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Graphite electrodes were modified with specifically designed Os-complex modified electrodeposition polymers exhibiting a formal potential of the polymer-bound complex of about 0 to 20 mV (vs. Ag/AgCl/3 M KCl) which is only about 100 mV anodic of the formal potential of pyrroloquinoline quinone (PQQ) in PQQ-dependent glucose dehydrogenase (PQQ-GDH). The efficiency of wiring the polymer-entrapped PQQ-GDH was dependent on the nature of the polymer backbone, the crosslinking with bifunctional crosslinkers and the co-entrapment of multi-walled carbon nanotubes. Due to the limited long-term stability a new polymer synthesis strategy was adapted using the same Os-complex but providing enhanced crosslinking capabilities by introducing epoxide functions at the polymer backbone. Related bioelectrodes showed enhanced glucose-dependent current and a stability of at least 3 days of continuous operation. [ABSTRACT FROM AUTHOR]

We developed a membraneless-microfluidic biofuel cell (MBFC) for the quantification of ethanol. The system employs anolyte and catholyte solutions, each containing a biocatalyst and redox mediator. The laminar flow conditions in the microfluidic chip minimize the mixing between anolyte and catholyte and obviate the need for a membrane to separate them. When ethanol is added to the anolyte, alcohol dehydrogenase (ADH) catalyzes its oxidation to acetaldehyde, releasing electrons to the anode. On the cathode, electrons are transferred to horseradish peroxidase (HRP), which reduces hydrogen peroxide in the catholyte to water. We optimized key design factors and operating conditions. We also studied the incorporation of glycerol as a viscosity modifier, which improved the power and current density supplied by the MBFC, with a maximum power output of 307 µW cm -2 and an open circuit voltage of 0.733 V. The proposed ethanol/hydrogen peroxide MBFC was successfully applied as a biofuel cell-based sensor for the quantification of ethanol in a commercial liquor.

We designed and optimized a glucose biosensor system based on a screen-printed electrode modified with the NAD-GDH enzyme. To enhance the electroactive surface area and improve the electron transfer efficiency, we introduced graphene oxide (GO) and ferrocene-modified linear poly(ethylenimine) (LPEI-Fc) onto the biosensor surface. This strategic modification exploits the electrostatic interaction between graphene oxide, which possesses a negative charge, and LPEI-Fc, which is positively charged. This interaction results in increased catalytic current during glucose oxidation and helps improve the overall glucose detection sensitivity by amperometry. We integrated the developed glucose sensor into a flow injection (FI) system. This integration facilitates a swift and reproducible detection of glucose, and it also mitigates the risk of contamination during the analyses. The incorporation of an FI system improves the efficiency of the biosensor, ensuring precise and reliable results in a short time. The proposed sensor was operated at a constant applied potential of 0.35 V. After optimizing the system, a linear calibration curve was obtained for the concentration range of 1.0-40 mM (R 2 = 0.986). The FI system was successfully applied to determine the glucose content of a commercial sports drink.

Photodynamic therapy (PDT) is a photochemical-based treatment approach that involves using light to activate photosensitizers (PSs). Attractively, PDT is one of the alternative cancer treatments due to its noninvasive technique. By utilizing the heavy atom effect, this work modified a class of formazan dyes to improve intersystem crossing (ISC) to improve reactive oxygen species (ROS) generation for PDT treatment. Two methods were used to observe the ROS generation enhanced by ISC of the synthesized complexes including, (1) recording DPBF decomposition caused by the ROS, and (2) calculating the potential energy curves for photophysical mechanisms of BF 2 -formazanate dyes using the DFT and nudged elastic band (NEB) methods. The photophysical properties of the dyes were studied using spectroscopic techniques and X-ray crystallography, as well as DFT calculations. The experimental and theoretical results and in vitro cellular assays confirmed the potential use of the newly synthesized iodinated BF 2 -formazanate dyes in PDT., (© 2023 Wiley-VCH GmbH.)

A new push-pull aza-BODIPY (AZB-CF 3 ) derivative comprised of dimethylamino groups and trifluoromethyl moieties was successfully synthesized. This derivative exhibited broad absorption in the near-infrared region in the range from 798 to 832 nm. It also exhibited significant near-infrared (NIR) signals in low-polar solvents with emission peaks around 835-940 nm, while non-fluorescence in high-polar environments due to the twisted intramolecular charge transfer (TICT) phenomenon. The nanoprecipitation of this compound with phospholipid-based polyethylene glycol (DSPE-PEG) yielded AZB-CF 3 @DSPE-PEG nanoparticles (NPs) with a hydrodynamic size of 70 nm. The NPs exhibited good photostability, colloidal stability, biocompatibility, and excellent photothermal (PTT) competence with a conversion efficiency ( η ) of 44.9%. These NPs were evaluated in vitro and in ovo in a 4T1 breast cancer cell line for NIR light-trigger photothermal therapy. Proven in the chicken egg tumor model, AZB-CF 3 @DSPE-PEG NPs induced severe vascular damage (∼40% vascular destruction), showed great anticancer efficacy (∼75% tumor growth inhibition), and effectively inhibited distant metastasis via photothermal treatment. As such, this PTT-based nanocarrier system could be a potential candidate for a clinical cancer therapy approach., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

