Applied Nanoscience (v.8, #1-2)

Specially designed B4C/SnO2 nanocomposite for photocatalysis: traditional ceramic with unique properties by Paviter Singh; Gurpreet Kaur; Kulwinder Singh; Bikramjeet Singh; Manpreet Kaur; Manjot Kaur; Unni Krishnan; Manjeet Kumar; Rajni Bala; Akshay Kumar (1-9).
Boron carbide: A traditional ceramic material shows unique properties when explored in nano-range. Specially designed boron-based nanocomposite has been synthesized by reflux method. The addition of SnO2 in base matrix increases the defect states in boron carbide and shows unique catalytic properties. The calculated texture coefficient and Nelson–Riley factor show that the synthesized nanocomposite has large number of defect states. Also this composite is explored for the first time for catalysis degradation of industrial used dyes. The degradation analysis of industrial pollutants such as Novacron red Huntsman (NRH) and methylene blue (MB) dye reveals that the composite is an efficient catalyst. Degradation study shows that 1 g/L catalyst concentration of B4C/SnO2 degrades NRH and MB dye up to approximately 97.38 and 79.41%, respectively, in 20 min under sunlight irradiation. This water-insoluble catalyst can be recovered and reused.
Keywords: B4C/SnO2 composite; Photocatalyst; Textile dye

Effect of heating on the structural and optical properties of TiO2 nanoparticles: antibacterial activity by Sirajul Haq; Wajid Rehman; Muhammad Waseem; Rehan Javed; Mahfooz-ur-Rehman; Muhammad Shahid (11-18).
TiO2 nanoparticles were synthesized at room temperature by chemical precipitation method and were then heated at 120, 300, 600 and 900 °C temperatures. The phase transition and crystallite size variation were determined by X-rays diffraction (XRD) analysis. The surface area, pore volume and pore size were measured using Brunauer–Emmet–Teller (BET) and Barrett–Joyner–Halenda (BJH) methods. The optical activity of heat treated and non-heat treated samples were carried out by diffuse reflectance (DR) spectroscopy. Four different methods were used to calculate band gap energy. The results obtained from thermogravimetric and differential thermal gravimetric (TG/TDG) analyses and Fourier transform infra-red (FTIR) spectroscopy agreed with each other. Agar well diffusion method has been applied to explore the antibacterial activity of nanoparticles against different bacterial strains such as Bacillus subtilis, Staphylococcus Aureus, Escherichia coli and Pseudomonas Aeruginosa. It was observed that TiO2 nanoparticles heated at 120 °C displayed maximum antibacterial activity while those heated at higher temperature showed no activity against the examined bacteria.
Keywords: Antibacterial activity; Heating; Phase transition; Rutile. Surface area

Changing the characteristics and properties of zeolite Y and nano-anatase in the formation of a nano-anatase/Y composite with improved photocatalytic and adsorption properties by E. N. Domoroshchina; V. V. Chernyshev; G. M. Kuz’micheva; A. V. Dorokhov; L. V. Pirutko; G. V. Kravchenko; R. B. Chumakov (19-31).
Zeolite Y and the NTD/Y nanocomposite, which were synthesized in situ (the addition of zeolite Y to the reaction mixture in the course of the synthesis of NTD by the sulfate method), were studied by a variety of methods. The decrease in the particle size (scanning electron microscopy) and the water content in pores (X-ray powder diffraction study, the full-profile Rietveld method, IR spectroscopy, differential scanning calorimetry), the increase in OH groups content and the decrease in the water content on the surface of zeolite (X-ray photoelectron spectroscopy) in the composition of NTD/Y compared to the initial zeolite Y were all established. A larger specific surface area of NTD/Y (Brunauer–Emmet–Teller method) compared to the initial zeolite Y is due to the fact that zeolite Y in the nanocomposite contains a smaller amount of water because of the synthesis conditions and the presence of nanocrystalline NTD on the surface of zeolite particles. It was found that NTD/Y nanocomposite exhibits a higher photocatalytic activity in the model decomposition reaction of methyl orange under UV and adsorption capacity for the extraction of P(V) and As(V) ions from aqueous media compared to the initial zeolite and pure NTD obtained under the same conditions, which differs from NTD/Y by the larger particle size, the smaller specific surface and the smaller content of OH groups and water on the surface. The role of Bronsted and Lewis centers in the realization of properties is discussed.
Keywords: Zeolite Y; Nanosized titanium dioxide; Nanocomposite; Crystalline structure and microstructure; Adsorption and photocatalytic properties

