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This work aimed to immobilize silver nanoparticles with catalytic and antibacterial activity (AgNPs) inside of the PEG-based hydrogel through a facile and green design. First, the hybrid hydrogels were prepared under solvent-free conditions based on dianhydride ethylenediamine tetraacetic acid, poly (ethylene glycol) of different molar mass, glycerol, and octa-aminopropyl polyhedral oligomeric silsesquioxane hydrochloride salt as organic and inorganic cross-linker agent. The well-dispersed AgNPs were fabricated in-situ in the polymeric matrix of the hybrid hydrogel through the reduction of Ag+ by NaBH4. The resulting hybrid nanocomposite hydrogels were characterized by various techniques, such as FT-IR spectroscopy, SEM, TEM, EDX, XRD, BET, and TGA. The swelling behavior, the antibacterial activity against the bacteria S. aureus (Gram-positive), and E. coli (Gram-negative), as well as the catalytic efficiency for the reduction reaction of 4-nitrophenol to 4-aminophenol of the nanocomposite hydrogels prepared, were examined. The facile and mass production synthetic method of the nanocomposite hydrogels, excellent dispersion of the AgNPs inside the hydrogel matrix, excellent catalytic recyclability, and antibacterial activity are some of the advantages of this system. The maximum inhibition zone was found to be 17.4 and 15.9 mm against the gram-positive species S. aureus and the gram-negative E. coli, respectively. Besides, the maximum catalytic activity was achieved in a short time period of 30 s.

A straightforward and facile method for the exfoliation of graphene sheets using poly(vinylpyrrolidone) nanoparticles of an average size of 42nm was developed and their dual role as pH-sensitive drug carrier and anti-cancer agent was evaluated. The cytotoxic impact of the exfoliated nanosheets (GRP-PVP-NP) was examined on various cells (HCT-116, HeLa, SCC-9, NIH-3T3 and HEK-293cells) by a series of assays. Their cytotoxic nature was attributed to affecting the mitochondrial enzyme activity, proliferation capability, and the formation of tight junctions in cancer cells. The endocytosis was found to be internalization mechanism for the cellular uptake of nanosheets. The generation of reactive oxygen species and elicitation of caspase-3 activity which was undoubtedly associated with triggering of oxidative stress speculated to be the dominant cause of the cytotoxic pattern of nanosheets against cancer cells. Additionally, the results also showed the role of the nanosheets as a pH-sensitive drug carrier through drug loading by supramolecular interaction. The efficient release of doxorubicin was seen at low pH and in an environment with a low oxygen concentration, thus under conditions mimicking the typical tumor microenvironment. Therefore, these findings provide the first evidence for a dual function of exfoliated graphene sheets and also elucidate the cytotoxic mechanism responsible for the cancer cell death.

Silver nanoparticles have attracted great attention in the biomedical research field, especially in cancer theranostics. In this study, we developed a synthesis method for silver nanoparticles in the solid state using high-speed vibration milling, in which biocompatible polymers such as poly(vinylpyrrolidone), poly(ethylene glycol) and chitosan were used for the reduction of the silver salt. The synthesis of the size-tunable silver nanoparticles was performed at room temperature and no surfactants to direct the anisotropic growth of the nanoparticles were required. The formation of the nanoparticles was studied using UV-visible and Fourier transform infrared spectroscopy as well as transmission electron microscopy. The synthesized nanoparticles showed an average diameter ranging from 3.1 ± 1.4 to 22.8 ± 5.8 nm. In addition, the anticancer activity of these silver nanoparticles was assessed using cytotoxicity studies with human breast adenocarcinoma (MCF-7), human lung adenocarcinoma (NCI-H358) and mouse embryonic fibroblast (NIH-3T3) cell lines. Accordingly, an effective suppression of the proliferation of cell growth was found. © 2016 Society of Chemical Industry

Halloysite is a unique biocompatible aluminosilicate clay mineral with powder particles predominantly comprising of concentrically rolled nanotubular aggregates. Some recent studies have also contributed to its prospective case in oral drug delivery and dosage forms albeit with limited commercial viability. In this study, we have investigated the use of halloysite nanotubes (HNTs) as a directly compressible multifunctional tableting excipient using SeDeM diagram expert tool. SeDeM experimentations revealed that ~68% HNTs in the formulations were enough to be used as a directly compressible filler, binder, and disintegrant in diclofenac potassium formulations. In the next phase, a total of 8 formulations blends (IRF1–8) of diclofenac potassium (50 mg) with HNTs and Starch 1500® were prepared in different ratio using simple lattice mixture design and all were found satisfactory for direct compression. Compressed tablets (167 mg) had narrow weight variation (SD = ± 1.78 mg), good hardness (~9–9.5 kg), acceptable friability ( 92% against 75%). The dissolution profile was best fitted with Peppas-Sahlin model with Fickian diffusion as the only mechanism. f2 similarity test revealed that almost all the tablets were pharmaceutical equivalent to the marketed formulation of the drug. A shelf-life of ~34 months was found upon long-term stability testing of the optimized formulation. This study demonstrates that this novel and economically viable clay material has a strong potential for commercial use in tableting of drug by direct compression.

