Umair Baig

Sol-gel synthesis of thorn-like ZnO nanoparticles endorsing mechanical stirring effect and their antimicrobial activities: Potential role as nano-antibiotics

The effect of mechanical stirring on sol-gel synthesis of thorn-like ZnO nanoparticles (ZnO-NPs) and antimicrobial activities is successfully reported in this study. The in-house synthesized nanoparticles were characterized by XRD, SEM, TEM, FTIR, TGA, DSC and UV-visible spectroscopy. The X-Ray Diffraction analysis revealed the wurtzite crystal lattice for ZnO-NPs with no impurities present. The diametric measurements of the synthesized thorn-like ZnO-NPs (morphology assessed by SEM) were well accounted to be less than 50 nm with the help of TEM. Relative decrease in aspect ratio was observed on increasing the agitation speed. The UV-visible spectroscopy showed the absorption peaks of the ZnO-NPs existed in both UVA and UVB region. A hypsochromic shift in λmax was observed when stirring pace was increased from 500 rpm to 2000 rpm. The FTIR spectroscopy showed the absorption bands of the stretching modes of Zn-O between 500 cm−1 to 525 cm−1. The Thermal analysis studies revealed better stability for ZnO-NPs prepared at 2000 rpm (ZnO-2000 rpm). TGA revealed the weight loss between two main temperatures ranges viz. around (90 °C–120 °C) and (240 °C–280 °C). Finally, the effect of ZnO-NPs prepared at different stirring conditions on the growth of Gram-positive (Bacillus subtilis), Gram-negative (Escherichia coli) bacteria and a fungi (Candida albicans) were examined; which showed good antibacterial as well as antifungal properties. These findings introduce a simple, inexpensive process to synthesize ZnO-NPs using conventional methods without the use of sophisticated equipments and its application as a potent nano-antibiotic.

Ferroquine and its derivatives: new generation of antimalarial agents.

Abstract Malaria has been teasing human populations from a long time. Presently, several classes of antimalarial drugs are available in market, but the issues of toxicity, lower efficacy and the resistance by malarial parasites have decreased their overall therapeutic indices. Thus, the search for new promising antimalarials continues, however, the battle against malaria is far from over. Ferroquine is a derivative of chloroquine with antimalarial properties. It is the most successful of the chloroquine derivatives. Not only ferroquine, but also its derivatives have shown promising potential as antimalarials of clinical interest. Presently, much research is dedicated to the development of ferroquine derivatives as safe alternatives to antimalarial chemotherapy. The present article describes the structural, chemical and biological features of ferroquine. Several classes of ferroquine derivatives including hydroxyferroquines, trioxaferroquines, chloroquine-bridged ferrocenophanes, thiosemicarbazone derivatives, ferrocene dual conjugates, 4-N-substituted derivatives, and others have been discussed. Besides, the mechanism of action of ferroquine has been discussed. A careful observation has been made into pharmacologically significant ferroquine derivatives with better or equal therapeutic effects to that of chloroquine and ferroquine. A brief discussion of the toxicities of ferroquine derivatives has been made. Finally, efforts have been made to discuss the current challenges and future perspectives of ferroquine-based antimalarial drug development.

Recent advances in iron complexes as potential anticancer agents

The revelation of the anticancer properties of cisplatin has inspired research into metal complexes for the treatment of cancer. Several second and third generation cisplatin analogues were developed with claims of good anticancer properties and reduced side effects. However, the persistence of some side effects and the resistance of cancer cells have tempted scientists to explore new metal complexes as anticancer drugs. Therefore, the approach of rational drug design has been extended to the development of non-platinum anticancer drugs, and a large number of such complexes have been developed. Iron complexes are of interest to inorganic medicinal chemists for the development of anticancer agents. The anticancer potency of iron complexes was first reported in ferrocenium picrate and ferrocenium trichloroacetate salts, and was attributed to their ability to form reactive oxygen species, leading to oxidative DNA damage. This review discusses the advances in iron complexes as anticancer agents. The aspects of the photocytotoxicity, redox activity and multinuclearity of anticancer iron complexes are discussed, in addition to discussing ferrocenyl derivatives and salen complexes. The legacy of nanotechnology and synergism in harnessing the potential of iron complexes is highlighted. Finally, the current challenges and future perspectives of iron complexes as anticancer agents are outlined.

