l-Cysteine-Conjugated Ruthenium Hydrous Oxide Nanomaterials with Anticancer Active Application.

Bioactive nanomaterials, namely: ruthenium hydrous oxide (or ruthenium oxy-hydroxide), RuOx(OH)y and also a surface-conjugated novel material of the same within the template of an amino acid molecule, l-cysteine, have been studied. These compounds have been prepared through a simple wet chemical route, under physiological conditions, such that they could be suitably used in anticancer applications. Several physical methods were used for the nanomaterial characterization, e.g.: thermal analysis of the as prepared ruthenium hydrous oxide by differential scanning calorimetry (DSC) followed by thermal gravimetric analysis (TGA). This confirms that the material is a precursor for anhydrous nanocrystalline ruthenium oxide (RuO2), as is affirmed by powder X-ray diffraction pattern. Also, optical spectroscopic absorption (UV-vis and FT-IR) study of these nanoparticles (NPs) to ascertain their surface conjugation with l-cysteine have been performed. Besides these, surface morphology of the NPs were studied by field emission scanning electron microscopy (FE-SEM) along with their elemental purity check through energy dispersive X-ray analysis (EDX). Their surface chemical microenvironments were examined by X-ray photo electron spectroscopy (XPS). The hydrodynamic size of the prepared NPs were measured through dynamic light scattering (DLS) studies. Further, biological consequences of these NPs on cancerous HeLa cells and their cytotoxicity effects have been reported with MTT assay, such an application has not been reported so far.

Correction: Tuneable light-emitting carbon-dot/polymer flexible films prepared through one-pot synthesis.

Correction for 'Tuneable light-emitting carbon-dot/polymer flexible films prepared through one-pot synthesis' by Susanta Kumar Bhunia, et al., Nanoscale, 2016, 8, 3400-3406.

Carbon-Dot/Silver-Nanoparticle Flexible SERS-Active Films.

Development of effective platforms for surface enhanced Raman scattering (SERS) sensing has mostly focused on fabrication of colloidal metal surfaces and tuning of their surface morphologies, designed to create "hot spots" in which plasmonic fields yield enhanced SERS signals. We fabricated distinctive SERS-active flexible films comprising polydimethylsiloxane (PDMS) embedding carbon dots (C-dots) and coated with silver nano-particles (Ag NPs). We show that the polymer-associated Ag NPs and C-dots intimately affected the physical properties of each other. In particular, the C-dot-Ag-NP-polymer films exhibited SERS properties upon deposition of versatile targets, both conventional SERS-active dyes as well as bacterial samples. We show that the SERS response was correlated to the formation C-dots within the polymer film and the physical proximity between the C-dots and Ag NPs, indicating that coupling between the plasmonic fields of the Ag NPs and C-dots' excitons constituted a prominent factor in the SERS properties.

Tuneable light-emitting carbon-dot/polymer flexible films prepared through one-pot synthesis.

Development of efficient, inexpensive, and environmentally-friendly light emitters, particularly devices that produce white light, have drawn intense interest due to diverse applications in the lighting industry, photonics, solar energy, and others. We present a simple strategy for the fabrication of flexible transparent films exhibiting tuneable light emission through one-pot synthesis of polymer matrixes with embedded carbon dots assembled in situ. Importantly, different luminescence colours were produced simply by preparing C-dot/polymer films using carbon precursors that yielded C-dots exhibiting distinct fluorescence emission profiles. Furthermore, mixtures of C-dot precursors could be also employed for fabricating films exhibiting different colours. In particular, we successfully produced films emitting white light with attractive properties (i.e."warm" white light with a high colour rendering index) - a highly sought after goal in optical technologies.

Photocatalytic hybrid Au/ZnO nanoparticles assembled through a one-pot method.

