Translating Molecular Recognition into a Pressure Signal to enable Rapid,Sensitive, and Portable Biomedical Analysis

Herein, we demonstrate that a very familiar, yet underutilized, physical parameter—gas pressure—can serve as signal readout for highly sensitive bioanalysis. Integration of a catalyzed gas‐generation reaction with a molecular recognition component leads to significant pressure changes, which can be measured with high sensitivity using a low‐cost and portable pressure meter. This new signaling strategy opens up a new way for simple, portable, yet highly sensitive biomedical analysis in a variety of settings.     

Biocomputing for Portable,Resettable, and Quantitative Point‐of‐Care Diagnostics: Making the Glucose Meter a Logic‐Gate Responsive Device for Measuring Many Clinically Relevant Targets

It is recognized that biocomputing can provide intelligent solutions to complex biosensing projects. However, it remains challenging to transform biomolecular logic gates into convenient, portable, resettable and quantitative sensing systems for point‐of‐care (POC) diagnostics in a low‐resource setting. To overcome these limitations, the first design of biocomputing on personal glucose meters (PGMs) is reported, which utilizes glucose and the reduced form of nicotinamide adenine dinucleotide as signal outputs, DNAzymes and protein enzymes as building blocks, and demonstrates a general platform for installing logic‐gate responses (YES, NOT, INHIBIT, NOR, NAND, and OR) to a variety of biological species, such as cations (Na⁺), anions (citrate), organic metabolites (adenosine diphosphate and adenosine triphosphate) and enzymes (pyruvate kinase, alkaline phosphatase, and alcohol dehydrogenases). A concatenated logical gate platform that is resettable is also demonstrated. The system is highly modular and can be generally applied to POC diagnostics of many diseases, such as hyponatremia, hypernatremia, and hemolytic anemia. In addition to broadening the clinical applications of the PGM, the method reported opens a new avenue in biomolecular logic gates for the development of intelligent POC devices for on‐site applications.     

Selective Adsorption and Molecular Recognition by a Molecularly Imprinted Polymer: Kinetic Study and Analysis

This article presents an original work aiming at kinetically surveying the substrate‐selective mechanism from a molecularly imprinted polymer. With Bisphenol A (BPA) as the template, the imprinted polymer was prepared. The result indicates that the imprinted polymer presents a much more complicated sorption toward the template than toward its analogue. The rate constant in the case of the template appears to be a function of coverage degree. There are also significant deviations from the idealized Langmuir model. Related information indicates that these logically can be a result from the induced molecular memory within the binding framework, which makes the polymer capable of selectively adsorbing the imprint species.     

Structural Insights into the Molecular Recognition Mechanism of the Cancer and Pathogenic Epitope,LacdiNAc by Immune-Related Lectins

Interactions of glycan-specific epitopes to human lectin receptors represent novel immune checkpoints for investigating cancer and infection diseases. By employing a multidisciplinary approach that combines isothermal titration calorimetry, NMR spectroscopy, molecular dynamics simulations, and X-ray crystallography, we investigated the molecular determinants that govern the recognition of the tumour and pathogenic glycobiomarker LacdiNAc (GalNAcβ1-4GlcNAc, LDN), including their comparison with the ubiquitous LacNAc epitope (Galβ1-4GlcNAc, LN), by two human immune-related lectins, galectin-3 (hGal-3) and the macrophage galactose C-type lectin (hMGL). A different mechanism of binding and interactions was observed for the hGal-3/LDN and hMGL/LDN complexes, which explains the remarkable difference in the binding specificity of LDN and LN by these two lectins. The new structural clues reported herein are fundamental for the chemical design of mimetics targeting hGal-3/hMGL recognition process.     

Studies Related to Norway Spruce Galactoglucomannans: Chemical Synthesis,Conformation Analysis,NMR Spectroscopic Characterization,and Molecular Recognition of Model Compounds

Galactoglucomannan (GGM) is a polysaccharide mainly consisting of mannose, glucose, and galactose. GGM is the most abundant hemicellulose in the Norway spruce (Picea abies), but is also found in the cell wall of flax seeds, tobacco plants, and kiwifruit. Although several applications for GGM polysaccharides have been developed in pulp and paper manufacturing and the food and medical industries, attempts to synthesize and study distinct fragments of this polysaccharide have not been reported previously. Herein, the synthesis of one of the core trisaccharide units of GGM together with a less‐abundant tetrasaccharide fragment is described. In addition, detailed NMR spectroscopic characterization of the model compounds, comparison of the spectral data with natural GGM, investigation of the acetyl‐group migration phenomena that takes place in the polysaccharide by using small model compounds, and a binding study between the tetrasaccharide model fragment and a galactose‐binding protein (the toxin viscumin) are reported.     

