A rapid responsive coumarin-naphthalene derivative for the detection of cyanide ions in cell culture.

Cyanide ion (CN-) is widely used in many industrial processes; however, it causes several diseases in humans. Therefore, rapid and accurate detection of CN- is very important and urgent. In this study, a CN- sensor (MH-2) which was capable of detecting CN- ions in living cell was developed. MH-2 gives a rapid color change, absorbance and fluorescence response to CN- in the presence of the anions tested in the working system. The binding ratio between the sensor and CN- was demonstrated by some spectrophotometric methods and the sensing mechanism was investigated by NMR titration experiments, suggesting that MH-2 gives response to CN- via the nucleophilic addition reaction. The fluorescence detection limit and the absorbance detection limit were calculated as 0.056 µM and 0.11 µM, respectively. Both of these detection limits are below the tolerable limit recommended by WHO for CN- in the drinking water (1.9 µM). MH-2 was also applied to living cells for bio-imaging and the results showed that the sensor penetrates the cells and can detect cyanide ions in living cells.

Recovery and Reusability of ApoUnaG Fluorescence Protein from the Unconjugated Bilirubin Complex Structure.

This study is the first report on the separation and reusability of ApoUnaG protein, indicating excellent fluorescence response with high affinity and specificity toward unconjugated bilirubin (UC-BR) molecules, from the UnaG-UC-BR complex structure. The fluorescence properties of the UnaG-UC-BR complex (holo-UnaG) are studied by addition of different metal ions to perform possible interactions with holo-UnaG through absorbance and emission spectra. After addition of metal ions, some changes with respect to the type of metal ions are observed in fluorescence intensity of the holo-UnaG. When compared to metal ions, an excellent quenching response is sighted in the presence of Cu2+ ions by binding with UC-BR in the UnaG-UC-BR complex structure. Obtained non-fluorescence holo-UnaG-Cu2+ complex mixture is passed through Ni-NTA agarose to remove the ingredients such as Cu2+, UC-BR and Cu2+-UC-BR coordination complex from holo-UnaG. From the obtained experiments, it is concluded that Cu2+ ion can be used as an agent for the recovery of ApoUnaG protein via binding with UC-BR molecules. Graphical Abstract Recovery and Reusability of ApoUnaG Fluorescence Protein from the Unconjugated Bilirubin Complex Structure.

Correction to: An Application of a Schiff-Base Type Reaction in the Synthesis of a New Rhodamine-Based Hg(II)-Sensing Agent.

The original version of this article unfortunately contained a mistake. The presentation of Scheme 1 was incorrect as the word "modifified" should be written as "modified" and the abbreviation "CS-F" should be replaced by "AA-AR".

An Application of a Schiff-Base Type Reaction in the Synthesis of a New Rhodamine-Based Hg(II)-Sensing Agent.

A facile synthesis procedure, whereby 9-Anthraldehyde (AA) is coupled to aminated rhodamine (AR) via a Schiff base-type reaction, is reported. The applicability and performance of the obtained material (AA-AR) as a sensing agent was studied towards 16 metal cations (i.e. Li+, Na+, Ag+, Ca2+, Ba2+, Co2+, Cs+, Cu2+, Mg2+, Hg2+, Mn2+, Pb2+, Ni2+, Sr2+, Zn2+, Al3+). Among the studied metals, an extraordinary selectivity was observed for Hg2+, and the observed selectivity was found not to be influenced by the presence of other cations and some common anions (i.e. Br-, Cl-, I-, HPO42-, H2PO4-, NO3-, NO2-, ClO4-, AcO-, HSO4-, SO42-, Cr2O7-, CO32-, OH- and HCO3-). The material, AA-AR, exhibited such a high selectivity and sensitivity towards Hg2+ that it could be detected even by naked eyes. The Hg2+-sensing property of AA-AR was found not to be limited to colorimetric detections so that a high fluorescent nature of the compound was also observed upon binding Hg2+ ion. The detection limit, which is correspondent to fluorescence emission intensity, was found as 0.87 µM. The underlying mechanism of sensing property was studied by using some spectroscopic techniques such as FT-IR, 1H-NMR, 13C-NMR, and UV-Vis. (Job-plot). In the final course of the experiments, the performance of AA-AR in cell-imaging was also studied, and even trace amounts of Hg2+ in living cells could be detected by the studied probe. Thus, the applicability of a new synthesis approach in producing a highly efficient new fluorescence sensor for the detection of Hg2+ ions is discussed in detail.

Pesticide binding and urea-induced controlled release applications with calixarene naphthalimide molecules by host-guest complexation.

