19F NMR Probes: Molecular Logic Material Implications for the Anion Discrimination and Chemodosimetric Approach for Selective Detection of H2O2.

Detection and discrimination of similar solvation energies of bioanalytes are vital in medical and practical applications. Currently, various advanced techniques are equipped to recognize these crucial bioanalytes. Each strategy has its own benefits and limitations. One-dimensional response, lack of discrimination power for anions, and reactive oxygen species (ROS) generally limit the utilized fluorescent probe. Therefore, a cutting-edge, refined method is expected to conquer these limitations. The use of 19F NMR spectroscopy for detecting and discriminating essential analytes in practical applications is an emerging technique. As an alternative strategy, we report two fluorinated boronic acid-appended pyridinium salts 5-F-o-BBBpy (1) and 5-CF3-o-BBBpy (2). Probe (1) acts as a chemosensor for identifying and discriminating inorganic anions with similar solvation energies with strong bidirectional 19F shifts in the lower ppm range. Probe (2) turns as a chemo dosimeter for the selective detection and precise quantification of hydrogen peroxide (H2O2) among other competing ROS. To demonstrate real-life applicability, we successfully quantified H2O2 via probe (2) in different pharmaceutical, dental, and cosmetic samples. We found that tuning the -F/-CF3 moiety to the arene boronic acid enables the π-conjugation, a crucial prerequisite for the discrimination of anions and H2O2. Characteristic 19F NMR fingerprints in the presence of anions revealed a complementary implication (IMP)/not implication (NIMP) logic function. Finally, the 16 distinct binary Boolean operations on two logic values are defined for "functional completeness" using the special property of the IMP gate. Boolean logic's ability to handle information by utilizing characteristic 19F NMR fingerprints has not been seen previously in a single chemical platform for detecting and differentiating such anions.

Quantifying CO-release from a photo-CORM using 19F NMR: An investigation into light-induced CO delivery.

Carbon monoxide (CO) is an innate signaling molecule that can regulate immune responses and interact with crucial elements of the circadian clock. Moreover, pharmacologically, CO has been substantiated for its therapeutic advantages in animal models of diverse pathological conditions. Given that an excessive level of CO can be toxic, it is imperative to quantify the necessary amount for therapeutic use accurately. However, estimating gaseous CO is notably challenging. Therefore, novel techniques are essential to quantify CO in therapeutic applications and overcome this obstacle precisely. The classical Myoglobin (Mb) assay technique has been extensively used to determine the amount of CO-release from CO-releasing molecules (CORMs) within therapeutic contexts. Nevertheless, specific challenges arise when applying the Mb assay to evaluate CORMs featuring innovative molecular architectures. Here, we report a fluorinated photo-CORM (CORM-FBS) for the photo-induced CO-release. We employed the 19F NMR spectroscopy approach to monitor the release of CO as well as quantitative evaluation of CO release. This new 19F NMR approach opens immense opportunities for researchers to develop reliable techniques for identifying molecular structures, quantitative studies of drug metabolism, and monitoring the reaction process.

Lysosome targeted visible light-induced photo-CORM for simultaneous CO-release and singlet oxygen generation.

We report a specific lysosome targeted light-responsive CO-releasing molecule (Lyso-CORM). Lyso-CORM is very stable under dark conditions. CO and singlet oxygen (1O2) generation was effectively triggered under one photon and two photon excitation (800 nm) conditions. The cytotoxicity results demonstrated that Lyso-CORM showed good phototoxicity due to the synergistic effect of CO and 1O2 release, and its good biocompatibility, negligible dark toxicity and specific lysosome targeting make Lyso-CORM a potent candidate for phototherapeutic applications.

Two-Photon-Induced CO-Releasing Molecules as Molecular Logic Systems in Solution, Polymers, and Cells.

Phototherapeutic applications of carbon monoxide (CO)-releasing molecules are limited because they require harmful UV and blue light for activation. We describe two-photon excitation with NIR light (800 nm)-induced CO-release from two MnI tricarbonyl complexes bearing 1,8-naphthalimide units (1, 2). Complex 2 behaves as a logic OR gate in solution, nonwovens, and in HeLa cells. CO release, indicated by fluorescence enhancement, was detected in solution, nonwoven, and HeLa cells by single- (405 nm) and two-photon (800 nm) excitation. The photophysical properties of 1 and 2 have been measured and supported by DFT and TDDFT quantum chemical calculations. Both photoCORMs are stable in the dark in solution and noncytotoxic, leading to promising applications as phototherapeutics with NIR light.

Affect and Cognition: Three Principles.