分散液液微萃取-气相色谱-串联质谱快速分析食用油中的酚类抗氧化剂

基于分散液液微萃取技术和气相色谱-串联质谱,建立了一种快速分析食用油中酚类抗氧化剂的新方法。对影响萃取效果的重要因素,如萃取剂种类及体积、分散剂种类及体积和萃取时间等进行了详细优化。优化条件为：500μL甲醇-乙腈(1：1, V/V)快速注射进3.0 mL 正己烷与1.0 g食用油的混合物中,并振荡萃取10 s 。在优化条件下,方法的线性范围为10~2000 ng/g,检出限为1.5~2.4 ng/g,相对标准偏差为4.0%~8.3%。将本方法应用于4种不同食用油样品的分析,其中3种有酚类抗氧化剂检出,样品加标回收率为81.9%~118%,结果满意。     

A Simple,Portable and Low Cost Device for a Colorimetric Spot-Test Quantitative Analysis

ABSTRACT

This paper describes a very simple device that can be used for colorimetric quantitative determinations, including spot-test analysis. The sensor is a light detector resistor (LDR) placed into a black PTFE cell and coupled to a low cost multimeter (Ohmmeter). The device has been tested and is easy and fast to use. Quantitative studies were performed with KMnO4 solutions and with the vanadium (V)/PAR/H₂O₂ system. Calibration curves were obtained by plotting the electric resistance of the LDR against the concentration of the colored species from 0 (blank) to 4.0 × 10^-3 mol L^-1 for permanganate and from 0 (blank) to 5.0 × 10^-5 mol L^-1 for vanadium. The detection limit (3σ) was found to be about 5.0 × 10^-5 mol L^-1 for permanganate and 4.0 × 10^-6 mol L^-1 for vanadium. The device was used to analyze total vanadium, as vanadium (V), in wastes from an adipic acid plant. The results obtained clearly show that the device can be used for accurate, precise, fast, in situ and low cost colorimetric analysis including quantitative spot-test procedures.     

Simultaneous Measurement of Cortisol,Cortisone, Dexamethasone and Additional Exogenous Corticosteroids by Rapid and Sensitive LC–MS/MS Analysis

The simultaneous measurement of dexamethasone and cortisol has proven the ability to increase the diagnostic performance of the overnight dexamethasone-suppression test. Furthermore, the therapeutic drug monitoring of administered corticosteroid drugs could represent a crucial tool for investigating unexpected variations of steroid hormones’ circulating levels. In this work, an LC–MS/MS method for the quantification of cortisol, cortisone, dexamethasone and six additional exogenous corticosteroids in the serum/plasma matrix was developed and validated in compliance with the ISO/IEC requirements. To assess the efficiency of the validated method, serum samples of 75 patients undergoing the dexamethasone-suppression test and 21 plasma samples of patients under immunosuppressive treatment after kidney transplant were analyzed. In all dexamethasone-suppression test samples, it was possible to measure the circulating levels of cortisol, cortisone and dexamethasone. Concentrations of the latter were for all tested patients above the proposed cutoff for the dexamethasone-suppression test’s results, and the cortisol concentrations showed good correlation with the ones measured by routine immunometric analysis, therefore confirming the screening outcome for all enrolled patients. Prednisone was detected and quantified in all enrolled patients, confirming the use of such a corticosteroid for immunosuppressive therapy. Thanks to these two applications, we proved the overall performance of the developed LC–MS/MS method for four target analytes. The future implementation of such an analytical tool in the clinical biochemistry laboratory’s routine will guarantee a single and versatile tool for simultaneously monitoring dexamethasone-suppression-test results and corticosteroid drugs’ administration.     

Portable Analyzer for Rapid Analysis of Total Protein, Fat and Lactose Contents in Raw Milk Measured by Non-dispersive Short-wave Near-infrared Spectrometry

A novel portable analyzer for raw milk quality control during the material purchase at dairy plants was developed, by which the percentages(mass fraction) of main components including total protein, fat, and lactose of an unhomogenized milk sample could be determinated in 1 min with the help of non-dispersive short-wave near-infrared (NDSWNIR) spectrometry in a wavelength range from 600 nm to 1100 nm and multivariate calibration. The analyzer was designed with a single-beam optical system, which comprised a temperature control module, a multi-channel narrow-band light source(16 wavelengths), a glass absorption cell with 15 mm sample thickness, a silicon photodiode detector, several compound lenses and a recorder module. A total of 80 raw milk samples were collected at a dairy farm twice a month for 4 months. The samples were scanned with a common UV-Vis-NIR spectrometer and analyzed according to China GB standard methods. The uninformative variables elimination(UVE) method was carried out on the spectrum data and the percentages of main components of all the samples to choose the peak emitting wavelength of each channel of the light source. Another 90 raw milk samples were collected from the same dairy farm thrice a month for 3 months. The samples were analyzed according to China GB standard methods and with the proposed analyzer. The percentages of the main components and the NDSWNIR absorption data of the samples were used for the construction and validation of the multivariate calibration model with partial least squares(PLS) method. The root-mean-square errors of prediction(RMSEP) of total protein, fat and lactose were 0.201, 0.172 and 0.247 and the coefficients of correlation(R) were 0.932, 0.981 and 0.933, respectively.     

