From energy storage to pathogen eradication: unveiling the antibacterial and antiviral capacities of flexible solid-state carbon cloth supercapacitors.

With the emergence of deadly viral and bacterial infections, preventing the spread of microorganisms on surfaces has gained ever-increasing importance. This study investigates the potential of solid-state supercapacitors as antibacterial and antiviral devices. We developed a low-cost and flexible carbon cloth supercapacitor (CCSC) with highly efficient antibacterial and antiviral surface properties. The CCSC comprised two parallel layers of carbon cloth (CC) electrodes assembled in a symmetric, electrical double-layer supercapacitor structure that can be charged at low potentials between 1 to 2 V. The optimized CCSC exhibited a capacitance of 4.15 ± 0.3 mF cm-2 at a scan rate of 100 mV s-1, high-rate capability (83% retention of capacitance at 100 mV s-1 compared to its value at 5 mV s-1), and excellent electrochemical stability (97% retention of the initial capacitance after 1000 cycles). Moreover, the CCSC demonstrated outstanding flexibility and retained its full capacitance even when bent at high angles, making it suitable for wearable or flexible devices. Using its stored electrical charge, the charged CCSC disinfects bacteria effectively and neutralizes viruses upon surface contact with the positive and negative electrodes. The charged CCSC device yielded a 6-log CFU reduction of Escherichia coli bacterial inocula and a 5-log PFU reduction of HSV-1 herpes virus. Antibacterial and antiviral carbon cloth supercapacitors represent a promising platform technology for various applications, including electronic textiles and electronic skins, health monitoring or motion sensors, wound dressings, personal protective equipment (e.g., masks) and air filtration systems.

Conducting Polymer-Infused Electrospun Fibre Mat Modified by POEGMA Brushes as Antifouling Biointerface.

Biofouling on surfaces, caused by the assimilation of proteins, peptides, lipids and microorganisms, leads to contamination, deterioration and failure of biomedical devices and causes implants rejection. To address these issues, various antifouling strategies have been extensively studied, including polyethylene glycol-based polymer brushes. Conducting polymers-based biointerfaces have emerged as advanced surfaces for interfacing biological tissues and organs with electronics. Antifouling of such biointerfaces is a challenge. In this study, we fabricated electrospun fibre mats from sulphonated polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (sSEBS), infused with conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) (sSEBS-PEDOT), to produce a conductive (2.06 ± 0.1 S/cm), highly porous, fibre mat that can be used as a biointerface in bioelectronic applications. To afford antifouling, here the poly(oligo (ethylene glycol) methyl ether methacrylate) (POEGMA) brushes were grafted onto the sSEBS-PEDOT conducting fibre mats via surface-initiated atom transfer radical polymerization technique (SI-ATRP). For that, a copolymer of EDOT and an EDOT derivative with SI-ATRP initiating sites, 3,4-ethylenedioxythiophene) methyl 2-bromopropanoate (EDOTBr), was firstly electropolymerized on the sSEBS-PEDOT fibre mat to provide sSEBS-PEDOT/P(EDOT-co-EDOTBr). The POEGMA brushes were grafted from the sSEBS-PEDOT/P(EDOT-co-EDOTBr) and the polymerization kinetics confirmed the successful growth of the brushes. Fibre mats with 10-mers and 30-mers POEGMA brushes were studied for antifouling using a BCA protein assay. The mats with 30-mers grafted brushes exhibited excellent antifouling efficiency, ~82% of proteins repelled, compared to the pristine sSEBS-PEDOT fibre mat. The grafted fibre mats exhibited cell viability >80%, comparable to the standard cell culture plate controls. Such conducting, porous biointerfaces with POEGMA grafted brushes are suitable for applications in various biomedical devices, including biosensors, liquid biopsy, wound healing substrates and drug delivery systems.

Conducting Polymer-Coated Carbon Cloth Captures and Releases Extracellular Vesicles by a Rapid and Controlled Redox Process.

