Oligoethylene-Glycol-Functionalized Polyoxythiophenes for Cell Engineering: Syntheses, Characterizations, and Cell Compatibilities

A series of methyl- or benzyl-capped oligoethylene glycol functionalized 2,5-dibromo-3-oxythiophenes are synthesized and successfully polymerized by either Grignard metathesis (GRIM) polymerization or reductive coupling polymerization to yield the corresponding polymers in reasonable yields and molecular weights with narrow molecular weight distribution. These synthesized polyoxythiophenes exhibit high electroactivity and stability in aqueous solution when a potential is applied. Polyoxythiophenes from different polymerization approaches display different colors after purification and spectroelectrochemical studies confirm that the difference of color is from the difference of doping state. Little cytotoxicity is observed for the polymers by in vitro cell compatibility assay. NIH3T3 fibroblast cells are well attached and proliferate on spin-coated films. These results indicate that oligoethylene-glycol-functionalized polyoxythiophenes are promising candidates as conducting biomatierals for biomedical and bioengineering applications

Polydioxythiophene Nanodots, Nonowires, Nano-Networks, and Tubular Structures: The Effect of Functional Groups and Temperature in Template-Free Electropolymerization

Various nanostructures, including nanofibers, nanodots, nanonetwork, and nano- to microsize tubes of functionalized poly(3,4-ethylenedioxythiophene) (EDOT) and poly(3,4-propylenedioxythiophene) (ProDOT) are created by using a template-free electropolymerization method on indium–tin–oxide substrates. By investigating conducting polymer nanostructures containing various functional groups prepared at different polymerization temperature, we conclude a synergistic effect of functional groups and temperature on the formation of polymer nanostructures when a template-free electropolymerization method is applied. For unfunctionalized EDOT and ProDOT, or EDOT containing alkyl functional groups, nanofibers and nanoporous structures are usually found. Interesting, when polar functional groups are attached, conducting polymers tend to form nanodots at room temperature while grow tubular structures at low temperature. The relationship between surface properties and their nanostructures is evaluated by contact angle measurements. The capacity and electrochemical impedance spectroscopy measurements were conducted to understand the electrical properties of using these materials as electrodes. The results provide the relationship between the functional groups, nanostructures, and electrical properties. We also discuss the potential restriction of using this method to create nanostructures. The copolymerization of different functionalized EDOTs may cause irregular and unexpected nanostructures, which indicates the complex interaction between different functionalized monomers during the electropolymerization

Surface Engineering of Phenylboronic Acid-Functionalized Poly(3,4-ethylenedioxythiophene) for Fast Responsive and Sensitive Glucose Monitoring

In this study, we have successfully demonstrated a nanostructured phenylboronic acid-grafted poly­(3,4-ethylenedioxythiophene), poly­(EDOT-PBA), platform for fast and sensitive glucose monitoring. The poly­(EDOT-PBA) films of well-organized tubular nanostructures can be fabricated by direct electropolymerization without templates. Compared to the smooth poly­(EDOT-PBA), the nanotubular poly­(EDOT-PBA) shows enhanced glucose sensitivity and a different adsorption process of bovine serum albumin (BSA). Besides, the BSA blocking and low concentration of fructose and galactose do not affect the sensitivity of this platform. Both quartz crystal microbalance (QCM) and electrochemical impedance spectroscopy (EIS) methods are used and compared for glucose monitoring by applying nanotubular poly­(EDOT-PBA) as conductive substrates. Compared to QCM analysis, EIS has a higher sensitivity to glucose and the detection limit is about 50 μM. Besides, the binding with glucose on poly­(EDOT-PBA) is highly reversibly. On the basis of these observations, the nanotubular poly­(EDOT-PBA) has a great potential for enzyme-free electrodes targeting continuous glucose monitoring applications

High Density of Aligned Nanowire Treated with Polydopamine for Efficient Gene Silencing by siRNA According to Cell Membrane Perturbation

High aspect ratio nanomaterials, such as vertically aligned silicon nanowire (SiNW) substrates, are three-dimensional topological features for cell manipulations. A high density of SiNWs significantly affects not only cell adhesion and proliferation but also the delivery of biomolecules to cells. Here, we used polydopamine (PD) that simply formed a thin coating on various material surfaces by the action of dopamine as a bioinspired approach. The PD coating not only enhanced cell adhesion, spreading, and growth but also anchored more siRNA by adsorption and provided more surface concentration for substrate-mediated delivery. By comparing plain and SiNW surfaces with the same amount of loaded siRNA, we quantitatively found that PD coating efficiently anchored siRNA on the surface, which knocked down the expression of a specific gene by RNA interference. It was also found that the interaction of SiNWs with the cell membrane perturbed the lateral diffusion of lipids in the membrane by fluorescence recovery after photobleaching. The perturbation was considered to induce the effective delivery of siRNA into cells and allow the cells to carry out their biological functions. These results suggest promising applications of PD-coated, high-density SiNWs as simple, fast, and versatile platforms for transmembrane delivery of biomolecules

Step-Economical Syntheses of Functional BODIPY-EDOT π‑Conjugated Materials through Direct C–H Arylation

Palladium-catalyzed direct C–H arylations of 4,4-difluoro-4-bora-3a,4a-diaza-<i>s</i>-indacene (BODIPY) with 3,4-ethylene­dioxythio­phene (EDOT) derivatives at relatively low temperature (60 °C) provide moderate to good yields (47%–72%) of products having potential applications in fluorescent bioimaging and organic optoelectronics

