Changes In UV Absorbance Research Articles

A Carbazole-based Fluorescent Probe with AIE Performance and a Large Stokes Shift for Peroxynitrite Detection and Imaging in Live Cells.

A carbazole-based fluorescent probe YCN with AIE performance and a large Stokes shift (242nm) shift was synthesized by attaching 4-acetonitrile pyridine to the 3-phenylaldehyde butylcarbazole. Its structure was characterized by 1H NMR, 13C NMR and MS. Probe YCN has high selectivity and sensitivity toward ONOO-. The addition of ONOO- to the probe YCN solution results in a noticeable color change from pale yellow to colorless under natural light, and a fluorescent color change from bright orange-yellow to bright yellow-green under a 365nm UV lamp, which can be distinguished by the naked eye. The research results on the reaction mechanism showed that when YCN reacted with ONOO-, -C = C- was oxidized and broken into -CHO, and the ICT effect was significantly inhibited, resulting in changes in UV absorption and fluorescence emission phenomenon. The recognition mechanism was verified by 1H NMR, mass spectrometry (MS) and density function theory (DFT) calculations. The experiments of live cells imaging suggested that compound YCN can be used as a fluorescent probe for the detection of ONOO- in HeLa cells. This result indicates that YCN has potential application prospects in the biological aspects.

Synthesis, photostability and antibacterial activity of a series of symmetrical α,β-unsaturated ketones as potential UV filters

A series of three symmetrical α,β-unsaturated ketones, namely, (1E,4E)-1,5-bis[4-(methylthio)phenyl]penta-1,4-dien-3-one, 1, (1E,4E)-1,5-bis[4-(dimethylamino)phenyl]penta-1,4-dien-3-one, 2, and (1E,4E)-1,5-bis[4-(ethyl)phenyl] penta-1,4-dien-3-one, 3, were synthesized in excellent yields (above 70%) and within a short reaction time (1 h), via an improved Knoevenagel condensation with acetyl acetone and substituted benzaldehydes. All the compounds were fully characterized by UV/Vis, IR, NMR and mass spectrometry. In addition, compound 1 was characterized by single crystal X-ray diffraction. The photostability of the prepared compounds was investigated in solvents of different polarity and proticity by exposure to simulated solar radiation. Three solvents were used, namely, ethyl acetate, dimethylsulfoxide and methanol. The change in UV absorption was monitored by a standard spectrophotometric method and photodegradation products were identified by 1H NMR. According to the results, 1 and 3 were not photostable, and suffered significant changes in their UV absorption spectra. Compound 2, on the other hand, was observed to be considerably photostable in the polar protic solvent methanol but less photostable in the polar aprotic solvent dimethylsulfoxide. All three compounds (1–3) photodegraded appreciably in the less polar aprotic solvent ethyl acetate. Therefore, their photostability is solvent dependent. The antibacterial activity of 1–3 was evaluated by means of the modified broth microdilution method against both gram-negative and gram-positive bacterial strains. Compounds 2 (methylated amine) and 3 (ethyl) have electron-releasing substituents and they were found to have excellent activity against all the tested bacteria. Thus, compounds 2 and 3 can be further explored as potential leads for the development of cheaper, safer, more effective and potent antibiotics against both gram-positive and gram-negative bacterial strains, and compound 2 is a good candidate for use in sunscreen formulations if dissolved in a polar solvent.

Maillard reaction between pea protein isolate and maltodextrin via wet-heating route for emulsion stabilisation

Pea protein isolate (PPI)-maltodextrin (MD) conjugates were prepared by using controlled Maillard reaction at 90 °C in the solution state (wet-heating route). The degree of conjugation between PPI and MD was measured in terms of evolved colour, UV absorbance, and molecular weight change. Results showed that the degree of Maillard reaction increased with the increase in pH and reaction time; however, the PPI-MD conjugation was optimised and was successfully controlled within the initial stage at pH 7.5 and 8.0 to avoid the formation of melanonids. The random coil content of PPI significantly increased upon conjugation with MD producing more flexible structure. The functional properties of PPI in terms of solubility, surface change (zeta-potential), and emulsifying properties of PPI were significantly improved after conjugation with MD. The highest solubility PPI-MD conjugates was observed at 5 h of reaction. The canola oil-in-water (O/W) emulsion stabilised by PPI-MD 5 h conjugate at 2% of emulsifier concentration and homogenised at 60 MPa for 3 passes had the highest physical stability when subjected to 25–60 °C. These findings indicate that Maillard reaction can be controlled in the initial stage via the wet-heating route and the resulting conjugates can be much effective emulsifiers than plant proteins.