We develop an electrochemical sensor for the determination of bromhexine hydrochloride (BHC), a widely use mucolytic drug. The sensor is prepared by electrodeposition of cobalt oxides (CoO x ) on a glassy carbon electrode modified with carboxylated single-walled carbon nanotubes (SWCNT). A synergistic effect between CoO x and SWCNT is observed, leading to a significant improvement in the BHC electrooxidation current. Based on cyclic voltammetry studies at varying scan rates, we conclude that the electrochemical oxidation of BHC is under mixed diffusion-adsorption control. The proposed sensor allows the amperometric determination of BHC in a linear range of 10-500 µM with a low applied voltage of 0.75 V. The designed sensor provides reproducible measurements, is not affected by common interfering substances, and shows excellent performance for the analysis of BHC in pharmaceutical preparations.

Biofuel cells allow for constructing sensors that leverage the specificity of enzymes without the need for an external power source. In this work, we design a self-powered glucose sensor based on a biofuel cell. The redox enzymes glucose dehydrogenase (NAD-GDH), glucose oxidase (GOx), and horseradish peroxidase (HRP) were immobilized as biocatalysts on the electrodes, which were previously engineered using carbon nanostructures, including multi-wall carbon nanotubes (MWCNTs) and reduced graphene oxide (rGO). Additional polymers were also introduced to improve biocatalyst immobilization. The reported design offers three main advantages: (i) by using glucose as the substrate for the both anode and cathode, a more compact and robust design is enabled, (ii) the system operates under air-saturating conditions, with no need for gas purge, and (iii) the combination of carbon nanostructures and a multi-enzyme cascade maximizes the sensitivity of the biosensor. Our design allows the reliable detection of glucose in the range of 0.1-7.0 mM, which is perfectly suited for common biofluids and industrial food samples.

In the title unsymmetrical tertiary amine, C 24 H 33 NO 2 , which arose from the ring-opening reaction of a di-hydro-benzoxazine, two 2,4-di-methyl-phenol moieties are linked by a 6,6'-(cyclo-hexyl-aza-nedi-yl)-bis-(methyl-ene) bridge: the dihedral angle between the dimethyl-phenol rings is 72.45 (7)°. The cyclo-hexyl ring adopts a chair conformation with the exocyclic C-N bond in an equatorial orientation. One of the phenol OH groups forms an intra-molecular O-H⋯N hydrogen bond, generating an S (6) ring, and a short intra-molecular C-H⋯O contact is also present. In the crystal, O-H⋯O hydrogen bonds link the mol-ecules into C (10) chains propagating along the [100] direction. The Hirshfeld surface analysis of the title compound confirms the presence of these intra- and inter-molecular inter-actions. The corresponding fingerprint plots indicate that the most significant contacts in the crystal packing are H⋯H (76.4%), H⋯C/C⋯H (16.3%), and H⋯O/O⋯H (7.2%)., (© Wannapaiboon et al. 2020.)

We propose the very first "Nernstian biosupercapacitor", a biodevice based on only one redox polymer: poly(vinyl imidazole-co-allylamine)[Os(bpy) 2 Cl], and two biocatalysts. At the bioanode PQQ-dependent glucose dehydrogenase reduces the Os 3+ moieties at the polymer to Os 2+ shifting the Nernst potential of the Os 3+ /Os 2+ redox couple to negative values. Concomitantly, at the biocathode the reduction of O 2 by means of bilirubin oxidase embedded in the same redox polymer leads to the oxidation of Os 2+ to Os 3+ shifting the Nernst potential to higher values. Despite the use of just one redox polymer an open circuit voltage of more than 0.45 V was obtained during charging and the charge is stored in the redox polymer at both the bioanode and the biocathode. By connecting both electrodes via a predefined resistor a high power density is obtained for a short time exceeding the steady state power of a corresponding biofuel cell by a factor of 8., (© 2016 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.)

