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By considering the importance of water and its purity, herein, a powerful adsorbent has been developed for the adsorption of two toxic contaminants that commonly exist in water, viz., divalent mercury and hexavalent chromium. The efficient adsorbent, CNTs–PLA–Pd, was prepared by covalent grafting polylactic acid to carbon nanotubes and subsequent deposition of palladium nanoparticles. The CNTs–PLA–Pd could adsorb Hg(II), and Cr(VI) entirely exists in water. The adsorption rate for Hg(II) and Cr(VI) was rapid at initial stage, followed by gradual decrease, and attained the equilibrium. The Hg(II) and Cr(VI) adsorption was perceived within 50 min and 80 min, respectively with CNTs–PLA–Pd,. Further, experimental data for Hg(II) and Cr(VI) adsorption was analyzed, and kinetic parameters were estimated using pseudo–first and second–order models. The adsorption process of Hg(II) and Cr(VI) followed the pseudo–second–order kinetics, and the rate–limiting step in the adsorption was chemisorption. The Weber−Morris intraparticle pore diffusion model revealed that the Hg(II) and Cr(VI) adsorption over CNTs–PLA–Pd occurs through multiple phases. The experimental equilibrium parameters for the Hg(II) and Cr(VI) adsorption were estimated by Langmuir, Freundlich, and Temkin isotherms models. All three models were well suited and demonstrated that Hg(II) and Cr(VI) adsorption over CNTs–PLA–Pd transpires through monolayer molecular covering and chemisorption. [ABSTRACT FROM AUTHOR]

A multimode, dual functional nanomaterial, CNTs-Ag2S, comprised of carbon nanotubes (CNTs) and silver sulfide (Ag2S) nanoparticles, was prepared through the facile hydrothermal process. Before the deposition of Ag2S nanoparticles, hydrophobic CNTs were modified to become hydrophilic through refluxing with a mixture of concentrated nitric and sulfuric acids. The oxidized CNTs were employed to deposit the Ag2S nanoparticles for their efficient immobilization and homogenous distribution. The CNTs-Ag2S could adsorb toxic Cd(II) and completely degrade the hazardous Alizarin yellow R present in water. The adsorption efficiency of CNTs-Ag2S was evaluated by estimating the Cd(II) adsorption at different concentrations and contact times. The CNTs-Ag2S could adsorb Cd(II) entirely within 80 min of the contact time, while CNTs and Ag2S could not pursue it. The Cd(II) adsorption followed the pseudo-second-order, and chemisorption was the rate-determining step in the adsorption process. The Weber−Morris intraparticle pore diffusion model revealed that intraparticle diffusion was not the sole rate-controlling step in the Cd(II) adsorption. Instead, it was contributed by the boundary layer effect. In addition, CNTs-Ag2S could completely degrade alizarin yellow R in water under the illumination of natural sunlight. The Langmuir-Hinshelwood (L-H) model showed that the degradation of alizarin yellow R proceeded with pseudo-first-order kinetics. Overall, CNTs-Ag2S performed as an efficient adsorbent and a competent photocatalyst. [ABSTRACT FROM AUTHOR]

Cancer is a current dreadful disease and the leading cause of death. Next to cardiovascular diseases, cancer is the most severe threat to human life and health. Breast cancer is the most common invasive cancer diagnosed in women. Each year about 2.3 million women are diagnosed with breast cancer. In consideration of the severity of breast cancer, herein we designed the biocompatible nanomaterials, CNTs-HAP and GR-HAP, through grafting of hydroxyapatite (HAP) to carbon nanotubes (CNTs) and graphene (GR) nanosheets. CNTs-HAP and GR-HAP have been tested for their cytotoxicity, growth and motility inhibitory effects, and their effects on the mesenchymal markers. All these demonstrated significant dose-dependent and time-dependent in vitro cytotoxicity against SUM-159 and MCF-7 breast cancer cell lines. The cell viability assay showed that the CNTs-HAP was more effective over SUM-159 cells than MCF-7 cells. It found that the increase in the concentration of GR-HAP has inhibited the clonogenic ability of breast cancer cells. The GR-HAP exhibited a substantial inhibitory effect on the cell motility of SUM-159 cell lines. It was investigated that the expression of vimentin (mesenchymal marker) was majorly reduced in SUM-159 cells by GR-HAP. [ABSTRACT FROM AUTHOR]