Affect and its object are separable, so that the same affective reaction can have different effects. Relevant principles from the affect-as-information approach include: (1) The impact of affect depends on implicit attributions -- what it appears to be about. (2) Affect is always taken to be about whatever is currently mentally accessible. Affective reactions can therefore serve as appraisals of objects of judgment or of initial thoughts and opinions about such objects, when they are more accessible. During problem solving, affect can serve as appraisals of thought style rather than thought content. Then, (3) positive and negative affect serve as go and stop signals for current inclinations. Affective influences on cognition are therefore not fixed, but malleable and context-dependent.

Light-responsive paper strips as CO-releasing material with a colourimetric response.

Carbon monoxide (CO) is known for its multifaceted role in human physiology, and molecules that release CO in a controlled way have been proposed as therapeutic drugs. In this work, a light-responsive CO-releasing molecule (CORM-Dabsyl) showed a strong colourimetric response upon photochemical CO-release, owing to the tight conjugation of a Mn(i) tricarbonyl centre to a dabsyl chromophoric ligand (L). Whereas the complex was very stable in the dark in nitrogen-purged aqueous media, CO-release was effectively triggered using 405 nm irradiation. CORM-Dabsyl, L and the inactive product iCORM-Dabsyl have been investigated by DFT and TD-DFT calculations. Only mild toxicity of CORM-Dabsyl was observed against LX-2 and HepaRG® human cell lines (IC50 ∼ 30 µM). Finally, to develop a CO storage and release material that is readily applicable to therapeutic situations, CORM-Dabsyl was loaded on low-cost and easily disposable paper strips, from which the light triggered CO-release was conveniently visible with the naked eye.

Red Light-Triggered CO Release from Mn2(CO)10 Using Triplet Sensitization in Polymer Nonwoven Fabrics.

Applicability of phototherapeutic CO-releasing molecules (photoCORMs) is limited because they are activated by harmful and poorly tissue-penetrating near-ultraviolet light. Here, a strategy is demonstrated to activate classical photoCORM Mn2(CO)10 using red light (635 nm). By mixing in solution a triplet photosensitizer (PS) with the photoCORM and shining red light, energy transfer occurs from triplet excited-state 3PS* to a photolabile triplet state of Mn2(CO)10, which, like under near-UV irradiation, led to complete release of carbonyls. Crucially, such "triplet-sensitized CO-release" occurred in solid-state materials: when PS and Mn2(CO)10 were embedded in electrospun nonwoven fabrics, CO was liberated upon irradiation with low-intensity red light (≤36 mW 635 nm).

Development of an advanced diagnostic concept for intestinal inflammation: molecular visualisation of nitric oxide in macrophages by functional poly(lactic-co-glycolic acid) microspheres.

We here describe a new approach to visualise nitric oxide (NO) in living macrophages by fluorescent NO-sensitive microspheres based on poly(lactic-co-glycolic acid) (PLGA). PLGA microspheres loaded with NO550 dye were prepared through a modified solvent-evaporation method. Microparticles were characterized by a mean hydrodynamic diameter of 3000 nm, zeta potential of -26.000 ± 0.351 mV and a PDI of 0.828 ± 0.298. Under abiotic conditions, NO release was triggered through UV radiation (254 nm) of 10 mM sodium nitroprusside dehydrate (SNP). After incubation, AZO550 microspheres exhibited an about 8-fold increased emission at 550 nm compared to NO550 particles. For biotic NO release, RAW 264.7 murine macrophages were activated with lipopolysaccharide (LPS) of Salmonella typhimurium. After treatment with NO550 microparticles, only activated cells caused a green particle fluorescence and could be detected by laser scanning microscopy. NO release was confirmed indirectly with Griess reaction. Our functional NO550 particles enable a simple and early evaluation of inflammatory and immunological processes. Furthermore, our results on particle-based NO sensing and previous studies in targeting intestinal inflammation via (PLGA)-based microspheres demonstrate that an advanced concept for visualizing intestinal inflammation is tangible.

Fluorinated Boronic Acid-Appended Pyridinium Salts and 19F NMR Spectroscopy for Diol Sensing.

The identification and discrimination of diols is of fundamental importance in medical diagnostics, such as measuring the contents of glucose in the urine of diabetes patients. Diol sensors are often based on fluorophore-appended boronic acids, but these severely lack discriminatory power and their response is one-dimensional. As an alternative strategy, we present the use of fluorinated boronic acid-appended pyridinium salts in combination with 19F NMR spectroscopy. A pool of 59 (bio)analytes was screened, containing monosaccharides, phosphorylated and N-acetylated sugars, polyols, carboxylic acids, nucleotides, and amines. The majority of analytes could be clearly detected and discriminated. In addition, glucose and fructose could be distinguished up to 1:9 molar ratio in mixtures. Crucially, the receptors feature high sensitivity and selectivity and are water-soluble, and their 19F-NMR analyte fingerprint is pH-robust, thereby making them particularly well-suited for medical application. Finally, to demonstrate this applicability, glucose could be detected in synthetic urine samples down to 1 mM using merely a 188 MHz NMR spectrometer.

