Specific Chemical Interactions Research Articles

A March to Shape Optical Artificial Olfactory System toward Ultrasensitive Detection of Improvised Explosives

Improvised explosives (IEs) have been frequently used in explosion‐based terrorist attacks, and have aroused widespread concerns from governments to academic societies. Due to the fact that IEs mostly exist as solids, there is a pressing demand for sensors to adapt to acquire the information from the solid state. Chemical sensors usually comprise with probes designed based on the chemical properties of the analytes, and generate signals through specific chemical interactions, which would not be affected by the state of the target substance. Colorimetry and fluorescence, known for their intuitionistic (recognizable by human eyes), portable (independent of large‐scale analytical equipment), highly specific, sensitive, and environmental interference‐free characteristics, are commonly adopted optical chemical detection methods in materials analysis and environmental monitoring. Based on this, the exploration of optical artificial olfactory system, which mimics the working principle of natural olfactory system and acquires sensing signal by optical methods, has emerged to be a promising tool for IEs detection. Here, the basic working principle and the necessary components of optical artificial olfactory system are recommended, including probe molecule, array composition, pattern recognition and device construction. The potential development direction employing molecular recognition of IEs, generation, and acquisition methodology of optical signals are also prospected.

Chemical design of self-propelled Janus droplets

Chemical design of self-propelled Janus droplets

Protein complex nanoparticles reinforced with industrial hemp essential oil: Characterization and application for shelf-life extension of Rainbow trout fillets

Essential oil of industrial hemp (Cannabis sativa L.) (IHEO) was reinforced in complexation of whey protein nanofibrils and mung bean protein nanoparticles (WPNF-MBP NPs) as a novel nano-carrier. A desirable retention rate range of 50.9–90.4% was confirmed for IHEO reinforced in WPNF-MBP NPs. Fourier transform infrared (FTIR) spectroscopy revealed that IHEO was successfully loaded within WPNF-MBP NPs without specific chemical interaction with the carrier matrix. The results indicated that incorporation of IHEO-reinforced WPNF-MBP NPs into active material coatings having acceptable inhibition activity against total viable and psychrotrophic bacteria. The coated fishes also retarded the increase of PV (peroxide value), TBA (thiobarbituric acid) and TVB-N (total volatile basic nitrogen) values during storage. The IHEO-reinforced WPNF-MBP NPs coating led to an extension in the shelf life of Rainbow trout fillets within 8–14 days of storage. Accordingly, IHEO-reinforced WPNF-MBP NPs can be suggested as a natural preservative for coating fishes.

Deuterated solvent effects in the kinetics and thermodynamics of keto-enol tautomerization of ETFAA

Ethyl 4,4,4-trifluoroacetoacetate (ETFAA) is a β-ketoester that is used as a starting material in the synthesis of a variety of biologically active compounds. The reactivity of this compound is solvent dependent, and here we investigate the kinetics and thermodynamics of keto-enol tautomerization of ETFAA through benchtop 19F NMR in both non-deuterated and deuterated solvents. We determined that tautomerization dynamics in protic and aprotic solvents displayed differences in reaction rates and in the proportion of the keto and enol tautomers present. Moreover, our results demonstrated a positive correlation in aprotic solvents between solvent polarity and the proportion of keto tautomer present. We further employed density functional theory (DFT) calculations to probe the specific chemical interactions responsible for these observed trends. From the DFT calculations it was found that the major source of stability of the enol tautomer compared to the keto tautomer was its intramolecular hydrogen bond. Knowing the equilibrium of the keto-enol tautomerization of ETFAA is vital for synthesis of biologically active compounds derived from ETFAA, and maintaining a computational perspective can be useful in determining the advantages and disadvantages of various computational methods used in modeling keto-enol tautomerization.

Fast and Selective Ionic Transport: From Ion-Conducting Channels to Ion Exchange Membranes for Flow Batteries

This review discusses selective and fast transport of ionic species (ions and their associates) through systems as diverse as ion-conducting transmembrane proteins and ion exchange membranes (IEMs) in aqueous environments, with special emphasis on the role of electrostatics, specific chemical interactions, and morphology (steric effects). Contrary to the current doctrine, we suggest that properly balanced ion-coordinating interactions are more important than steric effects for selective ion transport in biological systems. Steric effects are more relevant to the selectivity of ionic transport through IEMs. As a general rule, decreased hydration leads to higher selectivity but also to lower transport rate. Near-perfect selectivity is achieved by ion-conducting channels in which unhydrated ions transfer through extremely short hydrophobic passages separating aqueous environments. In IEMs, ionic species practically keep their hydration shell and their transport is sterically constrained by the width of aqueous pathways. We discuss the trade-off between selectivity and transport rates and make suggestions for choosing, optimizing, or developing membranes for technological applications such as vanadium-redox-flow batteries.

