A series of new electrofluorescent switches was prepared using electroactive fluorescent tetrazines, an original family of molecules featuring both highly stable reduced anion-radicals and ...fluorescence in the neutral state. The cells were prepared with four layers: the tetrazine polymer film, a photo cured polymer electrolyte film, and two indium-tin oxide films as the two contact electrodes. When externally biased, the fluorescence of the tetrazine fluorophore can be switched on and off reversibly, according to its redox state through scanning the potential between two transparent ITO electrodes. Electrochromism of a tetrazine containing conducting polymer has also been examined.
A polymethine dye was used as a fluorophore and an electroactive modulator in order to achieve reversible electrochemical fluorescence switching in the near infrared (NIR) region. An NIR emissive ...polymethine dye, 3 H -indolium, 2-2-2-chloro-3-2-1,3-dihydro-3,3-dimethyl-1-(phenylmethyl)-2 H -indol-2-ylideneethylidene-5-(1,1-dimethylethyl)-1-cyclohexen-1-ylethenyl-3,3-dimethyl-1-(phenylmethyl)-bromide (PM1), displayed high absorption and emission in the NIR region. In addition, it showed a relatively reversible electrochemical reaction between −0.5 and 1.1 V vs. Ag wire. In contrast, a keto group (CO) bridged polymethine analogue, 2,6-bis2-(1,3-dihydro-1-hexyl-3,3-dimethyl-2 H -indol-2-ylidene)ethylidene-4-(1,1-dimethylethyl)cyclohexanone (PM2), showed an irreversible electrochemical reaction, possibly due to the keto group interrupting the full conjugation of the entire molecule in PM2. The reversible redox reaction of PM1 allowed electrochemical fluorescence switching in the NIR region for the first time. The NIR fluorescence switching was visually observable through a visible light cut-off filter with a cyclability of over 100.
The single‐step preparation of highly ordered mesoporous silica hybrid nanocomposites with conjugated polymers was explored using a novel cationic 3,4‐propylenedioxythiophene (ProDOT) surfactant ...(PrS). The method does not require high‐temperature calcination or a washing procedure. The combination of self‐assembly of the silica surfactant and in situ polymerization of the ProDOT tail is responsible for creation of the mesoporosity with ultralarge pores, large pore volume, and electroactivity. As this novel material exhibits excellent textural parameters together with electrical conductivity, we believe that this could find potential applications in various fields. This novel concept of creating mesoporosity without a calcination process is a significant breakthrough in the field of mesoporous materials and the method can be further generalized as a rational preparation of various mesoporous hybrid materials having different structures and pore diameters.
Pore over: Highly ordered mesoporous silica hybrid nanocomposites with ultralarge pores and high conductivity were synthesized in a single step. The method employs a novel cationic surfactant having a bulky 3,4‐propylenedioxythiophene (ProDOT) tail group, and does not require high‐temperature calcination or a washing procedure.
The photophysical properties of near-infrared (NIR) emissive aza-boron-dipyrromethene (aza-BDP) dyes incorporating nitrofluorene and alkoxy decorations were intensively investigated. Their highly ...reversible one-electron reduction process showed characteristic electrofluorochromic (EF) properties in the NIR range, depending on the substituents. The nitrofluorene ethynyl-substituted (Type I) dyes showed smaller EF effects than the alkoxy-containing (Type II) dyes because of the difference in their intrinsic fluorescence contrast between the neutral and reduced states (radical anion). In addition, the Type II chromophores showed a larger diffusion coefficient for ion transport, which enhanced the EF contrast and the response time for the fluorescence change at a given step potential. With an optimized condition, the NIR EF ON/OFF ratio reached a value of 6.1 and a long cyclability over 1000 EF cycles between -0.4 V and +0.4 V switching potentials, with approximately 20% loss of the initial ON/OFF switching ratio. The NIR EF switching was visually observed through a visible light cut-off filter, featuring high fluorescence contrast.
•A new concept for clozapine in situ sensing with minimal pre-treatment procedures.•A catechol-chitosan redox cycling system amplifies clozapine oxidation current.•The modified amplifier signal is 3 ...times greater than the unmodified system.•Differentiation between clozapine and its metabolite norclozapine has been shown.•The sensor has the capability to detect clozapine in human serum.
