Cobalt Phthalocyanine-Sensitized Graphene–ZnO Composite: An Efficient Near-Infrared-Active Photothermal Agent

Herein, a promising near-infrared-responsive photothermal agent was designed by anchoring of rice grain-shaped ZnO particles over graphene (GR) nanosheets and subsequent sensitization with cobalt phthalocyanine (CoPc). Thus, produced GR–ZnO–CoPc was able to attain the temperature of 68 °C by irradiating to 980 nm laser for 7 min, which is extremely higher than the endurance temperature of cancer cells. The linear fashioned progression in the photothermal effect of GR nanosheets was conquered by immobilization of ZnO particles and successive sensitization with CoPc. The excellence found in the photothermal effect of GR–ZnO–CoPc was verified by estimation of its photothermal conversion efficiency. The photothermal conversion efficiency assessed for GR–ZnO–CoPc was higher than those for the popular gold- and CuS-based photothermal agents. In addition, it possessed significant stability against photobleaching and structural rupture. It was found that the photothermal effect of GR–ZnO–CoPc is proportional to its concentration. However, by replacement of a 980 nm laser system with 808 nm, the photothermal effect of GR–ZnO–CoPc was reduced, which could be due to lower absorption of GR–ZnO–CoPc at 808 nm compared to 980 nm. On account of its significance and important properties, GR–ZnO–CoPc could be an interesting photothermal agent to employ in future photothermal therapy for cancer

Graphene-Coupled ZnO: A Robust NIR-Induced Catalyst for Rapid Photo-Oxidation of Cyanide

Herein, we report the modulation of ZnO for enhancement of its ability toward plasmonic absorption of near-infrared (NIR) photons through coupling of graphene (GR). The reported modification led GR–ZnO to be a promising photocatalyst by the complete removal of poisonous and nonvolatile potassium cyanide from water. The photocatalytic degradation of cyanide was revealed by exposing it to NIR laser and comparing with the rate of UV, visible, and sunlight using their apparent reaction rate constants derived from the Langmuir–Hinshelwood model. The heteronanostructured GR–ZnO promoted rapid photo-oxidation of cyanide under illumination with NIR laser rather than UV, visible, and sunlight. It was assessed that the photothermal effect (PTE) is the main cause for higher catalytic efficiency of GR–ZnO in the presence of NIR radiations. Except for the NIR radiations, GR–ZnO does not show any indication of PTE by irradiating with UV, visible, or sunlight. On account of its significance, the PTE of GR–ZnO in KCN solution was evaluated and compared with its individual components viz., GR and ZnO upon exposure to a 980 nm laser system. Furthermore, it has been revealed that the PTE of GR–ZnO was proportional to its concentration. In addition to its effectiveness in the degradation of cyanide, GR–ZnO retained its special structure and exhibited an outstanding photostability after its repeated use in three successive cycles

Advancement in Photothermal Effect of Carbon Nanotubes by Grafting of Poly(amidoamine) and Deposition of CdS Nanocrystallites

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

Photothermal effect and cytotoxicity of CuS nanoflowers deposited over folic acid conjugated nanographene oxide

Herein, we present the rational synthesis of a multimode photothermal agent, NGO-FA-CuS, for the advancement of photothermal therapy of cancer. The hierarchical architecture created in NGO-FA-CuS was attained by the covalent conjugation of folic acid (FA) to nanographene oxide (NGO) through amide bonding, followed by the hydrothermal deposition of CuS nanoflowers. In this approach, instead of mere mixing or deposition, FA was covalently bonded to NGO, which helped in retaining their intrinsic properties after binding and allowed to access them in the resulting hybrid nanostructure. In this specifically designed photothermal agent, NGO-FA-CuS, each component has an explicit task,i.e., NGO, FA and CuS act as the quencher, cancer cell-targeting moiety and photothermal transduction agent, respectively. Prior to the grafting of FA molecules and the deposition of CuS nanoflowers, sulfonic acid groups were introduced into NGO to provide stability under physiological conditions. Under irradiation using a 980 nm laser, NGO-FA-CuS was able to attain a temperature of 63.1 °C within 5 min, which is far beyond the survival temperature for cancer cells. Therefore, the resulting temperature recorded for NGO-FA-CuS was sufficient to induce hyperthermia in cancer cells to cause their death. When coming into contact with cancer cells, NGO-FA-CuS can cause a rapid increase in the temperature of their nucleus, destroy the genetic substances, and ultimately lead to exhaustive apoptosis under illumination using a near-infrared (NIR) laser. An excellent photothermal efficiency of 46.2% under illumination using a 980 nm laser and outstanding cytotoxicity against HeLa, SKOV3 and KB cells were attained with NGO-FA-CuS. Moreover, NGO-FA-CuS displays exceptional persistent photo-stability without photo-corrosiveness. The photothermal effect of NGO-FA-CuS was found to be dependent on its concentration and the power density of the laser source. It was found that its cytotoxicity toward cancer cells was enhanced with an increase in the concentration of NGO-FA-CuS and the incubation period