Electrochemical techniques offer great opportunities for the capture of chemical and biological entities from complex mixtures and their subsequent release into clean buffers for analysis. Such methods are clean, robust, rapid, and compatible with a wide range of biological fluids. Here, we designed an electrochemically addressable system, based on a conducting terpolymer [P(EDOT-co-EDOTSAc-co-EDOTEG)] coated onto a carbon cloth substrate, to selectively capture and release biological entities using a simple electrochemical redox process. The conducting terpolymer composition was optimized and the terpolymer-coated carbon cloth was extensively characterized using electrochemical analysis, Raman and Fourier transform-infrared spectroscopy, water contact angle analysis, and scanning electron microscopy. The conductive terpolymer possesses a derivative of EDOT with an acetylthiomethyl moiety (EDOTSAc), which is converted into a "free" thiol that then undergoes reversible oxidation/reduction cycles at +1.0 V and -0.8 V (vs Ag/AgCl), respectively. That redox process enables electrochemical capture and on-demand release. We first demonstrated the successful electrochemical capture/release of a fluorescently labeled IgG antibody. The same capture/release procedure was then applied to release extracellular vesicles (EVs), originating from both MCF7 and SKBR3 breast cancer cell line bioreactors. EVs were captured using the substrate-conjugated HER2 antibody which was purified from commercially available trastuzumab. Capture and release of breast cancer EVs using a trastuzumab-derived HER2 antibody has not been reported before (to the best of our knowledge). A rapid (2 min) release at a low potential (-0.8 V) achieved a high release efficiency (>70%) of the captured, HER2+ve, SKBR3 EVs. The developed system and the electrochemical method are efficient and straightforward and have vast potential for the isolation and concentration of various biological targets from large volumes of biological and other (e.g., environmental) samples.

Noninvasive Detection of Ammonia in the Breath of Hemodialysis Patients Using a Highly Sensitive Ammonia Sensor Based on a Polypyrrole/Sulfonated Graphene Nanocomposite.

In this work, we fabricated fast-responsive and highly sensitive chemiresistive sensors based on nanocomposites of polypyrrole and graphitic materials such as graphene oxide (GO), reduced graphene oxide (RGO), and sulfonated graphene (SRGO) by an in situ chemical oxidative polymerization method. The synthesized nanocomposites were characterized using field emission scanning electron microscopy (FESEM), energy-dispersive spectroscopy (EDS), Fourier transform infrared (FT-IR) spectroscopy, and X-ray diffraction (XRD). The effects of the operating temperature of different nanocomposites were investigated at four temperatures (28, 40, 50, and 60 °C), and the results were compared with that of the polypyrrole-based sensor. The experimental results for sensors indicate that the proposed PPy/SRGO sensor could be an appropriate choice for NH3 detection at 28 °C in the range of 0.50 parts per billion (ppb) to 12 parts per million (ppm). The PPy/SRGO nanocomposite gas sensor exhibited fast responsivity, good repeatability, and high chemical selectivity to low-concentration ammonia against humidity, methanol, ethanol, acetone, formaldehyde, dibutylamine, dimethylamine, methylamine, carbon monoxide, and nitrogen oxide at 28 °C. We utilized the PPy/SRGO sensor for studying the variation of the ammonia concentration in hemodialysis (HD) patients' breath before and after dialysis and correlated it with the blood urea nitrogen (BUN) levels. The results of the PPy/SRGO sensor indicated that the breath ammonia concentration significantly decreased after dialysis in agreement with BUN. The results demonstrate the potential application of the PPy/SRGO sensor for noninvasive detection of ammonia in breath and make this type of sensor a promising tool for the diagnosis of renal and liver diseases.

A Heart-Breast Cancer-on-a-Chip Platform for Disease Modeling and Monitoring of Cardiotoxicity Induced by Cancer Chemotherapy.

Cardiotoxicity is one of the most serious side effects of cancer chemotherapy. Current approaches to monitoring of chemotherapy-induced cardiotoxicity (CIC) as well as model systems that develop in vivo or in vitro CIC platforms fail to notice early signs of CIC. Moreover, breast cancer (BC) patients with preexisting cardiac dysfunctions may lead to different incident levels of CIC. Here, a model is presented for investigating CIC where not only induced pluripotent stem cell (iPSC)-derived cardiac tissues are interacted with BC tissues on a dual-organ platform, but electrochemical immuno-aptasensors can also monitor cell-secreted multiple biomarkers. Fibrotic stages of iPSC-derived cardiac tissues are promoted with a supplement of transforming growth factor-ß 1 to assess the differential functionality in healthy and fibrotic cardiac tissues after treatment with doxorubicin (DOX). The production trend of biomarkers evaluated by using the immuno-aptasensors well-matches the outcomes from conventional enzyme-linked immunosorbent assay, demonstrating the accuracy of the authors' sensing platform with much higher sensitivity and lower detection limits for early monitoring of CIC and BC progression. Furthermore, the versatility of this platform is demonstrated by applying a nanoparticle-based DOX-delivery system. The proposed platform would potentially help allow early detection and prediction of CIC in individual patients in the future.

Electroactive Metal Complexes Covalently Attached to Conductive PEDOT Films: A Spectroelectrochemical Study.