Rehydration and restoration of fingerprint ridge detail in mummified post‐mortem tissue: Literature review and investigation of a simplified formulation

Mummified tissue presents challenges for fingerprinting due to rigidity, shrinkage, and other features obscuring epidermal ridge detail. A new cost-effective in-house solution was developed to obtain good quality fingerprints from mummified remains. The simplified procedure uses a sodium carbonate:sodium acetate mixture easily prepared using commonly available chemical products. An overview of the methods and solutions utilized to date for rehydration and restoration illustrates the main benefits of the developed formulation: the solution provided better tissue pliability and turgor than the sodium carbonate:ethanol formulation of Rüffer previously employed; the prepared solution proved stable for weeks at room temperature and poses minimum hazard risk to users. It functions as a weak base (pH 9.3) and is sufficiently corrosive to allow tissue softening over a flexible timeframe of 1-5days without causing any damage. The degree of effectiveness for rehydration of mummified tissue and restoration of ridge detail is attributed to three synergistic aspects: increased turgor as provided by a penetrating humectant and water; softening and pliability as a result of pH and any specific chemical interaction that affects calcium in collagen; ridge detail definition as a function of turgor and softening, with some secondary corrosive dependency related to the pH of a solution.

Collagen Suprafibrillar Confinement Drives the Activity of Acidic Calcium-Binding Polymers on Apatite Mineralization.

Bone collagenous extracellular matrix provides a confined environment into which apatite crystals form. This biomineralization process is related to a cascade of events partly controlled by noncollagenous proteins. Although overlooked in bone models, concentration and physical environment influence their activities. Here, we show that collagen suprafibrillar confinement in bone comprising intra- and interfibrillar spaces drives the activity of biomimetic acidic calcium-binding polymers on apatite mineralization. The difference in mineralization between an entrapping dentin matrix protein-1 (DMP1) recombinant peptide (rpDMP1) and the synthetic polyaspartate validates the specificity of the 57-KD fragment of DMP1 in the regulation of mineralization, but strikingly without phosphorylation. We show that all the identified functions of rpDMP1 are dedicated to preclude pathological mineralization. Interestingly, transient apatite phases are only found using a high nonphysiological concentration of additives. The possibility to combine biomimetic concentration of both collagen and additives ensures specific chemical interactions and offers perspectives for understanding the role of bone components in mineralization.

(Invited) Nanotube-Based Nanohybrids: Dyes Encapsulated inside Nanotubes

The inner and outer surfaces of a nanotube made of either carbon or boron nitride material can be functionalized to tailor the chemical and optical properties of the assembly. Our studies on the optical properties of dyes encapsulated in nanotubes (dyes@CNT) have shown, for instance, enhancement effects in both Raman and fluorescence spectroscopies, which are of interest for bio-imaging and photonics. A chemical functionalization of the outer wall has also been developed to promote specific chemical interactions of the nanohybrids with a host, such as a biomarker. Here we will review some of our recent progress on the nanotube-based nanohybrids. More particularly, we will present advances towards the development of the boron-nitride nanotube nanohybrids for fluorescence imaging in the visible and near-infrared. New results on the outer functionalization to work more effectively in biological media and infer an optical response to pH will be presented. Lastly, the mechanism of the encapsulation process and the optical response due to aggregation effects of the encapsulated dyes in different conditions will be discussed.This work was done in collaboration with E. Gaufrès, C. Allard, S. K. Mal, N. Tang, R. Nascimento, C. David, L. Durate, L. Gaboury and S. Blais-Ouellette

Adsorption characteristics of tetracycline onto particulate polyethylene in dilute aqueous solutions

The presence of ultrafine plastics particles and its potential to concentrate and transport organic contaminants in aquatic environments have become a major concern in recent years. Specifically, the uptake of hazardous chemicals by plastics particles may affect the distribution and bioavailability of the chemicals. In this study, the adsorption of tetracycline (TC), an antibiotic frequently found in aquatic environments, on high-density polyethylene (PE) particles with the average size of 45 μm, was investigated. The PE particles were characterized for surface acidity for the first time. Results showed that pH controls the surface charge of PE particles. TC adsorption onto PE particles was rapid as expected following the pseudo-second-order rate law (r2 > 0.99). Polar forces in addition to specific chemical interactions, such as hydrogen bonding and hydrophophilicity controlled TC adsorption onto PE particles. Parameters, including pH, dissolved organic matter, ionic strength, major cations and anions affected TC adsorption onto PE micro-particles. Results indicated that PE particles can function as a carrier of antibiotics in the aquatic environment, which potentially imposes ecosystem and human health risks.