In vitro DNA binding, molecular docking and antimicrobial studies on a newly synthesized poly(o-toluidine)–titanium dioxide nanocomposite

A poly(o-toluidine)–titanium dioxide (POT–TiO2) nanocomposite has been synthesized for the first time by in situ chemical oxidative polymerization of o-toluidine (OT) in the presence of titanium dioxide (TiO2) nanoparticles. FTIR, SEM, TEM, XRD, TGA and DTA were used to characterize the POT–TiO2 nanocomposite. The characterization results confirmed that there is a strong interaction between POT and TiO2 nanoparticles and the nanocomposite showed higher thermal stability than pristine POT. The in vitro DNA binding studies of POT and POT–TiO2 nanocomposite with ct-DNA in physiological buffer (pH-7.4) were investigated using spectrophotometry and circular dichroism. The absorption spectra of the POT and POT–TiO2 nanocomposite with DNA showed a hypochromic effect. The four types of 3D molecular field descriptors or field points as extrema of electrostatic, steric, and hydrophobic fields are described. These field points are used to define the properties necessary for a molecule to bind in a characteristic way into a specified active site. A molecular docking simulation was used to predict the modes of interactions of the drugs (POT and POT–TiO2) with DNA. The molecular docking results indicated that the modes of interactions between the two (POT and POT–TiO2) and DNA helix can be considered as groove binding. Moreover, the comparative antimicrobial activities of POT and its POT–TiO2 nanocomposite were tested and were found to exhibit antibacterial activity against Gram positive as well as Gram negative bacterial strains at micromolar concentration.

Direct spectral analysis of tea samples using 266 nm UV pulsed laser-induced breakdown spectroscopy and cross validation of LIBS results with ICP-MS.

Tea is one of the most common and popular beverages spanning vast array of cultures all over the world. The main nutritional benefits of drinking tea are its anti-oxidant properties, presumed protection against certain cancers, inhibition of inflammation and possible protective effects against diabetes. Laser induced breakdown spectrometer (LIBS) was assembled as a powerful tool for qualitative and quantitative analysis of various brands of tea samples using 266 nm pulsed UV laser. LIBS spectra for six brands of tea samples in the wavelength range of 200-900 nm was recorded and all elements present in our tea samples were identified. The major toxic elements detected in several brands of tea samples were bromine, chromium and minerals like iron, calcium, potassium and silicon. The spectral assignment was conducted prior to the determination of concentration of each element. For quantitative analysis, calibration curves were drawn for each element using standard samples prepared in known concentration in the tea matrix. The plasma parameters (electron temperature and electron density) were also determined prior to the tea samples spectroscopic analysis. The concentration of iron, chromium, potassium, bromine, copper, silicon and calcium detected in all tea samples was between 378-656, 96-124, 1421-6785, 99-1476, 17-36, 2-11 and 92-130 mg L(-1) respectively. The limits of detection estimated for Fe, Cr, K, Br, Cu, Si, Ca in tea samples were 22, 12, 14, 11, 6, 1 and 12 mg L(-1) respectively. To further confirm the accuracy of our LIBS results, we determined the concentration of each element present in tea samples by using standard analytical technique like ICP-MS. The concentrations detected with our LIBS system are in excellent agreement with ICP-MS results. The system assembled for spectral analysis in this work could be highly applicable for testing the quality and purity of food and also pharmaceuticals products.