Electrospinning pectin-based nanofibers: a parametric and cross-linker study by Devon McCune; Xiaoru Guo; Tong Shi; Samuel Stealey; Romare Antrobus; Matey Kaltchev; Junhong Chen; Subha Kumpaty; Xiaolin Hua; Weiping Ren; Wujie Zhang (33-40).
Pectin, a natural biopolymer mainly derived from citrus fruits and apple peels, shows excellent biodegradable and biocompatible properties. This study investigated the electrospinning of pectin-based nanofibers. The parameters, pectin:PEO (polyethylene oxide) ratio, surfactant concentration, voltage, and flow rate, were studied to optimize the electrospinning process for generating the pectin-based nanofibers. Oligochitosan, as a novel and nonionic cross-liker of pectin, was also researched. Nanofibers were characterized by using AFM, SEM, and FTIR spectroscopy. The results showed that oligochitosan was preferred over Ca2+ because it cross-linked pectin molecules without negatively affecting the nanofiber morphology. Moreover, oligochitosan treatment produced a positive surface charge of nanofibers, determined by zeta potential measurement, which is desired for tissue engineering applications.
Keywords: Pectin; Oligochitosan; Electrospinning; Nanofiber; Tissue engineering

BIS 2062-grade carbon steel is extensively used for fishing boat construction. The steel is highly susceptible to corrosion on the hull and welding joints under marine environment. Here, we demonstrate the application of a novel multifunctional nano-metal-oxide mixture comprised of iron, titanium, and cerium as a marine coating to prevent corrosion. The electrochemical performance of nano-metal-oxide mixture coatings, applied over boat-building steel, was evaluated at 3.5% NaCl medium. The nano-mixture surface coatings showed an efficient corrosion resistance with increased polarization resistance of 6043 Ω cm2 and low corrosion current density of 3.53 × 10−6 A cm−2. The electrochemical impedance spectral data exhibited improvement in the polarization resistance of outermost surface and internal layers. The coating responded faster recovery to normal state when subjected to an induced stress over the coating. The nano-material in the coating behaves as a semiconductor; this enhanced electronic activity over the surface of the steel.
Keywords: Marine corrosion; Nano-metal oxide; Corrosion protection; Electrochemical analysis

Polyvinyl alcohol (PVA) is an important industrial chemical, which is used in numerous chemical engineering applications. It is important to study and predict the flow behavior of PVA solutions and the role of nanoparticles in heat transfer applications to be used in chemical processes on industrial scale. Therefore, the present study deals with the PVA solution-based non-Newtonian Al2O3-nanofluid flow along with heat transfer over wedge. The power-law model is used for this non-Newtonian nanofluid which exhibited shear-thinning behavior. The influences of PVA and nanoparticles concentrations on the characteristics of velocity and temperature profiles are examined graphically. The impacts of these parameters on wall shear stress and convective heat transfer coefficient are also studied through tabular form. During the numerical computations, the impacts of these parameters on flow index and consistency index along with other physical properties of nanofluid are also considered. In this study, we found an improvement in heat transfer and temperature profile of fluid by distribution of Al2O3 nanoparticles. It is also noticed that resistance between adjacent layers of moving fluid is enhanced due to these nanoparticles which leads to decline in velocity profile and increases in shear stress at wall.
Keywords: Non-Newtonian nanofluids; PVA solutions; Al2O3 nanoparticles; Wedge