Design of silane-based UV-absorbing thin coatings on polyethylene films

UV-absorbing surfaces have received much attention and focus due to their relevance in a variety of research applications and industrial fields. However, these surfaces currently suffer from drawbacks such as instability due to leakage of the entrapped UV-absorbing compounds, complicated non-green synthetic processes, and/or lack of good optical properties. We propose a modified Stöber method where UV absorbing silane monomers containing the group2-hydroxy-4-(3-triethoxysilylpropoxy) diphenylketone (SiUV) in presence of the mesoporous producing surfactant cetyltrimethyl ammonium chloride (CTAC) was polymerized in an ethanol/water continuous phase under basic conditions. UV absorbing thin coatings onto polyethylene (PE) films were then spread with the former dispersion on corona-treated PE, followed by a thermal drying process. These films were highly UV absorbent and durable with excellent optical properties. Multiple applications of the UV absorbing coating were also tested and found to increase UV absorbance to approximately 100%, but on the other hand the optical properties were negatively affected. The coated samples underwent thermal shrinkage by 30% to simulate industrial applications. No significant change in UV absorbance and optical properties were discerned after their shrinkage. These results and synthetic simplicity indicate to the potential of the SiUV coated polymeric films to be used for industrial applications.

Zinc oxide-induced changes to sunscreen ingredient efficacy and toxicity under UV irradiation

Sunscreen safety and efficacy is generally evaluated based upon the properties of the individual chemicals in a formulation. However, the photostability of sunscreens has been shown to be highly dependent on the mixture of chemicals present. To better understand how sunscreen formulation influences stability, and to establish a foundation for probing the influence of zinc oxide additives, we formulated five different small-molecule based ultraviolet-filter (UV-filter) mixtures with a Sun Protection Factor (SPF) of 15. These mixtures contained active ingredients approved in either the United States or European Union and were designed to represent formulations of actual products on the market. We evaluated the photostability and toxicity of these mixtures in the absence and presence of zinc oxide after UV exposure for two hours. Changes in UV absorbance were minimal for all five small-molecule-based mixtures without zinc oxide. The presence of either micro- or nano-sized zinc oxide caused significant small-molecule photodegradation and the degraded mixtures exhibited higher levels of toxicity in embryonic zebrafish assays. This study suggests that caution must be taken when formulating sunscreens containing both zinc oxide and small-molecule UV-filters to avoid unintended consequences during use.Graphic abstract

Adsorption-Kinetic Studies of Mordant Exhaust Dyeing of Cotton and Silk Fabrics with Dye Extract of M. lucida Plant Species

ABSTRACT The kinetics and adsorption isotherms of the extremely slow traditional natural exhaust dyeing that takes many hours or days have been studied purposely to find means of improving the process. The dyeing of cotton and silk fabrics using dye extract of M. lucida at 50 °C were elucidated with graphs to predict the reaction orders and identify the appropriate adsorption isotherm model(s). Since the dye is UV active, changes in UV absorbance were used in place of changes in concentrations. The simultaneous and post mordanting methods followed pseudo-second-order reactions, hence chemisorption. However, mordant application to the dyed fabrics during post mordant followed a pseudo-first-order model, largely physisorption. Dyeing has followed Langmuir and Freundlich isotherm models with linear correlation r2 ranging between 1 and 0.998. From the Freundlich model and values of Langmuir constant RL (0.9307 to 1.0), the process is homogeneous, forming a favourable and linear monolayer. Accordingly, the dyeing speed can be improved by increasing the concentration of dye liquor. Additionally, according to the Freundlich model, higher dye intensity on fabrics is recorded in post mordanting. Keywords: adsorption isotherms, equilibrium, exhaust dyeing, mordant, rate law

Spectroelectrochemistry of Non-Aromatic Explosives in Acetonitrile and the Influence of Superoxide

