Development of a molecularly imprinted polymer on silanized graphene oxide for the detection of 17-estradiol in wastewater.

This research article demonstrates the synthesis, characterization, and electrochemical evaluation of a molecularly imprinted polymer (MIP) on the surface of silanized graphene oxide (silanized GO), which is nanostructured and used to quantify 17-estradiol (E2) in wastewater. As characterization methods, X-ray diffraction (XRD), Raman spectroscopy, dynamic scattering light (DSL), scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR) were utilized to examine the synthesized GO, silanized GO, MIP-GO composite, and non-imprinted polymer (NIP)-GO (NIP-GO) composite. FTIR results confirmed the successful synthesis of GO composites. Raman study confirmed the synthesis of monolayer silanized GO, MIP-GO composite, and NIP-GO composite. Surface morphology revealed that after polymerization, the surface of silanized GO sheet-like morphology is covered with nanoparticles. Adsorption kinetics studies revealed that adsorption follows the pseudo-second-order kinetics. Further, we studied the performance of a MIP-GO-based sensor by optimizing the effects of pH, scan rate, and incubation period. The linear calibration was achieved between the oxidation peak current and E2 concentration from 0.1 to 0.81 ppm, with a detection limit of 0.037 ppm. The selectivity of the MIP-GO composite was also checked by using other estrogens, and it was found that E2 is 3.3, 0.5, and 1.4 times more selective than equilin, estriol, and estrone, respectively. The composite was successfully applied to the wastewater samples for the detection of E2, and a good percentage of recoveries were achieved. It suggests that the reported composite can be applied to real samples. PRACTITIONER POINTS: An innovative electrochemical sensor was developed for selective detection of 17-estradiol through molecularly imprinted polymer fabricated on the surface of silanized GO (MIP-GO composite). The developed method was comprehensively validated and found to be linear in the range of 0.1 to 0.8 ppm of 17-estradiol, with 0.037 ppm of limit of detection and 0.1 ppm of limit of quantification, respectively. The developed MIP-GO-composite-based electrochemical sensor was found 3.3, 0.5, and 1.4 times more selective for 17-estradiol than equiline, estriol, and estrone, respectively. The applicability of a developed sensor was also checked on wastewater samples, and a good percent recovery was obtained.

Fabrication of para-dimethylamine calix[4]arene functionalized self-assembled graphene oxide composite material for effective removal of 2, 4, 6-tri-Cholorphenol from aqueous environment.

Water pollution caused by the release of organic pollutants is a major environmental concern worldwide. These pollutants can have harmful effects on aquatic ecosystems and the organisms living within them, as well as on human health when contaminated water is consumed. It is essential to implement proper treatment and management strategies to prevent and mitigate water pollution. Moreover, the major untreated industrial effluents are synthetic organic compounds especially 2,4,6-trichlorophenol (TCP) which cause several environmental issues and heath related problems in humans. To cope with this problem, an excellent 2D porous material based on p-DMAC4/GO composite has been synthesized as adsorbent material for the effective removal of 2,4,6-trichlorophenol pollutant from wastewater. In this regard, the advanced analytical tools such as Fourier-Transform infrared (FT-IR), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray spectroscopy (EDS) were used for its characterization. The results justified the chemical composition, excellent crystalline nature, surface morphology and elemental composition of the synthesized composite material. The synthesized adsorbent material showed 95% adsorption of TCP from wastewater system at optimal conditions i.e., pH (6), adsorbent dosage (30 mg) and shaking time (60 min). The mathematical models such as isotherms, thermodynamics and kinetics studies validate the nature of adsorption process of TCP pollutant. The adsorption data found to be best fitted with Langmuir isotherms (R2 = 0.99); whereas kinetic study suggested the pseudo-second-order nature of reaction with R2 = 0.99. The thermodynamics study confirmed the spontaneous and endothermic nature of the TCP pollutant onto the surface of p-DMAC4/GO material. Moreover, the results of current work were also compared with existing reported adsorbents and data suggested the higher efficiency, feasibility, and reusability of p-DMAC4/GO material to remove the TCP pollutant from the wastewater system.

A highly selective sensor based on p-tetranitrocalix[4]arene-capped copper nanoparticles for colorimetric and bare-eye detection of cyclophosphamide.

