Plasticizer and catalyst co-functionalized PEDOT:PSS enables stretchable electrochemical sensing of living cells

Recently, stretchable electrochemical sensors have stood out as a powerful tool for the detection of soft cells and tissues, since they could perfectly comply with the deformation of living organisms and synchronously monitor mechanically evoked biomolecule release. However, existing strategies for the fabrication of stretchable electrochemical sensors still face with huge challenges due to scarce electrode materials, demanding processing techniques and great complexity in further functionalization. Herein, we report a novel and facile strategy for one-step preparation of stretchable electrochemical biosensors by doping ionic liquid and catalyst into a conductive polymer (poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate), PEDOT:PSS). Bis(trifluoromethane) sulfonimide lithium salt as a small-molecule plasticizer can significantly improve the stretchability and conductivity of the PEDOT:PSS film, and cobalt phthalocyanine as an electrocatalyst endows the film with excellent electrochemical sensing performance. Moreover, the functionalized PEDOT:PSS retained good cell biocompatibility with two extra dopants. These satisfactory properties allowed the real-time monitoring of stretch-induced transient hydrogen peroxide release from cells. This work presents a versatile strategy to fabricate conductive polymer-based stretchable electrodes with easy processing and excellent performance, which benefits the in-depth exploration of sophisticated life activities by electrochemical sensing.

A facile strategy for constructing stretchable sensors with excellent mechanical, electrochemical and biocompatible performance is developed, and in situ inducing and monitoring of stretch-evoked H₂O₂ release from cells has been successfully achieved.     

Primary photodamage sites and mitochondrial events after Foscan photosensitization of MCF-7 human breast cancer cells

To determine the initial photodamage sites of Foscan-mediated photodynamic treatment, we evaluated the enzymatic activities in selected organelles immediately after light exposure of MCF-7 cells. The measurements indicated that the enzymes located in the Golgi apparatus (uridine 5'-diphosphate galactosyl transferase) and in the endoplasmic reticulum (ER) (nicotinamide adenine dinucleotide [reduced] [NADH] cytochrome c [cyt c] reductase) are inactivated by the treatment, whereas mitochondrial marker enzymes (cyt c oxidase and dehydrogenases) were unaffected. This indicates that the ER and the Golgi apparatus are the primary intracellular sites damaged by Foscan-mediated PDT in MCF-7 cells. We further investigated whether the specific mitochondria events could be associated with Foscan photoinduced cell death. The dose response profiles of mitochondrial depolarization and cytochrome c release immediately after Foscan-based PDT were very different from that of overall cell death. By 24 h post-PDT the fluence dependency was strikingly similar for both mitochondrial alterations and cell death. Therefore, although mitochondria are not directly affected by the treatment, they can be strongly implicated in Foscan-mediated MCF-7 cell death by late and indirect mechanism.     

Comparison of the Electrochemical Reactivity of Carbon Nanotubes Paste Electrodes with Different Types of Multiwalled Carbon Nanotubes

Carbon nanotubes (CNTs) are widely used in electrochemical studies. It is reported that CNTs with different source and dispersed in different agents [1] yield significant difference of electrochemical reactivity. Here we report on the electrochemical performance of CNTs paste electrodes (CNTPEs) prepared by multiwalled carbon nanotubes (MWNTs) with different diameters, lengths and functional groups. The resulting electrodes exhibit remarkable different electrochemical reactivity towards redox molecules such as NADH and K₃[Fe(CN)₆]. It is found that CNTPEs prepared by MWNTs with 20–30 nm diameter show highest catalysis to NADH oxidation, while CNTPEs prepared by MWNTs with carboxylate groups have best electron‐transfer rate (The peak‐peak separation (ΔE_p) is +0.108 V for MWNTs with carboxylate groups, +0.155 V for normal MWNTs, and +0.174 V for short MWNTs) but weak catalysis towards oxidation of NADH owing to the hydrophilicity of carboxylate groups. The electrochemical reactivity depends on the lengths of CNTs to some extent. The ‘long’ CNTs perform better in our study (The oxidation signals of NADH appear below +0.39 V for ‘long’ CNTs and above +0.46 V for the ‘short’ one totally). Readers may get some directions from this article while choose CNTs for electrochemical study.     