The spectroelectrochemistry of non-aromatic explosive compounds, namely two nitramines (RDX and HMX), a nitrate ester (PETN), and a plastic explosive composite (Semtex 1A) in acetonitrile (AN) is reported. The redox behavior of these compounds is studied using cyclic voltammetry while monitoring changes in UV absorbance to identify transient intermediates and product species. In search of a low-cost solution-phase detection technique for explosives, we compare the spectroelectrochemistry of these compounds in the presence and absence of naturally dissolved oxygen (2 mM in AN), where the superoxide radical is co-electrogenerated during analyte reduction. Free superoxide yields a prominent UV signal in this medium (λmax = 250 nm) that the explosives’ nitro or methylene groups attenuate stoichiometrically. Overlapping UV spectra of multiple species are deconvoluted using a new strategy, spectral regional baselining, for time- and potential-resolved spectroelectrochemical (SEC) analysis. SEC data for nitrite (NO2 -), nitrate (NO3 -), and nitromethane (CH3NO2) were also collected to support proposed reaction mechanisms for the transformation of explosives that include superoxide adducts and dimerized azoxy reduced intermediates. The findings expand the understanding of high-explosive solution-phase chemistry and offer a route to novel signal transduction for (electro-)chemical sensors for energetic materials.Figure 1. Spectroelectrochemistry of PETN in aerated acetonitrile with regions denoted for differential baseline analysis. (a) 3-D projected cyclic voltammogram (black) with UV absorbance from relevant wavelength (red, unscaled) as a function of time and potential; (b) full spectra (time domain) during cyclic voltammogram. Figure 1

In-line detection of monoclonal antibodies in the effluent of protein A chromatography with QCM sensor

A major drawback of the IgG capture step is the high cost of the protein A resin. For a better utilization of the resin, a continuous multi-column operation was recently proposed. In this method, accurate detection of leaking IgG is crucial to divert the breakthrough fluid from the waste to the next column and prolong the loading step without product loss. The detection of a breakthrough point as a change in UV absorption is based on a relatively small signal addition of IgGs to the bulk signal of host cell proteins. To achieve specificity, we used a quartz crystal microbalance and immobilized protein A as specific ligand on the sensor surface. We integrated the quartz crystal microbalance sensor in-line after the protein A column for real-time detection of IgGs in the breakthrough fluid. We show that this specific IgG detection in the breakthrough fluid can be more sensitive than with the UV detector. The use of the same product-specific ligand in the affinity column and in the sensor allows simultaneous in-line regeneration of column and sensor in a single step. Such a sensor could support cost-efficient load control during the entire continuous multi-column capture step in downstream processing.

Quantification of the electron donating capacity and UV absorbance of dissolved organic matter during ozonation of secondary wastewater effluent by an assay and an automated analyzer

Ozonation of secondary wastewater treatment plant effluent for the abatement of organic micropollutants requires an accurate process control, which can be based on monitoring ozone-induced changes in dissolved organic matter (DOM). This study presents a novel automated analytical system for monitoring changes in the electron donating capacity (EDC) and UV absorbance of DOM during ozonation. In a first step, a quantitative photometric EDC assay was developed based on electron-transfer reactions from phenolic moieties in DOM to an added chemical oxidant, the radical cation of 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS·+). The assay is highly sensitive (limit of quantification ∼0.5 mgDOC·L−1) and EDC values of model DOM isolates determined by this assay were in good agreement with values determined previously by mediated electrochemical oxidation (slope = 1.01 ± 0.07, R2 = 0.98). In a second step, the photometric EDC measurement method was transferred onto an automated fluidic system coupled to a photometer (EDC analyzer). The EDC analyzer was then used to monitor changes in EDC and UV absorbance of secondary wastewater effluent treated with ozone. While both parameters exhibited a dose-dependent decrease, a more pronounced decrease in EDC as compared to UV absorbance was observed at specific ozone doses up to 0.4 mgO3·gDOC−1. The concentration of 17α-ethinylestradiol, a phenolic micropollutant with a high ozone reactivity, decreased proportionally to the EDC decrease. In contrast, abatement of less ozone-reactive micropollutants and bromate formation started only after a pronounced initial decrease in EDC. The on-line EDC analyzer presented herein will enable a comprehensive assessment of the combination of EDC and UV absorbance as control parameters for full-scale ozonation.