Growth of metal domains on semiconductor nanoparticles is known to enhance their photocatalytic properties. We prepared ZnO nanoparticles decorated with metallic Au domains through a new one-pot microwave-based strategy. The synthetic route utilized microwave-heating of a mixture of only three components: Zn(2+) salt, Au(SCN)4(-) which served as a precursor for metallic gold, and Tris base. The Tris molecules had a dual role in the process, both shaping the morphology of the ZnO particles, as well as constituting docking and nucleation sites for the Au(SCN)4(-) ions. The Au complex subsequently underwent spontaneous crystallization/reduction without co-addition of reducing or stabilizing agents, yielding Au nanoparticles attached to the ZnO surface. We show that the hybrid Au/ZnO nanoparticles exhibited enhanced photocatalytic properties compared to the plain ZnO nanoparticles.

Polyamine-Mediated Interfacial Assembly of rGO-ZnO Nanostructures: A Bio-inspired Approach and Enhanced Photocatalytic Properties.

A bio-inspired approach for the fabrication of reduced graphene oxide (rGO) embedded ZnO nanostructure has been attempted to address issues pertaining to charge recombination and photocorrosion in ZnO for application as an effective photocatalyst. Herein we demonstrate the synthesis of rGO-ZnO nanostructures in a single step using polyamines, which simultaneously aid in the mineralization of ZnO nanostructures from zinc nitrate, reduction of graphene oxide (GO), and finally their assembly to form rGO-ZnO composite structures under environmentally benign conditions. The interspersed nanocomponents in the assembled heterostructures result in enhanced photocatalytic activity under UV light, indicating an effective charge separation of the excited electrons. Furthermore, the composite structure provides stability against photocorrosion for efficient recyclability of the catalyst.

Biomimetic Method To Assemble Nanostructured Ag@ZnO on Cotton Fabrics: Application as Self-Cleaning Flexible Materials with Visible-Light Photocatalysis and Antibacterial Activities.

A bioinspired mineralization route to prepare self-cleaning cotton fabrics by functionalizing their surface with nanostructured Ag@ZnO is demonstrated herein. In a polyamine-mediated mineralization process, while the nucleation, organization and coating of ZnO is done directly from water-soluble zinc salts under mild conditions, the entrapped polyamine in the ZnO matrix acts as reducing agent to generate Ag(0) from Ag(I) at room temperature. The Ag@ZnO coated cotton fabrics are characterized by FESEM, HRTEM, XRD, and UV-vis-DRS to confirm the formation and coating of Ag@ZnO particles on individual threads of the fabric. The presence of Ag nanoparticles not only enables the ZnO-coated fabrics exhibiting improved photocatalytic property but also allows for visible-light-driven activities. Furthermore, it exhibits efficient antimicrobial activity against both Gram-positive and Gram-negative bacteria. Therefore, besides these multifunctional properties, the polyamine-mediated bioinspired approach is expected to pave way for functionalization of flexible substrates under mild conditions as desirable for the development and fabrication of smart, lightweight, and wearable devices for various niche applications.

Confinement of CuII -phthalocyanine in a bioinspired hybrid nanoparticle-assembled structure yields selective and stable epoxidation catalysts.

Herein, we demonstrate that a bioinspired assembly of silica nanoparticles with polyamines as structure-directing agents similar to that known for the biosilicification of diatoms can pave the way for the efficient encapsulation of sulfonated copper-phthalocyanine in a hybrid microcapsule structure, in which the organic component provides a capable environment for its catalytic activity in epoxidation reactions and the nanoassembled structure imparts stability.

Enabling antibacterial coating via bioinspired mineralization of nanostructured ZnO on fabrics under mild conditions.