Nitrite Oxidation with Copper–Cobalt Nanoparticles on Carbon Nanotubes Doped Conducting Polymer PEDOT Composite

Copper–cobalt bimetal nanoparticles (Cu?Co) have been electrochemically prepared on glassy carbon electrodes (GCEs), which were electrodeposited with conducting polymer nanocomposites of poly(3,4‐ethylenedioxythiophene) (PEDOT) doped with carbon nanotubes (CNTs). Owing to their good conductivity, high mechanical strength, and large surface area, the PEDOT/CNTs composites offered excellent substrates for the electrochemical deposition of Cu?Co nanoparticles. As a result of their nanostructure and the synergic effect between Cu and Co, the Cu?Co/PEDOT/CNTs composites exhibited significantly enhanced catalytic activity towards the electrochemical oxidation of nitrite. Under optimized conditions, the nanocomposite‐modified electrodes had a fast response time within 2 s and a linear range from 0.5 to 430 μm for the detection of nitrite, with a detection limit of 60 nm . Moreover, the Cu?Co/PEDOT/CNTs composites were highly stable, and the prepared nitrite sensors could retain more than 96 % of their initial response after 30 days.     

Loss of NAD(H) from swollen yeast mitochondria

Background

The mitochondrial electron transport chain oxidizes matrix space NADH as part of the process of oxidative phosphorylation. Mitochondria contain shuttles for the transport of cytoplasmic NADH reducing equivalents into the mitochondrial matrix. Therefore for a long time it was believed that NAD(H) itself was not transported into mitochondria. However evidence has been obtained for the transport of NAD(H) into and out of plant and mammalian mitochondria. Since Saccharomyces cerevisiae mitochondria can directly oxidize cytoplasmic NADH, it remained questionable if mitochondrial NAD(H) transport occurs in this organism.

Results

NAD(H) was lost more extensively from the matrix space of swollen than normal, condensed isolated yeast mitochondria from Saccharomyces cerevisiae. The loss of NAD(H) in swollen organelles caused a greatly decreased respiratory rate when ethanol or other matrix space NAD-linked substrates were oxidized. Adding NAD back to the medium, even in the presence of a membrane-impermeant NADH dehydrogenase inhibitor, restored the respiratory rate of swollen mitochondria oxidizing ethanol, suggesting that NAD is transported into the matrix space. NAD addition did not restore the decreased respiratory rate of swollen mitochondria oxidizing the combination of malate, glutamate, and pyruvate. Therefore the loss of matrix space metabolites is not entirely specific for NAD(H). However, during NAD(H) loss the mitochondrial levels of most other nucleotides were maintained. Either hypotonic swelling or colloid-osmotic swelling due to opening of the yeast mitochondrial unspecific channel (YMUC) in a mannitol medium resulted in decreased NAD-linked respiration. However, the loss of NAD(H) from the matrix space was not mediated by the YMUC, because YMUC inhibitors did not prevent decreased NAD-linked respiration during swelling and YMUC opening without swelling did not cause decreased NAD-linked respiration.

Conclusion

Loss of endogenous NAD(H) from isolated yeast mitochondria is greatly stimulated by matrix space expansion. NAD(H) loss greatly limits NAD-linked respiration in swollen mitochondria without decreasing the NAD-linked respiratory rate in normal, condensed organelles. NAD addition can totally restore the decreased respiration in swollen mitochondria. In live yeast cells mitochondrial swelling has been observed prior to mitochondrial degradation and cell death. Therefore mitochondrial swelling may stimulate NAD(H) transport to regulate metabolism during these conditions.     

