-loaded poly(3,4-ethylenedioxythiophene) nanoparticles (CUR/PEDOT NPs), encapsulated inside coaxial poly(glycerol sebacate)/poly(caprolactone) (PGS/PCL) electrospun fibers. First, we show that the PGS/PCL nanofibers are biodegradable, which allows the delivery of NPs closer to the tumoral region, and have good mechanical properties, allowing the prolonged storage of the PEDOT NPs before their gradual release. Next, we demonstrate PEDOT/CUR nanoparticles can release CUR on-demand (65 % of release after applying a potential of -1.5 V for 180 s). Finally, a wireless electrostimulation platform using this NP/fiber system was set up to promote in vitro human prostate cancer cell death. We found a decrease of 67 % decrease in cancer cell viability. Overall, our results show the developed NP/fiber system has the potential to effectively deliver CUR in a highly controlled way to breast and prostate cancer in vitro models. We also show the potential of using wireless electrostimulation of drug-loaded NPs for cancer treatment, while using safe voltages for the human body. We believe our work is a stepping stone for the design and development of biomaterial-based future smarter and more effective delivery systems for anti-cancer therapy.

Permeable Bioelectronics toward Biointegrated Systems

Bioelectronics integrates electronics with biological organs, sustaining the natural functions of the organs. Organs dynamically interact with the external environment, managing internal equilibrium and responding to external stimuli. These interactions are crucial for maintaining homeostasis. Additionally, biological organs possess a soft and stretchable nature; encountering objects with differing properties can disrupt their function. Therefore, when electronic devices come into contact with biological objects, the permeability of these devices, enabling interactions and substance exchanges with the external environment, and the mechanical compliance are crucial for maintaining the inherent functionality of biological organs. This review discusses recent advancements in soft and permeable bioelectronics, emphasizing materials, structures, and a wide range of applications. The review also addresses current challenges and potential solutions, providing insights into the integration of electronics with biological organs.

Effect of pH Value on the Electrical Properties of PEDOT:PSS-Based Fiber Mats

Nanofiber mats containing poly(3,4-ethylenedioxythiophene) (PEDOT) hold potential for use in wearable electronic applications. Unfortunately, the use of PEDOT is often limited by the acidic nature of polystyrenesulfonate (PSS), a common dispersant for PEDOT. In this study, we explored the impact of increasing the pH value of PEDOT:PSS/poly(vinyl alcohol) (PVA) precursors on the morphological and electrical properties of the resultant electrospun fibers. Specifically, electrospun nanofibers were analyzed using scanning electron microscopy, bright-field microscopy, and two-point probe measurements. We discovered that neutral and even slightly basic PEDOT:PSS/PVA precursors could be electrospun without affecting the resultant electrical properties. While cross-linking effectively stabilized the fibers, their electrical properties decreased after exposure to solutions with pH values between 5 and 11, as well as with agitated soap washing tests. Additionally, we report that the fiber mats maintained their stability after more than 3000 cycles of voltage application. These findings suggest that PEDOT:PSS-based fibers hold potential for use in wearable textile and sensor applications, where long-term durability is needed.

Revolutionizing Drug Delivery and Therapeutics: The Biomedical Applications of Conductive Polymers and Composites-Based Systems

The first conductive polymers (CPs) were developed during the 1970s as a unique class of organic substances with properties that are electrically and optically comparable to those of inorganic semiconductors and metals while also exhibiting the desirable traits of conventional polymers. CPs have become a subject of intensive research due to their exceptional qualities, such as high mechanical and optical properties, tunable electrical characteristics, ease of synthesis and fabrication, and higher environmental stability than traditional inorganic materials. Although conducting polymers have several limitations in their pure state, coupling with other materials helps overcome these drawbacks. Owing to the fact that various types of tissues are responsive to stimuli and electrical fields has made these smart biomaterials attractive for a range of medical and biological applications. For various applications, including the delivery of drugs, biosensors, biomedical implants, and tissue engineering, electrical CPs and composites have attracted significant interest in both research and industry. These bimodalities can be programmed to respond to both internal and external stimuli. Additionally, these smart biomaterials have the ability to deliver drugs in various concentrations and at an extensive range. This review briefly discusses the commonly used CPs, composites, and their synthesis processes. Further highlights the importance of these materials in drug delivery along with their applicability in various delivery systems.

