Disposable Glucose Sensors for Flow Injection Analysis Using Substituted 1,4‐Benzoquinone Mediators

The redox chemistry of several substituted benzoquinones was investigated by cyclic voltammetry at a glassy carbon electrode and candidates for inclusion in a mediated biosensor for use in flow analysis were selected on the basis of oxidation potential, electrochemical reversibility and solubility. Glucose sensors constructed by sequential deposition onto a carbon pellet of 2,6‐dimethyl‐1,4‐benzoquinone, 2,3,5,6‐tetramethyl‐1,4‐benzoquinone or phenyl‐1,4‐benzoquinone mediator solution, followed by glucose oxidase in polyvinylalcohol‐Nafion solution, were tested for response to glucose using flow injection analysis. Sensors prepared from 2,6‐dimethyl‐1,4‐benzoquinone gave highest sensitivity, with a linear range of response to glucose of 2.5–40 mM. The use of an enzyme‐free comparative electrode to eliminate the response from interferents was investigated.     

G‐Quartet‐Based Nanostructure for Mimicking Light‐Harvesting Antenna

Artificial light‐harvesting systems have received great attention for use in photosynthetic and optoelectronic devices. Herein, a system involving G‐quartet‐based hierarchical nanofibers generated from the self‐assembly of guanosine 5′‐monophosphate (GMP) and a two‐step Förster resonance energy transfer (FRET) is presented that mimics natural light‐harvesting antenna. This solid‐state property offers advantages for future device fabrication. The generation of photocurrent under visible light shows it has potential for use as a nanoscale photoelectric device. The work will be beneficial for the development of light‐harvesting systems by the self‐assembly of supramolecular nanostructures.     

Visible‐Light‐Induced Nickel‐Catalyzed Negishi Cross‐Couplings by Exogenous‐Photosensitizer‐Free Photocatalysis

The merging of photoredox and transition‐metal catalysis has become one of the most attractive approaches for carbon–carbon bond formation. Such reactions require the use of two organo‐transition‐metal species, one of which acts as a photosensitizer and the other one as a cross‐coupling catalyst. We report herein an exogenous‐photosensitizer‐free photocatalytic process for the formation of carbon–carbon bonds by direct acceleration of the well‐known nickel‐catalyzed Negishi cross‐coupling that is based on the use of two naturally abundant metals. This finding will open new avenues in cross‐coupling chemistry that involve the direct visible‐light absorption of organometallic catalytic complexes.     

Optimizing conditions for the extraction of catechins from green tea using hot water

Six different factors involved in the extraction of catechins from green tea using water were examined for their impact on the yield of catechins and on the efficiency of water use. The best temperature and time combination for catechin extraction was at 80°C for 30 min. The yield of catechins was also optimal with a tea particle size of 1 mm, a brewing solution pH <6 and a tea‐to‐water ratio at 50:1 (mL/g). In terms of efficient use of water in a single extraction, a water‐to‐tea ratio of 20:1 (mL/g) gave the best results; 2.5 times less water was used per gram of green tea. At the water‐to‐tea ratio of 20:1 mL/g, the highest yield of catechins per gram of green tea was achieved by extracting the same sample of green tea twice. However, for the most efficient use of water, the best extraction was found to be once at a water‐to‐tea ratio of 12:1 (mL/g) and once at a water‐to‐tea ratio of 8:1 (mL/g). Therefore, all six of the factors investigated had an impact on the yield of catechins extracted from green tea using water and two had an impact on the efficiency of water use.     

Cooperative Catalysis of an Alcohol Dehydrogenase and Rhodium‐Modified Periodic Mesoporous Organosilica

The combined use of a metal‐complex catalyst and an enzyme is attractive, but typically results in mutual inactivation. A rhodium (Rh) complex immobilized in a bipyridine‐based periodic mesoporous organosilica (BPy‐PMO) shows high catalytic activity during transfer hydrogenation, even in the presence of bovine serum albumin (BSA), while a homogeneous Rh complex exhibits reduced activity due to direct interaction with BSA. The use of a smaller protein or an amino acid revealed a clear size‐sieving effect of the BPy‐PMO that protected the Rh catalyst from direct interactions. A combination of Rh‐immobilized BPy‐PMO and an enzyme (horse liver alcohol dehydrogenase; HLADH) promoted sequential reactions involving the transfer hydrogenation of NAD⁺ to give NADH followed by the asymmetric hydrogenation of 4‐phenyl‐2‐butanone with high enantioselectivity. The use of BPy‐PMO as a support for metal complexes could be applied to other systems consisting of a metal‐complex catalyst and an enzyme.     