The successful covalent attachment, via copper(I)-catalyzed azide alkyne cycloaddition (CuAAC), of alkyne-functionalized nickel(II) and copper(II) macrocyclic complexes onto azide (N3)-functionalized poly(3,4-ethylenedioxythiophene) (PEDOT) films on ITO-coated glass electrodes is reported. To investigate the surface attachment of the selected metal complexes, which are analogues of the cobalt-based complex previously reported to be a molecular catalyst for hydrogen evolution, first, three different PEDOT films were formed by electropolymerization of pure PEDOT or pure N3-PEDOT, and last, 1:2N3-PEDOT:PEDOT were formed by co-polymerizing a 1:4 mixture of N3-EDOT:EDOT monomers. The successful surface immobilization of the complexes on the latter two azide-functionalized films, by CuAAC, was confirmed by X-ray photoelectron spectroscopy (XPS) and electrochemistry as well as by UV-vis-NIR and resonance Raman spectroelectrochemistry. The ratio between the N3 groups, and hence, the number of surface-attached metal complexes after CuAAC functionalization, in pristine N3-PEDOT versus 1:2N3-PEDOT:PEDOT is expected to be 3:1 and seen to be 2.86:1 with a calculated surface coverage of 3.28 ± 1.04 and 1.15 ± 0.09 nmol/cm2, respectively. The conversion, to the metal complex attached films, was lower for the N3-PEDOT films (Ni 74%, Cu 76%) than for the copolymer 1:2N3-PEDOT:PEDOT films (Ni 83%, Cu 91%) due to the former being more sterically congested. The Raman and UV-vis-NIR results were simulated using density functional theory (DFT) and time-dependent DFT (TD-DFT), respectively, and showed good agreement with the experimental data. Importantly, the spectroelectrochemical behavior of both anchored metal complexes is analogous to that of the free metal complexes in solution. This proves that PEDOT films are promising conducting scaffolds for the covalent immobilization of metal complexes, as the existing electrochromic features of the complexes are preserved on immobilization, which is important for applications in electrocatalytic proton and carbon dioxide reduction, optoelectronics, and sensing.

The removal of metformin and other selected PPCPs from water by poly(3,4-ethylenedioxythiophene) photocatalyst.

The objective of this study was to investigate the photocatalytic removal of PPCPs using poly(3,4-ethylenedioxythiophene) (PEDOT) polymer. PEDOT is a conducting polymer that exhibits excellent photocatalytic activity and was used in this study without any additives or metal co-catalysts. The PEDOT was synthesized using chemical oxidative polymerization and characterized further for composition and morphology. PEDOT, in the presence of UV irradiation, showed >99% degradation of one of the most widely prescribed antidiabetic drugs, metformin, within 60 min. The effect of varying concentration of PEDOT, pH, and light irradiance was studied to achieve maximum photocatalytic efficiency. Two major degradation products of metformin of m/z 116 and 126 were detected using triple quadrupole LC-MS/MS, while the degradation kinetics was found to be of pseudo-first-order. Results revealed that photogenerated electrons, holes, and radical species played a role in the PPCPs' degradation. When a mixture of seven PPCPs in the ultra-pure water matrix was tested, more than 99% removal was observed for most of the PPCPs within 60 min. The removal efficiency decreased in a real wastewater effluent due to the presence of dissolved organic matter; however, still, more than 50% removal was observed for majority of the studied PPCPs. The results of PEDOT reusability revealed that the reuse contributed to the drop in the conductivity and subsequent drop in the photocatalytic activity; however, a simple acid treatment was found to be effective to recoup its conductivity. PEDOT was successfully immobilized on an electrospun fiber mat to enhance its applicability.

Novel Electrochemically Switchable, Flexible, Microporous Cloth that Selectively Captures, Releases, and Concentrates Intact Extracellular Vesicles.

There is a significant and growing research interest in the isolation of extracellular vesicles (EVs) from large volumes of biological samples and their subsequent concentration into clean and small volumes of buffers, especially for applications in medical diagnostics. Materials that are easily incorporated into simple sampling devices and which allow the release of EVs without the need for auxiliary and hence contaminating reagents are particularly in demand. Herein, we report on the design and fabrication of a flexible, microporous, electrochemically switchable cloth that addresses the key challenges in diagnostic applications of EVs. We demonstrate the utility of our electrochemically switchable substrate for the fast, selective, nondestructive, and efficient capture and subsequent release of EVs. The substrate consists of an electrospun cloth, infused with a conducting polymer and decorated with gold particles. Utilizing gold-sulfur covalent bonding, the electrospun substrates may be functionalized with SH-terminated aptamer probes selective to EV surface proteins. We demonstrate that EVs derived from primary human dermal fibroblast (HDFa) and breast cancer (MCF-7) cell lines are selectively captured with low nonspecific adsorption using an aptamer specific to the CD63 protein expressed on the EV membranes. The specific aptamer-EV interactions enable easy removal of the nonspecifically bound material through washing steps. The conducting polymer component of the cloth provides a means for efficient (>92%) and fast (<5 min) electrochemical release of clean and intact captured EVs by cathodic cleavage of the Au-S bond. We demonstrate successful capture of diluted EVs from a large volume sample and their release into a small volume of clean phosphate-buffered saline buffer. The developed cloth can easily be incorporated into different designs for separation systems and would be adaptable to other biological entities including cells and other EVs. Furthermore, the capture/release capability holds great promise for liquid biopsies if used to targeted disease-specific markers.