Physicochemical characterization and stability of some commercial olive oils imported to Sudan

The objectives of this study are to assess the quality of some commercial olive oils imported to Sudan. Six samples from different origins (Tunis, Turkey, Spain, Saudi Arabia, and Lebanon) were collected from the local markets. Physical properties (Refractive Index, Density, and Viscosity) and chemical properties (Free Fatty Acids, Peroxide value, Saponification value) of the samples were determined to assess their quality and discussed in the light of International Olive Oil Council (IOOC). Furthermore, The FT-IR spectra of all samples were determined to verify their structure. The quality of the oils during storage and heating were also examined. Physical analysis revealed that the refractive index and viscosity are consistent with the value set by the IOOC. As for the density, the samples J and M produced in Tunis and Lebanon, respectively, were slightly higher than the maximum limit of IOOC. The results of chemical properties showed that the acidity, as oleic acid%, falls in the range 0.11 to 1.07. According to IOOC, based on acidity, all the samples are extra virgin olive oils except sample M from Lebanon is virgin olive oil. The peroxide values PVs (meqO2/Kg) for all samples were found below the maximum limit (20) of IOOC. The saponification values SVs (mg KOH/g) for all samples were in good agreement of the range specified by IOOC (184-196) except sample S (Saudi Arabia) showed, significantly, higher value (233) than the maximum of IOOC. Based on changes in PVs, FFAs and UV absorption (E270) during heating and storage, sample J (originated from Tunis) is the most stable during heating, whereas, sample K (originated from Turkey) showed the highest stability during storage. The present studies indicate that all samples showed good quality for human consumption, during storage and heating, except the sample S (from Saudi Arabia) needs further investigation.

Exploration of Li-Organic Batteries Using Hexaphyrin as an Active Cathode Material.

Lithium-collaborating organic batteries (Li-[28]hexs) were investigated with [28]hexaphyrin(1.1.1.1.1.1) as an active electrode material. Each hexaphyrin of [28]Hex cathode ideally involved four electrons per unit cycle and performed a typical charge/discharge processes of Li-organic battery. Li-[28]Hex batteries set with fast charging rates showed reasonably stable charge and discharge performances over 200 cycles even though it caused incomplete (2~3 electrons) charge/discharge cycles due to failing the complete charging process. UV absorption changes of [28]hexaphyrin in CH2Cl2 were supplementary for the electrochemical oxidation, which performed a conversion from [28]hexaphyrin to [26]hexaphyrin.

Metal binding study of calreticulin: An immunomodulatory protein of human filarial parasite Brugia malayi

Calreticulin (CRT), a highly conserved ubiquitous eukaryotic protein with a molecular mass of 46 kDa, containing three domains (N, P, and C) is involved in promoting prolonged parasite-host relations. Brugia malayi Calreticulin (BmCRT) is involved in the establishment of parasite infection by suppression of C1q-mediated host immune response. Calcium plays important role in this immunomodulatory mechanism of BmCRT. In the present study binding of calcium with BmCRT region involved in this interaction was investigated and correlated with the accompanying changes in fluorescence, circular dichroism (CD) and UV absorption. The results obtained clearly indicated that BmCRT is a calcium binding protein and contains types two of Ca2+ binding sites, one high affinity Ca2+ binding site at P domain and another low affinity Ca2+ binding site at C domain. Zinc also binds to additional sites that do not have appreciable affinity for the calcium. These studies have provided new knowledge that allows us to describe how the structure of BmCRT responds to interactions with calcium and zinc which is different from human CRT and also discuss how this mechanism help to complex formation with host C1q.

Wood nails to fix softwoods: characterization of structural deformation and lignin modification

Softwoods can be nailed with high density solid wood like Santos Rosewood (Machaerium scleroxylon) or nails made of densified laminated beech wood composite by hammering or shooting, for example with air nail guns, without pre-drilling. Shooting with about 30 m/s causes friction between nail surface and softwood matrix, heating up the interface to temperatures high enough to soften lignin. Re-condensation of softened lignin causes wood welding which doubles pull out strength in comparison to wood nails fixed without wood welding. Changes in lignin UV-absorption within the single cell wall layer and deformation of main anatomical features of spruce wood tissue are characterized by scanning UV microspectrophotometry (UMSP) whereas structural deformations of spruce wood tissue are revealed by X-ray micro-computed tomography (µ-CT).

Antimicrobial and antioxidant capacity of glucosamine-zinc(II) complex via non-enzymatic browning reaction.

Coordination compounds play an important role in the life process, and have been widely used in food, cosmetics and pharmaceutical industry. Herein, we have developed a novel kind of glucosamine-zinc(II) complex (GlcN-ZC) for food additive using non-enzymatic browning reaction. The GlcN-ZC was characterized by FTIR and XRD. Moreover, UV absorbance changes, browning intensity, fluorescence changes, antioxidant activity and antimicrobial assessment of GlcN-ZC were also evaluated. Results showed the GlcN-ZC intermediate compounds were accumulated in non-enzymatic browning while prolonging heating time and melanoidins were produced in the final stage. The fluorescence changes confirmed that fluorophores were formed during the non-enzymatic reaction and fluorescence intensity reached a maximun at 60 min. The highest radical scavenging activity of GlcN-ZC formed after 180min of heating was 79.2%. Furthermore, GlcN-ZC exhibited excellent antibacterial activity against E. coli and S. aureus. Therefore, GlcN-ZC can be used as a novel promising additive in the food industry.