Mitochondria-targeted fluorescent probe based on vibration-induced emission for real-time monitoring mitophagy-specific viscosity dynamic

Directly monitoring mitophagy-specific viscosity dynamic in living cells is of great significance but remains challenging. Herein, this study reported a novel mitochondria-targeted fluorescent probe DPAC-DY based on vibration-induced emission (VIE) for monitoring viscosity changes during mitochondrial autophagy. This probe contained N,N'-diphenyl- dihydrodibenzo[a,c]phenazine (DPAC) as the VIE core and two positively charged pyridinium moieties for mitochondria anchoring. As the ambient viscosity increased, the vibration of DPAC-DY could be hindered, and subsequently resulting in the enhancement of fluorescence emission. In vitro and intracellular experiments indicated that the probe DPAC-DY showed highly sensitive response to viscosity due to VIE mechanism. Importantly, by virtue of this probe, in situ and real-time visualization of the specific viscosity dynamics during the mitochondrial autophagy process was achieved. Thus, this work provides a novel strategy for VIE-based viscosity response sensors applied to specific organelles and offers a platform for in-depth study of mitochondrial viscosity-related diseases.     

Optical microwell array for large scale studies of single mitochondria metabolic responses

Microsystems based on microwell arrays have been widely used for studies on single living cells. In this work, we focused on the subcellular level in order to monitor biological responses directly on individual organelles. Consequently, we developed microwell arrays for the entrapment and fluorescence microscopy of single isolated organelles, mitochondria herein. Highly dense arrays of 3-μm mean diameter wells were obtained by wet chemical etching of optical fiber bundles. Favorable conditions for the stable entrapment of individual mitochondria within a majority of microwells were found. Owing to NADH auto-fluorescence, the metabolic status of each mitochondrion was analyzed at resting state (Stage 1), then following the addition of a respiratory substrate (Stage 2), ethanol herein, and of a respiratory inhibitor (Stage 3), antimycin A. Mean levels of mitochondrial NADH were increased by 29 % and 35 % under Stages 2 and 3, respectively. We showed that mitochondrial ability to generate higher levels of NADH (i.e., its metabolic performance) is not correlated either to the initial energetic state or to the respective size of each mitochondrion. This study demonstrates that microwell arrays allow metabolic studies on populations of isolated mitochondria with a single organelle resolution.

Phosphomolybdate-modified multi-walled carbon nanotubes as effective mediating systems for electrocatalytic reduction of bromate

Electrocatalytic properties (towards reduction of bromate in 0.5 mol dm⁻³ H₂SO₄) of multi-walled carbon nanotubes (CNTs) modified with phosphododecamolybdate (PMo₁₂) monolayers have been diagnosed using cyclic voltammetry and amperometry. The ability of negatively charged PMo₁₂-modified CNTs to attract electrostatically ultra-thin, positively charged conducting polymer (PEDOT or polypyrrole) structures is explored to grow in controlled manner hybrid organic-inorganic network electrocatalytic films. Due to the presence of three-dimensionally distributed CNTs, the films’ conductivity and porosity are improved. The hybrid systems utilizing polypyrrole, rather than PEDOT, have produced fairly higher bromate electroreduction catalytic currents. Comparison is also made to Nafion-stabilized dispersion of PMo₁₂-modified CNTs inks. The latter system is characterized by good stability and relatively the highest sensitivities with respect to bromate concentration.     

