Polypyrrole-based conducting polymers and interactions with biological tissues (original) (raw)
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Biocompatibility implications of polypyrrole synthesis techniques
Biomedical Materials, 2008
Polypyrrole (PPy) is an inherently conducting polymer that has shown great promise for biomedical applications within the nervous system. However, to effectively use PPy as a biomaterial implant, it is important to understand and reproducibly control the electrical properties, physical topography, and surface chemistry of the polymer. Although there is much research published on the use of PPy in various applications, there is no systematic study linking the methodologies used for PPy synthesis to PPy's basic polymeric properties (e.g., hydrophilicity, surface roughness), and to the biological effects these properties have on cells. Electrochemically synthesized PPy films differ greatly in their characteristics depending on synthesis parameters such as dopant, substrate, and thickness, among other parameters. In these studies, we have used three dopants (chloride (Cl), tosylate (ToS), polystyrene sulfonate (PSS)), two substrates (gold and indium tin oxide-coated glass), and a range of thicknesses, to measure and compare the biomedically-important characteristics of surface roughness, contact angle, conductivity, dopant stability, and cell adhesion (using PC-12 cells and Schwann cells). As predicted, we discovered large differences in roughness depending on the dopant used and the thickness of the film, while substrate choice had little effect. From contact angle measurements, PSS was found to yield the most hydrophilic material, most likely because of free charges from the long PSS chains exposed on the surface of the PPy. ToS-doped PPy films were tenfold more conductive than Cl-or PSS-doped films. X-ray photoelectron spectroscopy studies were used to evaluate dopant concentrations of PPy films stored in water and phosphate buffered saline over 14 days, and conductance studies over the same timeframe measured electrical stability. PSS proved to be the most stable dopant, though all films experienced significant decay in conductivity and dopant concentration. Cell adhesion studies demonstrated the dependence of cell outcome on film thickness and dopant choice. The strengths and weaknesses of different synthesis parameters, as demonstrated by these experiments, are critical design factors that must be leveraged when designing biomedical implants. The results of these studies should provide practical insight to researchers working with conducting polymers, and particularly PPy, on the relationships between synthesis parameters, polymeric properties, and biological compatibility.
Bioactivating electrically conducting polypyrrole with fibronectin and bovine serum albumin
Journal of Biomedical …, 2010
Electrically conducting polypyrrole (PPy) and its composite materials are useful in interfacing electrical components and cells or living tissue. In recent years, significant efforts have been made to bioactivate PPy by incorporating biomolecules. The main objective of this work was to chemically bioactivate PPy particules by incorporating fibronectin (FN) and bovine serum albumin (BSA). Modified PPy particles were synthesized through a water-in-oil emulsion polymerization. XPS and FTIR confirmed the presence of biomolecules on the PPy particles, and the surface morphology was observed by SEM. A four-point probe was used to measure the conductivity of the newly synthesized PPy particles, which was in the range of 10−1 S cm−1. Conductive biodegradable membranes were prepared with 5 and 10% (wt/wt) PPy to poly(L,L-lactide) (PPy/PLLA). The contact angles of each synthesized membrane were ∼75°, supporting their usefulness for cell culture. The cultured human skin fibroblasts demonstrated normal morphology and significantly higher adhesion and spreading on the PPy/PLLA∼FN membrane than on the unmodified PPy/PLLA membrane. On the other hand, the PPy/PLLA∼BSA membranes showed decreased cell adhesion. Bioactivated PPy may be useful in tissue engineering to fabricate conducting biodegradable scaffolds with either improved or reduced cell adhesion properties for various cell culture and in vivo applications. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res, 2010
materials Electrochemically Enhanced Drug Delivery Using Polypyrrole Films
The delivery of drugs in a controllable fashion is a topic of intense research activity in both academia and industry because of its impact in healthcare. Implantable electronic interfaces for the body have great potential for positive economic, health, and societal impacts; however, the implantation of such interfaces results in inflammatory responses due to a mechanical mismatch between the inorganic substrate and soft tissue, and also results in the potential for microbial infection during complex surgical procedures. Here, we report the use of conducting polypyrrole (PPY)-based coatings loaded with clinically relevant drugs (either an anti-inflammatory, dexamethasone phosphate (DMP), or an antibiotic, meropenem (MER)). The films were characterized and were shown to enhance the delivery of the drugs upon the application of an electrochemical stimulus in vitro, by circa (ca.) 10-30% relative to the passive release from non-stimulated samples. Interestingly, the loading and release of the drugs was correlated with the physical descriptors of the drugs. In the long term, such materials have the potential for application to the surfaces of medical devices to diminish adverse reactions to their implantation in vivo. implants such as reconstructive joint replacements, dental implants, and spinal implants) or soft tissues (e.g., intraocular lenses, or the skin). The successful integration of such devices is dependent on the availability of sterile surgical conditions, patient health, etc., and their implantation is most commonly coupled with a course of condition-and patient-specific drugs .
Biosensing and drug delivery by polypyrrole
Analytica Chimica Acta, 2006
Conducting polypyrrole is a biological compatible polymer matrix wherein number of drugs and enzymes can be incorporated by way of doping. The polypyrrole, which is obtained as freestanding film by electrochemical polymerization, has gained tremendous recognition as sophisticated electronic measuring device in the field of sensors and drug delivery. In drug delivery the reversing of the potential 100% of the drug can be released and is highly efficient as a biosensor in presence of an enzyme. In this review we discuss the applications of conducting polypyrrole as biosensor for some biomolecules and drug delivery systems.
