Muhammad Naeem Ashiq

Preparation and characterization of SrTiO3–ZnTe nanocomposites for the visible-light photoconversion of carbon dioxide to methane

Limited fossil fuel resources and increasingly stringent requirement of environmental protection from major greenhouse gases, including carbon dioxide (CO2), which results directly from the burning of fossil fuels, energy savings and greenhouse-effect alleviation have emerged as major global concerns. The development of an “artificial photosynthetic system” (APS) having both the analogous important structural elements and the reaction features of photosynthesis to achieve solar-driven water splitting and CO2 reduction is highly challenging. Herein, it has been demonstrated that SrTiO3–ZnTe can be utilized as an efficient APS for the photoreduction of CO2 into methane (CH4) under visible-light irradiation (≥420 nm). The results indicate that the combination of ZnTe with SrTiO3 visibly increases the formation of CH4 by efficiently promoting electron transfer from the conduction band of ZnTe to that of SrTiO3 under visible-light irradiation, and thereby demonstrate this to be a promising candidate for the photocatalytic conversion of CO2 into hydrocarbon fuels.

Functionalized diamond nanopowder for phosphopeptides enrichment from complex biological fluids.

Diamond is known for its high affinity and biocompatibility towards biomolecules and is used exclusively in separation sciences and life science research. In present study, diamond nanopowder is derivatized as Immobilized Metal Ion Affinity Chromatographic (IMAC) material for the phosphopeptides enrichment and as Reversed Phase (C-18) media for the desalting of complex mixtures and human serum profiling through MALDI-TOF-MS. Functionalized diamond nanopowder is characterized by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy. Diamond-IMAC is applied to the standard protein (β-casein), spiked human serum, egg yolk and non-fat milk for the phosphopeptides enrichment. Results show the selectivity of synthesized IMAC-diamond immobilized with Fe(3+) and La(3+) ions. To comprehend the elaborated use, diamond-IMAC is also applied to the serum samples from gall bladder carcinoma for the potential biomarkers. Database search is carried out by the Mascot program (www.matrixscience.com) for the assignment of phosphorylation sites. Diamond nanopowder is thus a separation media with multifunctional use and can be applied to cancer protein profiling for the diagnosis and biomarker identification.

Hollow and mesoporous ZnTe microspheres: synthesis and visible-light photocatalytic reduction of carbon dioxide into methane

Hollow and mesoporous microstructures have been found to be an attractive class of materials due to their superior physical properties and potential applications. In the present work, a hydrothermal method has been used to synthesize hollow and mesoporous ZnTe hierarchical microspheres. The as-synthesized microspheres are characterized by a variety of techniques, including X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, high resolution transmission electron microscopy, X-ray photoelectron spectroscopy and ultraviolet-visible spectroscopy. Nitrogen adsorption–desorption measurements and the curve of relative pore size distribution via Brunauer–Emmett–Teller analysis confirm the existence of mesopores in the obtained nanomaterials. Different reaction parameters such as NaOH concentration, reaction temperature and time, and concentration of the tellurium precursor have been studied and the detailed growth mechanism has been proposed. These hollow and mesoporous microspheres are also used for the photoreduction of carbon dioxide into methane under visible-light illumination (λ ≥ 420 nm) with a solar energy conversion efficiency of 0.072%.

Synthesis of a Bi2S3/CeO2 nanocatalyst and its visible light-driven conversion of CO2 into CH3OH and CH4

Due to shortage of fossil fuels and rapid growth of energy demand, exploration of new energy resources becomes essential. Moreover, the CO2 level is increasing day by day, which has caused global warming as well as environmental pollution. Designing a suitable photocatalyst that can solve both issues always remains a challenge. In this work, we have designed such a nanocatalyst that may be helpful in solving these issues. A hydrothermal method has been used for the synthesis of Bi2S3 and CeO2, and their nanocomposite (Bi2S3/CeO2) has been prepared by a two-step method. X-ray diffraction results confirm the formation of the target materials. High resolution transmission electron microscopy and scanning electron microscopy show that Bi2S3 is rod-shaped and CeO2 is in the form of spherical particles. Both Bi2S3 and CeO2 are well distributed in the nanocomposite. The optical properties of the obtained nanocatalysts are analyzed by UV/visible absorption spectroscopy and photoluminescence spectroscopy. X-ray photoelectron spectra are used to determine the position of the valence band. All the synthesized materials are applied to the photoreduction of CO2 with water under visible-light irradiation (λ ≥ 420 nm). The Bi2S3/CeO2 nanocomposite exhibits higher yields of methane and methanol than the individual semiconductors. Moreover, the nanocomposite shows improved stability compared to the individual catalysts.