Photocatalytic degradation of metronidazole and methylene blue by PVA-assisted Bi2WO6–CdS nanocomposite film under visible light irradiation by Ranjith Rajendran; Krishnakumar Varadharajan; Venkatesan Jayaraman; Boobas Singaram; Jayaprakash Jeyaram (61-78).
The enhanced photocatalytic performance of nanocomposite is synthesized via the hydrothermal method and characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FT-IR), UV–visible diffuse reflectance spectroscopy (UV–Vis DRS) and photoluminescence spectroscopy (PL). Under visible light irradiation, PVA assisted Bi2WO6–CdS nanocomposite film displayed enhanced photocatalytic efficiency and inhibition of photocorrosion as compared with pure CdS, pure Bi2WO6 and Bi2WO6–CdS composite. The PVA assisted Bi2WO6–CdS composite film catalyst showed stable catalytic performance until seven successive runs with 92% of methylene blue(MB) degradation, and easy to recover after degradation of organic pollutant. PVA assisted Bi2WO6–CdS nanocomposite film has optimal band edge position for superior photocatalytic degradation. Furthermore, the trapping experiment was carried out using different scavenger for active species. Among the active species, OH· are the most responsive species which play a vital role in the degradation of metronidazole and MB.
Keywords: Nanocomposite; Optical properties; Trapping experiment; Photocatalytic activity; Methylene blue

Magnetism from Fe2O3 nanoparticles embedded in amorphous SiO2 matrix by A. Sendil Kumar; Anil K. Bhatnagar (79-87).
Fe2O3 nanoparticles are embedded in amorphous SiO2 matrix by coprecipitation method with varying concentrations. Conditions are optimized to get almost monodispersed Fe2O3 nanoparticles with high chemical stability. Microstructure of synthesized nanoparticles is well characterized and found that Fe2O3 is in nanocrystalline form and embedded uniformly in amorphous SiO2 matrix. Enhanced surface reactivity is found for nanoparticles which influences physical properties of the SiO2 supported Fe2O3 system due to adsorption. In oxide nanoparticles, significant number of defect sites at the surface is expected but when supported medium such as SiO2 it reduces this defect concentration. Field- and temperature-dependent magnetisation studies on these samples show superparamagnetic behaviour. Superparamagnetic behaviour is seen in all the concentration systems but the coercivity observed in the lower concentration systems is found to be anomalous compared to that of higher concentrations. The observed magnetic behaviour comes from either unsaturated bond existing due to the absence of anions at the surface of nanoparticles or reconstruction of atomic orbitals taking place at interface of Fe2O3–SiO2 system.
Keywords: Nanoparticles; Superparamagnetism; Electron diffraction; Maghemite

A dynamically reconfigurable logic cell: from artificial neural networks to quantum-dot cellular automata by Syed Rameez Naqvi; Tallha Akram; Saba Iqbal; Sajjad Ali Haider; Muhammad Kamran; Nazeer Muhammad (89-103).
Considering the lack of optimization support for Quantum-dot Cellular Automata, we propose a dynamically reconfigurable logic cell capable of implementing various logic operations by means of artificial neural networks. The cell can be reconfigured to any 2-input combinational logic gate by altering the strength of connections, called weights and biases. We demonstrate how these cells may appositely be organized to perform multi-bit arithmetic and logic operations. The proposed work is important in that it gives a standard implementation of an 8-bit arithmetic and logic unit for quantum-dot cellular automata with minimal area and latency overhead. We also compare the proposed design with a few existing arithmetic and logic units, and show that it is more area efficient than any equivalent available in literature. Furthermore, the design is adaptable to 16, 32, and 64 bit architectures.
Keywords: Quantum-dot Cellular Automata; reconfigurable logic; artificial neural networks; genetic algorithm; optimization