The effect of the particles size of ZnO nanoparticles, synthesized into the microstructure of honeycomb-porous block copolymer films (poly[(2-hydroxyethylmethacrylate)m-block-poly(N-phenylmaleimide)n]) with different lengths, on the thermal, morphological and optical properties of the porous-structured films were investigated. The functional nanoparticles (NPs) were synthesized by wet preparation methods involving the porous copolymer films. The presence of the copolymer allows the coordination of Zn2+ precursor with the hydrophilic part of the self-assembled block copolymers resulting in hierarchically-ordered NP arrays. With this approach, the microphase separation inside of the polymer domains was used for the organization of pre-formed NPs in their cavities. The results indicated that the sub-domains formed by hydrophilic moiety represent an additional advantage for the diffusion and formation of ZnO nanoparticles. Absorption spectra of the ZnO NPs showed an excitation band around 300 nm, indicating a blue-shift with respect to the ZnO bulk material (at 373 nm). The size and the spherical morphology of the prepared ZnO NPs were determined by transmission electron microscopy (TEM). The overall morphology of polymer nanocomposite (ZnO embedded in the block copolymer) was determined by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Keywords: ZnO nanoparticles, Honeycomb patterned porous films, Amphiphilic block copolymer, Thermal and optical properties

Hydrogen adsorption in porous nanostructured polyaniline (PANI) has been investigated to determine its potential as a hydrogen storage media. Residual gas analysis and thermogravimetric analysis were used to investigate the cyclical hydrogen adsorption in PANI. A hydrogen storage capacity of up to 3 wt % was obtained by charging the polymers at up to 3.0 × 106 Pa hydrogen at elevated temperature. Multiple charge and discharge cycles have been shown, with good retention beyond 106 sec.

In this study, commercially available cellulose membranes were hybridized with conjugated polymer via vapor-phase polymerization using pyrrole and iron chloride as a monomer and oxidant, respectively. The iron (III) chloride layer dip-coated on the hydrophilic cellulose surface oxidized the vaporized pyrrole monomer leading to the polypyrrole–cellulose hybrid membrane. The conductivity of hybrid membrane was optimized by varying the oxidant concentration and the monomer vapor exposure time. The various surface characterizations of polypyrrole–cellulose hybrid membrane show that the conductive polypyrrole layer was uniformly deposited onto the surface of cellulose fibrous networks unlike the polypyrrole–nylon hybrid membrane prepared in the similar way. The polypyrrole-incorporated cellulose networks exhibits steeper electrical conductance increase over the vertical pressure than its nylon counterpart. Our result suggests that the polypyrrole–cellulose hybrid membrane can be applicable for a disposable high-load pressure sensor.

The exfoliation of graphene sheets has been achieved by using commercial graphite in the presence of spherical polymer nanoparticles based on poly(ethylene glycol). The polymer nanoparticles with an average diameter of ~20 nm were prepared by two different methods including the ball milling technique and a magnetic stirring process. These nanoparticles in conjunction with an ultrasonication procedure yielded graphene sheets of about three layers or less. The polymer nanoparticles played a crucial role in the preparation of the graphene sheets through a wrapping process. The number of graphene layers can be tuned by varying the preparation method of the polymer nanoparticles.

A facile method for the preparation of electrically conducting polypyrrole nanoparticles and their nanocomposites with single-walled and multi-walled carbon nanotubes was developed. The polypyrrole nanoparticle size and conductivity varied as a function of reaction time with an average size of 143–195 nm and a conductivity of 0.43–0.82 S cm−1. The change in the electronic properties of the conducting nanocomposites and the influence of this change on the adsorption of hydrogen molecules onto the nanocomposites were investigated by considering the effect of the π-electron system on the hydrogen adsorption mechanism. The nanocomposite materials were characterized using microscopic and spectroscopic techniques, thermogravimetric analysis and electrical conductivity measurements. The hydrogen adsorption was measured volumetrically using a commercial computer-controlled pressure–composition–temperature method and was found to be 1.14 to 2.75 wt% at cryogenic conditions. © 2015 Society of Chemical Industry

Block copolymers have been recognized as versatile materials to prepare nanoporous polymer films or mem- branes, but their potential has not been completely explored. This study focuses on the formation and characterization of nanoporous polymer films based on poly(styrene)-block-(methylmethacrylate/methacrylic acid); (PS-b-MMA/MAA) were obtained through atom transfer radical polymerization (ATRP), by using two different protocols: annealing and annealing- irradiation; for improving the formation of microporous surface. The composition, crystallinity and structural order of the films were studied by Raman spectroscopy. The film polymer thickness was obtained through very high resolution ellip- sometry (VHRE). Finally, atomic force microcopy (AFM) and scanning electron microscopy (SEM) techniques were used to detect changes in the porous-structure. These results show that the morphological properties of the block copolymer were affected via the modification of two variables, UV-radiation time and annealing. SEM and AFM micrographs showed that the morphology exhibit a porous ordered structure. Contact angle measurement suggests additional interactions between hydrophilic functional groups that influence the film wettability.