In the current study, one of the outstanding facile and simple protocols is proposed for the synthesis of copper nanoparticles (CuNPs) using NaBH4 as a reducing agent and p-tetranitrocalix[4]arene (p-TNC4) as a capping agent. According to our knowledge, no such technique is available in the literature for colorimetric detection of cyclophosphamide (CPA) using CuNPs at the trace level. The well-organized synthesis was confirmed via advanced spectroscopic techniques. The crystallite size, shape, phase purity, and morphological characteristics were determined via XRD, AFM, FT-IR, and UV-visible spectroscopy. At the optimal conditions for CPA detection, the sensor reveals an excellent sensitivity, selectivity, as well as stability with LOD and LOQ 20 nM and 60 nM, respectively. However, the proposed sensor showed excellent potential and selectivity for the sensing of colorimetric detection of CPA that can be effectively applied to real blood serum samples. The proposed approach is better suited as compared to reported protocols in terms of handling, simplicity, economic, energy consumption, reproducibility, and excellent performance in a very short time.

Synthesis of an insulin intercalated graphene oxide nanogel composite: evaluation of its release profile and stability for oral delivery of insulin.

Diabetes mellitus (DM) is a disorder of glucose regulation produced due to insufficient availability of insulin. Generally, insulin is given to diabetes patients via subcutaneous injection which is a painful method to deliver this drug. In this work we have made an attempt to develop an oral drug delivery system that can efficiently deliver insulin to the small intestine. An insulin intercalated GO based nanogel composite (In@GO NgC) was fabricated for oral delivery of insulin. The in vitro release of insulin from In@GO NgC was studied in artificial gastric (pH 1.2) and intestinal (pH 7.5) fluids. The In@GO NgC produced better release in artificial intestinal fluid as compared to gastric fluid. The enzymatic degradation of released insulin was also examined and the results revealed that even after 6 h of incubation, the gel remained stable and the un-degraded insulin seemed to be sufficient for the physiological processes. The efficacy of In@GO NgC was also confirmed by comparing its release profile with non-intercalated GO NgC and nanogel (Ng) without GO. The prepared nanogels were thoroughly characterized using FTIR, SEM, EDS, DSC and DLS. The better release profile and enzymatic stability of In@GO NgC suggests that it can be utilized for oral drug delivery of insulin.

Gas Chromatographic and Spectrophotometric Determination of Diclofenac Sodium, Ibuprofen, and Mefenamic Acid in Urine and Blood Samples.

OBJECTIVES: Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used for the treatment of acute to chronic pain. A simple, fast, and reliable gas chromatographic (GC) method with flame ionization detection has been developed for the determination of NSAIDs such as diclofenac sodium, ibuprofen, and mefenamic acid after derivatization with ethyl chloroformate. MATERIALS AND METHODS: The GC conditions were optimized as elution from a DB-1 column (30 mx0.32 mm id) at column temperature 150 °C for 3 min, followed by a heating rate of 20 °C/min up to 280 °C and a hold time of 5 min. The nitrogen flow rate was 2.5 mL/min. For spectrophotometric studies, the absorbance was measured against methanol at a wavelength of 200-500 nm. RESULTS: The calibration curves were linear within 2-10 µg/mL with limits of detection of 0.4-0.6 µg/mL of each drug. The derivatization elution, separation, and quantitation were repeatable (n=3) with relative standard deviation (RSD) within 3.9%. The method was applied for the analysis of the drugs from pharmaceutical formulations and the results of the analysis agreed with labeled values with RSDs within 0.5-3.9%. The results were also confirmed by standard addition method. The percent recovery was calculated with spiked deproteinized human blood serum and urine samples and % recovery of the drugs was obtained within 96-98% with RSDs within 3.1%. CONCLUSION: The validated method proved its ability for the assay of NSAIDs in bulk and dosage form in a short analysis time. The method was also useful for the analysis of biological samples.

Phenolic compounds and antioxidant activity of Calligonum polygonoides stem and buds.

In the present study we demonstrate the identification of phenolic compounds and the phenolic contents of the methanol extracts from stem and buds of Calligonum polygonoides with antioxidant activity. Eleven and nine phenolic compounds were identified and quantified from stem and buds, respectively by high-performance liquid chromatography (HPLC). p-Coumaric acid was predominant in stem and gallic acid in buds. In general, the samples with the highest phenolic contents had the highest antioxidant activities. Stem and buds sparked attention due to their high phenolic contents and antioxidant activities. The Results from present study reveal that the C. polygonoides could be considered as a promising source of antioxidant phytochemicals.

Complexation of ibuprofen with water soluble p-sulfonatocalix [4]arene: A potential candidate for drug delivery applicatio.