An efficient adsorbent, CNTs–PAMAM–Ag, was prepared by grafting fourth-generation aromatic poly(amidoamine) (PAMAM) to carbon nanotubes (CNTs) and successive deposition of Ag nanoparticles. The FT–IR, XRD, TEM and XPS results confirmed the successful grafting of PAMAM onto CNTs and deposition of Ag nanoparticles. The absorption efficiency of CNTs–PAMAM–Ag was evaluated by estimating the adsorption of two toxic contaminants in water, viz., Pb(II) and As(III). Using CNTs–PAMAM–Ag, about 99 and 76% of Pb(II) and As(III) adsorption, respectively, were attained within 15 min. The controlling mechanisms for Pb(II) and As(III) adsorption dynamics were revealed by applying pseudo-first and second-order kinetic models. The pseudo-second-order kinetic model followed the adsorption of Pb(II) and As(III). Therefore, the incidence of chemisorption through sharing or exchanging electrons between Pb(II) or As(III) ions and CNTs–PAMAM–Ag could be the rate-controlling step in the adsorption process. Further, the Weber–Morris intraparticle pore diffusion model was employed to find the reaction pathways and the rate-controlling step in the adsorption. It revealed that intraparticle diffusion was not a rate-controlling step in the adsorption of Pb(II) and As(III); instead, it was controlled by both intraparticle diffusion and the boundary layer effect. The adsorption equilibrium was evaluated using the Langmuir, Freundlich, and Temkin isotherm models. The kinetic data of Pb(II) and As(III) adsorption was adequately fitted to the Langmuir isotherm model compared to the Freundlich and Temkin models. [ABSTRACT FROM AUTHOR]

The carbon nanotubes (CNTs) have been successfully modified to absorb in near‐infrared (NIR) region by synergetic functionalization with an important biopolymer, polylactic acid (PLA) and subsequent in‐situ deposition of Pd nanoparticles. This process has also extended the absorption ability of Pd nanoparticles towards NIR region apart from its classical absorption in UV and visible regions. Thus fabricated CNTs‐PLA‐Pd demonstrated excellent photothermal effect under exposure to 980 nm laser and significant stability against photo‐bleaching and corrosiveness. A stepwise increment in the photothermal effect of CNTs was attained by covalent grafting of PLA and successive deposition of Pd nanoparticles. The photothermal effect of CNTs‐PLA‐Pd was proportional to its concentration level and photothermal conversion efficiency calculated for CNTs‐PLA‐Pd was 26.5 %. The photothermal effect of CNTs‐PLA‐Pd under illumination to 980 nm laser was higher than that of 808 nm laser. The temperature attained during photothermal effect for CNTs‐PLA‐Pd was beyond 60 °C, which far exceeds the temperature survival level of cancer cells. Overall, the rational integration of CNTs, PLA and Pd nanoparticles in CNTs‐PLA‐Pd by reported strategy could offer a suitable avenue for advancement of cancer therapy. [ABSTRACT FROM AUTHOR]

This paper illustrates the potential of Ag nanoparticles based nanocomposites to use as effective agents in photothermal therapy apart from their traditional employment as antimicrobial materials. Herein an Near-Infrared active photothermal agent was fabricated by deposition of Ag nanoparticles over aromatic poly(amidoamine) grafted carbon nanotubes. Thus prepared CNTs-PAMAM-Ag possessed strong photothermal effect under exposure to 980 nm laser system and prominent photothermal stability. The photothermal conversion efficiency of CNTs-PAMAM-Ag was found to be higher than readily used Au and CuS based photothermal agents. The photothermal effect of CNTs-PAMAM-Ag was substantial in presence of 980 nm laser compared to 808 nm laser and a linear dependence of photothermal effect on its concentration was identified. The maximum temperature attained by CNTs-PAMAM-Ag during assessment of its photothermal effect was about 66.0 °C, which is significantly higher than the survival temperature level of cancer cells. So CNTs-PAMAM-Ag could be a promising photothermal agent to apply in future photothermal hyperthermia therapy to treat cancer. Moreover CNTs-PAMAM-Ag can synchronous trigger by a single wavelength (980 nm) laser system, so it could simplify the future therapeutic process. [ABSTRACT FROM AUTHOR]