Magnetic polymer nanoparticles are playing a vital role in various biomedical fields, such as diagnostics, drug delivery, cancer therapeutics, and biotechnology. In particular, magnetic zero-valent metal polymer nanoparticles are receiving considerable attention in the research field of magnetic nanomaterials due to their improved magnetic properties compared to conventional magnetic iron oxide polymer nanoparticles. Generally, two types of magnetic zero-valent metal polymer nanoparticles, metallic and bimetallic, are prepared using different techniques, and their selection depends on various factors, such as stability, particle size, and application. In this review, we present a brief description of the recent developments in the synthesis of these nanoparticle systems from an application point of view, and we also emphasize the scope and future outlook of this upcoming and promising research area.

An eco-friendly one-pot method to synthesize self-assembled palladium nanoclusters using a macrocycle, namely cucurbit[7]uril, in the alkaline medium without employing any special reducing or capping agents and/or external energy at room temperature is described. This greener approach, which utilizes water as a benign solvent and biocompatible cucurbit[7]uril as both reducing and protecting agents, can be applied to synthesize other noble metal nanoparticles such as gold, silver, and platinum. Owing to unique structural arrangement of cucurbit[7]uril, it was possible to prepare palladium nanoclusters of honeycomb-like structure irrespective of the reaction conditions. The honeycomb-like palladium nanoclusters were characterized using transmission electron microscopy (TEM), higher-resolution TEM (HR-TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), UV–vis, and FT-IR spectroscopy. Significantly, the synthesized palladium nanoclusters exhibited catalytic activity for the reduction reaction of 4-nitrophenol at room temperature. The approach launched here is easy, green, and user-friendly in contrast to the conventional techniques using polymers or surfactants and harsh reductants.

The biocompatibility and ease of functionalization of gold nanoparticles underlie significant potential in biotechnology and biomedicine. Eight different proteins were examined in the preparation of gold nanoparticles (AuNPs) in aqueous medium under microwave irradiation. Six of the proteins resulted in the formation of AuNPs. The intrinsic pH of the proteins played an important role in AuNPs with strong surface plasmon bands. The hydrodynamic size of the nanoparticles was larger than the values observed by TEM and ImageJ. The formation of a protein layer on the AuNPs accounts for this difference. The AuNPs exhibited sensitivity towards varying pH conditions, which was confirmed by determining the difference in the isoelectric points studied by using pH-dependent zeta potential titration. Cytotoxicity studies revealed anticancerous effects of the AuNPs at a certain micromolar concentration by constraining the growth of cancer cells with different efficacies due to the use of different proteins as capping agents. The positively charged AuNPs are internalized by the cells to a greater level than the negatively charged AuNPs. These AuNPs synthesized with protein coating holds promise as anticancer agents and would help in providing a new paradigm in area of nanoparticles.

Physical processes in laser–matter interaction used to be determined by generation of fast electrons resulting from efficient conversion of the absorbed laser radiation. Composite materials offer the possibility to control the absorption by choice of the host material and dopants. Reported here strong absorption of ultrashort laser pulse in a composite carbon-based nanomaterial including single-walled carbon nanotubes (SWCNTs) or multilayer graphene was measured in the intensity range between 1012 and 1016 W cm−2. A protein (lysozyme) was used as the host. The maximum absorption of femtosecond laser pulse has reached 92–96 %. The optical damage thresholds of the coatings were registered at an intensity of (1.1 ± 0.5) × 1013 W cm−2 for the embedded SWCNTs and at (3.4 ± 0.3) × 1013 W cm−2 for the embedded graphene. Encapsulated variant of the dispersed nanomaterial was investigated as well. It was found that supernatant protein in the coating material tends to dominate the absorption process, independently of the embedded nanomaterial. The opposite was observed for the encapsulated material.

Palladium nanoparticles are synthesized by an one-step, solvent-less, mechano-chemical reduction of potassium tetrachloropalladate(II) using an amphiphilic organic polymer, poly(vinylpyrrolidone). We demonstrate that poly(vinylpyrrolidone) can act both as reducing as well as capping agent in the solid state, without a solvent, for the synthesis of palladium nanoparticles at room temperature in conjunction with vibration milling. Besides, as an example, the application of the dendritic-like palladium nanoparticles as a catalyst is also investigated for the reduction reaction of 4-nitrophenol to 4-aminophenol at room temperature.

This paper presents the results of density and ultrasonic velocity measurements of three ternary systems, i.e., (1) D (−) glucose+lysozyme+water, (2) maltose+lysozyme+water, and (3) urea +lysozyme+water. The adiabatic compressibility has been calculated for these systems with the help of density and ultrasonic velocity values at temperatures 293.15, 303.15, 313.15, and 323.15 K for several concentrations of glucose, maltose, and urea. Interaction between sugar and water molecules is expected to create polar environment that helps to increase the hydrophobic interactions in proteins, thus stabilizing the protein, while urea creates an opposite effect on the stabilization of protein due to its role of a water structure breaker.