Molecular composites by incorporation of a rod-like polymer into a functionalized high-performance polymer,and their conversion into microcellular foams

Molecular composites were prepared from sulfonated modifications of polysulfone and polyphenylsulfone by incorporating relatively stiff polybenzimidazole (PBI) chains into them. The composites were characterized by Fourier-transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC), thermal mechanical analysis (TMA), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The FT-IR results demonstrated strong specific interactions between the sulfonated polymers and the PBI, which was presumed to be the reason for the enhanced miscibility observed. Miscibility was also indicated in the DSC and TMA results, by the presence of a single glass transition temperature (which was composition dependent), although there did appear to be a small degree of phase separation. TGA results showed improvements in the thermal stability of the polymer matrix because of the incorporation of PBI. Results from SEM were also consistent with considerable miscibility. Microcellular foams processed from these molecular composites had partial open-cell cell structures, with average cell sizes ranging from 0.2 to 5 m, in unusual bimodal cell-size distributions.     

Molecular Modeling Studies on Molecular Recognition: Crown Ethers,Cryptands and Cryptates. From Static Models in vacuo to Dynamical Models in Solution

Abstract

Molecular Mechanics, Monte Carlo and Molecular Dynamics simulations on free and complexed crown ethers, on bicyclic cryptands and cryptates provide deeper insights into their conformational and recognition properties and allow to address the questions of preorganisation, complementarity, and binding selectivity. Alternatively, references to experimental data allow to outline present theoretical and computational limitations. Of particular interest are the microscopic pictures obtained in solution, which demonstrate the importance of solvent and environment effects on the precise structure of free and complexed receptors, and on their dynamics. Quantitative insights into relative free energies in solution represents a most promising breakthrough for computational studies in molecular recognition.     

The Rapid and Practical Route to Cu@PCR Sensor: Modification of Copper Nanoparticles Upon Conducting Polymer for a Sensitive Non-Enzymatic Glucose Sensor

In this work, rapid, sensitive, practical, and economical strategy for non-enzymatic glucose sensor has been reported based on a modification of copper nanoparticles upon conducting polymer with high surface area (Cu@PCR). Firstly, PCR conducting polymer electrode (PCR) has been successfully fabricated by electrochemical polymerization of a specially synthesized and characterized star-shaped carbazole derivative. Then copper nanoparticles have been successfully electrodeposited on the PCR as a practical method with cyclic voltammetry. The morphologies of the synthesized materials have been characterized by scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) measurements. The Cu@PCR sensor platform has been displayed a synergistic effect of high catalytical properties of copper nanoparticles and high electroactive properties of PCR towards the glucose oxidation in alkaline medium. The Cu@PCR sensor platform has shown high sensitivity of 847 μAmM⁻¹cm⁻², good stability (10 weeks), a low detection limit of 0.043 μM, and a fast response of 3 s for the non-enzymatic electrochemical detection of glucose. This organic−inorganic hybrid composite sensor is a promising candidate for the fabrication of a highly sensitive and rapid glucose-sensing with the simple preparation procedure and use of a low-cost precursor.     

Simple,Rapid and Sensitive Electrochemical Method for the Determination of the Triketone Herbicide Sulcotrione in River Water Using a Glassy Carbon Electrode

We report a novel, simple, rapid and sensitive electrochemical method for the determination of sulcotrione, a member of the relatively new class of triketone herbicides, using differential pulse voltammetry on a glassy carbon electrode. Its electrochemical behavior including influences of electrolyte composition, pH and scan rate was studied to select optimal experimental parameters for its determination. In Britton? Robinson buffer at pH 3 sulcotrione provided a well‐defined reduction peak at ?0.84 V (vs. Ag/AgCl electrode), with good repeatability (relative standard deviation of 2.3 % for 8 measurements at 10 µM concentration level). With optimized parameters differential pulse voltammetry rendered two linear concentration ranges from 0.2 to 2 µM and from 2 to 50 µM with a detection limit of 0.05 µM. The proposed procedure was successfully applied to the determination of sulcotrione in spiked river water samples with satisfactory recoveries (93–109 %). The developed method may represent a simple, rapid and sensitive alternative to highly toxic mercury electrodes and chromatographic methods.     