Conductive polymers and composites-based systems: An incipient stride in drug delivery and therapeutics realm

Novel therapies and drug delivery systems (DDS) emphasis on localized, personalized, triggered, and regulated drug administration have heavily implicated electrically responsive DDS. An ideal DDS must deliver drugs to the target region at therapeutically effective concentrations to elicit a pharmacological response, resulting in better prophylaxis of the disease and the treatment. Biodegradable polymers are frequently employed for in-vivo long-term release; however, dose dumping can be anticipated. As a result, current DDSs can be tagged as dubbed "Smart Biomaterials" since they only focus on an on-demand cargo release in response to a trigger or stimulation. These organic materials have been recognized for their metal-like conductivity, as well as their mechanical stability and ease of production. These biomaterials can be programmed to respond to both internal and external stimuli. External pulsed triggers are required for extrinsic stimuli-responsive materials, whereas intrinsic stimuli-responsive materials rely on localized changes in the tissue environment. Furthermore, these materials have the ability to deliver active pharmaceutical agents at a varied concentration levels and across a broad spectrum of action. Drug delivery, biomedical implant technology, biosensor technology, and tissue engineering can be listed as a few prominent applications that have sparked immense interest for conductive polymers-based research and advancements in academia as well as in industry. This review comprehensively covers a cutting-edge collection of electrically conductive polymers and composites, and provide detailed insights of recent trends and advancements allied to conductive polymers for their potential applicability in an array of diverse meadows primarily focusing on drug delivery, biosensing and therapeutics. Furthermore, progressions in their synthesis, structural and functional properties have been presented in conjunction with futuristic directions for the smooth clinical translations.

Polymer-Magnetic Semiconductor Nanocomposites for Industrial Electronic Applications

Nanocomposite materials have acquired great importance, as have similar composite materials on a macroscopic scale, because the reinforcement complements the defects in the properties of the matrix, thus obtaining materials with better mechanical, thermal, and electrical properties, among others. At the same time, the importance and research of polymeric nanocomposites reinforced with nanoparticles of various types have grown. Among those that have stood out the most in the electronics industry are polymeric matrices reinforced with nanoparticles that present dual behavior, that is, both magnetic and semiconductor. This property has been very well used in developing electronic devices such as televisions, computers, and smartphones, which are part of everyday life. In this sense, this review presents a compilation of the synthetic methods to produce polymer nanocomposites with dual magnetic and semiconductor behavior and their potential applications within electronic fields and new relevant trends.

Water-Based Highly Stretchable PEDOT:PSS/Nonionic WPU Transparent Electrode

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) has the merits of high electrical conductivity and solution processability, and can be dispersed in water. To improve the stretchability of PEDOT:PSS-based transparent electrode films, the intrinsically conducting polymer PEDOT:PSS was blended with highly stretchable nonionic waterborne polyurethane (WPU) and coated on a thermoplastic polyurethane (TPU) film. Nonionic WPU has good compatibility with PEDOT:PSS, without affecting the acidity. WPU undergoes hydrogen bonding and coulombic attractions with PEDOT:PSS. With variation of the WPU content, differences in the electrical properties, such as the sheet resistance and mechanical stretchability, of the coated thin films were observed. The film with 2.0 wt% WPU could be stretched to 400% of the electrode surface without damage to the surface of the electrode films. The WPU and TPU films both have a polyester group, which provides good adhesion between the WPU-based transparent electrodes and the TPU substrate films. A stretchable alternating current electroluminescence (ACEL) device was constructed by using the water-based PEDOT:PSS/nonionic WPU composite as both the bottom and top transparent electrodes. The fabricated ACEL remained its initial luminance in the 500% stretched state.

PEDOT:PSS-Coated Polybenzimidazole Electroconductive Nanofibers for Biomedical Applications

Bioelectricity drives several processes in the human body. The development of new materials that can deliver electrical stimuli is gaining increasing attention in the field of tissue engineering. In this work, novel, highly electrically conductive nanofibers made of poly [2,2′-m-(phenylene)-5,5′-bibenzimidazole] (PBI) have been manufactured by electrospinning and then coated with cross-linked poly (3,4-ethylenedioxythiophene) doped with poly (styrene sulfonic acid) (PEDOT:PSS) by spin coating or dip coating. These scaffolds have been characterized by scanning electron microscopy (SEM) imaging and attenuated total reflectance Fourier-transform infrared (ATR-FTIR) spectroscopy. The electrical conductivity was measured by the four-probe method at values of 28.3 S·m⁻¹ for spin coated fibers and 147 S·m⁻¹ for dip coated samples, which correspond, respectively, to an increase of about 10⁵ and 10⁶ times in relation to the electrical conductivity of PBI fibers. Human bone marrow-derived mesenchymal stromal cells (hBM-MSCs) cultured on the produced scaffolds for one week showed high viability, typical morphology and proliferative capacity, as demonstrated by calcein fluorescence staining, 4′,6-diamidino-2-phenylindole (DAPI)/Phalloidin staining and MTT [3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyl tetrazolium bromide] assay. Therefore, all fiber samples demonstrated biocompatibility. Overall, our findings highlight the great potential of PEDOT:PSS-coated PBI electrospun scaffolds for a wide variety of biomedical applications, including their use as reliable in vitro models to study pathologies and the development of strategies for the regeneration of electroactive tissues or in the design of new electrodes for in vivo electrical stimulation protocols.