A robust, near-infrared (NIR) active photothermal agent, CNTs-PAMAM/G4-CdS, is designed by covalent grafting of fourth generation poly(amidoamine) (PAMAM) to carbon nanotubes (CNTs) and successive deposition of cadmium sulfide (CdS) nanocrystallites. The systematic advancement in photothermal effect of CNTs was achieved by grafting of first, second, third, and fourth generation PAMAM through the repeated process of Michael’s addition. The subsequent deposition of CdS nanocrystallites over fourth generation PAMAM grafted CNTs has further improved the photothermal effect (PTE) of CNTs. The photothermal effect of CNTs-PAMAM/G4-CdS was accessed by illuminating with 980 nm NIR laser. During measurement of PTE, maximum temperature attained by CNTs-PAMAM/G4-CdS was 64.1 °C which far exceeds the survival temperature of cancer cells. The photothermal conversion efficiency estimated for CNTs-PAMAM/G4-CdS was 32%, which is higher than the value reported for popular gold and copper based photothermal agents. Apart from its outstanding photothermal effect, CNTs-PAMAM/G4-CdS possessed excellence in both antiphoto-bleaching and antiphoto-corrosiveness. [ABSTRACT FROM AUTHOR]

Herein we present a successful strategy for enhancement of photothermal efficiency of hydroxyapatite (HAP) by its conjugation with carbon nanotubes (CNTs) and graphene nanosheets (GR). Owing to excellent biocompatibility with human body and its non-toxicity, implementation of HAP based nanomaterials in photothermal therapy (PTT) provides non-replaceable benefits over PTE agents. Therefore, in this report, it has been experimentally exploited that the photothermal effect (PTE) of HAP has significantly improved by its assembly with CNTs and GR. It is found that the type of carbon nanomaterial used to conjugate with HAP has influence on its PTE in such a way that the photothermal efficiency of GR-HAP was higher than CNTs-COOH-HAP under exposure to 980 nm near-infrared (NIR) laser. The temperature attained by aqueous dispersions of both CNTs-COOH-HAP and GR-HAP after illuminating to NIR radiations for 7 min was found to be above 50 °C, which is beyond the temperature tolerance of cancer cells. So that the rise in temperature shown by both CNTs-COOH-HAP and GR-HAP is enough to induce the death of tumoral or cancerous cells. Overall, this approach in modality of HAP with CNTs and GR provide a great potential for development of future nontoxic PTE agents. [ABSTRACT FROM AUTHOR]

Abstract: Herein we report the design of antimicrobial nanohybrids, f-MWCNTs-CdS and f-MWCNTs-Ag2S developed by covalent grafting of cationic hyperbranched dendritic polyamidoamine (PAMAM) onto multiwalled carbon nanotubes (MWCNTs) and successive deposition of CdS and Ag2S quantum dots (QDs). The CdS and Ag2S QDs were in situ deposited on PAMAM grafted MWCNTs instead of anchoring the pre-synthesized QDs. The fourth generation, amine terminated hyperbranched PAMAM was grafted on MWCNTs, which was achieved through repetitive reactions of Michael addition of methylmethacrylate to the surface amino groups and amidation of terminal ester groups with ethylenediamine. The covalent grafting of PAMAM onto MWCNTs and the consecutive conjugation of CdS and Ag2S QDs were characterized using Fourier transform infrared spectroscopy, elemental analysis, powder X-ray diffraction, Raman spectroscopy, transmission electron microscopy and energy dispersive spectroscopy. The antibacterial activity of f-MWCNTs-CdS and f-MWCNTs-Ag2S nanohybrids was evaluated against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus and the results were compared with the activity of carboxylated MWCNTs, PAMAM grafted MWCNTs, PAMAM dendrimer, and CdS and Ag2S QDs. It was found that the germicidal action of MWCNTs was enhanced by grafting of PAMAM, which was further improved with immobilization of CdS and Ag2S QDs. [Copyright &y& Elsevier]