Complexation of ibuprofen with water soluble p-sulfonatocalix[4]arene (3) was evaluated. Both molecules exhibit a host and guest type complexation. pH, complex stoichiometry and binding constant were determined by UV-Vis and FT-IR spectroscopy. The maximum complexation of 3 with ibuprofen occurs at pH 2. Stability constant values (9.897) show that there is favorable complex formed due to vital role of p-sulfonatocalix[4]arene, while the thermodynamic parameters, i.e. δG, ΔH and δS have been found as -24.09 KJ/mol, 0.012 KJ/mol and 0.12 KJ/mol. K, respectively. The results show that 3 has efficiency to carry the drug at particular conditions and can be used for drug delivery as a carrier.

Dual Fluorescence Response of Newly Synthesized Naphthalene Appended Calix[4]arene Derivative towards Cu2+ and I.

In the present work new naphthalene appended calix[4]arene (NAC4) i.e. 5,11,17,23-tetra-tert-butyl-25,27-di((2-amido(1-naphthlene)ethyl)-26,28-dihydroxy calix[4]arene (6) was designed and successfully synthesized. NAC4 was characterized by 1HNMR and FTIR. To explore the complexation behavior and fluorescence response of NAC4, UV-visible and fluorescence studies were carried out with series of metal ions and anions that include solvatochromic effect, ion-ligand response and interference on absorption and fluorescence spectra. Results show that the NAC4 is highly Cu2+ and I-selective. The ligand ion interaction follow photoinduced electron transfer (PET) mechanism. The stiochiomatric ratio of ion-ligand was calculated as 1:1 by using Job's plot method and binding constant Ka values were calculated by using Benesi-Hildebrand equation as 1×103 and 8×102 M-1 with detection limit of 1.05×10-5 and 4.0×10-5 M for Cu2+ and I- respectively. Graphical Abstract ᅟ.

Calix[4]arene Based Dual Fluorescent Sensor for Al(3+) and S2O7 (2.).

Specific functionalized calix[4]arene based fluorescent chemosensor was synthesized for cations and anions binding efficiency examination. Receptor C4MA displayed strong affinity for Al(3+)and S2O7 (2-) with enhanced fluorescence intensity. The selective response of C4MA was investigated in the presence of different co-existing competing ions. The limit of detection (LOD) of Al(3+)and S2O7 (2-) was calculated as 2.8 × 10(-6) M and 2.6 × 10(-7) M respectively. Sensor C4MA forms (1:1) stoichiometric complex with both Al(3+) and S2O7 (2-) and their binding constants were calculated as 12.1 × 10(4) and 8.3 × 10(3) respectively. Complexes were also characterized through FT-IR spectroscopy. Graphical Abstract ᅟ.

Calix[4]arene Based Highly Efficient Fluorescent Sensor for Au(3+) and I(.).

This approach disclose the selective fluorogenic ion sensing ability of 5,11,17,23-tetratertbutyl-25,27-bis((2hydroxynaphthylimino)1,2-ethylenediaminecarbonylmethoxy)-26,28 dihydroxycalix[4]arene (C4NSB). Binding property of receptor probed by using selected various cations and anions with conferring of results that demonstrates 'turn-off' fluorescence response and significantly high chromogenic selectivity toward Au(3+) and I(-). Furthermore, selective nature of receptor was investigated in the presence of different co-existing competing ions. The limit of detection (LOD) for Au(3+) and I(-) was determined as 1.5 × 10(-5) and 4.5 × 10(-6) M respectively. Receptor C4NSB form (1:1) stoichiometric complex with both ions and their binding constants were calculated as 8.0 × 10(2) for Au(3+) and 15.6 × 10(2) M(-1) for I(-). Complexes were also characterized through FT-IR spectroscopy.

Immobilization of α-amylase onto a calix[4]arene derivative: Evaluation of its enzymatic activity.

In order to enhance the cost-effectiveness practicability of enzymes in many industries such as pharmaceutical, food, medical and some other technological processes, there is great need to immobilize them onto a solid supports. In this study, a new and efficient immobilization of α-amylase from Saccharomyces cerevisiae has been developed by using the surface functionalization of calix[4]arene as support. A glutaraldehyde-containing amino group functionalized calix[4]arene was used to immobilize α-amylase covalently. In this procedure, imide bonds are formed between amino groups on the protein and aldehyde groups on the calix[4]arene surface. The surface modified support was characterized using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM). The effect of various preparation conditions on the immobilized α-amylase process such as immobilization time, enzyme concentration, temperature and pH were investigated. The influence of pH and temperature on the activity of free and immobilized α-amylase was also studied using starch as substrate. The optimum reaction temperature and pH value for the enzymatic conversion catalyzed by the immobilized α-amylase were 25°C and 7, respectively. Compared to the free enzyme, the immobilized α-amylase retained 85% of its original activity and exhibited significant thermal stability than the free one and excellent durability.