A Review on Electrospun PVC Nanofibers: Fabrication, Properties, and Application

Polyvinyl chloride (PVC) is a widely used polymer, not only in industry, but also in our daily life. PVC is a material that can be applied in many different fields, such as building and construction, health care, and electronics. In recent decades, the success of electrospinning technology to fabricate nanofibers has expanded the applicability of polymers. PVC nanofibers have been successfully manufactured by electrospinning. By changing the initial electrospinning parameters, it is possible to obtain PVC nanofibers with diameters ranging from a few hundreds of nanometers to several micrometers. PVC nanofibers have many advantages, such as high porosity, high mechanical strength, large surface area, waterproof, and no toxicity. PVC nanofibers have been found to be very useful in many fields with a wide variety of applications such as air filtration systems, water treatment, oil spill treatment, batteries technology, protective clothing, corrosion resistance, and many others. This paper reviews the fabricating method, properties, applications, and prospects of PVC nanofibers.

Ag Nanowire-Plasmonic-Assisted Charge Separation in Hybrid Heterojunctions of Ppy-PEDOT:PSS/GaN Nanorods for Enhanced UV Photodetection

The surface states, poor carrier life, and other native defects in GaN nanorods (NRs) limit their utilization in high-speed and large-gain ultraviolet (UV) photodetection applications. Making a hybrid structure is one of the finest strategies to overcome such impediments. In this work, a polypyrrole (Ppy)-poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/GaN NRs hybrid structure is introduced for self-powered UV photodetection applications. This hybrid structure yields high photodetection performance, while pristine GaN NRs showed negligible photodetection properties. The ability of the photodetector is further boosted by functionalizing the hybrid structure with Ag nanowires (NWs). The Ag NWs-functionalized hybrid structure exhibited a responsivity of 3.1 × 10³ (A/W), detectivity of 3.19 × 10¹⁴ Jones, and external quantum efficiency of 1.0⁶ × 10⁶ (%) under a UV illumination of λ = 382 nm. This high photoresponse is due to the huge photon absorption rising from the localized surface plasmonic effect of a Ag NWs network. Also, the Ag NWs significantly improved the rising and falling times, which were noted to be 0.20 and 0.21 s, respectively. The model band diagram was proposed with the assistance of X-ray photoelectron spectroscopy to explore the origin of the superior performance of the Ag NWs-decorated Ppy-PEDOT:PSS/GaN NRs photodetector. The proposed hybrid structure seems to be a promising candidate for the development of high-performance UV photodetectors.

Self-powered portable melt electrospinning for in situ wound dressing

Background

Electrospun (e-spun) nanofibers for wound dressing have attracted wide attention due to its large specific surface area, large porosity and breathability. Compared with solution electrospinning (e-spinning), melt e-spinning is more bio-friendly without toxic solvent participation, which provides the possibility of in situ e-spinning on wounds directly. However, previously reported melt e-spinning devices were usually bulky and cumbersome due to their necessary heating unit, and different components were separated to avoid electrostatic interference.

Results

In this article, we report on a self-powered hand-held melt e-spinning gun which can work without any external power supply (outdoors). The problem of electrostatic interference for this integrated device was solved by using a special high heat transfer insulation unit. The apparatus is easy and safe to operate by a single hand due to its small volume (24 × 6 × 13 cm³) and light weight (about 450 g). Some biodegradable polymers, for example, polycaprolactone (PCL) fibers were successful e-spun onto wounds directly by using this dressing gun.

Conclusions

PCL fibrous membrane has good biocompatibility and can be in situ electrospun to wound surface as a wound dressing by the portable melt e-spinning gun. Besides wound dressing, this hand-held melt e-spinning gun may be used in 3D printing and experimental teaching demonstration aids.