Gold nanoclusters (AuNCs) have gained interest during the recent years because of their low toxicity and finer size for the bioimaging and biolabeling applications in comparison to the semiconductor quantum dot analogues. Diverse materials such as sulfur compounds, peptides, dendrimers, proteins, etc., are exploited for the preparation of AuNCs. Henceforth, highly fluorescent, water-soluble, and few atom-containing gold nanoclusters are created using a rapid, straightforward, and green method. In this regard for the first time chicken egg white (CEW), one of the most unique materials, is utilized in an aqueous solution under basic conditions at physiological temperature for the preparation of AuNCs. Tyrosine and tryptophan amino acid residues are responsible for the conversion of Au ions to Au(0) under alkaline condtions. CEW contains four major proteins of which the main constituent protein, ovalbumin also leads to the formation of the AuNCs with a higher fluorescence emission compared to the CEW. The ratios between the different reaction partners are very crucial, along with temperature and time for the preparation of AuNCs with high photoluminescence emission. The limited vibrational motion of the proteins under alkaline condition and the bulkiness of the proteins help in the formation of AuNCs.

Two of the main types of nanotubular architectures are the single-walled carbon nanotubes (SWCNTs) and the self-assembling cyclic peptide nanotubes (SCPNs). We here report the preparation of the dual composite resulting from the ordered combination of both tubular motifs. In the resulting architecture, the SWCNTs can act as templates for the assembly of SCPNs that engage the carbon nanotubes noncovalently via pyrene "paddles", each member of the resulting hybrid stabilizing the other in aqueous solution. The particular hybrids obtained in the present study formed highly ordered oriented arrays and display complementary properties such as electrical conductivity. Furthermore, a self-sorting of the cyclic peptides toward semiconducting rather than metallic SWCNTs is also observed in the aqueous dispersions. It is envisaged that a broad range of exploitable properties may be achieved and/or controlled by varying the cyclic peptide components of similar SWCNT/SCPN hybrids.

Graphene nanosheets were prepared by the direct exfoliation of graphite in an aqueous lysozyme solution using ultrasonication. Atomic force microscopy studies indicated that the nanosheets possessed small lateral dimensions of less than three layers. Raman spectroscopy suggested that defects were introduced by the sonication process. These defects were primarily edge defects, not basal-plane defects. Cytotoxicity studies revealed that the lysozyme-supported nanosheets possessed anticancer activity at certain micromolar concentrations. Three other proteins and gold nanoparticles prepared with those proteins were examined as aids in graphene exfoliation. The overall protein or nanoparticle charge played an important role in the graphite exfoliation to graphene. All of the graphene dispersions were sensitive to pH. Changing the pH reversibly converted the graphene from a highly dispersed state to an aggregated state and vice versa. Although no lateral dimension differences were observed in the nanosheets prepared using the nanoparticles, their cell viability percentages varied depending on the particular protein used.

Novel well-dispersed nanocomposites of halloysite nanotubes and acrylonitrile–butadiene–styrene were prepared. The fire retardancy and thermal stability of these new nanocomposites were improved. A synergistic effect was observed between the halloysite nanotubes and an intumescent flame-retardant system consisting of ammonium polyphosphate, melamine polyphosphate and pentaerythritol in the acrylonitrile–butadiene–styrene composites. The incorporation of the intumescent flame-retardant material into the halloysite–polymer nanocomposite system also improved the thermal stability and reduced the peak heat release rate by up to 56.2%, and it significantly reduced the emission of CO and CO2 gases. The morphology and dispersion of the halloysite nanotubes were characterized using scanning and transmission electron microscopy. The thermal stability and flammability properties were investigated using thermogravimetric analysis and cone calorimeter tests. © 2013 Society of Chemical Industry

SUMMARY A new nanoporous polypyrrole material with permanent mesopores on the surface, internal pores, and pockets with sponge-like structures has been developed. The nanoporous polypyrrole was prepared as a material for hydrogen storage using a simple, environmentally friendly, and newly developed ‘solid-state vapor-phase polymerization’ method. The direct use of the solid powder of oxidant in the new preparation method is responsible for the pore formation mechanism, and preparation method also controls the pore diameter of the prepared nanoporous conducting polymer. The effect of reaction time on the pore volume and hydrogen storage capacity was investigated, and it was found that the hydrogen storage capacity and the mesopore volume decreased based on an increase in reaction time. The prepared nanoporous polypyrrole materials have been observed to reach a maximum reversible hydrogen adsorption capacity of 2.2 wt.% at 77 K. The average isosteric heat of adsorption of the obtained polypyrrole was 7.51 kJ/mol, which is larger than that reported for most metal-organic frameworks, porous carbon, and hypercross-linked polystyrenes. Copyright © 2013 John Wiley & Sons, Ltd.