Promotion of photodynamic therapy-induced apoptosis by the mitochondrial protein Smac/DIABLO: dependence on Bax

Photodynamic therapy (PDT) using the second-generation photosensitizer phthalocyanine (Pc) 4 causes mitochondrial damage and induces apoptosis through the release of cytochrome c to the cytosol. Another protein of the mitochondrial intermembrane space, Smac/DIABLO (second mitochondria-derived activator of caspase/direct inhibitor of apoptosis-binding protein with low pI), is also released to the cytosol in response to apoptotic stimuli and promotes caspase activation by binding IAP. To investigate the possible role of Smac/DIABLO in apoptosis induced by Pc 4-PDT, we transfected Smac/DIABLO (tagged at its C-terminus with green fluorescent protein [GFP]) into MCF-7c3 cells (human breast cancer MCF-7 cells stably transfected with procaspase-3) and DU-145 cells (human prostate cancer cells that express no Bax because of a frameshift insertion mutation). Confocal microscopy showed that recombinant Smac/DIABLO, like cytochrome c, localized to mitochondria and colocalized with MitoTracker Red. Three hours after exposure of MCF-7c3 cells to PDT (200 nM Pc 4 and 150 mJ/cm2 red light), Smac/DIABLO-GFP, as well as cytochrome c, was found largely in the cytosol. In contrast, for DU-145 cells, both Smac/DIABLO-GFP and cytochrome c remained in the mitochondria after PDT. By staining with Hoechst 33,342, typical apoptotic nuclei were observed in MCF-7c3 cells, but not in DU-145 cells, after Pc 4-PDT. These results suggest that the release of Smac/DIABLO from mitochondria may be regulated by a Bax-mediated mechanism and that Smac/DIABLO may cooperate with the cytochrome c-dependent apoptosis pathway. In addition, in MCF-7c3 cells transfected by Smac/DIABLO-GFP, apoptosis induced by Pc 4-PDT was greater than in cells transfected with the GFP vector alone or in untransfected cells, as determined by flow cytometry. Thus, Smac/DIABLO promotes apoptosis after Pc 4-PDT in a Bax-dependent manner and may facilitate the passage of PDT-treated cells through the late steps of apoptosis.     

866 — Interaction of cationic drugs with lipids of the spinach thylakoid membrane

Adriamycin, an anthracycline glycoside antibiotic that inhibits the electron flow in mitochondria, also inhibits photosynthetic electron transport (PSI+PSII). The oxygen consumption curves suggest an inhibitory effect of PSII activity at very low adriamycin concentrations. Surface potential and differential scanning calorimetry measurements coupled with the use of tritiated daunomycin demonstrated that adriamycin interacts specifically with negatively charged thylakoid lipids, and induces a clustering of these negatively charged lipids in a neutral lipid matrix. These properties have made it possible to suggest a mechanism for the adriamycin-induced inhibition of mitochondrial enzymes (cytochrome c oxidase, NADH: cytochrome c oxidoreductase). We did not identify precisely the target responsible for the adriamycin effect in the thylakoid membrane, but the preliminary studies reported herein indicate evident similarities between the two inhibition mechanisms.     

Fluorescent and Biocompatible Ruthenium-Coordinated Oligo(p-phenylenevinylene) Nanocatalysts for Transfer Hydrogenation in the Mitochondria of Living Cells

It is challenging to design metal catalysts for in situ transformation of endogenous biomolecules with good performance inside living cells. Herein, we report a multifunctional metal catalyst, ruthenium-coordinated oligo(p-phenylenevinylene) (OPV-Ru), for intracellular catalysis of transfer hydrogenation of nicotinamide adenine dinucleotide (NAD⁺) to its reduced format (NADH). Owing to its amphiphilic characteristic, OPV-Ru possesses good self-assembly capability in water to form nanoparticles through hydrophobic interaction and π–π stacking, and numerous positive charges on the surface of nanoparticles displayed a strong electrostatic interaction with negatively charged substrate molecules, creating a local microenvironment for enhancing the catalysis efficiency in comparison to dispersed catalytic center molecule (TOF value was enhanced by about 15 fold). OPV-Ru could selectively accumulate in the mitochondria of living cells. Benefiting from its inherent fluorescence, the dynamic distribution in cells and uptake behavior of OPV-Ru could be visualized under fluorescence microscopy. This work represents the first demonstration of a multifunctional organometallic complex catalyzing natural hydrogenation transformation in specific subcellular compartments of living cells with excellent performance, fluorescent imaging ability, specific mitochondria targeting and good chemoselectivity with high catalysis efficiency.     