Tuning the optoelectronic properties of PEDOT:PSS-PVP core-shell electrospun nanofibers by solvent-quantum dot doping and phase inversion

In the present study core-shell PEDOT:PSS-polyvinylpirrolidone nanofibers were synthesized by coaxial electrospinning. These fibers were doped with different solvents (dimethylsulphoxide, dimethyl sulfoxide (DMSO), isopropyl alcohol (IPA), and ethylene glycol), and PbS nanoparticles at different concentrations; additionally, the coaxial electrospinning setup process was inverted in order to exchange the phases comprising the core-shell morphology. Experimental results showed that DMSO and IPA solvents produced a change in the PEDOT:PSS phase from its benzoid structure to a more conjugated (quinoid) one. The synthesized samples displayed an increment in the conductance of the composite nanofibers, based on a more conjugated structure of the PEDOT:PSS phase, and a better dispersion of the PbS nanoparticles within the nanofibers; this increment was, under certain synthesis conditions, up to three orders of magnitude higher than in the case of the nanofibers with no solvent, nor nanoparticles, added. Photoresponse also showed a clear increment in the value of the photogenerated current as the concentration of the nanoparticles increased. Inverting the arrangement of the core-shell phases in the nanofibers increased the conductance and the photogenerated current in the cases analyzed. These results show novel evidence on the capability of tuning the conductance and photoresponse of composite core-shell nanofibers, based on the doping of the PEDOT:PSS phase with different solvents and PbS nanoparticles, and the arrangement of the core-shell phases. Tailoring the optoelectronic properties of conductive, flexible nanofibers is a desirable competence in technological areas such as transparent flexible conductors, biosensors and tissue engineering.

The promoting effect on pre-osteoblast growth under electrical and magnetic double stimulation based on PEDOT/Fe3O4/PLGA magnetic-conductive bi-functional scaffolds

Electrical stimulation (ES) and magnetic stimulation (MS) can promote bone tissue formation in vivo. Loading ES and MS simultaneously would be very beneficial for bone tissue construction in vitro or in vivo. Magnetic-conductive bi-functional scaffolds which are favorable for the transfer of ES and MS, could further facilitate bone cell/tissue growth. Poly(3,4-ethylenedioxythiophene) (PEDOT)/Fe₃O₄/polylactic acid-co-glycolic acid (PLGA) magnetic-conductive bi-functional fibrous scaffolds were prepared through in situ polymerization of EDOT on Fe₃O₄/PLGA fibers. MC3T3-E1 pre-osteoblasts were incubated on the PEDOT/Fe₃O₄/PLGA fibrous scaffolds and were stimulated by electrical, magnetic and electrical-magnetic signals respectively to detect the impact of different stimulation on cell viability. The measured results show that the scaffolds possess good conductivity and superparamagnetic responsiveness. Furthermore, both electrical and magnetic stimulation promoted cell proliferation and magnetic stimulation could induce cell alignment arrangement. Meanwhile, under electrical-magnetic double stimulation, cell viability was much higher than for cells under single electrical or magnetic stimulation. The growth promoting effects of PEDOT/Fe₃O₄/PLGA fibrous scaffolds under electrical-magnetic double stimulation has great practical potential for bone tissue engineering.

Synergistic Effects of Electrical Stimulation and Aligned Nanofibrous Microenvironment on Growth Behavior of Mesenchymal Stem Cells

Incontrollable cellular growth behavior is a significant issue, which severely affects the functional tissue formation and cellular protein expression. Development of natural extracellular matrix (ECM) like biomaterials to present microenvironment cues for regulation of cell responses can effectively overcome this problem. The external simulation and topological characteristics as typical guiding cues are capable of providing diverse influences on cellular growth. Herein, we fabricated two-dimensional aligned conductive nanofibers (2D-ACNFs) by an electrospinning process and surface polymerization, and the obtained 2D-ACNFs provided the effects of both alignment and electrical stimulation (ES) on cellular response of human mesenchymal cells (hMSCs). The results of cellular responses implied that the obtained 2D-ACNFs could offer a synergistic effect of both ES and aligned nanopattern on hMSC growth behavior. The effects could not only promote hMSCs to contact each other and maintain cellular activity but also provide positive promotion to regulate cellular proliferation. Thus, we believe that the obtained 2D-ACNFs will have a broad application in the biomedical field, such as cell culture with ES, directional induction for cell growth, and damaged tissue repair, etc.