Large-scale synthesis of coiled-like shaped carbon nanotubes using bi-metal catalyst by Vemula Mohana Krishna; T. Somanathan; E. Manikandan; Ahmad Umar; M. Maaza (105-113).
Carbon nanomaterials (CNMs), especially carbon nanotubes (CNTs) with coiled structure exhibit scientifically fascinating. They may be projected as an innovative preference to future technological materials. Coiled carbon nanotubes (c-CNTs) on a large-scale were successfully synthesized with the help of bi-metal substituted α-alumina nanoparticles catalyst via chemical vapor deposition (CVD) technique. Highly spring-like carbon nanostructures were observed by field emission scanning electron microscope (FESEM) examination. Furthermore, the obtained material has high purity, which correlates the X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDX) analysis. Raman spectroscopy reveals that the carbon multi layers are well graphitized and crystalline, even if they have defects in its structure due to coiled morphology. High-resolution transmission electron microscope (HRTEM) describes internal structure and dia of the product. Ultimately, results support the activity of bi-metal impregnated α-alumina nanoparticles catalyst to determine the high yield, graphitization and internal structure of the material. We have also studied the purified c-CNTs magnetic properties at room temperature and will be an added advantage in several applications.
Keywords: Coiled-like CNTs; CVD technique; Bi-metal catalyst; XPS; SEM + EDAX; Magnetic properties

Real-time cellular and molecular dynamics of bi-metallic self-therapeutic nanoparticle in cancer cells by Sandeep Kumar Vishwakarma; Avinash Bardia; Chandrakala Lakkireddy; Syed Ameer Basha Paspala; Md. Aejaz Habeeb; Aleem Ahmed Khan (115-124).
Since last decades various kinds of nanoparticles have been functionalized to improve their biomedical applications. However, the biological effect of un-modified/non-functionalized bi-metallic magnetic nanoparticles remains under investigated. Herein we demonstrate a multifaceted non-functionalized bi-metallic inorganic Gd-SPIO nanoparticle which passes dual high MRI contrast and can kill the cancer cells through several mechanisms. The results of the present study demonstrate that Gd-SPIO nanoparticles have potential to induce cancer cell death by production of reactive oxygen species and apoptotic events. Furthermore, Gd-SPIO nanoparticles also enhance the expression levels of miRNA-199a and miRNA-181a-7p which results in decreased levels of cancer markers such as C-met, TGF-β and hURP. One very interesting finding of this study reveals side scatter-based real-time analysis of nanoparticle uptake in cancer cells using flow cytometry analysis. In conclusion, this study paves a way for future investigation of un-modified inorganic nanoparticles to purport enhanced therapeutic effect in combination with potential anti-tumor drugs/molecules in cancer cells.
Keywords: Gd-SPIO nanoparticles; MRI contrast; Cancer treatment; Real-time analysis

The overall effectiveness of a photocatalytic water treatment method strongly depends on various physicochemical factors. Superparamagnetic photocatalysts have incomparable advantage of easy separation using external magnetic fields. So, the synthesis of efficient superparamagnetic photocatalysts and the development of a deep understanding of the factors influencing their catalytic performances are important. Co x Zn1−x Fe2O4 (x = 0, 0.5, 1) ferrite nanospheres were synthesized by the solvothermal route. The reduction of Cr(VI) and degradation of methyl orange (MO) impurities were carried out in single- and binary-component system under visible light irradiation. The adsorption experiments were done by the catalyst in the water solution containing the impurities. The magnetic and optical properties were studied by VSM and UV–Vis analysis. The nature of porosity was investigated using the BET method. 3D nanospheres of diameter about 5–10 nm were fabricated. The binary-contaminant system exhibited synergetic photocatalytic effect (80% improvement in activity rate) against the nanoparticles. The corresponding mechanism is discussed. CoFe2O4 exhibited better adsorption, photocatalytic and magnetic separation efficiency due to its higher surface area (50% higher), narrower band gap (25% lesser), smaller crystallite size, a strong magnetic strength (51.35 emu/g) and meso–macro hierarchical porous structure. The adsorption of Cr(VI) and MO can be approximated to the Langmuir and Freundlich model, respectively.
Keywords: Synergetic photocatalysis; Superparamagnetism; Meso–macro porosity; Cr(VI) reduction; Solvothermal synthesis; Dye degradation; Adsorption isotherm