Nanoscale Analysis of a Functionalized Polythiophene Surface by Adhesion Mapping

Functionalized ethylene­dioxy­thiophene (EDOT) monomers, hydroxymethyl EDOT (EDOT-OH), and zwitterionic phosphorylcholine EDOT (EDOT-PC) were electropolymerized to prepare the homopolymers poly­(EDOT-OH) and poly­(EDOT-PC), and mixtures of these monomers were used to produce the copolymer poly­(EDOT-OH)-<i>co</i>-poly­(EDOT-PC). Force–extension-curve-based atomic force microscopy (AFM) was utilized to analyze the surfaces of the films. The PEDOT-OH film yielded force–extension curves for short stretching, and the PEDOT-PC film yielded curves for long stretching. A dendron-modified AFM tip with anthracene groups tethered at the end resulted in adhesion maps with the highest contrast. The analytical data for the copolymer films correlated with the corresponding monomer composition, and the maps revealed that the average size for the copolymer nanodomains ranged from 10–14 nm. This approach can be applied to studies aimed at understanding the surface structure of other relevant polymers and copolymers at the nanoscale level

Detection of SARS-CoV‑2 Spike Protein Using Micropatterned 3D Poly(3,4-Ethylenedioxythiophene) Nanorods Decorated with Gold Nanoparticles

The sensitivity and fabrication process of the detection platform are important for developing viral disease diagnosis. Recently, the outbreak of SARS-CoV-2 compelled us to develop a new detection platform to control such diseases in the future. We present an electrochemical-based assay that employs the unique properties of gold nanoparticles (AuNPs) deposited on 3D carboxyl-functionalized poly(3,4-ethylenedioxythiophene) (PEDOTAc) nanorods for specific and sensitive detection of SARS-CoV-2 spike protein (S1). The 3D-shaped PEDOTAc nanorods offer an ample surface area for receptor immobilization grown on indium–tin oxide surfaces through transfer-printing technology. Characterization via electrochemical, fluorescence, X-ray photoelectron spectroscopy, and scanning electron microscopy techniques confirmed the structural and morphological properties of the AuNPs-decorated PEDOTAc. In contrast to antibody-based assays, our platform employs ACE2 receptors for spike protein binding. Differential pulse voltammetry records current responses, showing linear sensitivity from 100 ng to 10 pg/mL of S1. In addition, the SARS-CoV-2 assay (CoVPNs) also exhibited excellent selectivity against nonspecific target proteins (H9N2, IL-6, and Escherichia coli). Furthermore, the developed surface maintained good stability for up to 7 consecutive days without losing performance. The results provide new insight into effective 3D conductive nanostructure formation, which is promising in the development of versatile sensory devices

Electropolymerized Conjugated Polyelectrolytes with Tunable Work Function and Hydrophobicity as an Anode Buffer in Organic Optoelectronics

A new class of conductive polyelectrolyte films with tunable work function and hydrophobicity has been developed for the anode buffer layer in organic electronic devices. The work function of these films featuring a copolymer of ethylenedioxythiophene (EDOT), and its functionalized analogues were found to be easily tunable over a range of almost 1 eV and reach values as high as those of PEDOT:PSS. The new buffer material does not need the addition of any insulating or acidic material that might limit the film conductivity or device lifetime. Organic photovoltaic devices built with these films showed improved open-circuit voltage over those of the known PSS-free conductive EDOT-based polymers with values as high as that obtained for PEDOT:PSS. Furthermore, the surface hydrophobicity of these new copolymer films was found to be sensitive to the chemical groups attached to the polymer backbone, offering an attractive method for surface energy tuning

Controlled Protein Absorption and Cell Adhesion on Polymer-Brush-Grafted Poly(3,4-ethylenedioxythiophene) Films

Tailoring the surface of biometallic implants with protein-resistant polymer brushes represents an efficient approach to improve the biocompability and mechanical compliance with soft human tissues. A general approach utilizing electropolymerization to form initiating group (-Br) containing poly­(3,4-ethylenedioxythiophen)­s (poly­(EDOT)­s) is described. After the conducting polymer is deposited, neutral poly­((oligo­(ethylene glycol) methacrylate), poly­(OEGMA), and zwitterionic poly­([2-(methacryloyloxy)­ethyl]­dimethyl-(3-sulfopropyl)­ammonium hydroxide), poly­(SBMA), brushes are grafted by surface-initiated atom transfer radical polymerization. Quartz crystal microbalance (QCM) experiments confirm protein resistance of poly­(OEGMA) and poly­(SBMA)-grafted poly­(EDOT)­s. The protein binding properties of the surface are modulated by the density of polymer brushes, which is controlled by the feed content of initiator-containing monomer (EDOT-Br) in the monomer mixture solution for electropolymerization. Furthermore, these polymer-grafted poly­(EDOT)­s also prevent cells to adhere on the surface

Facile Syntheses of Dioxythiophene-Based Conjugated Polymers by Direct C–H Arylation

Various substituted dioxythiophenes bearing 3,4-propylenedioxythiophenes (ProDOT) and 3,4-ethylenedioxythiophene (EDOT) moieties successfully undergo Pd-catalyzed direct C–H arylation to yield π-conjugated polymers. The effects of palladium catalysts, phosphine ligands or additives, and functional groups on this facile polycondensation approach are investigated. Polymers from alkoxy-substituted ProDOT are synthesized with reasonable molecular weight (<i>M</i>_n = 6100–9600) and low PDI (1.3–1.9). Four substituted EDOT with alkoxy or protected functional groups also undergo direct C–H arylation polycondensation to yield corresponding polymers. The obtained polydioxythiophenes exhibit UV–vis absorptions ranging from 480 to 590 nm, and these conjugated polymers are electroactive and reversibly switched between the oxidized and neutral states upon applying potentials