Targeted Ultrasound‐Assisted Cancer‐Selective Chemical Labeling and Subsequent Cancer Imaging using Click Chemistry

Metabolic sugar labeling followed by the use of reagent‐free click chemistry is an established technique for in vitro cell targeting. However, selective metabolic labeling of the target tissues in vivo remains a challenge to overcome, which has prohibited the use of this technique for targeted in vivo applications. Herein, we report the use of targeted ultrasound pulses to induce the release of tetraacetyl N‐azidoacetylmannosamine (Ac₄ManAz) from microbubbles (MBs) and its metabolic expression in the cancer area. Ac₄ManAz‐loaded MBs showed great stability under physiological conditions, but rapidly collapsed in the presence of tumor‐localized ultrasound pulses. The released Ac₄ManAz from MBs was able to label 4T1 tumor cells with azido groups and significantly improved the tumor accumulation of dibenzocyclooctyne (DBCO)‐Cy5 by subsequent click chemistry. We demonstrated for the first time that Ac₄ManAz‐loaded MBs coupled with the use of targeted ultrasound could be a simple but powerful tool for in vivo cancer‐selective labeling and targeted cancer therapies.     

Harnessing Effective Molarity to Design an Electrochemical DNA‐based Platform for Clinically Relevant Antibody Detection

Easy‐to‐use platforms for rapid antibody detection are likely to improve molecular diagnostics and immunotherapy monitoring. However, current technologies require multi‐step, time‐consuming procedures that limit their applicability in these fields. Herein, we demonstrate effective molarity‐driven electrochemical DNA‐based detection of target antibodies. We show a highly selective, signal‐on DNA‐based sensor that takes advantage of antibody‐binding‐induced increase of local concentration to detect clinically relevant antibodies in blood serum. The sensing platform is modular, rapid, and versatile and allows the detection of both IgG and IgE antibodies. We also demonstrate the possible use of this strategy for the monitoring of therapeutic monoclonal antibodies in body fluids. Our approach highlights the potential of harnessing effective molarity for the design of electrochemical sensing strategies.     

Black Pigment Gallstone Inspired Platinum‐Chelated Bilirubin Nanoparticles for Combined Photoacoustic Imaging and Photothermal Therapy of Cancers

Bilirubin (BR), a bile pigment that exerts potent antioxidant and anti‐inflammatory effects, is also a major constituent of black pigment gallstones found in bile ducts under certain pathological conditions. Inspired by the intrinsic metal‐chelating power of BR found in gallstones, herein we report a cisplatin‐chelated BR‐based nanoparticle (cisPt@BRNP) for use as a new photonic nanomedicine for combined photoacoustic imaging and photothermal therapy of cancers. The cisPt@BRNPs were prepared by simply mixing cisplatin with BRNPs, yielding ca. 150‐nm‐size NPs. Upon near‐IR laser irradiation at 808 nm, cisPt@BRNPs generated considerable heat and induced clear death of cancer cells in vitro. Following intravenous injection into human colon cancer‐bearing mice, cisPt@BRNPs allowed effective tumor visualization by photoacoustic imaging and remarkable antitumor efficacy by photothermal therapy, suggesting their potential for use as a new photonic nanomedicine for cancer therapy.     

Fluorescence‐based lateral flow assays for rapid oral fluid roadside detection of cannabis use

With the recent worldwide changes in the legalization of marijuana, there is a significant need for rapid, roadside screening test for driving under the influence of drugs. A robust, sensitive, lateral flow assay has been developed to detect recent use via oral‐fluid testing for Δ⁹‐tetrahydrocannabinol (THC). This proof‐of‐concept assay uses a fluorescent‐based immunoassay detection of polymeric beads, conjugated to antibodies against native THC. The fluorescent technique allows for significantly lower limits of detection and higher precision determination of recent marijuana use without the use of urine or blood sampling—thus allowing for roadside identification. Detection levels of 0.01 ng/mL were distinguished from background and the lower limit of quantification was determined to approach 1 ng/mL.     