Optimization of HPLC method for determination of cefixime using 2-thiophenecarboxaldehyde as derivatizing reagent: A new approach.

The determination of cefixime 1 has clinical and analytical importance due to its broad spectrum antimicrobial activity and stability. Cefixime is a significant member of orally active third generation cephalosporin and has excellent activity against many pathogens. It is for first time that we have developed a new HPLC-DAD method for analysis of imine derivative 3 of cefixime by using reflux method at 100 °C for 50 min without any buffer solution. 2 Thiophenecarboxaldehyde (2TCA) 2 was used first time as a derivatizing reagent for cefixime drug. Furthermore, separation of three components, i.e. drug (cefixime), reagent (2TCA) and derivative was carried out using kromasil 100 C-18 (15 mm × 0.46 mm, 5 µm) column with isocratic elution of methanol: 0.1% aqueous formic acid (70:30 v/v) with flow rate of 1 ml min(-) (1) at retention time of 1.8, 2.4 and 3.3 min, respectively; while, total run time was 5 min. The developed method was repeatable with a relative standard deviation (RSD) of 0.81-1.88% for imine derivative. The limit of detection and quantification of imine derivative 3 were obtained within the range of 0.132-0.401 µg ml(-) (1) and compared with cefixime drug as 0.30-0.90 µg ml(-1), respectively. However, the formation of imine derivative 3 was confirmed by comparing peak height, retention time and spectral changes. The method is rapid, simple, very stable and accurate for the separation and determination of imine derivative 3 of cefixime 1.

Synthesis of Cr(III)-morin complex: characterization and antioxidant study.

The complex formation between Cr(III) and morin was carried out in methanol and confirmed by analytical characterization using UV-Vis, IR, (1)H NMR, and TG-DTA. UV-Vis shows significant bathochromic shift in benzoyl upon coordination as well as IR well illustrates the peak shift of C=O group and formation of a O-Cr(III) bond. Likewise, (1)H NMR studies clarify that Cr(III) metal ion replaces the 5OH proton hence; 5-hydroxy-4-keto site is employed by morin in chelation to form six-membered stable ring system out of three available chelating sites. In addition, TG-DTA denotes the presence of coordinated and crystalline water molecules. The melting point of the complex was found to be 389 °C by DSC. In addition, Cr(III)-morin complex was found to be a more potent antioxidant than morin as evaluated by DPPH• and FRAP methods.

Comparison of chemical composition of Aerva javanica seed essential oils obtained by different extraction methods.

Aerva javanica (Burm.f.) Juss. ex Schult. seed essential oils were obtained by hydrodistillation (HD) and dry steam distillation (SD) extracting methods and analyzed by using gas chromatography-mass spectrometry(GC-MS). Twenty and eighteen components representing 90.5% and 95.6% of the seed essential oil were identified, using hydrodistillation and dry steam distillation, respectively. The major constituent identified from seed essential oil obtained by HD were heptacosane (25.4%), 3-allyl-6-methoxyphenol (14.1%), pentacosane (12.1%), 6,10,14-trimethyl-2-pentade-canone (7.9%), nonacosane (7.1%), tricosane (3.6%), α-farnesene (3.5%), dodecanal (2.7%) and octacosane (2.1%). Whereas the major constituent identified from seed essential oil obtained by SD were heptacosane (41.4%), pentacosane (21.2%), nonacosane (14.8%), tricosane (6.3%), octacosane (4.2%) and tetracosane (3.0%).

Bifunctional calix[4]arene sensor for Pb(II) and Cr2O7(2-) ions.

A readily available chromionophore 5,11,17,23-tetra-tert-butyl-25,27-bis(hydrazidecarbonylmethoxy)-26,28-dihydroxycalix[4]arene (HCC4) was employed as a chromogenic sensing probe selective for Pb(II) and Cr2O7(2-) ions among a series of various ions such as Li(I), Na(I), K(I), Rb(I), Ba(II), Sr(II), Al(III), Cd(II), Co(II), Cu(II), Hg(II), Ni(II), Pb(II) and Zn(II) as well as Cr2O7(2-), CH3CO2(-), Br(-), Cl(-), F(-), I(-), ClO4(-) and NO3(-) that have been examined by UV-visible and fluorescence spectroscopic techniques. The HCC4 in DCM-MeCN system forms 2:1 (ligand-metal) complex with Pb(II). It also shows 2:1 stoichiometry with Cr2O7(2-). The complexation phenomenon has been confirmed by FTIR spectroscopy that favors the selective nature of HCC4 with Pb(II) and Cr2O7(2-). Thermal gravimetric analysis (TGA) also supports its utility in drastic conditions.