Enzyme immobilization and molecular modeling studies on an organic–inorganic polypyrrole–titanium(IV)phosphate nanocomposite

In this work we report the synthesis of an electrically conductive polypyrrole–titanium(IV)phosphate (PPy–TiP) nanocomposite using simple, facile in situ chemical oxidative polymerization of polypyrrole (PPy) in the presence of titanium(IV)phosphate (TiP) for immobilization of the yeast alcohol dehydrogenase enzyme. FTIR, FE-SEM and TGA were employed for the characterization of PPy, TiP and the PPy–TiP nanocomposite. YADH was successfully immobilized on the PPy–TiP nanocomposite with a loading efficiency of 69%. The immobilized YADH showed no change in the pH optima (pH 8.0) and there was a broadening of the peak both at acidic as well as in alkaline pH. The optimum temperature of immobilized YADH was increased by 5 °C with almost the same residual activity. Immobilized YADH showed improved thermal stability at 60 °C and retained about 71% activity after 5 h of incubation. Also, the immobilized YADH showed greater reusability and retained 75% activity after 10th successive use. All the results were compared to those of free YADH, immobilized YADH on PPy and immobilized YADH on TiP. The affinity of immobilized YADH for ethanol was decreased as evident from the Km value (223.71 mM) and also there was a decrease in the maximum velocity (201.53 μM min−1) as compared to soluble YADH. The improved residual activity, stability and reusability of YADH immobilized on the PPy–TiP nanocomposite make the enzyme more suitable for industry-based applications. Molecular docking was used to query the protein – the newly synthesized chemical entity interactions that help in understanding the affinity in enzyme activity.

Dispersive micro-solid phase extraction method using newly prepared poly(methyl methacrylate) grafted agarose combined with ICP-MS for the simultaneous determination of Cd, Ni, Cu and Zn in vegetable and natural water samples

Poly(methyl methacrylate) grafted agarose (agarose-g-PMMA) was prepared as a new adsorbent for the simultaneous separation and preconcentration of trace amounts of cadmium(II), nickel(II), copper(II) and zinc(II) in vegetable and natural water samples with a simple and facile dispersive micro-solid phase extraction (D-μ-SPE) prior to ICP-MS detection. Agarose-g-PMMA was prepared by microwave-assisted free radical polymerization, and the materials obtained under optimum conditions in high percentage of grafting were characterized by FTIR, FE-SEM, DSC and TGA. The effective parameters of the extraction process, such as mass of adsorbent, pH of sample solution, adsorption time, type of eluent, concentrations and volume of eluent and desorption time were optimized. A preconcentration factor (PF) of 100 was obtained for trace metals with an elution time of 120 s. Under the optimum conditions, the limits of detection (LODs) for Cd, Ni, Cu and Zn were 1.8, 0.9, 0.6 and 1.5 ng L−1 with relative standard deviations (RSDs) of 2.1%, 3.5%, 4.9% and 3.8%, respectively, at an analyte concentration of 10 ng L−1, n = 7. The proposed method was successfully applied for the determination of heavy metals in vegetable and natural water samples with good relative recoveries in the range of 92.0–104.0%.

Qualitative and quantitative spectro-chemical analysis of dates using UV-pulsed laser induced breakdown spectroscopy and inductively coupled plasma mass spectrometry.

Laser Induced Breakdown Spectroscopy (LIBS) is demonstrated for the spectral analysis of nutritional and toxic elements present in several varieties of date fruit samples available in the Saudi Arabia market. The method analyzes the optical emission of a test sample when subjected to pulsed laser ablation. In this demonstration, our primary focus is on calcium (Ca) and magnesium (Mg), as nutritional elements, and on chromium (Cr), as a toxic element. The local thermodynamic equilibrium (LTE) condition was confirmed prior to the elemental characterization of date samples to ensure accuracy of the LIBS analysis. This was achieved by measuring parameters associated with the plasma, such as the electron temperature and the electron number density. These plasma parameters aid interpretation of processes such as ionization, dissociation, and excitation occurring in the plasma plume formed by ablating the date palm sample. The minimum detection limit was established from calibration curves that involved plotting the LIBS signal intensity as a function of standard date samples with known concentrations. The concentration of Ca and Mg detected in different varieties of date samples was between 187 and 515 and 35-196mgL(-1) respectively, while Cr concentration measured between 1.72 and 7.76mgL(-1). In order to optimize our LIBS system, we have studied how the LIBS signal intensity depends on the incident laser energy and the delay time. In order to validate our LIBS analysis results, standard techniques such as inductively coupled plasma mass spectrometry (ICP-MS) were also applied on an identical (duplicate) date samples as those used for the LIBS analysis. The LIBS results exhibit remarkable agreement with those obtained from the ICP-MS analysis. In addition, the finger print wavelengths of other elements present in date samples were also identified and are reported here, which has not been previously reported, to the best of our knowledge.