Production of Conductive PEDOT-Coated PVA-GO Composite Nanofibers

Electrically conductive nanofiber is well known as an excellent nanostructured material for its outstanding performances. In this work, poly(3,4-ethylenedioxythiophene) (PEDOT)-coated polyvinyl alcohol-graphene oxide (PVA-GO)-conducting nanofibers were fabricated via a combined method using electrospinning and electropolymerization techniques. During electrospinning, the concentration of PVA-GO solution and the applied voltage were deliberately altered in order to determine the optimized electrospinning conditions. The optimized parameters obtained were 0.1 mg/mL of GO concentration with electrospinning voltage of 15 kV, which displayed smooth nanofibrous morphology and smaller diameter distribution. The electrospun PVA-GO nanofiber mats were further modified by coating with the conjugated polymer, PEDOT, using electropolymerization technique which is a facile approach for coating the nanofibers. SEM images of the obtained nanofibers indicated that cauliflower-like structures of PEDOT were successfully grown on the surface of the electrospun nanofibers during the potentiostatic mode of the electropolymerization process. The conductive nature of PEDOT coating strongly depends on the different electropolymerization parameters, resulting in good conductivity of PEDOT-coated nanofibers. The optimum electropolymerization of PEDOT was at a potential of 1.2 V in 5 min. The electrochemical measurements demonstrated that the fabricated PVA-GO/PEDOT composite nanofiber could enhance the current response and reduce the charge transfer resistance of the nanofiber.

Three-Dimensional Highly Stretchable Conductors from Elastic Fiber Mat with Conductive Polymer Coating

The manufacture of stretchable conductors with well-reserved electrical performance under large-degree deformations via scalable processes remains of great importance. In this work, a highly stretchable 3D conductive framework consisting of a polyurethane fiber mat (PUF) and poly(3,4-ethylenedioxythiophene) (PEDOT) is reported through facile approaches, electrospinning, and in situ interfacial polymerization, which was then backfilled with poly(dimethylsiloxane) to obtain 3D conductors. The excellent stretchability of the 3D conductive network imparted the as-prepared electrode a superior mechanical durability. Moreover, the applied strains can be effectively accommodated by the arrangement and orientation of the fibers resulting in a relatively stable electrical performance with only a 20% increased resistance at 100% stretching. Meanwhile, the resistance of the conductor could remain constant during 2000 bending cycles and showed a slight increase during 100 cycles of 50% stretching. The potential in the applications of large-area stretchable electrodes was demonstrated by the construction of LED arrays with the PUF-based conductors as electrical connections.

Electrically-responsive core-shell hybrid microfibers for controlled drug release and cell culture

It is an active research field to develop fiber-shaped smart materials for biomedical applications. Here we report the development of the multifunctional core-shell hybrid microfibers with excellent mechanical and electrical performance as a new smart biomaterial. The microfibers were synthesized using a combination of co-axial spinning with a microfluidic device and subsequent dip-coating, containing a hydrogel core of bacterial cellulose (BC) and a conductive polymer shell layer of poly(3,4-ethylenedioxythiophene) (PEDOT). The hybrid microfibers were featured with a well-controlled microscopic morphology, exhibiting enhanced mechanic properties. A model drug, diclofenac sodium, can be loaded in the core layer of the microfibers in situ during the process of synthesis. Our experiments suggested that the releasing behaviors of the drug molecules from the microfibers were enhanced by external electrical stimulation. Interestingly, we demonstrated an excellent biocompatibility and electroactivity of the hybrid microfibers for PC12 cell culture, thus promising a flexible template for the reconstruction of electrically-responsive tissues mimicking muscle fibers or nerve networks.

STATEMENT OF SIGNIFICANCE

Fiber-shaped biomaterials are useful in creating various functional objects from one dimensional to three-dimensional. The fabrication of microfibers with integrated physicochemical properties and bio-performance has drawn an increasing attention on researchers from chemical to biomedical. This study combined biocompatible bacterial cellulose with electroconductive poly(3,4-ethylenedioxythiophene) and further reduced them to a highly electroactive BC/PEDOT core-shell microfiber electrode for electrochemical actuator design. The result showed that the microfibers were well fabricated and the release of drugs from the microfibers was enhanced and could be controlled under electrical stimulation externally. Considering the excellent biocompatibility and electroactive toward PC12 cells, these microfibers may find use as templates for the reconstruction of fiber-shaped functional tissues that mimic muscle fibers, blood vessels or nerve networks in vivo.