Removal of methylene blue from aqueous solution using acid/base treated rice husk as an adsorbent

Abstract An agricultural waste, cheap and easily available rice husk is chemically modified with acid/base and used as an adsorbent for the removal of methylene blue (MB) (one of the industrially important dye) from aqueous media. The adsorption data were evaluated by Freundlich, Langmuir and Dubinin–Radushkevich isotherm models. Langmuir model showed best fit to the data indicating the formation of monolayer. The adsorption capacity (q m) of the chemically modified rice husk was found to be 93.5 mg/g at a temperature of 298 K which is higher than that reported earlier in the literature which suggests that the treated rice husk can be efficiently used for the removal of MB. The adsorption kinetics was investigated by pseudo-first-, pseudo-second-order kinetic and intra-particle diffusion models. The q e value calculated from pseudo-second-order kinetic model is in agreement with the experimental value with higher correlation coefficient (0.9988). The non-linearity of intra-particle diffusion model is an i...

Newly developed poly(allyl glycidyl ether/divinyl benzene) polymer for phosphopeptides enrichment and desalting of biofluids.

The polymeric materials have contributed significantly in the area of bioanalytical science. The functionalization of polymeric backbone after its development brings unique selectivity towards the target biomolecules. In present work, the functionalities of choice have been introduced through the ring-opening of allyl glycidyl ether. The utility of polymer is widened through derivatizations to immobilized metal ion affinity chromatographic (IMAC) material for the phosphopeptides enrichment and Reversed Phase (C-18) for the desalting prior to MALDI-MS analysis. The polymer-IMAC in addition to Fe(3+) is also immobilized with lanthanide ions like La(3+), Eu(3+), and Er(3+). The amount of Fe(3+) immobilized is determined as 0.7928 mg/g. Spherical morphology with narrow particle size dispersion is revealed by scanning electron microscopy (SEM). The surface area, pore volume and size distribution is determined by nitrogen adsorption porosimetery. The elemental composition and purity level is confirmed by energy dispersive X-ray spectroscopy (EDX) data. The derivatization to IMAC and RP is evaluated by Fourier transform infrared (FT-IR) spectroscopy. The polymer enables the efficient phosphopeptide enrichment to equal degree from casein variants, non-fat milk, egg yolk, human serum, and HeLa cell extract. The identification of phosphorylation sites can lead to the phosphorylation pathways to understand the post-translational modifications. The identification with their sequence coverage is made using Mascot and Phosphosite Plus. It is sensitive to enrich the phosphopeptides down to 2 femtomoles with very high selectivity of 1:2000 with BSA background. These attributes are linked to the higher surface area (173.1554 m(2)/g) of the designed polymer. The non-specific bindings, particularly the Fe(3+) linked acidic residues are also avoided. Four characteristic phosphopeptides (fibrinopeptide A and their hydrolytic products) from fibrinogen α-chain are identified from the human serum after the enrichment, which have link to the hepatocellular carcinoma (HCC). The proportions of fibrinogen and their phosphorylation products enriched by poly(AGE/DVB)-IMAC open new horizons in the biomarker discovery.

