Electrodeposited conductive polymers for controlled drug release: polypyrrole

Investigation of spectroscopic and electrical properties of doped poly(pyrrole-3-carboxylic acid)

The spectroscopic and electrical properties of poly(pyrrole-3-carboxylic acid) doped with p-TSA- (p-toluenesulfonate) and AQS- (anthraquinone sulfonate) were investigated. The variation in electrical conductivity as a function of temperature shows that the systems have semiconductor-like electrical characteristics. The investigated polymers exhibit 3D conductivity and less than 0.6 eV energy gaps. The IR and Raman spectra show that the charge carriers are polarons and bipolarons. Doping the poly(pyrrole-3-carboxylic acid) increases the number of charge carriers. Electron paramagnetic resonance has shown that localized polarons and bipolarons are formed within these polymers.

One-step electrodeposited hybrid nanofilms in amperometric biosensor development

This review summarizes recent developments in amperometric biosensors, based on one-step electrodeposited organic-inorganic hybrid layers, used for analysis of low molecular weight compounds. The factors affecting self-assembly of one-step electrodeposited films, methods for verifying their composition, advantages, limitations and approaches affecting the electroanalytical performance of amperometric biosensors based on organic-inorganic hybrid layers were systemized. Moreover, issues related to the formation of one-step organic-inorganic hybrid functional layers with different structures in biosensors produced under the same electrodeposition parameters are discussed. The systemized dependencies can support the preliminary choice of functional sensing layers with architectures tuned for specific biotechnology and life science applications. Finally, the capabilities of one-step electrodeposition of organic-inorganic hybrid functional films beyond amperometric biosensors were highlighted.

Stimuli-responsive hydrogel based on natural polymers for breast cancer

Aims: Breast cancer is the most common malignancy among women in both high- and low-resource settings. Conventional breast cancer therapies were inefficient and had low patient compliance. Stimuli-responsive hydrogels possessing similar physicochemical features as soft tissue facilitate diagnostic and therapeutic approaches for breast cancer subtypes. Scope: Polysaccharides and polypeptides are major natural polymers with unique biocompatibility, biodegradability, and feasible modification approaches utilized frequently for hydrogel fabrication. Alternating the natural polymer-based hydrogel properties in response to external stimuli such as pH, temperature, light, ultrasonic, enzyme, glucose, magnetic, redox, and electric have provided great potential for the evolution of novel drug delivery systems (DDSs) and various advanced technologies in medical applications. Stimuli-responsive hydrogels are triggered by specific cancer tissue features, promote target delivery techniques, and modify release therapeutic agents at localized sites. This narrative review presented innovation in preparing and characterizing the most common stimuli-responsive natural polymer-based hydrogels for diagnostic and therapeutic applications in the breast cancer area. Conclusion: Stimuli-responsive hydrogels display bioinspiration products as DDSs for breast cancer subtypes, protect the shape of breast tissue, provide modified drug release, enhance therapeutic efficacy, and minimize chemotherapy agents' side effects. The potential benefits of smart natural polymer-based hydrogels make them an exciting area of practice for breast cancer diagnosis and treatment.

Iontophoretically controlled insulin delivery via water-soluble conductive polymer PANI:PSS and thermoplastic polyurethane matrix

Transdermal insulin delivery is an alternative route to deliver insulin through the body skin with the challenges to overcome the low drug skin permeability and high molecular weight. Polyaniline doped with poly(4-styrenesulfonic acid) (PANI:PSS), a conductive polymer with the high electrical conductivity, was synthesized and utilized as a drug carrier to improve the drug delivery capability from a porous thermoplastic polyurethane (TPU) matrix. The insulin was electrostatically attached to PANI:PSS based on the ion exchange between insulin and PSS. For the in vitro drug release of insulin loaded PANI:PSS relative to the pristine insulin alone, the amount of insulin released was improved to 84.70% with the time to equilibrium of 2 h under the electrical field of 6 V. For the ex vivo release-skin permeation, the amount insulin released and permeated became lower at 57.02% with time to equilibrium of 2 h, due to the pig skin acting as a barrier for insulin permeation. The modified insulin transdermal delivery, with PANI:PSS as the drug carrier and drug enhancer relative to without, is shown here to influence the insulin release rate, amount, and duration, suitable to treat diabetes patients.