Photocatalytic photosystem I/PEDOT composite films prepared by vapor-phase polymerization

Photosystem I (PSI) achieves photo-induced charge separation with outstanding internal quantum efficiency and has been used to improve the performance of various photoelectrochemical systems. Herein, we describe a fast and versatile technique to assemble composite films containing PSI and a chosen intrinsically conductive polymer (ICP). A mixture of PSI and a Friedel-Crafts catalyst (FeCl₃) is drop cast atop a substrate of choice. Contact with ICP monomer vapor at low temperature stimulates polymer growth throughout PSI films in minutes. We assess the effects of PSI loading on the rapid vapor-phase growth of poly(3,4-ethylenedioxythiophene) (PEDOT) within and above PSI multilayer films, and characterize the resulting film's thickness, electrochemical capacitance, and photocatalytic response. Composite films generate cathodic photocurrent when in contact with an aqueous redox electrolyte, confirming retention of the photocatalytic activity of the polymer-entrapped PSI multilayer assembly.

Facile fabrication of flexible core–shell graphene/conducting polymer microfibers for fibriform supercapacitors

We fabricated graphene core conductive polymer (PEDOT) shell fibers (GF@PEDOT). The unique cloth-like structure enabled the graphene fibers excellent electrochemical performance and greatly enhanced the flexibility.

Fabrication, Characterization, and Biocompatibility of Polymer Cored Reduced Graphene Oxide Nanofibers

Graphene nanofibers have shown a promising potential across a wide spectrum of areas, including biology, energy, and the environment. However, fabrication of graphene nanofibers remains a challenging issue due to the broad size distribution and extremely poor solubility of graphene. Herein, we report a facile yet efficient approach for fabricating a novel class of polymer core-reduced graphene oxide shell nanofiber mat (RGO-CSNFM) by direct heat-driven self-assembly of graphene oxide sheets onto the surface of electrospun polymeric nanofibers without any requirement of surface treatment. Thus-prepared RGO-CSNFM demonstrated excellent mechanical, electrical, and biocompatible properties. RGO-CSNFM also promoted a higher cell anchorage and proliferation of human bone marrow mesenchymal stem cells (hMSCs) compared to the free-standing RGO film without the nanoscale fibrous structure. Further, cell viability of hMSCs was comparable to that on the tissue culture plates (TCPs) with a distinctive healthy morphology, indicating that the nanoscale fibrous architecture plays a critically constructive role in supporting cellular activities. In addition, the RGO-CSNFM exhibited excellent electrical conductivity, making them an ideal candidate for conductive cell culture, biosensing, and tissue engineering applications. These findings could provide a new benchmark for preparing well-defined graphene-based nanomaterial configurations and interfaces for biomedical applications.

Biocompatible, Free-Standing Film Composed of Bacterial Cellulose Nanofibers-Graphene Composite

In recent years, graphene films have been used in a series of wide applications in the biomedical area, because of several advantageous characteristics. Currently, these films are derived from graphene oxide (GO) via chemical or physical reduction methods, which results in a significant decrease in surface hydrophilicity, although the electrical property could be greatly improved, because of the reduction process. Hence, the comprehensive performance of the graphene films showed practical limitations in the biomedical field, because of incompatibility of highly hydrophobic surfaces to support cell adhesion and growth. In this work, we present a novel fabrication of bacterial cellulose nanofibers/reduced graphene oxide (BC-RGO) film, using a bacterial reduction method. Thus-prepared BC-RGO films maintained excellent hydrophilicity, while electrical properties were improved by bacterial reduction of GO films in culture. Human marrow mesenchymal stem cells (hMSCs) cultured on these surfaces showed improved cellular response with higher cell proliferation on the BC-RGO film, compared to free-standing reduced graphene oxide film without the nanoscale fibrous structure. Furthermore, the cellular adhesion and proliferation were even comparable to that on the tissue culture plate, indicating that the bacterial cellulose nanofibers play a critically contructive role in supporting cellular activities. The novel fabrication method greatly enhanced the biochemical activity of the cells on the surface, which could aid in realizing several potential applications of graphene film in biomedical area, such as tissue engineering, bacterial devices, etc.