Inorganic nanotubes as a support material for polyaniline were used for hydrogen storage. To this end, a solid-state preparation method has been developed for controlling the hydrogen storage capacity of these nanocomposites. The hydrogen storage capacities have measured at room temperature and at a low pressure of 0.5 MPa using the precise quadrupole quartz crystal microbalance technique in a chamber free of moisture. The optimum nanocomposite shows an enhanced hydrogen storage capacity of 0.78 wt.% with excellent reversibility when compared to less than 0.019 wt.% capacity of the pristine nanotubes and 0.05 wt.% of polyaniline. This large increase in the hydrogen capacity can be attributed to the chemisorption hydrogen uptake, which was enhanced by the sorption sites created through the milling process of polyaniline with the nanotubes. This is in addition to the hydrogen adsorption contribution by a controlled lumen size that is suitable for a maximum hydrogen adsorption through inserting polyaniline chains into the nanotubes.

New nanoporous carbon materials were synthesized using a nano-casting method with agglomerated porous silica nanoparticles that originated from rice husk as an inorganic template material and sucrose and glycerol as carbon precursors. The nanoporous carbon materials obtained have a specific surface area that reached 749 m2/g and a pore volume of 1.44 cm3/g. The type and molecular size of the carbon precursor played a significant role for the textural properties of the resulting carbon materials. The hydrogen storage capacity of the porous rice husk silica nanoparticles and the nanoporous carbon materials from the two carbon sources have been investigated at different temperature and pressure. In addition, the effect of the slit-shaped pore structure has been demonstrated. The highest excess hydrogen adsorption was found to be 2.41 wt.% achieved at 77 K and 7.3 MPa and the total hydrogen uptake was 5.7 wt.% at 77 K and 7.3 MPa. The isosteric heat of adsorption of the nanoporous carbon materials has been investigated and reached 7.3 kJ/mol which was higher than the values reported on porous activated carbon AX-21_33 (5.53 kJ/mol), Norit R0.8 (5 kJ/mol), and metal–organic frameworks MOF-177 (3.7 kJ/mol), MOF-5 (4 kJ/mol).

A facile method for the synthesis of polyaniline–polypyrrole composite materials with network morphology is developed based on polyaniline nanofi bers covered by a thin layer of polypyrrole via vapor phase polymerization. The hydrogen storage capacity of the composites is evaluated at room temperature exhibits a twofold increase in hydrogen storage capacity. The HCl-doped polyaniline nanofi bers exhibit a storage capacity of 0.46 wt%, whereas the polyaniline–polypyrrole composites could store 0.91 wt% of hydrogen gas. In addition, the effect of the dopant type, counteranion size, and the doping with palladium nanoparticles on the storage properties are also investigated.

A series of well-defined amphiphilic poly[(2-hydroxyethyl methacrylate)-block-(N-phenylmaleimide)] diblock copolymers containing hydrophilic and hydrophobic blocks of different lengths were synthesized by atom transfer radical polymerization. The properties of the diblock copolymers and their ability to form large compound spherical micelles are described. Their optical, morphological and thermal properties and self-assembled structure were also investigated. The chemical structure and composition of these copolymers have been characterized by elemental analysis, Fourier transform infrared, 1H NMR, UV–visible and fluorescence spectroscopy, and size exclusion chromatography. Furthermore, the self-assembly behavior of these copolymers was investigated by transmission electron microscopy and dynamic light scattering, which indicated that the amphiphilic diblock copolymer can self-assemble into micelles, depending on the length of both blocks in the copolymers. These diblock copolymers gave rise to a variety of microstructures, from spherical micelles, hexagonal cylinders to lamellar phases. © 2013 Society of Chemical Industry

A new layout of predictable and controllable complementary logic circuits based on hybrid nanodevices comprising p-channel single-walled carbon nanotube (SWNT) and n-channel zinc oxide (ZnO) nanowire transistors providing a hybrid approach to combine advantageous characteristic functions for the modulation of the current and operating voltage in transistors through proton radiation generated charge, was studied. A suspension of SWNTs obtained through an arc discharge process in 1,2, dichlorobenzene (o-DCB) was prepared by a combination of sonication and centrifugation. 1 mg of SWNTs in 10 mL of o-DCB was sonicated for 5 mm and the SWNT suspension was then centrifuged for 200 mm at 16000 g followed by ultra centrifugation for 2 h at 325 000 g. The current-VTCs of transistors and logic circuits were measured using a semiconductor parameter analyzer. It was possible to achieve high performance logic circuits by selectively controlling the threshold voltages of transistors through the population of proton radiation generated charges in the dielectric layer.