Phenothiazine-modified redox hydrogels were synthesized and used for the wiring of the aldehyde oxidoreductase PaoABC to electrode surfaces. The effects of the pH value and electrode surface modification on the biocatalytic activity of the layers were studied in the presence of vanillin as the substrate. The enzyme electrodes were successfully employed as bioanodes in vanillin/O2 biofuel cells in combination with a high potential bilirubin oxidase biocathode. Open circuit voltages of around 700 mV could be obtained in a two compartment biofuel cell setup. Moreover, the use of a rather hydrophobic polymer with a high degree of crosslinking sites ensures the formation of stable polymer/enzyme films which were successfully used as bioanode in membrane-less biofuel cells., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Multistep synthesis and electrochemical characterization of an Os complex-modified redox hydrogel exhibiting a redox potential ≈+30 mV (vs. Ag/AgCl 3 M KCl) is demonstrated. The careful selection of bipyridine-based ligands bearing N,N-dimethylamino moieties and an amino-linker for the covalent attachment to the polymer backbone ensures the formation of a stable redox polymer with an envisaged redox potential close to 0 V. Most importantly, the formation of an octahedral N6-coordination sphere around the Os central atoms provides improved stability concomitantly with the low formal potential, a low reorganization energy during the Os(3+/2+) redox conversion and a negligible impact on oxygen reduction. By wiring a variety of enzymes such as pyrroloquinoline quinone (PQQ)-dependent glucose dehydrogenase, flavin adenine dinucleotide (FAD)-dependent glucose dehydrogenase and the FAD-dependent dehydrogenase domain of cellobiose dehydrogenase, low-potential glucose biosensors could be obtained with negligible co-oxidation of common interfering compounds such as uric acid or ascorbic acid. In combination with a bilirubin oxidase-based biocathode, enzymatic biofuel cells with open-circuit voltages of up to 0.54 V were obtained., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A miniaturized biofuel cell (BFC) is powering an electrolyser invoking a glucose concentration dependent formation of a dye which can be determined spectrophotometrically. This strategy enables instrument free analyte detection using the analyte-dependent BFC current for triggering an optical read-out system. A screen-printed electrode (SPE) was used for the immobilization of the enzymes glucose dehydrogenase (GDH) and bilirubin oxidase (BOD) for the biocatalytic oxidation of glucose and reduction of molecular oxygen, respectively. The miniaturized BFC was switched-on using small sample volumes (ca. 60 μL) leading to an open-circuit voltage of 567 mV and a maximal power density of (6.8±0.6) μW cm(-2). The BFC power was proportional to the glucose concentration in a range from 0.1 to 1.0 mM (R(2)=0.991). In order to verify the potential instrument-free analyte detection the BFC was directly connected to an electrochemical cell comprised of an optically-transparent SPE modified with methylene green (MG). The reduction of the electrochromic reporter compound invoked by the voltage and current flow applied by the BFC let to MG discoloration, thus allowing the detection of glucose., (Copyright © 2015 Elsevier B.V. All rights reserved.)

The authors report on the fabrication of a thermoresponsive biosensor for the amperometric detection of glucose. Screen printed electrodes with heatable gold working electrodes were modified by a thermoresponsive statistical copolymer [polymer I: poly(ω-ethoxytriethylenglycol methacrylate-co-3-(N,N-dimethyl-N-2-methacryloyloxyethyl ammonio) propanesulfonate-co-ω-butoxydiethylenglycol methacrylate-co-2-(4-benzoyl-phenoxy)ethyl methacrylate)] with a lower critical solution temperature of around 28 °C in aqueous solution via electrochemically induced codeposition with a pH-responsive redox-polymer [polymer II: poly(glycidyl methacrylate-co-allyl methacrylate-co-poly(ethylene glycol)methacrylate-co-butyl acrylate-co-2-(dimethylamino)ethyl methacrylate)-[Os(bpy)2(4-(((2-(2-(2-aminoethoxy)ethoxy)ethyl)amino)methyl)-N,N-dimethylpicolinamide)](2+)] and pyrroloquinoline quinone-soluble glucose dehydrogenase acting as biological recognition element. Polymer II bears covalently bound Os-complexes that act as redox mediators for shuttling electrons between the enzyme and the electrode surface. Polymer I acts as a temperature triggered immobilization matrix. Probing the catalytic current as a function of the working electrode temperature shows that the activity of the biosensor is dramatically reduced above the phase transition temperature of polymer I. Thus, the local modulation of the temperature at the interphase between the electrode and the bioactive layer allows switching the biosensor from an on- to an off-state without heating of the surrounding analyte solution.

Ceric ammonium nitrate has been used for qualitative analysis of ethanol. It forms an intensely colored unstable complex with alcohol. In this work, a simple flow injection (FI) colorimetric method was developed for the determination of ethanol, based on the reaction of ethanol with ceric ion in acidic medium to produce a red colored product having maximum absorption at 415 nm. Absorbance of this complex could be precisely measured in the FI system. A standard or sample solution was injected into a deionized water donor stream and flowed to a gas diffusion unit, where the ethanol diffused through a gas permeable membrane made of plumbing PTFE tape into an acceptor stream to react with ceric ammonium nitrate in nitric acid. Color intensity of the reddish product was monitored by a laboratory made LED based colorimeter and the signal was recorded on a computer as a peak. Peak height obtained was linearly proportional to the concentration of ethanol originally presented in the injected solution in the range of 0.1-10.0% (v/v) (r(2)=0.9993), with detection limit of 0.03% (v/v). With the use of gas diffusion membrane, most of the interferences could be eliminated. The proposed method was successfully applied for determination of ethanol in some alcoholic beverages, validating by gas chromatographic method., (Copyright © 2011 Elsevier B.V. All rights reserved.)