Three novel calix[4]arene molecule-based 1,8 naphthalimide fluoroionophore for the selective determination of kesoxim-methyl were synthesized and used in pesticide binding studies. The possible interaction between pesticides and fluorescent calix[4]arene molecules was monitored by UV/Vis absorption and fluorescence spectroscopy. When compared the studied pesticides, kesoxim-methyl was strongly quenched the fluorescence intensity of upper rim-modified calix[4]arene. UV and fluorescence titration experiments were also studied to determine both the quenching mechanism and stoichiometric ratio consisted in complex formation. Furthermore, pesticide release experiments were also performed with a fertilizing agent as urea by using fluorescence spectroscopy technique.

Electrospun Nanofibrous Polyacrylonitrile/calixarene Mats: an Excellent Adsorbent for the Removal of Chromate Ions from Aqueous Solutions.

Herein, calixarene molecules containing piperidine units at lower rim or upper rim of calix skeleton was turned into a water resistant composite nanofiber adsorbent using polyacrylonitrile (PAN) polymeric support via electrospinning process. The PAN based calixarene nanofibrous adsorbents showed an excellent adsorption capacity toward the toxic chromate anions in aqueous solution. Furthermore, this new nanofiber mats would be promising filter materials for drinking water purification.

Improvement of catalytic activity of Candida rugosa lipase in the presence of calix[4]arene bearing iminodicarboxylic/phosphonic acid complexes modified iron oxide nanoparticles.

In the present study, iron oxide magnetite nanoparticles, prepared through a co-precipitation method, were coated with phosphonic acid or iminodicarboxylic acid derivatives of calix[4]arene to modulate their surfaces with different acidic groups. Candida rugosa lipase was then directly immobilized onto the modified nanoparticles through sol-gel encapsulation. The catalytic activities and enantioselectivities of the two encapsulated lipases in the hydrolysis reaction of (R/S)-naproxen methyl ester and (R/S)-2-phenoxypropionic acid methyl ester were assessed. The results showed that the activity and enantioselectivity of the lipase were improved when the lipase was encapsulated in the presence of calixarene-based additives; the encapsulated lipase with the phosphonic acid derivative of calix[4]arene had an excellent rate of enantioselectivity against the (R/S)-naproxen methyl and (R/S)-2-phenoxypropionic acid methyl esters, with E=350 and 246, respectively, compared to the free enzyme. The encapsulated lipases (Fe-Calix-N(COOH)) and (Fe-Calix-P) showed good loading ability and little loss of enzyme activity, and the stability of the catalyst was very good; they only lost 6-11% of the enzyme's activity after five batches.

A highly sensitive fluorescent sensor for fenamiphos detection in vegetable samples and living cells based-on an enzyme free system.

Fenamiphos (Fena), an organophosphorous pesticide, is widely used in agricultural soils to control nematodes and thrips. This nematicide is harmful to fish, birds and humans and, causes several diseases. Therefore, the determination of the nematicide is crucial. Fena has been generally detected by enzyme-based systems which require specific conditions. Herein, we integrated a xanthene moiety and a pyrimidine moiety to obtain an enzyme-free detection system for Fena and, a fluorescent sensor (N-(6-(diethylamino)-9-(pyrimidin-5-yl)-3H-xanthen-3-ylidene)-N-ethylethanaminium hexafluorophosphate(V)) (RosPm) was easily prepared. The colorimetric and spectroscopic properties of RosPm were investigated using the UV-vis and fluorescence spectroscopy. RosPm exhibited a high selectivity and sensitivity to Fena over all the metal ions, the anions and pesticides tested in acetonitrile (ACN)/water (H2O) (v:v, 1:1) solution. RosPm showed a clear visual change from purple to light-purple resulting fluorescent quenching with Fena. This sensor could be preferred for detecting Fena in vegetable samples such as tomato, pepper, and cucumber, and visualizing Fena in living MFC-7 cells.

Synthesis and Spectroscopic Studies of Novel Rhodanine Azo Dyes: An Excellent Selective Chemosensor for Naked-eye Detecting of Cu2+ Ion.

This study is first report on the synthesis of novel rhodanine based azo dyes and their fluorogenic and chromogenic sensing behaviors with metal ions (Li+, Na+, K+, Rb+, Pb2+, Ni2+, Zn2+, Cu2+) by using UV-vis and fluorescence spectroscopy techniques. The results of spectroscopic experiments for rhodanine based azo dye 1a exhibited excellent selectivity for Cu2+ over the other metal ions. Furthermore, anti-bacterial studies of rhodanine azo dyes were performed towards some selected bacteria via microbroth dilution method. Obtained results showed that rhodanine ionophore 1a showed strong antibacterial activity against S.aureus.

