Controlled Microwave-Assisted Synthesis of the 2D-BiOCl/2D-g-C3N4 Heterostructure for the Degradation of Amine-Based Pharmaceuticals under Solar Light Illumination.

Designing efficient 2D-bismuth oxychloride (BiOCl)/2D-g-C3N4 heterojunction photocatalysts by the microwave-assisted method was studied in this work using different amounts of BiOCl plates coupled with g-C3N4 nanosheets. The effects of coupling the 2D structure of g-C3N4 with the 2D structure of BiOCl were systematically examined by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy, X-ray diffraction, photoluminescence (PL), lifetime decay measurement, surface charges of the samples at various pH conditions, and UV-vis diffuse reflectance spectroscopy (UV-vis DRS). The prepared photocatalysts were used for the degradation of amine-based pharmaceuticals, and nizatidine was used as a model pollutant to evaluate the photocatalytic activity. The UV-vis DRS and other optical properties indicated the major effect of coupling of BiOCl with g-C3N4 into a 2D/2D structure. The results showed a narrowing in the band gap energy of the composite form, whereas the PL and lifetime analysis showed greater inhibition of the electron-hole recombination process and slightly longer charge carrier lifetime. Accordingly, the BiOCl/g-C3N4 composite samples exhibited an enhancement in the photocatalytic performance, specifically for the 10% BiOCl/g-C3N4 sample. Moreover, the zeta potential of this sample at different pH values was evaluated to determine the isoelectric point of the synthesized composite material. Consequently, the pH was adjusted to match the isoelectric point of the complex materials, which further enhanced the activity. Further degradation of pharmaceuticals was studied under solar light irradiation, and 96% degradation was achieved within 30 min.

Cellulose an ageless renewable green nanomaterial for medical applications: An overview of ionic liquids in extraction, separation and dissolution of cellulose.

Cellulose is a renewable natural fiber, which has gained enormous and significant research interest and evolved as the prime and promising candidate for replacing synthetic fibers. The various sources of cellulose, which is one of the world's most ubiquitous and renewable biopolymer resources, include trees, plants, tunicate and bacteria. The renewable biomaterial in the form of nanocellulose and its composites have been included in this review having the broad range of medical applications, viz.; tissue engineering, cardiovascular surgery, dental, pharmaceuticals, veterinary, adhesion barriers and skin therapy. These grafts are being fabricated from biodegradable materials. Bacterial cellulose is also an emerging renewable biomaterial with immense potential in biomedical field. The fabrication methods, characteristic properties and various overwhelming applications of cellulosic composites are explicitly elucidated in this review. The crux of this review is to exhibit the latest state of art, development in the field of cellulosic nanocomposite science and technology research and their applications towards biomedical field. Among the fourteen principle of green chemistry the two key principles i.e. using environmentally preferable solvents and bio-renewable feed-stocks covers in dissolution of cellulose in ionic liquids (ILs). In addition, this review covers about the comprehensive extraction and dissolution of cellulose and nanocellulose using ILs.

Tuning the constrained photophysics of a pyrazoline dye 3-naphthyl-1-phenyl-5-(4-carboxyphenyl)-2-pyrazoline inside the cyclodextrin nanocavities: A detailed insight via experimental and theoretical approach.

The modulation in the photophysics of a pyrazoline dye 3-naphthyl-1-phenyl-5-(4-carboxyphenyl)-2-pyrazoline (NPCP), when it drifts from bulk water into the nanocages of aqueous cyclodextrin solutions was investigated. The intramolecular charge transfer (ICT) fluorescence band intensity was found to increase with a blue shift in the presence of cyclodextrins. The results from 1H NMR and 1HH COSY NMR spectral analysis clearly points out the position of pyrazoline ring inside the cavity and its role in complexation process. A quantitative assessment of the emission intensity data on Benesi-Hildebrand (B-H) equation along with ESI-MS spectra reveals the probable stoichiometry of NPCP-CD complexes. Molecular docking and molecular dynamics studies were conducted for ß/γ cyclodextrin associated inclusion complexes of NPCP. The results obtained by computational studies are in good relation with the data obtained through experimental methods and both ascertain the encapsulation of NPCP into cyclodextrins.