Schizophrenia is a lifelong mental disorder with few recent advances in treatment. Clozapine is the most effective antipsychotic for schizophrenia treatment. However, it remains underutilized since frequent blood draws are required to monitor adverse side effects, and maintain clozapine concentrations in a therapeutic range. Micro-system technology utilized towards real-time monitoring of efficacy and safety will enable personalized medicine and better use of this medication. Although work has been reported on clozapine detection using its electrochemical oxidation, no in situ monitoring of clozapine has been described. In this work, we present a new concept for clozapine in situ sensing based on amplifying its oxidation current. Specifically, we use a biofabricated catechol-modified chitosan redox cycling system to provide a significant amplification of the generated oxidizing current of clozapine through a continuous cycle of clozapine reduction followed by re-oxidation. The amplified signal has improved the signal-to-noise ratio and provided the required limit-of-detection and dynamic range for clinical applications with minimal pre-treatment procedures. The sensor reports on the functionality and sensitivity of clozapine detection between 0.1 and 10μg/mL. The signal generated by clozapine using the catechol-modified chitosan amplifier has shown to be 3 times greater than the unmodified system. The sensor has the ability to differentiate between clozapine and its metabolite norclozapine, as well as the feasibility to detect clozapine in human serum in situ within the required dynamic range for clinically related applications. This new biosensing approach can be further developed towards its integration in miniaturized devices for improved personalized mental health care.
Individually, advances in microelectronics and biology transformed the way we live our lives. However, there remain few examples in which biology and electronics have been interfaced to create ...synergistic capabilities. We believe there are two major challenges to the integration of biological components into microelectronic systems: (i) assembly of the biological components at an electrode address, and (ii) communication between the assembled biological components and the underlying electrode. Chitosan possesses a unique combination of properties to meet these challenges and serve as an effective bio-device interface material. For assembly, chitosan's pH-responsive film-forming properties allow it to "recognize" electrode-imposed signals and respond by self-assembling as a stable hydrogel film through a cathodic electrodeposition mechanism. A separate anodic electrodeposition mechanism was recently reported and this also allows chitosan hydrogel films to be assembled at an electrode address. Protein-based biofunctionality can be conferred to electrodeposited films through a variety of physical, chemical and biological methods. For communication, we are investigating redox-active catechol-modified chitosan films as an interface to bridge redox-based communication between biology and an electrode. Despite significant progress over the last decade, many questions still remain which warrants even deeper study of chitosan's structure, properties, and functions.
Dendrimers crosslinked with a photochromic diarylethene (blue in picture) were labeled with the fluorescent dye Cy3 (red) for reversible fluorescence photoswitching. If the obtained nanoclusters are ...irradiated with UV light, the Cy3 fluorescence is quenched by the diarylethene in its ring‐closed form, whereas upon irradiation with visible light, the nanoclusters show fluorescence. High‐contrast fluorescence imaging was achieved inside a living zebrafish.
A roll-type conducting polymer film was explored as a flexible organic p-type thermoelectric leg using poly(3,4-ethylenedioxythiophene) (PEDOT) doped with tosylate. The PEDOT films were prepared ...through solution casting polymerization and rolled up for a roll-type leg. Due to the high flexibility, the roll-type PEDOT leg enabled easy contact to both top and bottom electrodes. Simulation on the dynamic heat transfer and convective cooling for a vertically roosted rod- and roll-type PEDOT leg showed that the temperature difference (ΔT) between the hot and cold sides of the leg was much higher in the roll than that of the rod. The PEDOT legs were integrated with n-type Bi2Te3 blocks, to give a 36-couple rigid-flexible thermoelectric generator (RF-TEG). The maximum output voltage from the 36-couple RF-TEG under a ΔT of 7.9 K was determined as 36.7 mV along with a high output power of 115 nW. A wearable RF-TEG was prepared upon the combination of the 36-couple RF-TEG with an arm warmer, to afford an output voltage of 10.6 mV, which was generated constantly and steadily from human wrist heat.
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