Adsorption behavior of carboxy- and amine-terminated magnetic beads for patulin: Batch experiments in aqueous solution and apple juice.

Patulin (PAT) is a highly water soluble, heat resistant and toxic fungal metabolite mostly contaminating apple juice. Due to its serious health effects, its removal from foodstuffs is required to ensure food safety. In this study, carboxy- and amine-terminated iron oxide spheres (Fe3O4-COOH and Fe3O4-NH2) were investigated for their adsorbing capacity of PAT in both aqueous solution and apple juice, and evaluated for being an effective detoxifying agent for PAT. The physical and chemical properties of adsorbents were characterized by X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR) and Scanning Electron Microscopy (SEM). The maximum adsorption capacities Fe3O4-COOH and Fe3O4-NH2 for PAT obtained at 25 °C, pH 6 for 5 h were 0.206 mg/g and 0.104 mg/g, respectively. Best fitting adsorption isotherm and kinetics models of PAT adsorption process were Hill isotherm (Radj2 = 0.985) and pseudo-second kinetic models (Radj2 > 0.99) for carboxy groups and Langmuir isotherm (Radj2 = 0.974) and pseudo-second kinetic models (Radj2 > 0.99) for amine groups on the surface of adsorbents. These models with the experimental results confirmed the physical adsorption process, while thermodynamic analysis indicated that adsorption process was spontaneous and endothermic between PAT and both adsorbents. Reusability study showed the effective removal of PAT at four cycles by both adsorbents. This study indicated that carboxy- and amine-terminated magnetic spheres have promising potentials in PAT removal from both aqueous solution and apple juice without affecting quality parameters of juice.

Antibacterial, thermal decomposition and in vitro time release studies of chloramphenicol from novel PLA and PVA nanofiber mats.

The present investigation is the first report containing design and synthesis of novel calixarene derivatives (6-8) and their inclusion complexes (IC6-IC8) with Chloramphenicol (CAM). After synthesis, the antibiotic CAM, calixarene derivatives (6-8) and their inclusion complexes (IC6-IC8) were successfully incorporated into biodegradable PVA and/or PLA nanofiber skeleton by electrospinning. The obtained electrospun nanofibers were tested and compared for inhibition of bacterial growth towards multiple bacterial species (Escherichia coli, and Bacillus subtilis). Moreover, we evaluated thermal decomposition and release profile of CAM by spectrophotometric methods. The results suggested that CAM can be successfully encapsulated in nanofiber webs by inclusion complexation, and these fibers could be used as a part of new controlled release packaging system for food preservation.

Novel integrated sensing system of calixarene and rhodamine molecules for selective colorimetric and fluorometric detection of Hg2+ ions in living cells.

Three novel and facile calixarene derivatives (5, 6 and 7), which were appended with four rhodamine units at the upper rim of calixarene skeleton, were firstly prepared and evaluated for selective detection of metal ions in solution. Receptors (5) and (7) indicated immediate turn on fluorescence output toward Hg2+ ions over other most competitive metal ions with the ultralow detection limits, indicating their high efficiency and reliability. The binding response to Hg2+ ions in solution was also observed through a chromogenic change (from colorless to pale pink). Furthermore, in vitro and bio-imaging studies with MCF-7 or MIA PaCa-2 cell lines were also performed to investigate the use of receptors in biological systems in order to monitor of mercury ions. Results showed that new receptors (5) or (7) were cell permeable and suitable for real-time imaging of Hg2+ in living cells (MCF-7) or (MIA PaCa-2) without any damage to healthy cell lines (HEK 293).

Evaluation of Anticancer Activities of Novel Facile Synthesized Calix[n]arene Sulfonamide Analogs.

Here, new calixarene sulfonamide analogs were synthesized from the reaction of chlorosulfonated calix[n]arene (n: 4, 6, and 8) with N,N'-dimethylethylenediamine or ethylenediamine for the first time and an excellent calixarene sulfonamide analog showing potent and selective cytotoxic activity on some cancer cell lines were discovered. Cytotoxicity of the prepared calix[n]arene sulfonamide analogs towards both cancer and healthy cell lines was assessed by performing cell growth inhibition assays. In cytotoxicity assay results, it was observed that while sulfonamide analog based calix[4]arene (9) was not affecting the growth of epithelial cell lines (HEK), and it was especially effective on inhibiting the growth of some human cancer cell lines (MCF-7 and MIA PaCa-2). These results highlight that sulfonamide analog-based calix [4] arene (9) can be further studied as a potential anticancer agent.

A Simple and Highly Sensitive Turn-on Schiff Base Type Naked-eye Fluorescent Sensor for Aluminum Ion in Living Cells.