Owing to their multiple mechanisms of bactericidal activity, inorganic metal oxides and hybrid metal oxide nanocomposites may serve as a new class of effective disinfectants. Among metal oxide nanoparticles, iron oxide nanoparticles exhibit minimal or no cytotoxicity to human cells with very efficient bactericidal properties over a wide spectrum of bacteria. This paper presents the very first report on antibacterial properties of novel nanocomposites of iron oxide and cobalt oxide nanoparticles against pathogenic bacterial strains B. subtilis, S. aureus, E.coli and S. typhi. The enhanced bactericidal activity of the Fe/Co oxide nanocomposite was the result of synergistic effect of iron oxide and cobalt oxide nanoparticles. The nanocomposites were synthesized using co-precipitation route with increasing cobalt content in the sample and further characterized using XRD, TEM, Raman and VSM to investigate structural, optical and magnetic properties of the prepared nanocomposites, respectively. Also, the prepared nanocomposites were highly biocompatible and found non-toxic to human cell line MCF7.
Keywords: α-Fe2O3 ; Co3O4 ; Nanocomposite; Antibacterial; Ferromagnetic

Photocatalytic degradation of organic dyes using composite nanofibers under UV irradiation by Ahmed Salama; Alaa Mohamed; Nada M. Aboamera; T. A. Osman; A. Khattab (155-161).
In this work, photocatalytic degradation of organic dyes such as methylene blue (MB) and indigo carmine (IC) have been studied by composite nanofibers systems containing cellulose acetate (CA), multiwall carbon nanotubes (CNT) and TiO2 nanoparticles under UV light. The amino factionalized TiO2–NH2 NPs cross-linked to the CA/CNT composite nanofibers works as a semiconductor catalyst. The morphology and crystallinity were characterized by scanning electron microscopy, transmission electron microscopy (TEM), X-ray diffraction, and Fourier transform infrared spectroscopy. It was also seen that many factors affected the photodegradation rate, mainly the pH of the solution and the dye concentration, temperature, etc. The study demonstrated that IC degrades at a higher rate than MB. The maximum photodegradation rate of both organic dyes was achieved at a pH 2. In comparison to other studies, this work achieved high photodegradation rate in lower time and using less power intensity.
Keywords: Photocatalytic; Electrospinning; Composite nanofibers; UV light

In this paper, superfine SiO2 nanoparticles are utilized as composite abrasive additive to improve the polishing property of CeO2, which is prepared through chemical precipitation method by rare-earth chloride as raw materials, silicofluoric acid as fluoride, Na2CO3 as modifier, and NH4HCO3 as precipitator. XRD, SEM, particle size analyzer, and atomic force microscopy are applied to characterize the physical structure, morphology, and size distribution. Furthermore, the as-prepared composite abrasive is used to perform chemical mechanical polishing (CMP) experiment on K9 glass to identify the impact of different mass fraction of SiO2 on the CMP property of work materials. The results show that the composite abrasive contained 0.5% SiO2 has the best polishing property, the surface roughness, and material removal rate of glass after polishing can reach at 1.3157 nm and 22.6 nm/min, respectively.
Keywords: CeO2 ; SiO2 ; Composite abrasives; Characterization; Chemical mechanical polishing