Nanotechnology: a clean and sustainable technology for the degradation of pharmaceuticals present in water and wastewater.

Pharmaceuticals, newly recognized classes of environmental pollutants, are becoming increasingly problematic contaminants of either surface water or ground water around industrial and residential communities. Pharmaceuticals are constantly released into aquatic environments, mainly due to their widespread consumption and complicated removal in wastewater treatment plants. Heterogeneous photocatalysis appear to be one of the most destructive advanced oxidation processes (AOPs) for organic contaminants and are possible to obtain complete mineralization of organic pollutants into eco-friendly end products under visible and solar light irradiation. In this study, flower-like In2S3 hierarchical nanostructures were successfully prepared via a facile solution-phase route, using thioacetamide as both sulfur source and capping agent. X-ray diffractometry (XRD) of the flowers revealed that the cubic structure of In2S3; morphological studies examined by scanning electron microscopy (SEM) showed the synthesized In2S3 nanostructure was flower-like hierarchitecture assembled from nanoscale flakes. X-ray photoelectron spectroscopy (XPS) analysis confirmed the stoichiometry of In2S3 nanoflowers. Furthermore, the photocatalytic activity studies revealed that the prepared indium(III) sulfide(In2S3) nanoflowers exhibit an excellent photocatalytic performance, degrading rapidly the aqueous pharmaceutical solution of Lisinopril under visible light irradiation. These results suggest that In2S3 nanoflowers will be a promising candidate of photocatalyst working in thevisible light range.

Microfluidic Precolumn Derivatization of Environmental Phenols with Coumarin-6-Sulfonyl Chloride and HPLC Separation.

A simple, fast, sensitive and versatile method for the analysis of phenols in water is proposed using microfluidic precolumn derivatization with the fluorogenic label coumarin-6-sulfonyl chloride (C6SCl) and HPLC separation on monolithic columns. Phenols react with C6SCl within 3.0 min in the microreactor at ambient temperature to produce phenol-coumarin sulphonamides derivatives which were separated in reversed phase high-performance liquid chromatography followed by postcolumn ring-opening and fluorescence detection at λexc = 360 nm and λem = 460 nm. The optimum conditions for the derivatization, separation and ring-opening reaction have been established. The calibration curves were linear for the studied phenols in the range of 0.75-12.5 mg L(-1). The application of the method to environmental samples was demonstrated by analyzing tap and fountain water samples spiked with the phenolic compounds.

Determination of the pseudoephedrine content in pharmaceutical formulations and in biological fluids using a microbore HPLC system interfaced to a microfluidic chemiluminescence detector.

A novel automated precolumn derivatization followed by separation using liquid chromatography for the determination of pseudoephedrine (PSE) by a microfluidic chemiluminescence detector has been developed. An on-line derivatization procedure was utilized by converting PSE into a highly light emitting species in a Ru(bipy)3(2+)-peroxydisulphate chemiluminescence (CL) system by derivatizing it with a 1.0 M formaldehyde solution. The derivatized analyte was directly injected into a microbore high-performance liquid chromatography (HPLC) system coupled to an on-chip chemiluminescence detector. The newly developed highly selective, sensitive and fast HPLC-CL method was validated and successfully applied for the analysis of PSE in pharmaceutical formulations and a human urine sample. The selectivity of the method is not only due to the HPLC separation but is also due to the highly selective detection principle of the Ru(bipy)3(2+)-peroxydisulphate CL system used. There was no interference observed from the common preservatives and excipients used in pharmaceutical preparations, which did not show any significant CL signal. The retention time of PSE was less than 3 min, and the detection limits and quantification limits were found to be 5.7 and 26.0 µg L(-1), respectively.

Study on the spectral and inclusion properties of a sensitive dye, 3-naphthyl-1-phenyl-5-(5-fluoro-2-nitrophenyl)-2-pyrazoline, in solvents and ß-cyclodextrin.