Hydrophilic Organic Electrodes on Flexible Hydrogels

Prompted by the rapidly developing field of wearable electronics, research into biocompatible substrates and coatings is intensifying. Acrylate-based hydrogel polymers have gained widespread use as biocompatible articles in applications such as contact and intraocular lenses. Surface treatments and/or coatings present one strategy to further enhance the performance of these hydrogels or even realize novel functionality. In this study, the conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT) is deposited from the vapor phase onto hydrated hydrogel substrates and blended with biocompatibilizing coconstituents incorporating polyethylene glycol (PEG) and polydimethyl siloxane (PDMS) moieties. Plasma pretreatment of the dehydrated hydrogel substrate modifies its surface topography and chemical composition to facilitate the attachment of conductive PEDOT-based surface layers. Manipulating the vapor phase polymerization process and constituent composition, the PEDOT-based coating is engineered to be both hydrophilic (i.e. to promote biocompatibility) and highly conductive. The fabrication of this conductively coated hydrogel has implications for the future of wearable electronic devices.

Three-Dimensional BC/PEDOT Composite Nanofibers with High Performance for Electrode-Cell Interface

There is an increasing need to synthesize biocompatible nanofibers with excellent mechanical and electrical performance for electrochemical and biomedical applications. Here we report a facile approach to prepare electroactive and flexible 3D nanostructured biomaterials with high performance based on bacterial cellulose (BC) nanofibers. Our approach can coat BC nanofibers with poly(3,4-ethylenedioxythiophene) (PEDOT) by in situ interfacial polymerization in a controllable manner. The PEDOT coating thickness is adjustable by the monomer concentration or reaction time during polymerization, producing nanofibers with a total diameter ranging from 30 to 200 nm. This fabrication process also provides a convenient method to tune different parameters such as the average pore size and electrical conductivity on the demands of actual applications. Our experiments have demonstrated that the 3D BC/PEDOT nanofibers exhibit high specific surface area, excellent mechanical properties, electroactive stability, and low cell cytotoxicity. With electrical stimulation, calcium imaging of PC12 neural cells on BC/PEDOT nanofibers has revealed a significant increase in the percentage of cells with higher action potentials, suggesting an enhanced capacitance effect of charge injection. As an attractive solution to the challenge of designing better electrode-cell interfaces, 3D BC/PEDOT nanofibers promise many important applications such as biosensing devices, smart drug delivery systems, and implantable electrodes for tissue engineering.

Soft Graphene Nanofibers Designed for the Acceleration of Nerve Growth and Development

Soft graphene nanofibers with recoverable electrical conductivity and excellent physicochemical stability are prepared by a controlled assembly technique. By using the soft graphene nanofibers for cellular electrical stimulation, the common inhibitory effect of long-term electrical stimulation on nerve growth and development is avoided, which usually happens with traditional 2D conductive materials.

Poly(3,4-ethylenedioxythiophene) nanoparticle and poly(ɛ-caprolactone) electrospun scaffold characterization for skeletal muscle regeneration

Injuries to peripheral nerves and/or skeletal muscle can cause scar tissue formation and loss of function. The focus of this article is the creation of a conductive, biocompatible scaffold with appropriate mechanical properties to regenerate skeletal muscle. Poly(3,4-ethylenedioxythiophene) (PEDOT) nanoparticles (Np) were electrospun with poly(ɛ-caprolactone) (PCL) to form conductive scaffolds. During electrospinning, ribboning, larger fiber diameters, and unaligned scaffolds were observed with increasing PEDOT amounts. To address this, PEDOT Np were sonicated prior to electrospinning, which resulted in decreased conductivity and increased mechanical properties. Multi-walled carbon nanotubes (MWCNT) were added to the 1:2 solution in an effort to increase conductivity. However, the addition of MWCNT had little effect on scaffold conductivity, and the elastic modulus and yield stress of the scaffold increased as a result. Rat muscle cells attached and were active on the 1-10, 1-2, 3-4, and 1-1 PCL-PEDOT scaffolds; however, the 3-4 scaffolds had the lowest level of metabolic activity. Although the scaffolds were cytocompatible, further development of the fabrication method is necessary to produce more highly aligned scaffolds capable of promoting skeletal muscle cell alignment and eventual regeneration.