Electrochemical sensors based on conducting polymer—polypyrrole
Electrochimica Acta, 2006
Conducting polymers can be exploited as an excellent tool for the preparation of nanocomposites with nano-scaled biomolecules. Polypyrrole(Ppy) is one of the most extensively used conducting polymers in design of bioanalytical sensors. In this review article significant attention ispaid to immobilization of biologically active molecules within Ppy during electrochemical deposition of this polymer. Such unique properties ofthis polymer as prevention of some undesirable electrochemical interactions and facilitation of electron transfer from some redox enzymes are discussed. Recent advances in application of polypyrrole in immunosensors and DNA sensors are presented. Some new electrochemical targetDNA and target protein detection methods based on changes of semiconducting properties of electrochemically generated Ppy doped by affinityagents are introduced. Recent progress and problems in development of molecularly imprinted polypyrrole are considered. A. Ramanavicius, A. Ramanaviciene, A. Malinauskas, Electrochemical sensors based on conducting polymerpolypyrrole (Review) Electrochimica Acta 2006, 51, 6025-6037. A. Ramanavicius, A. Ramanaviciene, A. Malinauskas, Electrochemical sensors based on conducting polymerpolypyrrole (Review) Electrochimica Acta 2006, 51, 6025-6037.
Evaluation of Biocompatibility of Polypyrrole In Vitro and In Vivo
… Research Part A, 2004
Abstract: In this study, the biocompatibility of the electri-cally conductive polymer polypyrrole (PPy) with nerve tis-sue was evaluated in vitro and in vivo. The extraction solu-tion of PPy powder, which was synthesized chemically, was tested for acute toxicity, subacute ...
Erodible Conducting Polymers for Potential Biomedical Applications
Angewandte Chemie International Edition, 2002
Electrically conducting polymers have been investigated for numerous applications, including organic substitutes for metals in electronic circuits, coatings for electromagnetic shielding, [2] analytical and biological sensing devices, [3±5] and as substrates for the manipulation of mammalian cell growth and function. [6] From a separate standpoint, the development and application of biodegradable polymers has had a profound impact in numerous medical and surgical applications. It occurred to us that the creation of biocompatible, degradable conducting polymers could open the door to a number of new biomedical applications. [8] Several groups have reported the synthesis and characterization of conducting poly(thiophene) derivatives containing hydrolyzable ester groups in the polymer backbone. However, to our knowledge, the degradability and biocompatibility of these polymers has not been established, and the reduced environmental stability of oxidized polythiophenes could limit their application under physiological conditions.
Electrochemical sensors based on conducting polymer -polypyrrole (Review)
Electrochimica Acta, 2005
Conducting polymers can be exploited as an excellent tool for the preparation of nanocomposites with nano-scaled biomolecules. Polypyrrole(Ppy) is one of the most extensively used conducting polymers in design of bioanalytical sensors. In this review article significant attention ispaid to immobilization of biologically active molecules within Ppy during electrochemical deposition of this polymer. Such unique properties ofthis polymer as prevention of some undesirable electrochemical interactions and facilitation of electron transfer from some redox enzymes are discussed. Recent advances in application of polypyrrole in immunosensors and DNA sensors are presented. Some new electrochemical targetDNA and target protein detection methods based on changes of semiconducting properties of electrochemically generated Ppy doped by affinityagents are introduced. Recent progress and problems in development of molecularly imprinted polypyrrole are considered.
Biomaterials, 2004
A novel electrically conductive biodegradable composite material made of polypyrrole (PPy) nanoparticles and poly(d,l-lactide) (PDLLA) was prepared by emulsion polymerization of pyrrole in a PDLLA solution, followed by precipitation. The composite was characterized by scanning electron microscopy and X-ray photoelectron spectroscopy. The electrical stability of the composite containing 5 wt% PPy was investigated in a cell culture environment for 1000 h with 100 mV DC applied voltage. Fibroblasts were cultured on the composite membranes and were stimulated with various DC currents. The PPy particles formed aggregations and constituted microdomains and networks embedded in the PDLLA. With the 1-17% increase in the PPy content, the conductivity of the composite increased by six orders of magnitude. The surface resistivity of the PPy/PDLLA membrane with 3% PPy was as low as 1 Â 10 3 O/square. The electrical stability was significantly better in the PPy/PDLLA composite than in the PPy-coated polyester fabrics. For the composite with 5% PPy, the test membrane retained 80% and 42% of the initial conductivity in 100 and 400 h, respectively, following the addition of the MEM solution, compared to 5% and 0.1% for the PPy-coated polyester fabrics. Under 100 mV, a composite membrane 3.0 Â 2.5 Â 0.03 cm 3 in size and containing 5% PPy sustained a biologically meaningful electrical conductivity in a typical cell culture environment for 1000 h. The growth of fibroblasts was up regulated under the stimulation of medium range intensity of DC current.
Interfacial physicochemical properties of functionalized conducting polypyrrole particles
Polymer, 2005
Polypyrrole-coated polystyrene latex particles bearing reactive N-succinimidyl ester functional groups (PS-PPyNSE 75 ) were prepared by the in situ copolymerization of pyrrole 1 and the active N-succinimidyl ester-functionalized pyrrole 2 (pyrroleNSE), with initial 1:2 fractions of 25:75 (%) in the presence of sterically stabilized polystyrene (PS) latex particles. PS particles were prepared by dispersion polymerization leading to particles having a diameter of 600G10 nm. The PS-PPyNSE 75 particles were characterized in terms of surface morphology and chemical composition. Surface analysis of the colloidal materials by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) indicated a substantial coating of PS by the reactive conducting copolymer. Infrared spectroscopy permitted to detect pyrroleNSE repeat units at the surface of the particles indicating that 1 and 2 did indeed copolymerise.