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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. [ABSTRACT FROM AUTHOR]

Naturally available diatomaceous earth (DE) microparticles are ideal candidates for drug delivery due to their excellent features like biocompatibility, non-toxicity, porosity, high surface area and ease of surface modification. On the other hand, they have some limitations, especially in drug delivery applications, such as poor drug loading capacity and a very high initial burst release. In order to address these drawbacks, we have surface modified the diatoms with silica xerogel, which forms a novel hybrid material. The modification process was carried out by a facile sol–gel method, the silica xerogel decorated DE microparticles were extensively characterized by SEM, BET, ATR-IR spectroscopy and XRD in order to confirm the covalent linkage of the new material on the surface of the DE microparticles. The prepared hybrid material DE-XER (xerogel) acts as a pH-sensitive micro drug carrier for diclofenac sodium (DS) drug. The results indicate that surface modification plays a critical role, enhancing the drug loading capacity in comparison with neat DE microparticles, achieving effective controlled release. Furthermore, the obtained drug release data were fitted to the zero order model to understand the drug release mechanism. [ABSTRACT FROM AUTHOR]

A key auxiliary role of photothermal effect (PTE) in the enhancement of photocatalytic activity under illumination to near-infrared (NIR) radiations has been experimentally revealed. It was found that the photoexcitation of electrons, required for the process of photocatalysis does not occur in presence of NIR radiations alone without the support of both UV and visible radiations. Herein, a binary heterogeneous nanophotocatalyst, GR-ZnO was fabricated by a novel approach using hydrothermal process. In which ZnO nanotrapezoids were deposited over the surfaces of graphene nanosheets. In the reported unique approach, reduction of graphene oxide to graphene has been accomplished using water by an entirely alternative mechanism compared to traditional reduction processes those employ the hazardous reducing agents. Thus produced GR-ZnO photocatalyst has exhibited the excellence in rapid degradation of industrially voluntarily employing perilous dye, methyl orange. It is explored that PTE is mainly responsible for the rapid degradation of methyl orange transpired under illumination to NIR laser. Further, it has been established that PTE could not emerge with NIR radiations alone without the support of both UV and visible radiations. In consideration of its importance, PTE of GR-ZnO nanocatalyst has been revealed and compared with its individual components, viz., graphene and ZnO. Moreover, the photothermal conversion efficiency of GR-ZnO nanocatalyst was evaluated. Overall, the excellent catalytic activity found in GR-ZnO nanocatalyst was accounted for its decreased band gap, transpired by hybridization of ZnO with graphene could efficiently prevent the recombination of photo-generated charge carriers. In addition, admired catalytic activity of GR-ZnO nanocatalyst was attributed to improved optical absorption and enhancement in the adsorption affinity to methyl orange molecules.