Integrated 3D conducting polymer-based bioelectronics for capture and release of circulating tumor cells

Here we develop a novel fabrication approach for producing three-dimensional (3D) conducting polymer-based bioelectronic interfaces (BEIs) that can be integrated on electronic devices for rare circulating tumor cell (CTC) isolation, detection, and collection via an electrically triggered cell released from chips. Based on the chemical oxidative polymerization of carboxylic acid-modified 3,4-ethylenedioxythiophene and modified poly(dimethylsiloxane) (PDMS) transfer printing technology, the high-aspect-ratio structures of poly(3,4-ethylenedioxythiophene) (PEDOT)-based "nanorod" arrays can be fabricated on indium tin oxide (ITO) electrodes when using the Si "microrod" arrays as masters. Furthermore, we integrated the biotinylated poly-(l)-lysine-graft-poly-ethylene-glycol (PLL-g-PEG-biotin) coating with 3D PEDOT-based BEIs for dynamic control of the capture/release performance of CTCs on chips; this combination exhibited an optimal cell-capture yield cells of ∼45 000 cells cm^-2 from EpCAM-positive MCF7 while maintaining resistance from the adhesion of EpCAM-negative HeLa cells at a density of ∼4000 cells cm^-2. By taking advantage of the electrochemical doping/dedoping properties of PEDOT materials, the captured CTCs can be triggered to be electrically released through the desorption phenomena of the PLL-g-PEG-biotin. More than 90% of the captured cells can be released while maintaining very high cell viability. Therefore, it is conceivable that the use of a 3D PEDOT-based BEI platform will meet the requirements for the development of downstream characterization of CTCs, as well as the next generation of bioelectronics for biomedical applications.

Electrically conductive polymers and composites for biomedical applications

This paper provides a review of the recent advances made in the field of electroactive polymers and composites for biomedical applications.

Conducting polyaniline based cell culture substrate for embryonic stem cells and embryoid bodies

Noncytotoxic polyaniline–poly(2-acrylamido-2-methyl-1-propanesulfonate) films which are electrically conducting at the physiological pH were applied as cell culture substrate. The films demonstrate selective interaction with specific target cells.

Synergistic effects of a novel free-standing reduced graphene oxide film and surface coating fibronectin on morphology, adhesion and proliferation of mesenchymal stem cells

Fabrication of free-standing reduced graphene oxide (RGO) films by vacuum filtration of graphene oxide aqueous solution through a nanofiber membrane in combination with chemical reduction.

Electrospun Polymer Fibers for Electronic Applications

Nano- and micro- fibers of conjugated polymer semiconductors are particularly interesting both for applications and for fundamental research. They allow an investigation into how electronic properties are influenced by size confinement and chain orientation within microstructures that are not readily accessible within thin films. Moreover, they open the way to many applications in organic electronics, optoelectronics and sensing. Electro-spinning, the technique subject of this review, is a simple method to effectively form and control conjugated polymer fibers. We provide the basics of the technique and its recent advancements for the formation of highly conducting and high mobility polymer fibers towards their adoption in electronic applications.

Multifunctional structural energy storage composite supercapacitors

This paper addresses the challenge of producing multifunctional composites that can simultaneously carry mechanical loads whilst storing (and delivering) electrical energy. The embodiment is a structural supercapacitor built around laminated structural carbon fibre (CF) fabrics. Each cell consists of two modified structural CF fabric electrodes, separated by a structural glass fibre fabric or polymer membrane, infused with a multifunctional polymeric electrolyte. Rather than using conventional activated carbon fibres, structural carbon fibres were treated to produce a mechanically robust, high surface area material, using a variety of methods, including direct etching, carbon nanotube sizing, and carbon nanotubein situgrowth. One of the most promising approaches is to integrate a porous bicontinuous monolithic carbon aerogel (CAG) throughout the matrix. This nanostructured matrix both provides a dramatic increase in active surface area of the electrodes, and has the potential to address mechanical issues associated with matrix-dominated failures. The effect of the initial reaction mixture composition is assessed for both the CAG modified carbon fibre electrodes and resulting devices. A low temperature CAG modification of carbon fibres was evaluated using poly(3,4-ethylenedioxythiophene) (PEDOT) to enhance the electrochemical performance. For the multifunctional structural electrolyte, simple crosslinked gels have been replaced with bicontinuous structural epoxy–ionic liquid hybrids that offer a much better balance between the conflicting demands of rigidity and molecular motion. The formation of both aerogel precursors and the multifunctional electrolyte are described, including the influence of key components, and the defining characteristics of the products. Working structural supercapacitor composite prototypes have been produced and characterised electrochemically. The effect of introducing the necessary multifunctional resin on the mechanical properties has also been assessed. Larger scale demonstrators have been produced including a full size car boot/trunk lid.

Fabrication, mechanical properties, and biocompatibility of reduced graphene oxide-reinforced nanofiber mats

Graphene-based nanofibers with superior electrical and mechanical properties have been developed for application in tissue engineering.