Effect of annealing temperature and substitution of Zr-Cu on magnetic properties of strontium hexaferrite nanoparticles

ZnTe and ZnTe:Cr films were prepared onto glass substrates using the thermal evaporation method. Structural properties of the prepared samples were analyzed using X-ray diffractometry, and the presence of a ZnCrTe phase was identified along with poor crystallinity. Composition analysis was done using XPS and the Cr content in the film was found to be 0.05 atomic percent. Transmittance spectra were recorded using UV-Vis spectrophotometry. The valence state of Cr in ZnTe:Cr film is determined to be +2 using electron spin resonance (ESR) spectroscopy. Magnetic moment data as a function of magnetic field were recorded using a Superconducting Quantum Interference Device (SQUID) magnetometer at temperatures of 5, 77 and 300 K. The results showed minority ferromagnetic behavior even at room temperature. Magnetic domains were observed using Magnetic Force Microscopy and the average domain size is 3.7 nm.

Biocompatibility of cobalt iron oxide magnetic nanoparticles in male rabbits

Present study was conducted to study the in vivo biocompatibility of cobalt iron oxide magnetic nano-particles (CoFe2O4 MNPs) in rabbits. CoFe2O4 MNPs were synthesized by the conventional micro emulsion technique in crystallite size range of 30 to 50 nm. The lattice constant (a) and cell volume were found to be 8.386 Å and 589.75 Å3, respectively, revealed by XRD. Subject animals were divided in three groups—low dose, high dose and control group without nanoparticles implantation for biocompatibility evaluation. CoFe2O4 was intraperitoneally implanted in rabbits: low dose (1mg CoFe2O4/Kg body weight) and high dose (10mg CoFe2O4/Kg body weight). Blood, serum and histological study of vital organs (liver, heart, kidney and spleen) were carried out in seven days of time protocol after sacrificing of animals. Results indicated that CoFe2O4 had drastically affected the blood chemistry in a dose-dependent manner as RDWa (P=0.01), Platelet (P<0.001) and Plateletcrit (P<0.001) concentrations reduced significantly in low dose and high dose CoFe2O4 treatments as compared to sham treated control group. Histological analysis revealed that CoFe2O4 exposure resulted in disordered and abnormal histology of liver, kidney and that of muscles at surgical site. It is concluded that CoFe2O4 has low biocompatibility and higher toxicity levels in living system at the applied doses.

Chemically modified diamond-like carbon (DLC) for protein enrichment and profiling by MALDI-MS

The development of new high throughput methods based on different materials with chemical modifications for protein profiling of complex mixtures leads towards biomarkers; used particularly for early diagnosis of a disease. In this work, diamond-like carbon (DLC) is developed and optimized for serum protein profiling by matrix-assisted laser/desorption ionization mass spectrometry (MALDI-MS). This study is carried out in connection with a material-based approach, termed as material-enhanced laser desorption ionization mass spectrometry. DLC is selected as carrier surface which provides large surface to volume ratio and offers high sensitivity. DLC has a dual role of working as MALDI target while acting as an interface for protein profiling by specifically binding peptides and proteins out of serum samples. Serum constituents are bound through immobilized metal ion affinity chromatography (IMAC) functionality, created through glycidyl methacrylate polymerization under ultraviolet light followed by further derivatization with iminodiacetic acid and copper ion loading. Scanning electron microscopy highlights the morphological characteristics of DLC surface. It could be demonstrated that IMAC functionalized DLC coatings represent a powerful material in trapping biomolecules for their further analysis by MALDI-MS resulting in improved sensitivity, specificity and capacity in comparison to other protein-profiling methods.

Gadolinium oxide: Exclusive selectivity and sensitivity in the enrichment of phosphorylated biomolecules.

Selectivity and sensitivity define the dynamic applicability of separation and enrichment techniques. Owing to proteome complexity, numbers of separation media have been introduced in phosphoproteomics. Complex samples are pretreated to make the low-abundance molecules detectable by mass spectrometry. Gadolinium oxide nanoparticles, offering mono- and bi-dentate interactions, are optimized to capture the phosphopeptides. Selectivity of 1:11 000 is achieved for digested β-casein phosphopeptides in bovine serum albumin digest background using gadolinium oxide nanoparticles. The limit of detection goes down to 1 attomole. With the optimized sample preparation protocol, gadolinium oxide nanoparticles enrich phosphopeptides of κ-casein (Ser148 and Ser170 ) from digested milk sample, fibrinogen alpha chain phosphopeptide (Ser609 ) along with four hydrolytic products of Ser22 -modified phosphopeptides from serum.