PEDOT:PSS-Based Bioelectrodes for Multifunctional Drug Release and Electric Cell-Substrate Impedance Sensing

Electric cell-substrate impedance sensing (ECIS) is an innovative approach for the label-free and real-time detection of cell morphology, growth, and apoptosis, thereby playing an essential role as both a viable alternative and valuable complement to conventional biochemical/pharmaceutical analysis in the field of diagnostics. Constant improvements are naturally sought to further improve the effective range and reliability of this technology. In this study, we developed poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) conducting polymer (CP)-based bioelectrodes integrated into homemade ECIS cell-culture chamber slides for the simultaneous drug release and real-time biosensing of cancer cell viability under drug treatment. The CP comprised tailored PEDOT:PSS, poly(ethylene oxide) (PEO), and (3-glycidyloxypropyl)trimethoxysilane (GOPS) capable of encapsulating antitumor chemotherapeutic agents such as doxorubicin (DOX), docetaxel (DTX), and a DOX/DTX combination. This device can reliably monitor impedance signal changes correlated with cell viability on chips generated by cell adhesion onto a predetermined CP-based working electrode while simultaneously exhibiting excellent properties for both drug encapsulation and on-demand release from another CP-based counter electrode under electrical stimulation (ES) operation. Cyclic voltammetry curves and surface profile data of different CP-based coatings (without or with drugs) were used to analyze the changes in charge capacity and thickness, respectively, thereby further revealing the correlation between their drug-releasing performance under ES operation (determined using ultraviolet-visible (UV-vis) spectroscopy). Finally, antitumor drug screening tests (DOX, DTX, and DOX/DTX combination) were performed on MCF-7 and HeLa cells using our developed CP-based ECIS chip system to monitor the impedance signal changes and their related cell viability results.

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.

On-demand electrochemically controlled compound release from an ultrasonically powered implant

On-demand drug delivery systems are promising for a wide range of therapeutic applications. When combined with wireless implants for controlled drug delivery, they can reduce overall dosage and side effects. Here, we demonstrate release of fluorescein from a novel on-demand release system for negatively charged compounds. The release system is based on a modified electroresponsive polypyrrole nanoparticulate film designed to minimize ion exchange with the stored compound - a major passive leakage mechanism. We further designed an ultrasonically powered mm-sized implant to electronically control the on-demand drug delivery system in vivo. Release kinetics are characterized both in vitro and in vivo in mice using fluorescein as a model drug, demonstrating the feasibility of wireless, controllable drug release using an ultrasonically powered implant.

Polypyrrole-Silicon Nanowire Arrays for Controlled Intracellular Cargo Delivery

Intracellular cargo delivery is a critical and challenging step in controlling cell states. Silicon nanowire (NW) arrays have emerged as a powerful platform for accessing the intracellular space through a combination of their nanoscale dimensions and electrical properties. Here, we develop and characterize a conductive polypyrrole (PPy)-NW device for temporally controlled intracellular delivery. Fluorescent cargos, doped in electroresponsive PPy matrices at wire tips as well as entire NW arrays, are released with an applied reducing potential. Intracellular delivery into endothelial cells from PPy-Si substrates demonstrated comparable kinetics to solution-based delivery methods while requiring an order of magnitude less cargo loading. This hybrid polymer-semiconductor platform extends methods available for intracellular delivery and links electrical signaling from artificial systems with living molecular transduction.

New Impedimetric Sandwich Immunosensor for Ultrasensitive and Highly Specific Detection of Spike Receptor Binding Domain Protein of SARS-CoV-2

An impedance sensing platform-combined conducting nanocomposite layer was fabricated to develop an effective and rapid method for detection of coronavirus infection (COVID-19) specific spike receptor binding domain (RBD) protein, a precious antigen marker of COVID-19 disease. Coronavirus infection has spread globally and swiftly with major impacts on health, economy, and quality of life of communities. Fast and reliable detection of COVID-19 is a very significant issue for the effective treatment of this bad illness. For this aim, first, an Epoxy functional group-substituted thiophene monomer was synthesized and electrodeposited on a single-use indium tin oxide (ITO) platform in the presence of acetylene black by employing a cyclic voltammetry technique; thus, a conducting nanocomposite (C-NC) layer with high conductivity was obtained. This composite was electrodeposited for the first time on the ITO surface to generate a facile and cost-effective impedimetric biosensor. In addition, this composite provided proper attachment points for antibody binding and also supported the biosensor construction. The immuno-specific biointeractions between anti-RBD and RBD proteins hampered the electron transfer between the ITO substrate surface and electrolyte, and this reaction caused variations in impedance signals, and these signals were proportional to the immobilized RBD antigen amounts. The as-prepared immunosensor showed a wide linear dynamic range (0.0012-120 pg/mL), an ultra-low detection limit of 0.58 fg/mL with added superiorities of great selectivity, suitable repeatability, multiple reusability, and excellent reproducibility.