Abstract: Two novel ternary nanocatalysts, f-MWCNTs-CdS and f-MWCNTs-Ag2S were successfully constructed by covalent grafting of fourth generation (G4) hyperbranched, crosslinked poly(amidoamine) (PAMAM) to carboxylated multi-walled carbon nanotubes (MWCNTs-COOH) and subsequent deposition of CdS or Ag2S quantum dots (QDs). The structural transformation, surface potential, and morphology of functionalized MWCNTs (f-MWCNTs) and nanocatalysts were characterized by UV–vis spectrophotometer, Fourier transform infrared spectroscopy, powder X-ray diffraction, Raman spectroscopy, thermogravimetric analysis, scanning electron microscopy and energy dispersive spectroscopy. Transmission electron microscopy reveals the effective anchoring of QDs on f-MWCNTs. The catalytic activity of nanocatalysts was evaluated by photodegradation of methyl orange under illumination of UV light. The coupling of MWCNTs, PAMAM and CdS or Ag2S QDs significantly enhanced the catalytic efficiency of nanocatalysts. The rate constants for degradation of methyl orange in presence of nanocatalysts were calculated using the Langmuir–Hinshelwood model. Overall, the excellence in photodegradation was accomplished by hybridizing f-MWCNTs with CdS or Ag2S QDs. [Copyright &y& Elsevier]

Abstract: Herein a simple and effective approach is introduced to functionalize single walled carbon nanotubes (SWCNTs) by in-situ grafting of hydroxyapatite (HA). The pristine SWCNTs were chemically activated through introduction of carboxylic groups on their surfaces by refluxing in the mixture of H2SO4 and HNO3. The resulting carboxylated SWCNTs were further utilized for grafting of HA. The Fourier transform infrared and Raman spectroscopic studies demonstrated the formation of HA and its grafting over SWCNTs. The phase composition of HA and existence Ca2+ and PO4 3− ions were studied using X-ray diffraction and energy dispersive X-ray analyses, respectively. The surface morphology of functionalized SWCNTs was analyzed using scanning electron microscopy and transmission electron microscopy. Thermogravimetric analysis confirmed the existence of HA on SWCNTs by exhibiting different thermogram for pure HA and functionalized SWCNTs. Overall, this method produced uniform grafting of low crystalline HA on carboxylated SWCNTs with strong interfacial bonding. [Copyright &y& Elsevier]

Abstract: Herein we described the synthesis of a novel f-CNTs-Pd nanocatalyst by covalent grafting of poly(lactic acid) (PLA) onto carbon nanotubes (CNTs) and subsequent deposition of Pd nanoparticles. Prior to grafting of PLA, CNTs were oxidized with a mixture of HNO3/H2SO4 and successively activated with thionyl chloride. The PLA grafted CNTs (f-CNTs) were then used as platform for in situ deposition of Pd nanoparticles. The formation of f-CNTs-Pd nanocatalyst was analyzed by UV–vis, FTIR and Raman spectroscopy, powder XRD, energy dispersive spectroscopy and thermogravimetric analysis. The morphologies of the nanocatalyst were characterized using scanning and transmission electron microscopes. The f-CNTs stabilized Pd nanoparticles are found to be more effective in the promotion of Heck cross-coupling reaction between aryl halides and n-butyl acrylate. The f-CNTs-Pd nanocatalyst was regenerated for three cycles of reaction without any significant loss in its activity. [Copyright &y& Elsevier]

In the present study, hydroxyapatite (HA) was successfully grafted to carboxylated carbon nanotubes (CNTs) and graphene nanosheets. The HA grafted CNTs and HA-graphene nanosheets were characterized using FT-IR, TGA, SEM and X-ray diffraction. The HA grafted CNTs and graphene nanosheets (CNTs-HA and Gr-HA) were further used to examine the proliferation and differentiation rate of temperature-sensitive human fetal osteoblastic cell line (hFOB 1.19). Total protein assays and western blot analysis of osteocalcin expression were used as indicators of cell proliferation and differentiation. Results indicated that hFOB 1.19 cells proliferate and differentiate well in treatment media containing CNTs-HA and graphene-HA. Both CNTs-HA and graphene-HA could be promising nanomaterials for use as scaffolds in bone tissue engineering. [ABSTRACT FROM AUTHOR]

Abstract: The single walled carbon nanotubes (CNTs) were effectively functionalized through grafting with chitosan (CTS) and poly(methyl methacrylate) (PMMA). Prior to grafting reaction, the carboxylated SWNCTs (SWNCTs–COOH) were obtained by treating pristine CNTs with a mixture of 3:1 (v/v) H2SO4 and HNO3, and the successive treatment of SWNCTs–COOH with SOCl2 yielded the acylated CNTs (CNTs–COCl). The functionalized derivatives of CNTs were characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis, atomic force microscopy, scanning electron microscopy and transmission electron microscopy. Both CTS and PMMA grafted CNTs showed better dispersability in acetic acid and tetrahydrofuran, in addition to higher stability in solution. [Copyright &y& Elsevier]