Integrating a Luminescent Porous Aromatic Framework into Indicator Papers for Facile,Rapid, and Selective Detection of Nitro Compounds

Porous aromatic framework materials with high stability, sensitivity, and selectivity have great potential to provide new sensors for optoelectronic/fluorescent probe devices. In this work, a luminescent porous aromatic framework material (LNU-23) was synthesized via the palladium-catalyzed Suzuki cross-coupling reaction of tetrabromopyrene and 1,2-bisphenyldiborate pinacol ester. The resulting PAF solid exhibited strong fluorescence emission with a quantum yield of 18.31%, showing excellent light and heat stability. Because the lowest unoccupied molecular orbital (LUMO) of LNU-23 was higher than that of the nitro compounds, there was an energy transfer from the excited LNU-23 to the analyte, leading to the selective fluorescence quenching with a limit of detection (LOD) ≈ 1.47 × 10⁻⁵ M. After integrating the luminescent PAF powder on the paper by a simple dipping method, the indicator papers revealed a fast fluorescence response to gaseous nitrobenzene within 10 s, which shows great potential in outdoor fluorescence detection of nitro compounds.     

Cycling a Tether into Multiple Rings: Pt-Bridged Macrocycles for Differentiated Guest Recognition,Pseudorotaxane Transformations,and Guest Capture and Release

Macrocycle engineering is a key topic in supramolecular chemistry. When synthesizing a ring, one can obtain either complex mixtures of macrocycles of different sizes or a single ring if a template is utilized. Here, we unite these approaches along with post-synthetic modifications to transform a single tether into multiple rings—up to five per tether. The macrocycles contain two bridged phenylpyridine ligands that are connected through a Pt atom, which defines the rings’ shape, size, and host activity. All rings undergo redox reactions (between Pt^II and Pt^IV) that allow for large conformational changes. Their reactivity, together with their host performance, is a convenient way to control the capture and release of guests, to mediate ring transformations, and to control pseudorotaxane-to-pseudorotaxane conversions. This novel approach could serve to assemble other libraries of small ring molecules, create cyclic polymers bridged by responsive-at-metal nodes, and produce processable mechanically interlocked molecules.     

Kinetic Insights into the Elongation Reaction of Actin Filaments as a Function of Temperature,Pressure, and Macromolecular Crowding

Actin polymerization is an essential process in eukaryotic cells that provides a driving force for motility and mechanical resistance for cell shape. By using preformed gelsolin–actin nuclei and applying stopped‐flow methodology, we quantitatively studied the elongation kinetics of actin filaments as a function of temperature and pressure in the presence of synthetic and protein crowding agents. We show that the association of actin monomers to the pointed end of double‐stranded helical actin filaments (F‐actin) proceeds via a transition state that requires an activation energy of 56 kJ mol^?1 for conformational and hydration rearrangements, but exhibits a negligible activation volume, pointing to a compact transition state that is devoid of packing defects. Macromolecular crowding causes acceleration of the F‐actin elongation rate and counteracts the deteriorating effect of pressure. The results shed new light on the combined effect of these parameters on the polymerization process of actin, and help us understand the temperature and pressure sensitivity of actin polymerization under extreme conditions.     

Sensitive determination of fluphenazine at a dodecanethiol self-assembled monolayer-modified gold electrode, and its electrocatalysis to phenylephrine

Fluphenazine, an important tranquilizer, was found to undergo effective accumulation on dodecanethiol (DDT) self-assembled monolayer modified gold electrode (i.e. DDT/Au) and generated two anodic peaks at about 0.7 and 0.79 V (vs. SCE) in 0.05 M Na₂B₄O₇ (pH = 9.3) buffer solution. Sensitive and quantitative measurement of fluphenazine based on the former anodic peak was established under optimum conditions. The peak current was linear to fluphenazine concentration in the range from 5 × 10⁻⁷ to 5 × 10⁻⁵ M, with a detection limit of 5 × 10⁻⁹ M. This method was successfully applied to the determination of fluphenazine in drug tablets and proved to be reliable compared with UV spectrophotometry. In the presence of fluphenazine, the electrochemical oxidation of phenylephrine was catalyzed. The DDT self-assembled monolayer was characterized by Fourier transform infrared spectroscopy, surface Raman spectroscopy, X-ray photoelectron spectroscopy, electrochemical impedance spectroscopy, and electrochemical probing.