Polymer-Infiltrated Nanoparticle Films Using Capillarity-Based Techniques: Toward Multifunctional Coatings and Membranes

Polymer-infiltrated nanoparticle films (PINFs) are a new class of nanocomposites that offer synergistic properties and functionality derived from unusually high fractions of nanomaterials. Recently, two versatile techniques,capillary rise infiltration (CaRI) and solvent-driven infiltration of polymer (SIP), have been introduced that exploit capillary forces in films of densely packed nanoparticles. In CaRI, a highly loaded PINF is produced by thermally induced wicking of polymer melt into the nanoparticle packing pores. In SIP, exposure of a polymer-nanoparticle bilayer to solvent vapor atmosphere induces capillary condensation of solvent in the pores of nanoparticle packing, leading to infiltration of polymer into the solvent-filled pores. CaRI/SIP PINFs show superior properties compared with polymer nanocomposite films made using traditional methods, including superb mechanical properties, thermal stability, heat transfer, and optical properties. This review discusses fundamental aspects of the infiltration process and highlights potential applications in separations, structural coatings, and polymer upcycling-a process to convert polymer wastes into useful chemicals.

Electrically-responsive antimicrobial coatings based on a tetracycline-loaded poly(3,4-ethylenedioxythiophene) matrix

The growth of bacteria and the formation of complex bacterial structures on biomedical devices is a major challenge in modern medicine. The aim of this study was to develop a biocompatible, conducting and antibacterial polymer coating applicable in biomedical engineering. Since conjugated polymers have recently aroused strong interest as controlled delivery systems for biologically active compounds, we decided to employ a poly(3,4-ethylenedioxythiophene) (PEDOT) matrix to immobilize a powerful, first-line antibiotic: tetracycline (Tc). Drug immobilization was carried out simultaneously with the electrochemical polymerization process, allowing to obtain a polymer coating with good electrochemical behaviour (charge storage capacity of 19.15 ± 6.09 mC/cm²) and high drug loading capacity (194.7 ± 56.2 μg/cm²). Biological activity of PEDOT/Tc matrix was compared with PEDOT matrix and a bare Pt surface against a model Gram-negative bacteria strain of Escherichia coli with the use of LIVE/DEAD assay and SEM microscopy. Finally, PEDOT/Tc was shown to serve as a robust electroactive coating exhibiting antibacterial activity.

Smart Porous Multi-Stimulus Polysaccharide-Based Biomaterials for Tissue Engineering

Recently, tissue engineering and regenerative medicine studies have evaluated smart biomaterials as implantable scaffolds and their interaction with cells for biomedical applications. Porous materials have been used in tissue engineering as synthetic extracellular matrices, promoting the attachment and migration of host cells to induce the in vitro regeneration of different tissues. Biomimetic 3D scaffold systems allow control over biophysical and biochemical cues, modulating the extracellular environment through mechanical, electrical, and biochemical stimulation of cells, driving their molecular reprogramming. In this review, first we outline the main advantages of using polysaccharides as raw materials for porous scaffolds, as well as the most common processing pathways to obtain the adequate textural properties, allowing the integration and attachment of cells. The second approach focuses on the tunable characteristics of the synthetic matrix, emphasizing the effect of their mechanical properties and the modification with conducting polymers in the cell response. The use and influence of polysaccharide-based porous materials as drug delivery systems for biochemical stimulation of cells is also described. Overall, engineered biomaterials are proposed as an effective strategy to improve in vitro tissue regeneration and future research directions of modified polysaccharide-based materials in the biomedical field are suggested.