Among carbon-based nanomaterials such as fullerenes, carbon nanotubes and nanodiamonds, the latter are good candidates as prospective materials in the future due to their potential physical, chemical and biological properties. Thus, nanodiamonds were wrapped with biocompatible polymers in the solid state. The dispersibility of the polymer-wrapped nanodiamonds in water was investigated with respect to reaction time and mass ratio of the polymers during the wrapping process. The dispersibility of the materials was monitored using UV spectroscopy, and the size distribution of the polymer-wrapped nanodiamonds was analyzed using high-resolution transmission electron microscopy and dynamic light scattering measurements. In addition, molecular modeling calculations were performed. Finally, the best dispersion for the polymer-wrapped nanodiamonds in water was found for a reaction time of 120 min. Copyright © 2012 Society of Chemical Industry

Among the carbon-based nanomaterials such as carbon nanotubes, fullerenes, graphene and nanodiamonds, graphene received recently widespread attention owing to its exceptional structural, electronic and mechanical properties and potential applications in various domains. However, all currently known forms of graphene materials are not well dispersible or soluble in most common solvents. This limitation deters to explore the chemistry of graphene at the molecular level and its nanobio device applications. One well known solution to this problem is the use of dispersing agents such as polymers, biopolymers, or surfactants in conjunction with the appropriate experimental conditions. Among the various biomolecules, deoxyribonucleic acid (DNA) has emerged as an appealing biomacromolecule for functional materials due to its biocompatibility and renewability in addition to its very interesting double helix structure, which guarantees a range of unique properties that are difficult to detect in other molecules and polymers. Hence, the combination of graphene (a carbon-based nanomaterial), showing exceptional electronic properties, and DNA (a nanostructured biomolecule), having extraordinary recognition properties, demonstrates a new type of nanobio hybrid material. This, in turn, leads to a successful incorporation of the properties of the two different components in new hybrid materials that present important features for potential applications that range from advanced biomedical systems by means of very sensitive electrochemical sensors and biosensors to highly efficient electronics- and optics-based biochips. This article will focus on the recent advancement of the methods available for the chemical functionalization of graphene using DNA by different interactions (covalent or non-covalent and insertion of DNA through graphene nanopore or nanogap), various types of assemblies, and future prospects. Furthermore, the various potential applications of the resulting new nanobio hybrid materials are also highlighted.

Novel paclitaxel-loaded polymer nanoparticles were developed for circumventing multidrug resistance (MDR) of malignant cancerous diseases, which is an unsolved clinical problem in cancer chemotherapy. In many cases, MDR is due to the intrinsic or acquired expression of an efflux pump, the P-170 glycoprotein (P-gp). By encapsulating paclitaxel in a water-soluble and biocompatible synthetic polyampholyte using a solid-state reaction the highly water-soluble paclitaxel-loaded nanoparticles are formed. The resulting paclitaxel nanoparticles with an average diameter of 250 nm show a significant reversal of chemoresistance in the drug-resistant variants (MCF7/ADR, MT3/ADR) by a factor of 100 or more. The novel paclitaxel nanoparticles enter MDR breast cancer cells by adsorptive endocytosis bypassing the P-gp, preventing the efflux of paclitaxel and thus restoring the anti-proliferative effect of paclitaxel.

The cytotoxicity and cellular uptake of carbon nanotubes (CNTs) has recently attracted considerable interest because of the issue of biosphere-nanomaterial interactions. The biocompatibility of CNTs is determined by the metal impurities in the CNTs, the size of the CNTs and the CNT dispersion states; in particular, the type of surface modifications on the CNTs affects how they interact with cells and determines their cytotoxicity and cellular uptake. In this study, biocompatible single-walled carbon nanotubes (SWNTs) wrapped with a water-soluble copolymer, poly[2-(dimethylamino)ethyl methacrylate-co-methacrylic acid] (PDM), were prepared. We report that these SWNTs have enhanced water dispersibility and cellular internalization but no significant cytotoxic activity against mouse embryonic fibroblast NIH-3T3 cells.

Polymer nanoparticles have attracted the interest of many research groups and have been utilized in an increasing number of fields during the last decades. Generally, two main strategies are employed for their preparation: the dispersion of preformed polymers and the polymerization of monomers. Various techniques can be used to produce polymer nanoparticles, such as solvent evaporation, salting-out, dialysis, supercritical fluid technology, micro-emulsion, mini-emulsion, surfactant-free emulsion, and interfacial polymerization. The choice of method depends on a number of factors, such as, particle size, particle size distribution, area of application, etc. This review covers the general description of the preparation of polymer nanoparticles and the detailed description of the crucial parameters involved in techniques designed to obtain the desired properties.