Surface-Enhanced Raman Scattering (SERS) Taster: A Machine-Learning-Driven Multireceptor Platform for Multiplex Profiling of Wine Flavors.

Integrating machine learning with surface-enhanced Raman scattering (SERS) accelerates the development of practical sensing devices. Such integration, in combination with direct detection or indirect analyte capturing strategies, is key to achieving high predictive accuracies even in complex matrices. However, in-depth understanding of spectral variations arising from specific chemical interactions is essential to prevent model overfit. Herein, we design a machine-learning-driven "SERS taster" to simultaneously harness useful vibrational information from multiple receptors for enhanced multiplex profiling of five wine flavor molecules at parts-per-million levels. Our receptors employ numerous noncovalent interactions to capture chemical functionalities within flavor molecules. By strategically combining all receptor-flavor SERS spectra, we construct comprehensive "SERS superprofiles" for predictive analytics using chemometrics. We elucidate crucial molecular-level interactions in flavor identification and further demonstrate the differentiation of primary, secondary, and tertiary alcohol functionalities. Our SERS taster also achieves perfect accuracies in multiplex flavor quantification in an artificial wine matrix.

Systemic Adaptive Immune Parameters Associated with Neuroblastoma Outcomes: the Significance of Gamma-Delta T Cells

We mined a set of neuroblastoma (NBL) exomes for immune receptor recombinations representing all seven, human adaptive immune receptor genes, using a very high standard for identifications of V- and J-gene segments in sequencing reads. Results indicated an unusually large number of TRD recombination reads in the NBL samples, possibly related to the younger age of the patients. In general, recovery of immune receptor (IR) recombination reads representing any of the immune receptors, from either blood or tumor samples, was associated with a lower overall survival rate, consistent with an emerging literature indicating that systemic immunology parameters can be informative for cancer evaluations. Despite the overall negative association of IR recombination frequencies and outcomes, survival rate distinctions could still be established as associated with certain chemical features of IR complementarity determining region-3 (CDR3) amino acid sequences, thereby likely revealing a distinction between the negative impacts of a general adaptive immune response versus the positive aspects of specific CDR3 chemical interaction potentials. These data underscore the relevance of gamma-delta T cells in the development of cancer in younger patients. And for the first time, these data allow a distinction within an NBL cohort with active disease, between two contrasting systemic immune states: (i) general and likely harmful adaptive immunity development versus (ii) a likely positive, adaptive immune response with particular antigenic specificities.

Surface Complexation of Chromium(VI) on Iron(III) Hydroxide: Mechanisms and Stability Constants of Surfaces Complexes

The adsorption of chromate ions H2-yA (y = 1, 2, and A = CrO42–) on iron(III) hydroxide was conducted as a function of adsorbent mass, solution pH, and hydration time. The surface complexation technique, based on the examination of the chromate distribution between the solid and liquid phases, was adopted to predict the adsorption mechanism. To specify stoichiometry of the chromate surface complexes, the proton (n > 0), and hydroxyl (n < 0) ion-exchange was evaluated at a pH range of 2–12. The obtained “n” values are ranging between -1 and 1. As a result, the sorption process involved specific chemical interaction with surface sites, resulting in 1H+ and 1OH– release of the adsorbate molecule. The surface species identified were ; ; ; ; ; ; ; and . The logarithmic values of their complexing constants were: log K00 = 1.81 ± 0.04; log K11 = -3.53 ± 0.07; log K21 = -1.03 ± 0.23, log K1-1 = 7.15 ± 0.14 and log K2-1 = 9.62 ± 0.53. The results showed that the chromate adsorption on Fe(III) hydroxide was of electrostatic and chemical nature at pH lower than 5.5, and only of chemical nature at pH superior to 5.5. Taking into account these considerations, Fe(III) hydroxide could be considered an excellent sorbent for the removal of Cr(VI) from wastewater solutions.