Electrochemical Synthesis of Polypyrrole and Polypyrrole-Indomethacin Coatings on NiCr Alloys Involving Deep Eutectic Solvents

There is an increased interest in the use of the deep eutectic solvents (DESs) as electrolytic media for electrochemical synthesis of conducting polymers, which could influence their characteristics. Moreover, the polypyrrole layers represent an attractive route for pharmaceutical drug release. The paper presents several experimental results regarding the electrodeposition of polypyrrole and of polypyrrole-indomethacin coatings on nickel-chromium NiCr alloy substrates widely used in dentistry, involving DES-based electrolytes, namely eutectic mixtures of choline chloride and malonic acid. This type of electrolyte also allowed an enhanced dissolution of indomethacin as compared to aqueous ones. The electropolymerization process has been investigated by cyclic voltammetry and chronoamperometry. The obtained indomethacin containing polymeric coatings have been thoroughly characterized involving scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, contact angle measurements in simulated body fluid (SBF) and indomethacin release studies. Adherent and uniform polypyrrole-indomethacin layers have been obtained on NiCr alloy substrates. The release tests showed that the polypyrrole coatings containing indomethacin may deliver the drug molecules for longer periods of at least 17 days. The maximum released amount was around 99.6% suggesting these layers may act as an active reservoir for indomethacin. Kinetics analysis based on the Korsmeyer–Peppas model suggested the diffusion of the drug out of the polymer layer as the most probable mechanism governing the release.

Enzymatic Biofuel Cells for Self-Powered, Controlled Drug Release

Self-powered drug-delivery systems based on conductive polymers (CPs) that eliminate the need for external power sources are of significant interest for use in clinical applications. Osmium redox polymer-mediated glucose/O₂ enzymatic biofuel cells (EBFCs) were prepared with an additional CP-drug layer on the cathode. On discharging the EBFCs in the presence of glucose and dioxygen, model drug compounds incorporated in the CP layer were rapidly released with negligible amounts released when the EBFCs were held at open circuit. Controlled and ex situ release of three model compounds, ibuprofen (IBU), fluorescein (FLU), and 4',6-diamidino-2-phenylindole (DAPI), was achieved with this self-powered drug-release system. DAPI released in situ in cell culture media was incorporated into retinal pigment epithelium (RPE) cells. This work demonstrates a proof-of-concept responsive drug-release system that may be used in implantable devices.

Polymeric Composites Based on Carboxymethyl Cellulose Cryogel and Conductive Polymers: Synthesis and Characterization

In this study, a super porous polymeric network prepared from a natural polymer, carboxymethyl cellulose (CMC), was used as a scaffold in the preparation of conductive polymers such as poly(Aniline) (PANi), poly(Pyrrole) (PPy), and poly(Thiophene) (PTh). CMC–conductive polymer composites were characterized by Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA) techniques, and conductivity measurements. The highest conductivity was observed as 4.36 × 10−4 ± 4.63 × 10−5 S·cm−1 for CMC–PANi cryogel composite. The changes in conductivity of prepared CMC cryogel and its corresponding PAN, PPy, and PTh composites were tested against HCl and NH3 vapor. The changes in conductivity values of CMC cryogel upon HCl and NH3 vapor treatment were found to increase 1.5- and 2-fold, respectively, whereas CMC–PANi composites showed a 143-fold increase in conductivity upon HCl and a 12-fold decrease in conductivity upon NH3 treatment, suggesting the use of natural polymer–conductive polymer composites as sensor for these gases.

Development of a rapidly made, easily personalized drug-eluting polymer film on the electrode array of a cochlear implant during surgery

OBJECTIVE

To develop a drug-eluting polymer film which can be easily personalized and rapidly made on the electrode array of a cochlear implant during surgery.

METHODS

A precursor solution was prepared with poly lactic-co-glycolic acid (PLGA) and trichloromethane. Using a dip-coating method, the silicone electrode array (HiFocus 1J, Advanced Bionics) was coated in polymer film produced from the precursor solution containing one of three drugs: dexamethasone sodium phosphate (DSP), cytosine arabinoside hydrochloride (Ara-C), or nicotinamide adenine dinucleotide (NAD), and the release of these drugs from the polymer film was studied. The drug-eluting film on the electrode array was analyzed by environmental scanning electron microscopy (ESEM). The water contact angle and the impedance of the electrode array were measured before and after coating. Drug release kinetics was evaluated in a quasi-stationary release model, using high performance liquid chromatography every 24 h for 15 days.

RESULTS

Five electrode arrays were tested with each of the three drugs in the polymer film coating. Before and after coating, ESEM studies revealed that the drug-loaded PLGA coating yielded a smooth covering with an average thickness of 1.02 ± 0.05 μm. The mass of the coated electrode increased by 1.00 ± 0.03 mg. The water contact angle decreased after coating (102 ± 0.6° vs 77 ± 1.6°, p < 0.01) but there was no significant change in the average impedance of the electrodes after coating (0.9 ± 0.22 kΩ vs 1.0 ± 0.18 kΩ, p > 0.05). An in vitro drug kinetics study revealed a faster release in the first 24 h (63.4 ± 0.6%) and a sustained release over the following 15 days (78.3 ± 1.7% in 2 days, 95.6 ± 1.0% in 7 days and 99.1 ± 0.4% in 14 days). The release rate was not affected by the drug, dose or the thickness of the coating.