The commercial sunscreen agent Tinosorb S (TS) is a promising oil-soluble broad spectrum UV filter. Here, we report for the first time a water-dispersible inclusion complex of TS using cucurbituril. The synthesis was carried out via a supramolecular approach in the solid state by using the high-speed vibration milling technique. The formation and the photophysical properties of the solid inclusion complex were investigated by spectroscopic techniques such as UV–vis spectrophotometry, Fourier-transform infrared and solid-state proton nuclear magnetic resonance spectroscopy as well as by thermal gravimetric analysis and X-ray diffractometry. An increase in the absorbance and a shift of the maximum absorption from 380 nm to 345 nm for the inclusion complex were observed in comparison to the precursor complex TS. The stochiometric ratio of cucurbituril and TS in the inclusion complex was found to be 2:1

The unexpected formation of supramacromolecules of β-cyclodextrin in aqueous solution under ambient conditions is reported in this article. The shape and size of the supramacromolecules could be controlled by varying the stirring time and the concentration. The supramolecular interactions of the supramacromolecules were confirmed by ¹H NMR spectroscopy. Additionally, visual evidence of the supramacromolecules was provided by transmission and scanning electron microscopy. The thermal behavior of the supramacromolecules was examined by thermogravimetric analysis. The molecular mass determination by gel permeation chromatography showed that the supramacromolecules had a high molar mass.

Plasma polymerization of styrene was used to modify the hydrophilic surfaces of halloysite nanotubes to investigate the reinforcement effect of new hydrophobic surfaces on the dynamic mechanical properties of halloysite–polystyrene nanocomposites at various degrees of loading. Pristine and plasma-modified halloysite–polystyrene nanocomposites were synthesized by solution blending and characterized using various techniques. The storage moduli and glass transition temperatures of the composites were analyzed using dynamic mechanical thermal analysis. It was found that the rubbery moduli increased substantially after plasma coating with styrene due to the compatibility of the new hydrophobic halloysite surfaces with the polystyrene polymer matrix. In addition, the rubbery moduli increased with increasing amount of clay. The glass transition temperatures of the composites did not change significantly with the amount of clay. The strengths of the plasma-modified composites were also compared with those of recently reported halloysite–epoxy resin composites. Copyright © 2010 Society of Chemical Industry

A simple, green, one-pot synthesis of gold nanoparticles was achieved through the reaction of an aqueous mixture of potassium tetrachloroaurate(III) and the macrocycle cucurbit[7]uril in the presence of sodium hydroxide at room temperature without introducing any kind of traditional reducing agents and/or external energy. The as-prepared gold nanoparticles showed catalytic activity for the reduction reaction of 4-nitrophenol in the presence of NaBH(4), which has been established by visual inspection and UV/Vis spectroscopy. This report is the first for the preparation of gold nanoparticles using cucurbit[7]uril in aqueous media through chemical reduction without employing conventional reducing agents and/or external energy.

Ce travail est finance par la bourse no ST2*35I du programme Stimulation de la Commission des Communautes Europeennes

In the present work water-soluble lactose based oligomers of β-cyclodextrin were synthesized by a simple and efficient condensation polymerization process. Proposed water-soluble β-cyclodextrin oligomers were prepared by controlled reaction between β-cyclodextrin and a triazine linker and purification by an ultrafiltration process. Similarly, lactose based β-cyclodextrin oligomers were synthesized for enhanced water solubility. The physical and chemical properties of the synthesized polymers were characterized by FT-IR and 1 H NMR spectroscopy, XRD analysis, thermogravimetric analysis (TGA) and aqueous solubility determination. Molecular weights of these β-cyclodextrin based oligomers were measured by ESI technique. These β-cyclodextrin based water-soluble oligomers polymers were used as supramolecular carriers for efavirenz (an anti HIV drug), improving the inclusion property and aqueous solubility properties of this drug. These synthesized oligomers were found to improve stability and aqueous solubility of efavirenz on their (1:1) inclusion complex through phase solubility and dissolution studies. Reduced cytotoxicity than the parent β-CD was observed in hemolysis test.

Silver nanoparticles have been used for a long time and recently various methods have been additionally developed for their production. Here we report for the first time a solid-state highspeed vibration milling method for the synthesis of silver nanoparticles, in which poly-(vinylpyrrolidone) is used for the reduction of the silver salt. The synthesis is performed at room temperature and no surfactant to direct the anisotropic growth of the nanoparticles is required. The formation of the nanoparticles was studied by UV―Visible spectroscopy, transmission electron microscopy, and powder X-ray diffraction techniques. The nanoparticles synthesized were found to be uniform in size and shape with an average diameter of less than 5 nm. In addition, the antimicrobial activity of these silver nanoparticles was investigated against Escherichia coli and found to be positive.