3-Naphthyl-1-phenyl-5-(5-fluoro-2-nitrophenyl)-2-pyrazoline (NPFP), a fluorogenic probe and its derivative NPFP-Phenylephrine were synthesized and their absorption and fluorescence properties were recorded in solvents of varying polarity. Spectroscopic studies reveal that, the solvatochromic behavior of the compounds depend not only on the polarity but also on the hydrogen-bonding properties of the solvents. The effects of ß-cyclodextrin on the fluorescence properties of both compounds were studied. It was found that there is an enhancement in the fluorescence intensity of labeled drug (NPFP-Phenylephrine) in the presence of ß-cyclodextrin. In the present study, the molecular motions of NPFP-Phenylephrine embedded in a ß-cyclodextrin cavity have been investigated by fluorescence techniques in steady-state and time resolved modes.

Parallel microdevice for high throughput analysis of levofloxacin using tris (2,2'-bipyridyl) ruthenium (II) and peroxydisulfate chemiluminescence system.

A parallel microdevice has been developed for high throughput analysis using microfluidics. The detection method is based on a chemiluminescence (CL) system based on the oxidation of tris (2,2'-bipyridyl) Ru(ll) [Ru (bipy)3(2+)] by peroxydisulfate. The device consists of a photoreactor chip and two detection chips. The sample throughput can reach up to 720 runs/h with the total reagent consumption of only 2.4 mL. The parallel microdevice was evaluated using levofloxacin (LEVO) in pharmaceutical preparations. The various factors that affect the CL signal were optimized, and the LOD was found to be 30 and 27 microg/L for the two detectors, respectively (S/N = 3), while RSD was 1.1% (n = 15) for 1.0 mg/L LEVO. Two tablet samples that contain LEVO as an active ingredient were successfully analyzed using the proposed parallel microdevice.

Nanotechnology in environmental remediation: degradation of volatile organic compounds (VOCs) over visible-light-active nanostructured materials.

Volatile organic compounds (VOCs) are major pollutants and are considered to be one of the most important contaminants generated by human beings living in urban and industrial areas. Methyl tert-butyl ether (MTBE) is a VOC that has been widely used as a gasoline additive to reduce VOC emissions from motor vehicles. However, new gasoline additives like MTBE are having negative environmental impacts. Recent survey reports clearly show that groundwater is often polluted owing to leakage of petroleum products from underground storage tanks. MTBE is highly soluble in water (e.g., 0.35-0.71 M) and has been detected at high concentrations in groundwater. The presence of MTBE in groundwater poses a potential health problem. The documented effects of MTBE exposure are headaches, vomiting, diarrhea, fever, cough, muscle aches, sleepiness, disorientation, dizziness, and skin and eye irritation. To address these problems, photocatalytic treatment is the preferred treatment for polluted water. In the present work, a simple and template-free solution phase synthesis method has been developed for the preparation of novel cadmium sulfide (CdS) hollow microspheres using cadmium nitrate and thioacetamide precursors. The synthesized products have been characterized by a variety of methods, including X-ray powder diffraction, high-resolution scanning electron microscopy (HR-SEM), X-ray photoelectron spectroscopy, and UV-visible diffused reflectance spectroscopy. The HR-SEM measurements revealed the spherical morphology of the CdS microspheres, which evolved by the oriented aggregation of the primary CdS nanocrystals. Furthermore, studies of photocatalytic activity revealed that the synthesized CdS hollow microspheres exhibit an excellent photocatalytic performance in rapidly degrading MTBE in aqueous solution under visible light illumination. These results suggest that CdS microspheres will be an interesting candidate for photocatalytic detoxification studies under visible light radiation.

Determination of amlodipine using terbium-sensitized luminescence in the presence of europium(III) as a co-luminescence reagent.

A sensitive time-resolved luminescence method for the determination of amlodipine (AM) in methanol and in aqueous solution is described. The method is based on the luminescence sensitization of terbium (Tb(3+) ) by formation of a ternary complex with AM in the presence of tri-n-octylphosphine oxide (TOPO) as co-ligand, dodecylbenzenesulfate as surfactant and europium ion as a co-luminescence reagent. The signal for Tb-AM-TOPO is monitored at λex = 242 nm and λem = 550 nm. Optimum conditions for the formation of the complex in aqueous system were 0.015 m Tris (hydroxylmethyl) amino methane buffer, pH 9.0, TOPO (1.0 × 10(-4) m), Eu(3+) (2.0 × 10(-7) m), dodecylbenzenesulfate (0.14%) and 6.0 × 10(-5) m of Tb(3+) , which allows the determination of 10-50 ppb of AM with a limit of detection of 1.2 ppb. The relative standard deviations of the method range between 0.1 and 0.2% indicated excellent reproducibility of the method. The proposed method was successfully applied for the assay of AM in pharmaceutical formulations and in plasma samples. Average recoveries of 98.5 ± 0.2% and 95.2 ± 0.2% were obtained for AM in tablet and plasma samples respectively.