Dynamic and reversible electrowetting with low voltage on the dimethicone infused carbon nanotube array in air

Unremitting efforts have been intensively making for pursuing the goal of the reversible transition of electrowetting owing to its vital importance to many practical applications, but which remains a major challenge for carbon nanotubes due to the irreversible electrochemical damage. Herein, we proposed a subtly method to prevent the CNT array from electrochemical damage by using liquid medium instead of air medium to form a liquid/liquid/solid triphase system. The dimethicone dynamically refills in CNT arrays after removing of voltage that makes the surface back to hydrophobic, which is an elegant way to not only decrease energy dissipation in electrowetting process but also obtain extra energy in reversible dewetting process. Repeated cycles of in situ experiments showed that more than four reversible electrowetting cycles could be achieved in air. It worth mention that the in situ reversible electrowetting voltage of the dimethicone infused CNT array has been lowered to 2 V from 7 V which is the electrowetting voltage for the pure CNT array. The surface of the dimethicone infused CNT array can maintain hydrophobicity with a contact angle of 145.6° after four cycles, compared with 148.1° of the initial state. Moreover, a novel perspective of theoretical simulations through the binding energy has been provided which proved that the charged CNTs preferred binding with water molecules thereby replacing the dimethicone molecules adsorbed on the CNTs, whereas reconnected with dimethicone after removing the charges. Our study provides distinct insight into dynamic reversible electrowetting on the nanostructured surface in air and supplies a way for precise control of wettability in surface chemistry, smart phase-change heat transfer enhancement, liquid lenses, microfluidics, and other chemical engineering applications.     

Influence of addition of lithium salt solution into PEDOT:PSS dispersion on the electrochemical and spectroscopic properties of film electrodes

The present work has studied electrochemical and optical properties of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) film electrodes drop-casted from commercial PEDOT:PSS aqueous dispersion with preliminary addition and without addition of LiClO₄ electrolyte (further denoted as PEDOT:PSS/LiClO₄ and PEDOT:PSS). Cyclic voltammetry measurements showed the significant increase in capacitance of PEDOT:PSS/LiClO₄ film electrodes in comparison to PEDOT:PSS. Furthermore, the improved charge transport in PEDOT:PSS/LiClO₄ films was demonstrated by electrochemical impedance spectra. In situ spectroelectrochemical measurements revealed that preliminary addition of LiClO₄ into PEDOT:PSS aqueous dispersion allows to increase amount of free charge carriers (polaron and bipolaron states) in the resulting film during electrochemical oxidation in LiClO₄ propylene carbonate solution. This increase was attributed to ion-induced charge screening between positively charged PEDOT and negatively charged PSS in polyelectrolyte structure, which was supported by structural investigations of both types of film electrodes by using FTIR, SEM, and XPS measurements. Charge screening results from a more open structure that allows conformational relaxation of PEDOT molecules during charge transport, which leads to partial separation of oppositely charged PSS and PEDOT molecules and facilitating the increase of electrochemical activity.

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Graphical abstract ?

     

Amperometric Detection and Quantification of Nitrate Ions Using a Highly Sensitive Nanostructured Membrane Electrocodeposited Biosensor Array