Synthesis of highly fluorescent water-soluble polypyrrole for cell imaging and iodide ion sensing.

Conjugated polymers for bioimaging and sensing chemical/biological reagents have received much attention owing to their outstanding photophysical properties. However, most conventional synthetic strategies result in aggregates of conjugated polymers with limited solubility in most common organic and aqueous solvents. Therefore, advancement in molecular design and synthetic pathways is required to tune the optical and solubility properties of the resulting conjugated polymers. Herein, a simple, general, and effective approach for the synthesis of water-soluble polypyrrole (PPy) is reported based on the chemical polymerization in the presence of a homologue series of dicarboxylic acids with different chain lengths as multifunctional dopant molecules, possessing two carboxylic acid groups which serve as both dopants and stabilizing agents. The role of dopant chain length on the emission properties of resulting water-soluble polymers has been investigated. Among the synthesized water-soluble polymers, succinic acid-stabilized polymer (PPy-Suc) showed the highest emission wavelength (λem = 453 nm), high quantum yield (12.87), very good photostability and low cytotoxicity, suggesting its applicability in bioimaging and sensing applications. As a proof of concept, the PPy-Suc polymer was successfully utilized in cellular imaging. Moreover, a novel fluorescence iodide sensor with two linear ranges of 0.012-0.200 and 0.200-8.825 µM and a low detection limit of 9 nM was developed based on the prepared PPy-Suc polymer. The superior properties of the synthesized water-soluble polymers confirm the potential applicability of developed method as a general, facile and effective synthesis approach in preparation of water-soluble conjugated polymers with several potential applications.

CdS QDs/N-methylpolypyrrole hybrids as fluorescent probe for ultrasensitive and selective detection of picric acid.

Inorganic-organic hybrids are an advanced class of luminescent materials showing great promise for fabrication of highly sensitive and selective optical sensors. In the present study, a novel CdS quantum dots/N-methylpolypyrrole (CdS QDs/NMPPY) hybrid was synthesized via the direct polymerization of NMPPY on L-cysteine capped CdS QD aggregates. A number of characterization techniques including FTIR, DLS, FESEM, UV-vis, and fluorescence spectroscopies were used to study the chemical composition, morphology and optical properties of the resultant QDs/polymer hybrid. The as-synthesized CdS QDs/NMPPY hybrid shows a bright emission at 459 nm under excitation at 367 nm in water. Also the results show the role of sodium dodecyl benzenesulfonate (SDBS) to control the mechanism of synthesis and spectroscopic of the prepared CdS/NMPPY hybrid. Moreover, in this work was reported the direct hybridization procedure without other modification such as ligand exchange and coating. We demonstrated that the hybridization of CdS QDs with NMPPY polymer leads to a significant change in fluorescence sensing properties toward nitroaromatic compounds. Further studies unveiled that the emission of CdS QDs/NMPPY hybrid is strongly and selectively quenched by picric acid molecule with a large Stern-Volmer constant of 843,900 M-1 and an excellent detection limit of 4.6 × 10-7 M. The changes in the UV-vis spectra of picric acid solutions in the presence and absence of CdS QDs/NMPPY hybrid displayed that the fluorescence quenching occurs through a static quenching mechanism. Finally, the proposed CdS QDs/NMPPY sensor was successfully utilized to determine the amount of picric acid in real water samples.

Photophysical Diversity of Water-Soluble Fluorescent Conjugated Polymers Induced by Surfactant Stabilizers for Rapid and Highly Selective Determination of 2,4,6-Trinitrotoluene Traces.