High throughput method for the analysis of cetrizine hydrochloride in pharmaceutical formulations and in biological fluids using a tris(2,2'-bipyridyl)ruthenium(II)-peroxydisulphate chemiluminescence system in a two-chip device.

A fast, economic and sensitive chemiluminescence (CL) method has been developed for the analysis of cetrizine hydrochloride (CET) in pharmaceutical formulations and in biological fluids. The CL method is based on the oxidation of tris(2,2'-bipyridyl)ruthenium(II) (Ru (bipy)(3)(2+)) by peroxydisulphate in a two-chip device. Up to 180 samples can be analysed per hour, consuming only minute quantities of reagents. Three instrumental setups were tested to find the most economical, sensitive and high throughput setup. In the first setup, a continuous flow of sample and CL reagents was used, whereas in the second setup, a fixed volume (2 µL) of (Ru (bipy)(3)(2+)) was introduced into a continuous infusion of peroxydisulphate and the sample. In the third design, a fixed volume of sample (2 µL) was injected while the CL reagents were continuously infused. Compared to the first setup, a 200% signal enhancement was observed in the third setup. Various parameters that influence the CL signal intensity, including pH, flow rates and reagent concentrations, were optimized. A linear response was observed over the range of 50 µg L(-1) to 6400 µg L(-1) (R(2)=0.9959) with RSD values of 1.1% (n=15) for 1000 µg L(-1). The detection limit was found to be 15 µg L(-1) (S/N=3). The amount of consumed sample was only 2 µL, from which the detected amount of CET was found to be 6.5 × 10(-14)mol. This procedure was successfully applied to the analysis of CET in pharmaceutical formulations and biological fluids.

Analysis of fexofenadine in pharmaceutical formulations using tris(1,10-phenanthroline)-ruthenium(II) peroxydisulphate chemiluminescence system in a multichip device.

A simple, rapid and sensitive method has been developed for the analysis of fexofenadine (FEX) in pharmaceutical formulations, using a tris(1,10-phenanthroline)-ruthenium(II) [Ru(phen)(3)(2+)] peroxydisulphate chemiluminescence (CL) system in a multichip device. Various parameters that influence the CL signal intensity were optimized. These included pH, flow rates and concentration of reagents used. Under optimum conditions, a linear calibration curve in the range 0.05-5.0 µg/mL was obtained. The detection limit was found to be 0.001 µg/mL. The procedure was applied to the analysis of FEX in pharmaceutical products and was found to be free from interference from concomitants usually present in these preparations.

Spectrofluorimetric determination of aluminium using 2-hydroxy-1-naphthylidene-(8-aminoquinoline).

A sensitive and selective spectrofluorimetric method has been developed for the rapid determination of aluminium. This method is based on the complex formation between aluminium and 2-hydroxy-1-naphthylidene-(8-aminoquinoline) (HNAQ). The optimum conditions for the complex formation were a metal-to-ligand (M : L) stoichiometric ratio of 1:1, a pH of 5.5 and a 0.20 m acetate buffer. The fluorescence of the complex was monitored at an emission wavelength of 502 nm with excitation at 438 nm. Under these conditions, linear calibration curves were obtained in the ranges 0.05-1 and 1-5 ppm. The detection limit was 3.4 ppb for the former and 13.5 ppb for the latter. The maximum relative standard deviation of the method for an aluminium standard of 200 ppb was 1.5% (n = 5). This method was successfully applied for the determination of aluminium in drinking water, pharmaceutical antacid tablets and suspension samples.

Fluorescence quenching studies of nitrated polycyclic aromatic hydrocarbons.