Pharmacological evaluation of poly(3-methylthiophene) and its titanium(IV)phosphate nanocomposite: DNA interaction, molecular docking, and cytotoxic activity.

Cancer and pathogenic microbial diseases have terribly affected human health over a longer period of time. In response to the increasing casualties due to cancer and microbial diseases, unique poly(3-methylthiophene) and poly(3-methylthiophene)-titanium(IV)phosphate composite were prepared via in-situ oxidative chemical polymerization in this work. The poly(3-methylthiophene) and poly(3-methylthiophene)-titanium(IV)phosphate composite were well characterized by Fourier transform infrared spectroscopy and field emission scanning electron microscopy. DNA binding studies by UV-Visible and fluorescence spectroscopic investigations indicated strong binding affinities of poly(3-methylthiophene) and poly(3-methylthiophene)-titanium(IV)phosphate nanocomposite; leading to structural damage of DNA. Poly(3-methylthiophene)-titanium(IV)phosphate nanocomposite showed stronger interactions with DNA as compared to poly(3-methylthiophene) and from dye displacement assay it was confirmed that mode of binding of both the formulations was intercalative. The antimicrobial screening revealed that polymer and its composite displayed stronger antibacterial effects than ampicillin against Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa and Salmonella typhimurium. Besides, the poly(3-methylthiophene) and poly(3-methylthiophene)-titanium(IV)phosphate nanocomposite showed dose dependent effects towards estrogen receptor positive breast cancer (MCF-7) and estrogen receptor negative breast cancer (MDA-MB-231) cell lines; with poly(3-methylthiophene)-titanium(IV)phosphate nanocomposite showing better activities against both cell lines. In all in-vitro biological investigations, poly(3-methylthiophene)-titanium(IV)phosphate composite showed superior properties to that of the pure poly(3-methylthiophene), which encouraged us to suggest its potential as future therapeutic gear in drug delivery and other allied fields.

Multi-walled carbon nanotubes-agarose gel micro-solid phase extraction for the determination of triazine herbicides in water samples

In this work, a new extraction procedure termed multi-walled carbon nanotubes-agarose gel micro-solid phase extraction (MWCNTs-AG-μSPE) combined with gas chromatography-mass spectrometry (GC-MS) was developed and used for the determination of triazine herbicides in water samples. A high performance synthetic adsorbent, MWCNTs-AG, was prepared using a simple stirring method. Different stoichiometric ratios of MWCNTs and agarose were mixed in deionized water for at least 24 h at room temperature in order to obtain agarose solutions with homogeneously mixed MWCNTs. Two selected triazine herbicides, namely, atrazine (ATR) and secbumeton (SEC) were employed as model compounds. Several important parameters, such as the effects of concentration of MWCNTs, type of conditioning solvent, extraction time, type of desorption solvent and desorption time, were comprehensively optimized. Under the optimized conditions, the calibration results showed good linearity with the correlations of determination (r2) in the range of 0.9925–0.9981 for both analytes. Limits of detection (LODs) were found to be 0.319 μg L−1 and 0.340 μg L−1, while the LOQs were found to be 1.064 μg L−1 and 1.136 μg L−1 for ATR and SEC, respectively. High relative recoveries were obtained in the range of 84.9–108% for the analytes with a relative standard deviation of <15.2% (n = 3). The results showed that MWCNTs-AG-μSPE method is superior to AG-μSPE for both the analytes. This new method was successfully applied for the determination of triazine herbicides in selected water samples. Atrazine was found to be present in the lake water sample because it had a signal higher than the LODs and lower than LOQs. The proposed technique proved to be simple and requires relatively short extraction time and low amounts of organic solvents; thus, contributing towards green chemistry.