Stability and degradation products of imipenem applying high‐resolution mass spectrometry: An analytical study focused on solutions for infusion

Carbapenems show recognized instability in aqueous solutions; therefore some care must be taken in their handling and preparation and their use in the hospital environment. The stability and degradation products of imipenem were investigated from conditions that simulate its clinical use. For this, a simple stability‐indicating method by HPLC‐DAD was validated with a focus on the quantitation of drug concentration remaining from infusion solutions (sodium chloride 0.9% and glucose 5%). The degradation products formed were identified by high‐resolution mass spectrometry (ESI‐Q‐TOF‐MS/MS), with detection of the [M + H]⁺ ions at m/z 318 (DP‐1), m/z 599 (DP‐2) and m/z 658 (DP‐3). The most probable elemental compositions were obtained with a high degree of confidence, where the error between the masses observed and calculated was 1.25 ppm for DP‐1, ?0.33 ppm for DP‐2 and 1.82 ppm for DP‐3. The DP‐1 degradation product resulted from cleavage of the β‐lactam ring; DP‐2 corresponded to the drug dimer; and DP‐3 was generated from the interaction between imipenem and cilastatin. The proposed method provides a safe and reliable alternative for the quantitation of imipenem, and the stability data obtained by ESI‐Q‐TOF help in understanding the drug behavior under the conditions of clinical use.     

Oxidation of Organic Molecules with a Redox‐Active Guanidine Catalyst

Herein, we report the first examples of the use of redox‐active guanidines as catalysts in the green oxidation of organic molecules with dioxygen. In one half‐reaction, the oxidized form of the redox‐active guanidine is converted into the reduced, protonated state, thereby enabling dehydrogenative oxidation of the substrate (3,5‐di‐tert‐butylcatechol→ortho‐benzoquinone, benzoin→benzil, and 2,4‐di‐tert‐butylphenol→biphenol). In the other half‐reaction, efficient re‐oxidation of the guanidine to the oxidized state is achieved with dioxygen in the presence of a copper catalyst. These results pave the way for the broader use of redox‐active guanidines as oxidation catalysts.     

A Cooperative Pillar–Template Strategy as a Generalized Synthetic Method for Flexible Homochiral Porous Frameworks

A new strategy for creating homochiral metal–organic frameworks through a fusion of pillaring and templating concepts is demonstrated. This strategy makes use of the synergy among various chemical interactions during self‐assembly processes, and leads to the synthesis of a series of homochiral frameworks. In the presence of only pillar‐to‐pillar π–π interactions, inter‐pillar forces compete against metal–pillar interactions, resulting in mismatch between pillar‐to‐pillar and metal‐to‐metal separations and consequently 2D materials without pillaring. To create 3D materials, a method was developed to use various aromatic molecules, polycyclic aromatic hydrocarbons in particular, as templates to modulate the inter‐pillar interaction and separation, leading to the formation of 3D homochiral frameworks. The use of aromatic molecules, especially hydrocarbons, as structure‐directing agents, represents a new approach in the development of crystalline porous materials. Aromatic templates can be post‐synthetically extracted to yield flexible porous homochiral materials with gate‐opening gas sorption behaviors for both N₂ and CO₂ at partial pressures tunable by temperature.     

Ni(COD)(DQ): An Air‐Stable 18‐Electron Nickel(0)–Olefin Precatalyst

We report that Ni(COD)(DQ) (COD=1,5‐cyclooctadiene, DQ=duroquinone), an air‐stable 18‐electron complex originally described by Schrauzer in 1962, is a competent precatalyst for a variety of nickel‐catalyzed synthetic methods from the literature. Due to its apparent stability, use of Ni(COD)(DQ) as a precatalyst allows reactions to be conveniently performed without use of an inert‐atmosphere glovebox, as demonstrated across several case studies.     