Six different Schiff bases to be used as turn-on fluorescent probes based on photoinduced electron transfer (PET) mechanism for the recognition of aluminum ions were successfully synthesized and characterized. The binding abilities of synthesized compounds with different metal cations was investigated by absorption and emission spectra. From the spectrophotometric experiments, it was seen that compound SK-1 displayed an excellent fluorescence response towards targeted aluminum ions probably due to its suitable chelating structure. Furthermore, such compound SK-1 also showed high sensitivity and selectivity response towards aluminum ions over other competing ions. In addition, the potential biological applications of SK-1 to detect aluminum ions in living cells were also investigated and results showed that fluorescence sensor SK-1 could be a promising probe for determining and/or monitoring aluminum ions in both biological and/or chemical samples.

Calixarene-immobilized monolithic cryogels for preparative protein chromatography.

New cation exchanger monolithic stationary phases were prepared by immobilization of three different calixarene derivatives (i.e. tetracarboxylate calix[4]arene, CLX-COO, tetrasulfonate calix[4]arene, CLX-SO3, and tetraphosphonate calix[4]arene, CLX-PO4) onto a monolithic cryogel support (i.e. poly(2-hydroksyethylmethacrilate-co-glycidyl methacrylate, P) and investigated with respect to preparative protein chromatography. The obtained monoliths were characterized through various techniques such as FTIR spectroscopy, isoelectric point measurements, titrimetric analyses, and mercury intrusion porosimetry. Protein retention was investigated using some model proteins (i.e. lysozyme, cytochrome c, and ɑ-chymotrypsinogen A, human serum albumin, and myoglobin), and the role of modifier (i.e. NaCl) concentration and pH was thoroughly analyzed under isocratic and gradient elution conditions. Overloading experiments were also conducted to study dynamic adsorption capacity and the obtained values were found to be ranging between 3 and 8 mg/mL depending on the type of calixarene molecule. Hence, higher or comparable protein adsorption capacities were seen to be applicable on calixarene-immobilized cryogels when compared to any other functionalized cryogels in the literature. Combined with the favorable properties of these monoliths, with respect to mass transport of large molecules, these results qualify calixarene functionalized monolithic cryogels as promising stationary phases for protein preparative purification.

Novel humic acid-bonded magnetite nanoparticles for protein immobilization.

The present paper is the first report that introduces (i) a useful methodology for chemical immobilization of humic acid (HA) to aminopropyltriethoxysilane-functionalized magnetite iron oxide nanoparticles (APS-MNPs) and (ii) human serum albumin (HSA) binding to the obtained material (HA-APS-MNPs). The newly prepared magnetite nanoparticle was characterized by using Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and elemental analysis. Results indicated that surface modification of the bare magnetite nanoparticles (MNPs) with aminopropyltriethoxysilane (APS) and HA was successfully performed. The protein binding studies that were evaluated in batch mode exhibited that HA-APS-MNPs could be efficiently used as a substrate for the binding of HSA from aqueous solutions. Usually, recovery values higher than 90% were found to be feasible by HA-APS-MNPs, while that value was around 2% and 70% in the cases of MNPs and APS-MNPs, respectively. Hence, the capacity of MNPs was found to be significantly improved by immobilization of HA. Furthermore, thermal degradation of HA-APS-MNPs and HSA bonded HA-APS-MNPs was evaluated in terms of the Horowitz-Metzger equation in order to determine kinetic parameters for thermal decomposition. Activation energies calculated for HA-APS-MNPs (20.74 kJmol(-1)) and HSA bonded HA-APS-MNPs (33.42 kJmol(-1)) implied chemical immobilization of HA to APS-MNPs, and tight interactions between HA and HA-APS-MNPs.

Removal of chromate and phosphate anion from aqueous solutions using calix[4]aren receptors containing proton switchable units.

In the present study four new calix[4]arene amide ionophores (4-7) have been prepared by aminolysis of calix[4]arene diester (3) and investigated their extraction ability toward phosphate and dichromate anions at different pH. The (1)H NMR data showed that the synthesized compounds exist in the cone conformation. Liquid-liquid extraction experiments have been performed to evaluate the dichromate and phosphate anions extraction efficiency of both calix[4]arene bearing amide-pyridinium units (4-7) and the calix[4]arene derivative bearing aminomethyl pyridinium units (8, 9). It was observed that, compounds 4-7 exhibited lower affinity toward phosphate ions than the calix[4]arene derivative bearing amine pyridinium units (8, 9). The extraction of phosphate and dichromate anions by these compounds indicates that the partially protonated pyridyl or amino groups play the major role for the formation of hydrogen bonds and electrostatic interactions.