The analysis of nitrated polycyclic aromatic hydrocarbons (NPAHs) is of great importance because of the mutagenicity and possible carcinogenic activity of these compounds, which are distributed widely in the environment. Nitro-substituents in aromatic compounds are known to quench fluorescence and NPAHs have no intrinsic fluorescence, but they can be determined using their quenching effects on other fluorophores. The quenching effects of several important NPAHs on 1,2,3,4- tetrahydro-1-naphthol,5,6,7,8-tetrahydro-1-naphthol,4-(2-hydroxy-4-sulfo-1-naphthylazo)-2-naphthalene carboxylic acid and 7-amino-4-methyl coumarin have been studied. The singlet emission of these fluorophores is efficiently quenched by all the NPAHs, the quenching following the Stern-Volmer relationship. Quenching constants and the limits of detection and linear ranges of the quenchers have been determined in each case: the limits of detection are ca 1 µm.

Enhancement of on chip chemiluminescence signal intensity of tris(1,10-phenanthroline)-ruthenium(II) peroxydisulphate system for analysis of chlorpheniramine maleate in pharmaceutical formulations.

The effect of detection chip geometry on chemiluminescence (CL) signal intensity of tris(1,10-phenanthroline)-ruthenium(II) peroxydisulphate system for analysis of chlorpheniramine maleate (CPM) in pharmaceutical formulations was investigated. It was observed that the design of the detection chip is very crucial and can play an important role in enhancing the CL signal intensity in this system. The CL signal intensity was enhanced 250% when a teardrop micromixer chip was used, compared to the commonly used serpentine chip geometry. The study was conducted using a multi-chip device. In this device, chip 1 was used to prepare and pump the reagent mixture, whereas chip 3 was used for pumping the sample. The two chips were connected to the teardrop chip (2) via silica capillary where detection took place. Non-linear regression curve fitting of the calibration data revealed that the calibration curves are best described by third order polynomial equation with excellent correlation coefficients (R(2)=0.9998) for the concentration range 7.69 × 10(-8) to 5.12 ×1 0(-5)mol L(-1). A linear response is also observed over the range 7.69 × 10(-8) to 1.28 × 10(-5)mol L(-1) (R(2)=0.9996) and the detection limit was found to be 5.49 × 10(-8)mol L(-1). The device was successfully used for the analysis of CPM in tablets and a multi-component cough syrup. Results were reproducible with relative standard deviation (RSD) of 0.6-1.1%.

Chemiluminescence determination of chlorpheniramine using tris(1,10-phenanthroline)-ruthenium(II) peroxydisulphate system and sequential injection analysis.

A sequential injection (SI) method was developed for the determination of chlorpheniramine (CPA), based on the reaction of this drug with tris(1,10-phenanthroline)-ruthenium(II) [Ru(phen)(3)(2+)] and peroxydisulphate (S(2)O(8)(2-)) in the presence of light. The instrumental set-up utilized a syringe pump and a multiposition valve to aspirate the reagents [Ru(phen)(3)(2+) and S(2)O(8)(2-)] and a peristaltic pump to propel the sample. The experimental conditions affecting the chemiluminescence reaction were systematically optimized, using the univariate approach. Under the optimum conditions linear calibration curves of 0.1-10 microg/ml were obtained. The detection limit was 0.04 microg/ml and the relative standard deviation (RSD) was always < 5%. The procedure was applied to the analysis of CPA in pharmaceutical products and was found to be free from interferences from concomitants usually present in these preparations.

Terbium sensitized luminescence for the determination of ketoprofen in pharmaceutical formulations.

This paper explores an ultra-sensitive luminescence method for the determination of Ketoprofen (KP) in pharmaceutical formulations. The technique is indirect and exploits the luminescence enhancement of terbium (Tb(3+)) by complexation with KP (Tb(3+)-KP), which was monitored at respective excitation and emission wavelengths of lambda(ex) = 258 nm and lambda(em) = 549 nm. The effect of varying the Tb(3+) concentration and using multiple solvents was examined to determine optimal experimental conditions. Maximum sensitization was accomplished in the presence of methanol where the most favourable condition for the formation of the complex was recorded at a level of 1.0 x 10(-5) M of Tb(3+). Under these optimum experimental conditions, linear calibration curve was obtained in the range of 2.8 x 10(-7)-3.1 x 10(-6) M with a detection limit of 8.7 x 10(-8) M. The technique was validated with 'working' reference standards and produced relative standard deviations < 2% indicating that the reproducibility was highly acceptable. The proposed method was successfully applied to assays of KP in pharmaceutical formulations with average recoveries of 92-98%. The results were found to be in good agreement with those obtained by HPLC. The method is highly suited for general applications of this nature.