Co-Registered Molecular Logic Gate with a CO-Releasing Molecule Triggered by Light and Peroxide.

Co-registered molecular logic gates combine two different inputs and outputs, such as light and matter. We introduce a biocompatible CO-releasing molecule (CORM, A) as Mn(I) tricarbonyl complex with the ligand 5-(dimethylamino)-N, N-bis(pyridin-2-ylmethyl) naphthalene-1-sulfonamide (L). CO release is chaperoned by turn-on fluorescence and can be triggered by light (405 nm) as well as with hydrogen peroxide in aqueous phosphate buffer. Complex A behaves as a logic "OR" gate via co-registering the inputs of irradiation (light) and peroxide (matter) into the concomitant outputs fluorescence (light) and CO (matter). Cell viability assays confirm the low toxicity of A toward different human cell lines. The CORM has been used to track the inclusion of A into cancer cells.

Remote-controlled delivery of CO via photoactive CO-releasing materials on a fiber optical device.

Although carbon monoxide (CO) delivery materials (CORMAs) have been generated, remote-controlled delivery with light-activated CORMAs at a local site has not been achieved. In this work, a fiber optic-based CO delivery system is described in which the photoactive and water insoluble CO releasing molecule (CORM) manganese(i) tricarbonyl [(OC)3Mn(µ3-SR)]4 (R = nPr, 1) has been non-covalently embedded into poly(l-lactide-co-d/l-lactide) and poly(methyl methacrylate) non-woven fabrics via the electrospinning technique. SEM images of the hybrid materials show a porous fiber morphology for both polymer supports. The polylactide non-woven fabric was attached to a fiber optical device. In combination with a laser irradiation source, remote-controlled and light-triggered CO release at 405 nm excitation wavelength was achieved. The device enabled a high flexibility of the spatially and timely defined application of CO with the biocompatible hybrid fabric in aqueous media. The rates of liberated CO were adjusted with the light intensity of the laser. CO release was confirmed via ATR-IR spectroscopy, a portable electrochemical CO sensor and a heterogeneous myoglobin assay.

Bactericidal Effect of a Photoresponsive Carbon Monoxide-Releasing Nonwoven against Staphylococcus aureus Biofilms.

Staphylococcus aureus is a leading pathogen in skin and skin structure infections, including surgical and traumatic infections that are associated with biofilm formation. Because biofilm formation is accompanied by high phenotypic resistance of the embedded bacteria, they are almost impossible to eradicate by conventional antibiotics. Therefore, alternative therapeutic strategies are of high interest. We generated nanostructured hybrid nonwovens via the electrospinning of a photoresponsive carbon monoxide (CO)-releasing molecule [CORM-1, Mn2(CO)10] and the polymer polylactide. This nonwoven showed a CO-induced antimicrobial activity that was sufficient to reduce the biofilm-embedded bacteria by 70% after photostimulation at 405 nm. The released CO increased the concentration of reactive oxygen species (ROS) in the biofilms, suggesting that in addition to inhibiting the electron transport chain, ROS might play a role in the antimicrobial activity of CORMs on S. aureus The nonwoven showed increased cytotoxicity on eukaryotic cells after longer exposure, most probably due to the released lactic acid, that might be acceptable for local and short-time treatments. Therefore, CO-releasing nonwovens might be a promising local antimicrobial therapy against biofilm-associated skin wound infections.

Fluorinated Boronic Acid-Appended Bipyridinium Salts for Diol Recognition and Discrimination via (19)F NMR Barcodes.

Fluorinated boronic acid-appended benzyl bipyridinium salts, derived from 4,4'-, 3,4'-, and 3,3'-bipyridines, were synthesized and used to detect and differentiate diol-containing analytes at physiological conditions via (19)F NMR spectroscopy. An array of three water-soluble boronic acid receptors in combination with (19)F NMR spectroscopy discriminates nine diol-containing bioanalytes--catechol, dopamine, fructose, glucose, glucose-1-phosphate, glucose-6-phosphate, galactose, lactose, and sucrose--at low mM concentrations. Characteristic (19)F NMR fingerprints are interpreted as two-dimensional barcodes without the need of multivariate analysis techniques.

Sensitization of NO-Releasing Ruthenium Complexes to Visible Light.

We report a combined spectroscopical-theoretical investigation on the photosensitization of transition metal nitrosyl complexes. For this purpose, ruthenium nitrosyl complexes based on tetradentate biscarboxamide ligands were synthesized. A crystal structure analysis of a lithium-based ligand intermediate is described. The Ru complexes have been characterized regarding their photophysical and nitric oxide (NO) releasing properties. Quantum chemical calculations have been performed to unravel the influence of the biscarboxamide ligand frame with respect to the molecular electronic properties of the NO-releasing pathway. A quantitative measure for the ligand design within photosensitized Ru complexes is introduced and evaluated spectroscopically and theoretically by using time-dependent density functional theory.