In the past few decades, there has been a steady rise in the release of nitrate (NO₃^?), a prominent water soluble contaminant associated with the increasing use of nitrate based fertilizers. In this study, we suggest the use of a highly sensitive, enzymatic biosensor capable of quantifying minute concentrations of nitrate. The disposable nitrate biosensor consists of a sensing element in the form of nitrate reductase which is immobilized within a conductive polymer matrix to generate a quantifiable amperometric response. In this work, nanoarrays of co‐immobilized nitrate reductase and poly(3,4‐ethylenedioxythiophene) (PEDOT), were grown using a template assisted electropolymerization route. The performance of the biosensor is a strong function of electropolymerization conditions and the morphology of the PEDOT nanostructures. The electropolymerized biosensor displays excellent specificity w.r.t other interfering ions as evidenced from the initial rate kinetics. With a response time of a few seconds, limit of detection (LOD) as low as 0.16 ppm and sensitivity of about 92 µA/mM , the one‐step electropolymerized nanostructured nitrate biosensor developed in this study shows improved performance compared to similar electrochemical sensors reported in literature. The PEDOT/nitrate reductase nanowire sensor developed in this work shows superior attributes compared to a flat 2D nitrate reductase‐co‐immobilized PEDOT film grown using similar electropolymerization conditions. This combined with easy and fast fabrication technique opens up exciting opportunities for developing high accuracy PEDOT based nanobiosensors for field testing of nitrate contaminants in the future.     

Electrochemical synthesis of PEDOT and PPP macroporous films and nanowire architectures from ionic liquids

We report on the electrochemical synthesis of macroporous films and on nanowire architectures of conducting polymers from ionic liquids. The electrodeposition of poly(3,4-ethylenedioxythiophene) (PEDOT) and of poly(para-phenylene) (PPP) from the air and water stable ionic liquids 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([EMIm]TFSA) and from 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ([HMIm]FAP) within the voids of a polystyrene opal structure on gold and on platinum substrates yield macroporous films. For this purpose, polystyrene spheres with an average diameter of about 600?nm were applied onto the employed electrodes by a simple dipping process resulting in a layer thickness of about 10?μm. The macroporous films turn into yellow, orange, blue, and green colors owing to the Bragg reflection of the incident artificial white light. PPP and PEDOT nanowires were electrochemically prepared in a track-etched polycarbonate (PC) membrane with an average pore diameter of 90?nm. One side of the membrane was sputtered with a thin gold film to serve as a working electrode. Electrodeposition occurs along the pores of the template. Nanowires with an average diameter of 90?nm and a length of up to 17?μm can be easily synthesized by this electrochemical template-assisted method. Such materials are of interest as catalyst in metal/air batteries and as cathode material in, e.g., microbatteries.     

Application of PEDOT‐CNT Microelectrodes for Neurotransmitter Sensing

In this work, composite microelectrodes from poly(3,4‐ethylenedioxythiophene) (PEDOT) and carbon nanotubes (CNT) are characterized as electrochemical sensing material for neurotransmitters. Dopamine can be detected using square wave voltammetry at these microelectrodes. The CNTs improve the sensitivity by a factor of two. In addition, the selectivity towards dopamine in the presence of ascorbic acid and uric acid was examined. While both electrodes, PEDOT and PEDOT‐CNT are able to detect all measured concentrations of dopamine in the presence of uric acid, small concentrations of dopamine and ascorbic acid are only distinguishable at PEDOT‐CNT electrodes. Changing the pH has a strong influence on the selectivity. Moreover, it is possible to detect concentrations as low as 1 µM dopamine in complex cell culture medium. Finally, other catecholamines like serotonin, epinephrine, norepinephrine and L ‐dopa are also electrochemically detectable at PEDOT‐CNT microelectrodes.     

The characteristics of highly ordered mesoporous carbons as electrode material for electrochemical sensing as compared with carbon nanotubes

In this paper, the unique properties of highly ordered mesoporous carbons modified glassy carbon electrode (OMCs/GE) are illustrated from comparison with carbon nanotubes modified glassy carbon electrode (CNTs/GE) for the electrochemical sensing applications. Electrochemical behaviors of eight kinds of inorganic and organic electroactive compounds were studied at OMCs/GE, which shows more favorable electron transfer kinetics than that at CNTs/GE. Especially, OMCs/GE exhibits remarkably strong and stable electrocatalytic response toward NADH compared with CNTs/GE. The ability of OMCs to promote electron transfer not only provides a new platform for the development of dehydrogenase-based bioelectrochemical devices, but also indicates a potential of OMCs in a wide range of sensing applications. OMCs prepared are the novel carbon electrode materials, exhibiting more favorable electrochemical reactivity than CNTs for the wide electrochemical sensing applications without pretreatments, while purification or end-opening processing was usually required in case of CNTs.     