Two-Dimensional Metal-Organic Framework Nanosheets as an Enzyme Inhibitor: Modulation of the α-Chymotrypsin Activity.

Two-dimensional metal-organic framework (MOF) nanosheets are utilized as effective enzyme inhibitors, providing an inspiring means to enhance the control of cellular processes as well as improve our understanding of the surface chemistry between MOFs and enzymes. In this paper, we demonstrated that the activity of α-chymotrypsin (ChT) can be effectively inhibited with 96.9% inhibition by 2-D Cu(bpy)2(OTf)2 nanosheets, while Zn2(bim)4 nanosheets show no significant inhibition effect toward ChT. Kinetic studies revealed that the material acts as a competitive inhibitor toward ChT. Furthermore, fluorescence and circular dichroism spectroscopy reveal that the 2-D MOF nanosheets do not change the secondary structure of the enzyme. The Cu(II) center of the 2-D nanosheets binds the 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) molecules in the buffer, leading to an electrostatic interaction between the nanosheets and the enzyme. In addition, the irreversible coordination interactions between Cu(II) center and His-57 played an important role during the inhibition process, as supported by ionic strength experiments and UV absorbance changes of Cu(II) d-d transitions. As a result, the substrate is prevented from reaching the active sites of the enzyme causing enzyme inhibition. The modulation of enzyme activity by 2-D MOF nanosheets opens up a new direction for the exploration of the MOF-bio interface in physiological and catalytic systems.

Nitrate formation during ozonation as a surrogate parameter for abatement of micropollutants and the N-nitrosodimethylamine (NDMA) formation potential

In this study, nitrate formation from ammonium and/or dissolved organic nitrogen (DON) was investigated as a novel surrogate parameter to evaluate the abatement of micropollutants during ozonation of synthetic waters containing natural organic matter (NOM) isolates, a natural water and secondary wastewater effluents. Nitrate formation during ozonation was compared to the changes in UV absorbance at 254 nm (UVA254) including the effect of pH. For low specific ozone doses UVA254 was abated more efficiently than nitrate was formed. This is due to a relatively slow rate-limiting step for nitrate formation from the reaction between ozone and a proposed nitrogen-containing intermediate. This reaction cannot compete with the fast reactions between ozone and UV-absorbing moieties (e.g., activated aromatic compounds). To further test the kinetics of nitrate formation, two possible intermediates formed during ozonation of DON were tested. At pH 7, nitrate was formed during ozonation of acetone oxime and methyl nitroacetate with second-order rate constants of 256.7 ± 4.7 M−1 s−1 and 149.5 ± 5.8 M−1 s−1, respectively. The abatement of the selected micropollutants (i.e., 17α-ethinylestradiol (EE2), carbamazepine (CBZ), bezafibrate (BZF), ibuprofen (IBU), and p-chlorobenzoic acid (pCBA)) was investigated for specific ozone doses ≤1.53 mgO3/mgDOC and its efficiency depended strongly on the reactivity of the selected compounds with ozone. The relative abatement of micropollutants (i.e., EE2 and CBZ) with high ozone reactivity showed linear relationships with nitrate formation. The abatement of micropollutants with intermediate-low ozone reactivity (BZF, IBU, and pCBA) followed one- and two-phase behaviors relative to nitrate formation during ozonation of water samples containing high and low concentrations of nitrate-forming DON, respectively. During ozonation of a wastewater sample, the N-nitrosodimethylamine formation potential (NDMA-FP) during chloramination decreased with increasing specific ozone doses. A good correlation was obtained between NDMA-FP abatement and nitrate formation. Therefore, nitrate formation after pre-ozonation may be a useful parameter to estimate the reduction of the NDMA-FP during post-chloramination. Overall, the results of this study suggest that nitrate formation (possibly in combination with UVA254 abatement) during ozonation of DON-containing waters may be a good surrogate for assessing the abatement of micropollutants and the NDMA-FP.