The increasing application of fluorescence spectroscopy in development of reliable sensing platforms has triggered a lot of research interest for the synthesis of advanced fluorescent materials. Herein, we report a simple, low-cost strategy for the synthesis of a series of water-soluble conjugated polymer nanoparticles with diverse emission range using cationic (hexadecyltrimethylammonium bromide, CTAB), anionic (sodium dodecylbenzenesulfonate, SDBS), and nonionic (TX114) surfactants as the stabilizing agents. The role of surfactant type on the photophisical and sensing properties of resultant polymers has been investigated using dynamic light scattering (DLS), FT-IR, UV-vis, fluorescence, and energy dispersive X-ray (EDS) spectroscopies. The results show that the surface polarity, size, and spectroscopic and sensing properties of conjugated polymers could be well controlled by the proper selection of the stabilizer type. The fluorescent conjugated polymers exhibited fluorescence quenching toward nitroaromatic compounds. Further studies on the fluorescence properties of conjugated polymers revealed that the emission of the SDBS stabilized polymer, N-methylpolypyrrole-SDBS (NMPPY-SDBS), is strongly quenched by 2,4,6-trinitrotoluene molecule with a large Stern -Volmer constant of 59 526 M(-1) and an excellent detection limit of 100 nM. UV-vis and cyclic voltammetry measurements unveiled that fluorescence quenching occurs through a charge transfer mechanism between electron rich NMPPY-SDBS and electron deficient 2,4,6-trinitrotoluene molecules. Finally, the as-prepared conjugated polymer and approach were successfully applied to the determination of 2,4,6-trinitrotoluene in real water samples.

A highly thermal-resistant electrospun-based polyetherimide nanofibers coating for solid-phase microextraction.

A high-temperature-resistant solid-phase microextraction (SPME) fiber was prepared based on polyetherimide (PEI) by the electrospinning method. The PEI polymeric solution was converted to nanofibers using high voltages and directly coated on a stainless steel SPME needle. The scanning electron microscopy images of PEI coating showed fibers with diameter range of 500-650 nm with a homogeneous and smooth surface morphology. The SPME nanofibers coating was optimized for PEI percentage, electrospinning voltage, and time. The extraction efficiency of the coating was investigated for headspace SPME of some environmentally important polycyclic aromatic hydrocarbons from aqueous samples followed by gas chromatography-mass spectrometry measurement. In addition, the important extraction parameters including extraction temperature, extraction time, ionic strength, as well as desorption temperature and time were investigated and optimized. The detection limits of the method under optimized conditions ranged from 1 to 5 ng L(-1) using time-scheduled selected ion monitoring mode. The relative standard deviations of the method were between 1.1 and 7.1 %, at a concentration level of 500 ng L(-1). The calibration curves of polycyclic aromatic hydrocarbons showed linearity in the range of 5-1000 ng L(-1). The developed method was successfully applied to real water samples and the relative recovery percentages obtained from the spiked water samples were from 84 to 98 % for all the selected analytes except for acenaphthene which was from 75 to 106 %.

Novel polyamide-based nanofibers prepared by electrospinning technique for headspace solid-phase microextraction of phenol and chlorophenols from environmental samples.

A novel solid phase microextraction (SPME) fiber was fabricated by electrospinning method in which a polymeric solution was converted to nanofibers using high voltages. A thin stainless steel wire was coated by the network of polymeric nanofibers. The polymeric nanofiber coating on the wire was mechanically stable due to the fine and continuous nanofibers formation around the wire with a three dimensional structure. Polyamide (nylon 6), due to its suitable characteristics was used to prepare the unbreakable SPME nanofiber. The scanning electron microscopy (SEM) images of this new coating showed a diameter range of 100-200 nm for polyamide nanofibers with a homogeneous and porous surface structure. The extraction efficiency of new coating was investigated for headspace solid-phase microextraction (HS-SPME) of some environmentally important chlorophenols from aqueous samples followed by gas chromatography-mass spectrometry (GC-MS) analysis. Effect of different parameters influencing the extraction efficiency including extraction temperature, extraction time, ionic strength and polyamide amount were investigated and optimized. In order to improve the chromatographic behavior of phenolic compounds, all the analytes were derivatized prior to the extraction process using basic acetic anhydride. The detection limits of the method under optimized conditions were in the range of 2-10 ng L(-1). The relative standard deviations (RSD) (n=3) at the concentration level of 1.7-6.7 ng mL(-1) were obtained between 1 and 7.4%. The calibration curves of chlorophenols showed linearity in the range of 27-1330 ng L(-1) for phenol and monochlorophenols and 7-1000 ng L(-1) for dichloro and trichlorophenols. Also, the proposed method was successfully applied to the extraction of phenol and chlorophenols from real water samples and relative recoveries were between 84 and 98% for all the selected analytes except for 2,4,6 tricholophenol which was between 72 and 74%.