Lithographically Formed Fine Wavy Surface Morphology for Universal Alignment Control of Mesochannels in Mesostructured Silica Films

In-plane orientation of mesochannels in mesostructured silica films is fully controlled by a lithographically formed anisotropic surface morphology of a substrate. The orientation is determined simply by elastic properties of a liquid crystal phase, which appears in the course of the formation of mesostructured silica films through the sol-gel process. When an array of linear microscopic grooves with a round cross section is closely formed on the substrate surface, the cylindrical mesochannels in the films are entirely aligned strictly perpendicular to the grooves, as a consequence of minimization of the total elastic energy. When the surface morphology geometrically fits to the hexagonal arrangement of the mesochannels, the orientation abruptly changes into the direction parallel to the long axis of the grooves. The alignment control based on the elastic property of the liquid crystal phase described in this report does not require any specific chemical interactions between the surfactant molecules and the substrate surface. Therefore, aligned mesostructured silica films with a large structural periodicity can successfully be formed using block copolymer surfactants, which hardly form an aligned mesostructure without the support of external fields. The vapor-phase synthesis, which enables considerable retardation of the solidification process of siliceous species, is the most favorable way, and totally aligned mesostructured silica films with significantly large thickness, more than 1 μm, can be obtained. Appropriate combination of the bottom-up and the top-down nanoprocesses reported in this paper, that is, self-assembly and photolithography, will enable the formation of highly anisotropic nanostructured materials, which will find various practical applications.

Electrochemical Assay for Extremely Selective Recognition of Fructose Based on 4-Ferrocene-Phenylboronic Acid Probe and β-Cyclodextrins Supramolecular Complex.

The aim of the present paper is to highlight a novel electrochemical assay for an extremely-selective detection of fructose thanks to the use of a supramolecular complex between β-cyclodextrins (β-CDs) and a chemically modified ferrocene with boronic acid named 4-Fc-PB/natural-β-CDs. Another kind of β-CDs, the 4-Fc-PB/3-phenylboronic-β-CDs, is proposed for the detection of glucose. The novel electrochemical probe is fully characterized by 1 H nuclear magnetic resonance, mass spectroscopy, and elemental analysis, while the superior electrochemical performance is assessed in terms of sensitivity and detection limit. The novelty of the present work consists in the role of CDs that for the first time are employed in electrochemistry with a unique detection mechanism based on specific chemical interactions with the target molecule by the introduction of proper binding groups. Ahighly selective detection of fructose is obtained and it is believed that the proposed mechanism of detection represents a new way to electrochemically sense other molecules by varying the combination of specific groups of the supramolecular complex. The findings are of impactful importance since a quick, easy, cheap, and extremely selective detection of fructose is not yet available in the market, here achieved by using electrochemical methods which are a very growing field.

Spectroelectrochemistry of Poly(3,4-Ethylenedioxythiophene)–Tungsten Oxide Composite Films in Dilute Sulfuric Acid Solution

Using electrochemical deposition of tungsten oxide from a metastable acidic solution of isopolytungstates into a poly(3,4-ethylenedioxithiophene) film, composite films were obtained on optically transparent electrodes made of fluorine-doped tin oxide on glass. In situ electronic spectra of poly(3,4-ethylenedioxithiophene)–tungsten oxide composite films and their components, poly(3,4-ethylenedioxithiophene) and tungsten oxide films, were studied using the spectroelectrochemistry method at various electrode potentials. The good additivity of the spectra of the composite and its constituent components suggests that there is no pronounced specific chemical interaction between the components, except for the electrostatic interaction between positively charged polymer fragments and negatively charged polymer oxo anions of tungsten oxide.

A model for self‐assembling circuits with voltage‐controlled growth

SummaryThe circuit tile assembly model (cTAM) consists of a voltage source and resistive circuit tiles, configured as a voltage divider, that attach to form resistive ladders or grids if the voltage on the boundary is greater than or equal to a threshold. The model produces a family of circuits whose composition and properties change with time. As growth proceeds, the voltage decreases until it no longer exceeds a threshold, which causes growth to cease. This is referred to as self‐controlled growth, because the properties of the assembly itself are the primary determinant in controlling the extent of the assembly. The model augments tile assembly models, which are programmable through specific chemical interactions, with an alternative electrical mechanism. The ladder and grid assemblies have bounded size and unique shape that are determined by parameters from the electrical network. Using the harmonicity of the electric potential, the shape of the grid assembly is shown to be symmetric around the main diagonal. Finally, two models of growth, differentiated by whether the voltage is measured before or after attachment, are equivalent. The model and analysis have potential application to self‐assembly of nanostructures, as well as to networks whose structure changes over time.