Tuning the gas sensing performance of single PEDOT nanowire devices

This paper reports the synthesis and dopant dependent electrical and sensing properties of single poly(ethylenedioxythiophene) (PEDOT) nanowire sensors. Dopant type (i.e. polystyrenesulfonate (PSS(-)) and perchlorate (ClO(4)(-))) and solvent (i.e. acetonitrile and 1 : 1 water-acetonitrile mixture) were adjusted to change the conjugation length and hydrophilicity of nanowires which resulted in change of the electrical properties and sensing performance. Temperature dependent coefficient of resistance (TCR) indicated that the electrical properties are greatly dependent on dopants and electrolyte where greater disorder was found in PSS(-) doped PEDOT nanowires compared to ClO(4)(-) doped nanowires. Upon exposure to different analytes including water vapor and volatile organic compounds, these nanowire devices displayed substantially different sensing characteristics. ClO(4)(-) doped PEDOT nanowires from an acetonitrile bath show superior sensing responses toward less electronegative analytes and followed a power law dependence on the analyte concentration at high partial pressures. These tunable sensing properties were attributed to variation in the conjugation lengths, dopant type and concentration of the wires which may be attributed to two distinct sensing mechanisms: swelling within the bulk of the nanowire and work function modulation of Schottky barrier junction between nanowire and electrodes.     

Electrochemical synthesis of poly(3,4‐ethylenedioxythiophene) nanotube arrays using ZnO templates

A new method toward vertically oriented poly(3,4‐ethylenedioxythiophene) (PEDOT) nanotube arrays on transparent conductive oxide substrates is presented. The approach is based on the use of ZnO nanowire arrays as templates for the electropolymerization of PEDOT. Robust arrays of vertically oriented PEDOT nanotubes with different lengths and wall thicknesses were obtained by modifying the ZnO nanowire length and charge density passed during the electropolymerization, respectively. Furthermore, PEDOT nanotubes with different morphologies (top‐closed and mushroom‐like) were successfully designed by varying the PEDOT electropolymerization kinetics or monomer diffusion or both. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Unique assembly of carbonylpyridinium and chromene reveals mitochondrial thiol starvation under ferroptosis and novel ferroptosis inducer

To reveal the delicate function of mitochondria, spatiotemporally precise detection tools remain highly desirable. However, current probes with positively charged warheads for targeting mitochondria diffuse out of the mitochondria as the potential of the mitochondrial membrane changes, which directly influences the accuracy of the detection. Herein, we assembled carbonylpyridinium and chromene to afford the probe CM-Mit. Following the ultrafast response to thiol and the dissociation of carbonylpyridinium, the formation of o-quinone methide from CM-Mit was proposed to label proteins, thus avoiding diffusion out of the mitochondria. Therefore, the accurate spatiotemporal detection of thiol in mitochondria was realized. With this excellent probe, ferroptosis inducers were proved to stimulate thiol starvation in mitochondria for the first time in cancer cells. Moreover, CM-Mit was used to screen a compound library developed in-house and the stemona alkaloid analog SA-11 was shown to induce ferroptosis in various cancer cell lines, including a drug-resistant one.

Carbonylpyridinium and chromene were elaborately assembled to highly target mitochondrial thiol assay by releasing o-quinone methide from CM-Mit to label proteins, thus avoiding diffusion out of the mitochondria, which enabled accurately spatiotemporal detection of thiol.