A spectrofluorimetric sequential injection method for the determination of penicillamine using fluorescamine in the presence of beta-cyclodextrins.

A simple, robust and sensitive sequential injection spectrofluorimetric method for the determination of penicillamine (PA) in pharmaceutical formulations is developed. The method is based on the formation of a highly fluorescent derivative when penicillamine is reacted with fluorescamine (FL) in borate buffer of pH 9.3. The derivative produced is monitored at an emission wavelength of 495 nm using an excitation wavelength of 355 nm. The optimum conditions for the determination of PA with FL were: 3 mM FL, pH 9.3, 5 mM methyl-beta-cyclodextrin, sample volume of 75 microL and reagent volume of 75 microL. Furthermore, the effect of various media on the fluorescence intensity of the PA-FL derivative was studied and methyl-beta-cyclodextrin was found to give the largest enhancement. A linear dynamic range for the determination of PA of 5-80 ppm was obtained with a sampling frequency of 50 h(-1) and a relative standard deviation of less than 2.5%. The method was applied to the determination of PA in pharmaceutical formulations with reasonable recoveries ranging from 101.0-103.1%, indicating that no interference is observed from concomitants usually present in dosage forms.

Spectrofluorimetric determination of zinc using 8-hydroxy-7-(4-sulfo-1-naphthylazo)-5-quinoline sulfonic acid.

A sensitive and a selective spectrofluorimetric method have been developed for the rapid determination of zinc. The method is based on the complex formation between zinc and 8-hydroxy-7-(4-sulfo-1-naphthylazo)-5-quinoline sulfonic acid (HSNQ). The optimum conditions for the complex formation were metal to ligand stoichiometric ratio of 1:1 at pH 8.0 with 0.2M acetate buffer. The fluorescence of the complex is monitored at an emission wavelength of 545 nm with excitation at 360 nm. Under these conditions linear calibration curves were obtained from 50 ppb to 400 ppb. The detection limit was 7 ppb. The maximum relative standard deviation of the method was 2% for water samples, 4% for milk samples and 7% for hair samples (n = 5). The method was successfully applied for the determination of zinc in drinking water, hair and milk samples. The results were found to be in good agreement with those obtained by flame atomic absorption spectrophotometric methods. The t-test and F-test indicated no significant difference at 95% confidence level.

Enhancement of the chemiluminescence of penicillamine and ephedrine after derivatization with aldehydes using tris(bipyridyl)ruthenium(II) peroxydisulfate system and its analytical application.

A novel sequential injection (SI) method was developed for the determination of penicillamine (PA) and ephedrine (EP) based on the reaction of these drugs with tris(bipyridyl)ruthenium(II) (Ru(bpy)(3)(2+)) and peroxydisulfate (S(2)O(8)(2-)) in the presence of light. Derivatization of PA and EP with aldehydes has resulted in a significant enhancement of the chemiluminescence emission signal by at least 25 times for PA and 12 times for EP, leading to better sensitivities and lower detection limits for both drugs. The instrumental setup utilized a syringe pump and a multiposition valve to aspirate the reagents, (Ru(bpy)(3)(2+) and S(2)O(8)(2-)), and a peristaltic pump to propel the sample. The experimental conditions affecting the derivatization reaction and the chemiluminescence reaction were systematically optimized using the univariate approach. Under the optimum conditions linear calibration curves between 0.2-24 microgmL(-1) for PA and 0.2-20 microgmL(-1) for EP were obtained. The detection limits were 0.1 microgmL(-1) for PA and 0.03 microgmL(-1) for EP. The procedure was applied to the analysis of PA and EP in pharmaceutical products and was found to be free from interferences from concomitants usually present in these preparations.