Mussel inspired green synthesis of silver nanoparticles-decorated halloysite nanotube using dopamine: characterization and evaluation of its catalytic activity by Tushar Kanti Das; Sayan Ganguly; Poushali Bhawal; Sanjay Remanan; Subhadip Mondal; N. C. Das (173-186).
Naturally occurring ceramic tubular clay, Halloysite nanotubes (HNTs), having a significant amount of surface hydroxyls has been coated by self-polymerized dopamine in this work. The polydopamine-coated HNTs acts as a self-reducing agent for Ag+ ion to Ag0 in nanometer abundance. Herein, nano size Ag0 deposited on solid support catalyst has been used to mitigate water pollution within 10 min. To establish the versatility of the catalyst, nitroaryl (4-nitrophenol) and synthetic dye (methylene blue) have been chosen as model pollutant. The degradation/reduction of the aforementioned pollutants was confirmed after taking UV–visible spectra of the respective compounds. All the study can make sure that the catalyst is green and the rate constant value for catalytic reduction of 4-nitrophenol and methylene blue was calculated to be 4.45 × 10−3 and 1.13 × 10−3 s−1, respectively, which is found to be more efficient in comparison to other nanostructure and commercial Pt/C nanocatalyst (1.00 × 10−3 s−1).
Keywords: Halloysite nanotubes; Dopamine; Polydopamine; Catalyst; 4-Nitrophenol; Methylene blue

Effect of cadmium incorporation on the properties of zinc oxide thin films by S. P. Bharath; Kasturi V. Bangera; G. K. Shivakumar (187-193).
Cd x Zn1−x O (0 ≤ x ≤ 0.20) thin films are deposited on soda lime glass substrates using spray pyrolysis technique. To check the thermal stability, Cd x Zn1−x O thin films are subjected to annealing. Both the as-deposited and annealed Cd x Zn1−x O thin films are characterized using X-ray diffraction (XRD), scanning electron microscope (SEM) and energy-dispersive X-ray analysis (EDAX) to check the structural, surface morphological and compositional properties, respectively. XRD analysis reveals that the both as-deposited and annealed Cd x Zn1−x O thin films are (002) oriented with wurtzite structure. SEM studies confirm that as-deposited, as well as annealed Cd x Zn1−x O thin films are free from pinholes and cracks. Compositional analysis shows the deficiency in Cd content after annealing. Optical properties evaluated from UV–Vis spectroscopy shows red shift in the band gap for Cd x Zn1−x O thin films. Electrical property measured using two probe method shows a decrease in the resistance after Cd incorporation. The results indicate that cadmium can be successfully incorporated in zinc oxide thin films to achieve structural changes in the properties of films.
Keywords: CdZnO; Thin films; Spray pyrolysis technique

Smart multifunctional nanoagents for in situ monitoring of small molecules with a switchable affinity towards biomedical targets by Konstantin G. Shevchenko; Vladimir R. Cherkasov; Irina L. Nikitina; Andrey V. Babenyshev; Maxim P. Nikitin (195-203).
The great diversity of nanomaterials provides ample opportunities for constructing effective agents for biomedical applications ranging from biosensing to drug delivery. Multifunctional nanoagents that combine several features in a single particle are of special interest due to capabilities that substantially exceed those of molecular drugs. An ideal theranostic agent should simultaneously be an advanced biosensor to identify a disease and report the diagnosis and a biomedical actuator to treat the disease. While many approaches were developed to load a nanoparticle with various drugs for actuation of the diseased cells (e.g., to kill them), the nanoparticle-based approaches for the localized biosensing with real-time reporting of the marker concentration severely lag behind. Here, we show a smart in situ nanoparticle-based biosensor/actuator system that dynamically and reversibly changes its structural and optical properties in response to a small molecule marker to allow real-time monitoring of the marker concentration and adjustment of the system ability to bind its biomedical target. Using the synergistic combination of signal readout based on the localized surface plasmon resonance and an original method of fabrication of smart ON/OFF-switchable nanoagents, we demonstrate reversible responsiveness of the system to a model small molecule marker (antibiotic chloramphenicol) in a wide concentration range. The proposed approach can be used for the development of advanced multifunctional nanoagents for theranostic applications.
Keywords: In situ biosensors; Nanoparticles; Surface plasmon resonance; Smart materials; Self-assembly systems; Supramolecular complexes