CONCLUSION

The dip-coating method is feasible for rapid casting of a drug-eluting PLGA film on an electrode array during CI surgery. The coated electrode array maintained its original morphology and became more hydrophilic. The loaded drug is released in a sustained manner and is easily regulated, and so the method might represent a potential application for clinical use in cochlear implantation.

Synthesis and electrochemical characterization of a new benzodioxocine-fused poly(N-methylpyrrole) derivative: a joint experimental and DFT study

Synthesis of a new electropolymerizable monomer, XyPMe, regarding the reaction of diethylN-methyl-3,4-dihydroxypyrrole-2,5-dicarboxylate and 1,2-bis(bromomethyl)benzene with concomitant hydrolysis and decarboxylation reactions was accomplished.

Self-assembled nanostructures in ionic liquids facilitate charge storage at electrified interfaces

Driven by the potential applications of ionic liquids (ILs) in many emerging electrochemical technologies, recent research efforts have been directed at understanding the complex ion ordering in these systems, to uncover novel energy storage mechanisms at IL-electrode interfaces. Here, we discover that surface-active ILs (SAILs), which contain amphiphilic structures inducing self-assembly, exhibit enhanced charge storage performance at electrified surfaces. Unlike conventional non-amphiphilic ILs, for which ion distribution is dominated by Coulombic interactions, SAILs exhibit significant and competing van der Waals interactions owing to the non-polar surfactant tails, leading to unusual interfacial ion distributions. We reveal that, at an intermediate degree of electrode polarization, SAILs display optimum performance, because the low-charge-density alkyl tails are effectively excluded from the electrode surfaces, whereas the formation of non-polar domains along the surface suppresses undesired overscreening effects. This work represents a crucial step towards understanding the unique interfacial behaviour and electrochemical properties of amphiphilic liquid systems showing long-range ordering, and offers insights into the design principles for high-energy-density electrolytes based on spontaneous self-assembly behaviour.

Polymer nanocomposites having a high filler content: synthesis, structures, properties, and applications

The recent development of nanoscale fillers, such as carbon nanotubes, graphene, and nanocellulose, allows the functionality of polymer nanocomposites to be controlled and enhanced. However, conventional synthesis methods of polymer nanocomposites cannot maximise the reinforcement of these nanofillers at high filler content. Approaches for the synthesis of high content filler polymer nanocomposites are suggested to facilitate future applications. The fabrication methods address the design of the polymer nanocomposite architecture, which encompasses one, two, and three dimensional morphologies. Factors that hamper the reinforcement of nanostructures, such as alignment, dispersion of the filler and interfacial bonding between the filler and polymer, are outlined. Using suitable approaches, maximum potential reinforcement of nanoscale fillers can be anticipated without limitations in orientation, dispersion, and the integrity of the filler particle-matrix interface. High filler content polymer composites containing emerging materials such as 2D transition metal carbides, nitrides, and carbonitrides (MXenes) are expected in the future.

Intracellular calcium ions and morphological changes of cardiac myoblasts response to an intelligent biodegradable conducting copolymer

A novel biodegradable conducting polymer, PLA-b-AP-b-PLA (PAP) triblock copolymer of poly (l-lactide) (PLA) and aniline pentamer (AP) with electroactivity and biodegradability, was synthesized and its potential application in cardiac tissue engineering was studied. The PAP copolymer presented better biocompatibility compared to PANi and PLA because of promoted cell adhesion and spreading of rat cardiac myoblasts (H9c2 cell line) on PAP/PLA thin film. After pulse electrical stimulation (5 V, 1 Hz, 500 ms) for 6 days, the proliferation ratio, and intracellular calcium concentration of H9c2 cells on PAP/PLA were improved significantly. Meanwhile, cell morphology changed by varying the pulse electrical signals. Especially, the oriented pseudopodia-like structure was observed from H9c2 cells on PAP/PLA after electrical stimulation. It is regarded that the novel conducting copolymer could enhance electronic signals transferring between cells because of its special electrochemical properties, which may result in the differentiation of cardiac myoblasts.