(Invited) Nanotube-Based Nanohybrids Made of Dyes Encapsulated inside Nanotubes

The inner and outer surfaces of a nanotube made of either carbon or boron nitride materials can be functionalized to tailor the chemical and optical properties of the assembly. Our studies on the optical properties of dyes encapsulated in nanotubes show for instance enhancement effects in both Raman and fluorescence spectroscopies, which are interesting for making optical nanoprobes for bio-imaging. Chemical functionalization of the outer wall has also been effective in promoting specific chemical interaction with a host, such as a biomarker. Here we will more specifically review our recent progress on the nanotube-based nanohybrids and focus the discussion on the case of the boron-nitride nanotubes for optical imaging. More particularly, we have made advances towards the preparation of boron-nitride nanotube nanohybrids for fluorescence imaging with visible and near-infrared emissions. Recent results on the outer functionalization to work more effectively in biological media and on the aggregation effects of encapsulated dyes probed optically in different conditions will be discussed.This work was done in collaboration with E. Gaufrès, C. Allard, S. K. Mal, N. Tang, R. Nascimento, C. David, L. Durate, Louis Gaboury and S. Blais-Ouellette

Molecular simulation of nanocolloid rheology: Viscosity, viscoelasticity, and time-concentration superposition

A particulate molecular model in which the solvent particles are considered explicitly is developed for studying the linear viscoelasticity of nanocolloidal suspensions using molecular dynamics simulations. Nanocolloidal systems of volume fractions ranging from 0.10 to 0.49 are studied. The hydrodynamics in these model systems are governed by interparticle interactions. The volume fraction dependence of the relative zero shear viscosity exhibited by this molecular model is consistent with that reported in the literature experiments and simulations. Over the range of frequencies studied, the relative dynamic viscosity values follow the same qualitative trend as that seen in the literature experiments. The time-concentration superposition (TCS) principle is successfully applied to construct the viscoelastic master curves that span nine decades of frequency in the case of the elastic modulus and more than four decades of frequency in the case of the loss modulus. The TCS principle was observed to fail at high volume fractions that are near the glass transition concentration; this finding is consistent with the literature experimental and simulation observations. The volume fraction dependence of the shift factors used in the construction of the viscoelastic master curves is in good quantitative agreement with that of the viscosity of the nanocolloidal systems. Our results demonstrate that molecular simulations in conjunction with an explicit solvent model can be used to quantitatively represent the viscosity and the viscoelastic properties of nanocolloidal suspensions. Such particulate models will be useful for studying the rheology of systems whose properties are governed by specific chemical interactions.

Ratiometric electrochemical molecular switch for sensing hypochlorous acid: Applicable in food analysis and real-time in-situ monitoring

A ratiometric electrochemical molecular sensing platform for real-time quantification of extracellular hypochlorous acid (HClO) production has been developed based on a latent electrochemical probe aminoferrocene thiocarbamate (AFTC 3). The substrate AFTC consist of a masked redox reporter amino ferrocene (AF 4) linked with a dimethylthiocarbamate trigger via hydroxyl benzyl alcohol. The conceptual idea behind the probe design is based on a specific chemical interaction between HClO and dimethylthiocarbamate, which allows only HClO to unmask the probe to releases AF. The scheme was manipulated to establish a highly selective (in presence of various reactive oxygen species, anions and other biological interfering species) and sensitive (detection limit 75 nM) sensing platform not only in lab samples but also in real samples (food samples, and live cells). Real-time in situ quantification platform was developed to profile HClO productions in macrophages, and it did so with great consistency.

Bioinspired surface activators for wet/dry environments through greener epoxy-catechol amine chemistry

Specific chemical interactions found in marine mussels led to a sprout in synthetic surfaces modification approaches especially for wet environment adhesiveness albeit often resulting in poor mechanical robustness. In this contribution, with a view towards robust mechanical adhesion, we present a superior, greener, low cost adhesion “promoter” concept at the interface of aluminium (Al) and epoxy adhesive suitable for both wet and dry conditions by mimicking mussel's adhesion chemistry. Catechol functionalized polymers were realized by the reaction of 3,4 dihydroxyphenylethylamine (DA) with epoxy monomers in 1:1 and 2:1 ratio which upon crosslinking in alkaline medium produced the adhesion promoter primers P1 and P2. P1 under dry condition showed adhesion strength of 9 MPa which is 2-fold and 9-fold higher than uncoated and DA-coated Al specimens respectively. As a highlight, the underwater adhesion strength obtained using P1 is in the range of 7–7.5 MPa, the highest reported till date. P1 substantially surpassed the adhesive strength offered by commercial primers and conventional etching methods, thanks to the effective interface interactions (binding energy 111.5 kcal/mol) revealed by computational studies. The advantages of this mussel-inspired greener priming approach are manifold for a wide range of applications involving interfaces/load-bearing materials under wet/dry conditions.