Photothermal effect and cytotoxicity of CuS nanoflowers deposited over folic acid conjugated nanographene oxide

Herein, we present the rational synthesis of a multimode photothermal agent, NGO-FA-CuS, for the advancement of photothermal therapy of cancer. The hierarchical architecture created in NGO-FA-CuS was attained by the covalent conjugation of folic acid (FA) to nanographene oxide (NGO) through amide bonding, followed by the hydrothermal deposition of CuS nanoflowers. In this approach, instead of mere mixing or deposition, FA was covalently bonded to NGO, which helped in retaining their intrinsic properties after binding and allowed to access them in the resulting hybrid nanostructure. In this specifically designed photothermal agent, NGO-FA-CuS, each component has an explicit task,i.e., NGO, FA and CuS act as the quencher, cancer cell-targeting moiety and photothermal transduction agent, respectively. Prior to the grafting of FA molecules and the deposition of CuS nanoflowers, sulfonic acid groups were introduced into NGO to provide stability under physiological conditions. Under irradiation using a 980 nm laser, NGO-FA-CuS was able to attain a temperature of 63.1 °C within 5 min, which is far beyond the survival temperature for cancer cells. Therefore, the resulting temperature recorded for NGO-FA-CuS was sufficient to induce hyperthermia in cancer cells to cause their death. When coming into contact with cancer cells, NGO-FA-CuS can cause a rapid increase in the temperature of their nucleus, destroy the genetic substances, and ultimately lead to exhaustive apoptosis under illumination using a near-infrared (NIR) laser. An excellent photothermal efficiency of 46.2% under illumination using a 980 nm laser and outstanding cytotoxicity against HeLa, SKOV3 and KB cells were attained with NGO-FA-CuS. Moreover, NGO-FA-CuS displays exceptional persistent photo-stability without photo-corrosiveness. The photothermal effect of NGO-FA-CuS was found to be dependent on its concentration and the power density of the laser source. It was found that its cytotoxicity toward cancer cells was enhanced with an increase in the concentration of NGO-FA-CuS and the incubation period

One-pot synthesis of cobalt-salen catalyst immobilized in silica by sol-gel process and applications in selective oxidations of alkanes and alkenes

Salen ligand prepared from 1,2-phenylenediamine and 2-hydroxy-3(3-triethoxysilyl-propyl)-benzaldehyde has been used as cobalt-chelate for the immobilization of the catalytic site by a one-pot synthesis method. Sol-gel hydrolysis and polycondensation of this chelate with 10 equivalents of tetraethyl orthosilicate produced the heterogeneous catalyst. This catalyst is active in selective molecular oxygen oxidations of cyclohexane, cyclohexene, toluene, styrene and anthracene in the presence of butyraldehyde at room temperature. © 2006 Elsevier B.V. All rights reserved

Single-step, size-controlled synthesis of colloidal silver nanoparticles stabilized by octadecylamine

A single step process for the synthesis of size-controlled silver nanoparticles has been developed using a bifunctional molecule, octadecylamine (ODA). Octadecylamine complexes to Ag+ ions electrostatically, reduce them, and subsequently stabilizes the nanoparticles thus formed. Hence, octadecylamine simultaneously functions as both a reducing and a stabilizing agent. The amine-capped nanoparticles can be obtained in the form of dry powder, which is readily redispersible in aqueous and organic solvents. The particle size, and the nucleation and growth kinetics of silver nanoparticles could be tuned by varying the molar ratio of ODA to AgNO3. The UV-vis spectra of nanoparticles prepared with different concentrations of ODA displayed the well-defined plasmon band with maximum absorption around 425 nm. The formation of silver metallic nanoparticles was confirmed by their XRD pattern. The binding of ODA molecule on the surface of silver has been studied by FT-IR and NMR spectroscopy. The formation of well-dispersed spherical Ag nanoparticles has been confirmed by TEM analysis. The particle size and distribution are found to be dependent on the molar concentration of the amine molecule. Open aperture z-scans have been performed to measure the nonlinearity of Ag nanoparticles. (C) 2015 Published by Elsevier B.V