Effects of heat treatment parameters on liquid whole egg proteins

The aim of this study was to analyse the effect of heat treatment parameters on liquid whole egg (LWE) proteins by using ultraviolet–visible (UV–VIS) spectroscopy and capillary electrophoresis (CE). Heat treatment (at 60–68°C for 1–5min) was applied to LWE. Treated LWE was centrifuged and supernatant was taken for measurement of UV–VIS spectroscopy and CE. The change in UV absorbance showed loss of protein solubility depending on heat treatments parameters. Electropherograms of samples demonstrated the effect of treatment parameters on composition of LWE proteins. It was found that conalbumin and lysozyme were influenced by the treatment, while ovalbumin and ovomucoid were not affected. CE combined with principal component analysis (PCA) was used for classification of samples untreated or treated and treated at different treatment parameters. The results of the study revealed that the extent of heat treatment in LWE samples could be determined with PCA of the CE measurements.

CO2-Responsive Polymer-Functionalized Au Nanoparticles for CO2 Sensor.

Metallic nanoparticles (NPs) coated with stimuli-responsive polymers (SRPs) exhibit tunable optical properties responding to external stimuli and show promising sensing applications. We present a new CO2-responsive polymer, poly(N-(3-amidino)-aniline) (PNAAN), coated gold NPs (AuNPs) synthesized by directly reducing HAuCl4 with a CO2-responsive monomer N-(3-amidino)-aniline (NAAN). The amidine group of PNAAN can be protonated into a hydrophilic amidinium group by dissolved CO2 (dCO2). This induces the PNAAN to swell and detach from the AuNP surface, resulting in AuNP aggregation and color change. By monitoring the UV absorbance change of AuNPs, a sensitive dCO2 sensor with a linear range of 0.0132 to 0.1584 hPa and a limit of detection (LOD) of 0.0024 hPa is developed. This method shows dramatic improvement in sensitivity and convenience of sample preparation compared with the previously reported dCO2 sensor.

Characterizing the binding interaction between antimalarial artemether (AMT) and bovine serum albumin (BSA): Spectroscopic and molecular docking methods

Artemether (AMT), a peroxide sesquiterpenoides, has been widely used as an antimalarial for the treatment of multiple drug-resistant strains of plasmodium falciparum malaria. In this work, the binding interaction of AMT with bovine serum albumin (BSA) under the imitated physiological conditions (pH7.4) was investigated by UV spectroscopy, fluorescence emission spectroscopy, synchronous fluorescence spectroscopy, Fourier transform infrared spectroscopy (FT-IR), circular dichroism (CD), three-dimensional fluorescence spectroscopy and molecular docking methods. The experimental results indicated that there was a change in UV absorption of BSA along with a slight red shift of absorption wavelength, indicating that the interaction of AMT with BSA occurred. The intrinsic fluorescence of BSA was quenched by AMT due to the formation of AMT–BSA complex. The number of binding sites (n) and binding constant of AMT–BSA complex were about 1 and 2.63×103M−1 at 298K, respectively, suggesting that there was stronger binding interaction of AMT with BSA. Based on the analysis of the signs and magnitudes of the free energy change (ΔG0), enthalpic change (ΔH0) and entropic change (ΔS0) in the binding process, it can be concluded that the binding of AMT with BSA was enthalpy-driven process due to |ΔH°|>|TΔS°|. The results of experiment and molecular docking confirmed the main interaction forces between AMT and BSA were van der Waals force. And, there was a slight change in the BSA conformation after binding AMT but BSA still retains its secondary structure α-helicity. However, it had been confirmed that AMT binds on the interface between sub-domain IIA and IIB of BSA.

Selective fluorescent and colorimetric recognition of cyanide via altering hydrogen bonding interaction in aqueous solution and its application in bioimaging

In this paper, we report a new pyrene imine derivative which bears a relatively rigid intramolecular hydrogen bonding pocket, for fluorescent and colorimetric sensing of cyanide. In CH3CN solution, the chemosensor displayed distinct fluorescent and UV absorption changes towards CN−, CH3CO2−, F−, and H2PO4−. Notably, in an aqueous CH3CN medium (10%, v/v), the selectivity towards cyanide over other various anions were observed with an obvious fluorescence enhancement and colorimetric change. Thus, we demonstrated that the selectivity of the pyrene based chemosensor towards anions can be optimized via controlling hydrogen bonding interactions in different solvent systems. Finally the application of the chemosensor in fluorescent imaging cellular cyanide variation was demonstrated with living HeLa cells.