Electro‐assembly of a Chromophore–Catalyst Bilayer for Water Oxidation and Photocatalytic Water Splitting

The use of electropolymerization to prepare electrocatalytically and photocatalytically active electrodes for water oxidation is described. Electropolymerization of the catalyst Ru^II(bda)(4‐vinylpyridine)₂ (bda=2,2′‐bipyridine‐6,6′‐dicarboxylate) on planar electrodes results in films containing semirigid polymer networks. In these films there is a change in the water oxidation mechanism compared to the solution analogue from bimolecular to single‐site. Electro‐assembly construction of a chromophore–catalyst structure on mesoporous, nanoparticle TiO₂ films provides the basis for a dye‐sensitized photoelectrosynthesis cell (DSPEC) for sustained water splitting in a pH 7 phosphate buffer solution. Photogenerated oxygen was measured in real‐time by use of a two‐electrode cell design.     

Catalytic Borylation using an Air‐Stable Zinc Boryl Reagent: Systematic Access to Elusive Acylboranes

The use of borylzinc reagents in palladium‐catalyzed borylation chemistry is described (i.e. a boron analogue of the Negishi coupling), including a one‐pot bench‐top protocol using an air‐ and moisture‐stable bis(boryl)zinc reagent. The steric/electronic properties of the boryl fragment employed enable a systematic method for accessing acylboranes, a rare class of organoboron species with great potential in chemical synthesis. The reactions proceed under mild conditions, use inexpensive commercial sources of palladium, and demonstrate a remarkable functional‐group tolerance.     

Intermolecular Stereospecific Substitution of Underivatized Enantioenriched Secondary Alcohols by Organocatalysis

The stereospecific substitution of non‐derivatized and non‐allylic enantioenriched alcohols with only water as a by‐product would enable the use of readily available alcohols as substrates for green and sustainable transformations. However, the poor leaving group ability of the OH group has hampered the development of such a process. Denton and co‐workers recently described the use of (2‐hydroxybenzyl)diphenylphosphine oxide as a catalyst of a redox‐neutral and zero‐waste‐generating Mitsunobu reaction. This innovative process constitutes the first intermolecular stereospecific substitution of non‐allylic alcohols, and might find industrial applications.     

High‐Throughput Design of Biocompatible Enzyme‐Based Hydrogel Microparticles with Autonomous Movement

Micro‐ and nanomotors and their use for biomedical applications have recently received increased attention. However, most designs use top‐down methods to construct inorganic motors, which are labour‐intensive and not suitable for biomedical use. Herein, we report a high‐throughput design of an asymmetric hydrogel microparticle with autonomous movement by using a microfluidic chip to generate asymmetric, aqueous, two‐phase‐separating droplets consisting of poly(ethylene glycol) diacrylate (PEGDA) and dextran, with the biocatalyst placed in the PEGDA phase. The motor is propelled by enzyme‐mediated decomposition of fuel. The speed of the motors is influenced by the roughness of the PEGDA surface after diffusion of dextran and was tuned by using higher molecular weight dextran. This roughness allows for easier pinning of oxygen bubbles and thus higher speeds of the motors. Pinning of bubbles occurs repeatedly at the same location, thereby resulting in constant circular or linear motion.     

Topotecan‐Loaded Mesoporous Silica Nanoparticles for Reversing Multi‐Drug Resistance by Synergetic Chemoradiotherapy

Multi‐drug resistance (MDR) has become a major challenge for the further improvement of chemotherapy. Thus, more effective strategies for further enhancing the treatment against cancer by overcoming MDR are warranted. In this study, by the encapsulation of the radiosensitizing drug TPT into mesoporous silica nanoparticles (MSNs), the combined use of drug‐delivered chemotherapy and high‐energy X‐ray induced radiotherapy could produce synergetic chemoradiotherapeutic effects to kill multi‐drug resistant cells through significant DNA damage, thus leading to an efficient circumvention of MDR. We hope that this synergetic dual‐mode treatment strategy may achieve higher oncolytic efficacy and find use in future clinical anti‐MDR applications.