Sugar-based molecular computing by material implication.

A method to integrate an (in principle) unlimited number of molecular logic gates to construct complex circuits is presented. Logic circuits, such as half- or full-adders, can be reinterpreted by using the functional completeness of the implication function (IMP) and the trivial FALSE operation. The molecular gate IMP is represented by a fluorescent boronic acid sugar probe. An external wiring algorithm translates the fluorescent output from one gate into a chemical input for the next gate on microtiter plates. This process is demonstrated on a four-bit full adder.

Carbon monoxide--physiology, detection and controlled release.

Carbon monoxide (CO) is increasingly recognized as a cell-signalling molecule akin to nitric oxide (NO). CO has attracted particular attention as a potential therapeutic agent because of its reported anti-hypertensive, anti-inflammatory and cell-protective effects. We discuss recent progress in identifying new effector systems and elucidating the mechanisms of action of CO on, e.g., ion channels, as well as the design of novel methods to monitor CO in cellular environments. We also report on recent developments in the area of CO-releasing molecules (CORMs) and materials for controlled CO application. Novel triggers for CO release, metal carbonyls and degradation mechanisms of CORMs are highlighted. In addition, potential formulations of CORMs for targeted CO release are discussed.

Light-triggered CO release from nanoporous non-wovens.

The water insoluble and photoactive CO releasing molecule dimanganese decacarbonyl (CORM-1) has been non-covalently embedded into poly(l-lactide-co-d/l-lactide) fibers via electrospinning to enable bioavailability and water accessibility of CORM-1. SEM images of the resulting hybrid non-wovens reveal a nanoporous fiber morphology. Slight CO release from the CORM-1 in the electrospinning process induces nanoporosity. IR spectra show the same set of carbonyl bands for the CORM-1 precursor and the non-woven. When the material was exposed to light (365-480 nm), CO release from the incorporated CORM-1 was measured via heterogeneous myoglobin assay, a portable CO electrode and an IR gas cuvette. The CO release rate was wavelength dependent. Irradiation at 365 nm resulted in four times faster release than at 480 nm. 3.4 µmol of CO per mg non-woven can be generated. Mouse fibroblast 3T3 cells were used to show that the hybrid material is non-toxic in the darkness and strongly photocytotoxic when light is applied.

Allosteric indicator displacement enzyme assay for a cyanogenic glycoside.

Indicator displacement assays (IDAs) represent an elegant approach in supramolecular analytical chemistry. Herein, we report a chemical biosensor for the selective detection of the cyanogenic glycoside amygdalin in aqueous solution. The hybrid sensor consists of the enzyme ß-glucosidase and a boronic acid appended viologen together with a fluorescent reporter dye. ß-Glucosidase degrades the cyanogenic glycoside amygdalin into hydrogen cyanide, glucose, and benzaldehyde. Only the released cyanide binds at the allosteric site of the receptor (boronic acid) thereby inducing changes in the affinity of a formerly bound fluorescent indicator dye at the other side of the receptor. Thus, the sensing probe performs as allosteric indicator displacement assay (AIDA) for cyanide in water. Interference studies with inorganic anions and glucose revealed that cyanide is solely responsible for the change in the fluorescent signal. DFT calculations on a model compound revealed a 1:1 binding ratio of the boronic acid and cyanide ion. The fluorescent enzyme assay for ß-glucosidase uses amygdalin as natural substrate and allows measuring Michaelis-Menten kinetics in microtiter plates. The allosteric indicator displacement assay (AIDA) probe can also be used to detect cyanide traces in commercial amygdalin samples.

Enzymatic glycosylation of small molecules: challenging substrates require tailored catalysts.

Glycosylation can significantly improve the physicochemical and biological properties of small molecules like vitamins, antibiotics, flavors, and fragrances. The chemical synthesis of glycosides is, however, far from trivial and involves multistep routes that generate lots of waste. In this review, biocatalytic alternatives are presented that offer both stricter specificities and higher yields. The advantages and disadvantages of different enzyme classes are discussed and illustrated with a number of recent examples. Progress in the field of enzyme engineering and screening are expected to result in new applications of biocatalytic glycosylation reactions in various industrial sectors.

Molecular logic with a saccharide probe on the few-molecules level.

In this Communication we describe a two-component saccharide probe with logic capability. The combination of a boronic acid-appended viologen and perylene diimide was able to perform a complementary implication/not implication logic function. Fluorescence quenching and recovery with fructose was analyzed with fluorescence correlation spectroscopy on the level of a few molecules of the reporting dye.