An excellent copper selective chemosensor based on calix[4]arene framework.

The article depicts a detailed study regarding copper selective chemosensing and complexation nature of 5,11,17,23-tetrakis[(N,N-diphenylamino)methyl]-25,26,27,28-tetrahydroxycalix[4]arene (PAC4). Its photophysical characteristics in various solvents of different polarities along with the influence of acid and base on its spectral properties in these solvents are also discussed. The complexation affinity of PAC4 with regard to its latent applications as Cu(II) selective colorimetric and fluorescent sensor among the selected series of various cations such as Li(I), Na(I), K(I), Rb(I), Ba(II), Sr(II), Al(III), Fe(III), Cd(II), Co(II), Hg(II), Mn(II), Ni(II), Pb(II) and Zn(II) was examined by UV-visible and fluorescence emission spectroscopy in dichloromethane:acetonitrile (DCM:MeCN) solvent system. In addition, the process of complexation has been investigated through Job's plot and it has been observed that the complex between PAC4 and Cu(II) is formed in 1:1 stoichiometric ratio. The complex formation between PAC4 and Cu(II) has also been confirmed by FT-IR spectroscopy and thermal gravimetric analysis (TGA).

Chemical composition of essential oil from Calligonum polygonoides Linn.

The essential oil from air dried buds and roots of Calligonum polygonoides Linn., has been extracted from dry steam distillation and analysed for chemical composition by gas chromatography-mass spectrometry. In total, 27 and 10 compounds were analysed qualitatively and quantitatively, accounting for 68.42% and 82.12% total contents of the essential oils of buds and roots, respectively. It contains a complex mixture of terpenoids, hydrocarbons, phenolic compounds, acid derivatives and ketones. The main component of essential oil was ethyl homovanillate (11.79%) in buds and drimenol (29.42%) in roots.

Determination of free phenolic acids and antioxidant capacity of methanolic extracts obtained from leaves and flowers of camel thorn (Alhagi maurorum).

The present study comprises the determination of some phenolic acids from the leaves and flowers of Alhagi maurorum by HPLC-DAD, confirmed by LC-MS-APCI. The antioxidant properties and measurements of the total phenolic contents of the extracts were assessed by 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging and Folin-Ciocalteu methods, respectively. It was found that the leaf extract had higher antioxidant potential (83.5%) than the flower extract (72.3%). The antioxidant properties and total phenolic contents of the leaves were higher than those of the flowers.

Analytical evaluation of Cu2+ selective behavior of calix[4]arene derivative.

The present article describes the solvatochromic effect including solvent system selection, time study and a detailed complexation study along with exploration of extraction properties of 5,11,17,23-tetrakis[(diethylamino)methyl]-25,26,27,28-tetrahydroxycalix[4]arene (4) that bears nitrogen atom as a donor group available for chelating metal ions. Complexation properties of 4 toward selected transition metal ions have been investigated by UV-visible and fluorescence spectroscopies. The% efficiency of 4 toward selected transition metal ions was found in order Cu(2+)>Ni(2+)>Hg(2+)>Zn(2+)>Co(2+)>Cd(2+)>Pb(2+). It has been noticed that 4 is not only proved to be an efficient Cu(2+) selective chromoionophore but also possesses an effective extraction property for transferring Cu(2+) ions from an aqueous to dichloromethane layer. The FT-IR spectroscopic method has also been applied for further confirmation of the complexation phenomenon of 4 with Cu(2+) ion and found adequate.

Hg(II) selective complexation by chromoionophoric calix[4]arene derivative.

The present article describes an exploration regarding Hg(II) selective complexation behavior of 5,11,17,23-tetrakis[(N,N-dimethylamino)methyl]-25,26,27,28-tetrahydroxycalix[4]arene (4). The binding affinity of 4 toward selected transition metal ions such as Cd(II), Co(II), Cu(II), Hg(II), Ni(II), Pb(II) and Zn(II) have been investigated by UV-visible and fluorescence spectroscopies. From the results it has been noticed that 4 confers a pronounced preference for Hg(II) in complexation phenomenon even in the presence of other metal ions. The results of Job's plot analysis reveal 1:1 host-guest complex formation between Hg(II) and 4. The FT-IR spectroscopy also supports the complexation affinity of 4 for Hg(II).