Hydrophilic copolymer gels were prepared by free-radical copolymerization of 1-vinyl-2-pyrrolidone (NVP) and N-hydroxymethyl acrylamide (HMAm). The ratios of both monomers and crosslinker agent (CA) were varied, and the effect of external stimuli such as pH of the swelling media and inorganic ion interaction were investigated. The gels showed a pH-responsive behavior. The interactions of inorganic ions with the hydrophilic hydrogels were determined as a function of pH, copolymer composition, and variation of the composition crosslinking degree. Additionally, a decrease of the pH of the solution caused a decrease in the equilibrium degree of swelling of the copolymer gels. The capacity to remove several metal ions such as Cu(II), Cr(III), Co(II), Zn(II), Ni(II), Cd(II), and Fe(III) in the aqueous phase was determined by using the liquid-phase polymer-based retention (LPR) technique. In addition, the copolymers and their complexes with transition metal ions were characterized by the monomer reactivity ratios by using the Kelen-Tudos method, elemental analysis, FTIR and 1H-NMR spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. Based on the results of swelling and retention capacity of metal ions of poly(NVP-co-HMAm), it was concluded that the swelling and retention capacity properties of the hydrogels depends on the reaction environment's pH. This is regarded as a functional hydrogel, which could be employed as biodegradable materials for applications in agriculture chemicals and as drug delivery systems. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Several copolymer hydrogels were prepared from radical copolymerization of 2-hydroxypropyl methacrylate (HPMA) with itaconic acid (IA) and also with citraconic acid (CA) by using different feed ratios. The copolymers were characterized by FTIR, 1H-NMR, and 13C-NMR spectroscopy as well as by thermal analysis. The swelling process of the different hydrogels immersed in water at different pH has been studied, and also the swelling of the hydrogels loaded with metal ions (Pb2+, Cd2+) was investigated. The metal-binding properties were studied by using the liquid-phase polymer-based retention technique, including studies on the influence of pH on the binding process. The efficiency of these hydrogels for the recovery of metal ions in solution was determined by atomic absorption spectroscopic analysis. The thermal characteristics of these copolymers were studied by using differential scanning calorimetry and thermogravimetric analysis in nitrogen atmosphere. Accordingly, the gels loaded with metal ions showed a slight increase of the thermal decomposition temperature when compared with the pristine gels. The copolymer gel HPMA-co-CA showed a single glass transition temperature, whereas for the copolymer systems, HPMA-co-IA, only the copolymers loaded with Cd2+ ions showed a glass transition temperature. The morphology of film produced from the copolymers was investigated by scanning electron microscopy, revealing generally smooth surfaces. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

The effect of ultrasonication on the enzymatic stability, conformation, and catalytic activity of the important oxidoreductase, glucose oxidase (GOx), was investigated. Thus, buffer-free aqueous solutions of GOx were ultrasonicated (23 kHz at 4 °C) for different periods of time (10, 30, and 60 min) and studied in terms of their enzymatic activity. The ultrasonicated GOx was also studied by UV/vis and circular dichroism (CD) spectroscopy and by thermogravimetric analysis, and compared with pristine GOx. The CD spectra of ultrasonicated GOx showed a different composition with reduced α-helix and β-sheet fractions upon extended sonication compared with the pristine GOx. Along with the changes of the secondary structure, the enzymatic activity measured via HRP-coupled bioassay of the sonicated GOx showed a small corresponding decrease. Low temperature ultrasonic processing of GOx does not appreciably compromise bioactivity.

BACKGROUND: The insufficient dispersability of single-walled carbon nanotubes (SWNTs) in most common solvents (as a result of substantial van der Waals tube–tube attractions) makes it difficult to explore and understand their chemistry, and, therefore, implies many limitations for their practical applications. In this study, in order to overcome the intrinsic problems of SWNTs, a facile mechanochemical approach was developed to prepare polystyrene-SWNT nanocomposites, which could be well-dispersed in organic media. RESULTS: Here we report a simple method to prepare polystyrene-wrapped single-walled carbon nanotubes, which can be well dispersed in a series of organic solvents. The nanocomposites were prepared in the solid state using the high-speed vibration milling technique and were characterized by UV-VIS and FT-IR spectroscopy. In addition, their morphology was determined by TEM as well as SEM studies. CONCLUSION: This facile and simple solid-state reaction technique to prepare SWNT-PS nanocomposites eases not only the preparation of dispersions of SWNTs for further applications like device fabrications, but also in general the production of carbon nanotube-polymer nanocomposites. Furthermore, this facile preparation method to synthesize nanohybrids by a mechanochemical reaction has a superior potential for electronic applications of single-walled carbon nanotubes. Copyright © 2009 Society of Chemical Industry

Supramolecular conjugates of single-walled carbon nanotubes and glucose oxidase were prepared in aqueous solution using ultrasonication processing and then isolated by high-speed centrifugation. The conjugates of the single-walled carbon nanotubes and the pristine glucose oxidase, serving as control, were investigated for their enzymatic bioactivity. In addition, the effect of the extent of ultrasonication was studied. The conjugates were also characterized by UV–VIS and circular dichroism spectroscopy as well as by high-resolution transmission electron microscopic and thermogravimetric analysis. Ultrasonication is shown to reduce catalytic activity by ca. 30% (10 min) and that prolonged ultrasonication (up to 60 min) further reduces V max by 40%. However, most of this decrease arises from ultrasonication itself. The presence of carbon nanotubes (CNTs), while not eliminating changes in catalytic activity, mitigates the magnitude of these changes and is effectively de-bundled by the presence of the surfactant properties of the protein. The enzymatic activity and conformation were found to be predominantly retained after the supramolecular conjugation process assisted by ultrasonication in the presence of the CNTs.