Herein, we present an environmentally benign method capable of mineralization and deposition of nanomaterials to introduce antibacterial functionalities into cotton fabrics under mild conditions. Similar to the way in which many naturally occurring biominerals evolve around the living organism under ambient conditions, this technique enables flexible substrates like the cotton fabric to be coated with inorganic-based functional materials. Specifically, our strategy involves the use of long-chain polyamines known to be responsible in certain biomineralization processes, to nucleate, organize, and deposit nanostructured ZnO on cotton bandage in an aqueous solution under mild conditions of room temperature and neutral pH. The ZnO-coated cotton bandages as characterized by SEM, confocal micro-Raman spectroscopy, XRD, UV-DRS, and fluorescence microscopy demonstrate the importance of polyamine in generating a stable and uniform coating of spindle-shaped ZnO particles on individual threads of the fabric. As the coating process requires only mild conditions, it avoids any adverse effect on the thermal and mechanical properties of the substrate. Furthermore, the ZnO particles on cotton fabric show efficient antibacterial activity against both gram-positive and gram-negetive bacteria. Therefore, the developed polyamine mediated bioinspired coating method provides not only a facile and "green" synthesis for coating on flexible substrate but also the fabrication of antibacterial enabled materials for healthcare applications.

Zinc oxide nanoflowers make new blood vessels.

It is well established that angiogenesis is the process of formation of new capillaries from pre-existing blood vessels. It is a complex process, involving both pro- and anti-angiogenic factors, and plays a significant role in physiological and pathophysiological processes such as embryonic development, atherosclerosis, post-ischemic vascularization of the myocardium, tumor growth and metastasis, rheumatoid arthritis etc. This is the first report of zinc oxide (ZnO) nanoflowers that show significant pro-angiogenic properties (formation of new capillaries from pre-existing blood vessels), observed by in vitro and in vivo angiogenesis assays. The egg yolk angiogenesis assay using ZnO nanoflowers indicates the presence of matured blood vessels formation. Additionally, it helps to promote endothelial cell (EA.hy926 cells) migration in wound healing assays. Formation of reactive oxygen species (ROS), especially hydrogen peroxide (H(2)O(2))-a redox signaling molecule, might be the plausible mechanism for nanoflower-based angiogenesis. Angiogenesis by nanoflowers may provide the basis for the future development of new alternative therapeutic treatment strategies for cardiovascular and ischemic diseases, where angiogenesis plays a significant role.

Controlled orientation in a bio-inspired assembly of Ag/AgCl/ZnO nanostructures enables enhancement in visible-light-induced photocatalytic performance.

In a bio-inspired approach, polyamine-mediated mineralization of ZnO was explored to develop an environmentally benign methodology for synthesizing Ag/AgCl/ZnO nanostructures. The assembling properties displayed by the polyamines to create composite structures was utilized to have the nanocomponents effectively interact with each other in a way that is desirable for the application envisaged. The polyamines, which act as a mineralizing agent for ZnO nanoparticles, also facilitate the formation of Ag/AgCl within ZnO under ambient conditions. Thus synthesized Ag/AgCl/ZnO nanostructures represent a multi-heterojunction system in which the nanocomponents lead in a synergistic way to enhancement in the photocatalytic activity under visible-light irradiation.

Oriented morphogenesis of ZnO nanostructures from water-soluble zinc salts under environmentally mild conditions and their optical properties.

Herein, we report a bottom-up, mineralization strategy, which borrows key principles from biomineralization processes, to synthesize nanostructured materials. A long-chain polyamine simultaneously mineralizes and assembles ZnO nanoparticles directly from water-soluble zinc salts under sustainable synthesis conditions. These thus-generated oriented structures undergo interesting morphogenesis that is controlled by changing the ratio of polyamine/Zn(2+) ions. As the ratio increases, the morphology changes from a spherical shape to oval-, dumbbell-, and finally hexagonal-rod-shaped structures that contain unique hollow rod structures. Using XPS, XRD, FT-IR, Raman spectroscopy, DLS, and confocal fluorescence microscopic analysis, we elucidate the mechanism of structural evolution; this mechanism involves the initial formation of a zinc/amine complex that is furnished with polyamine chains. These chains facilitate the condensation process to form ZnO nanoparticles and their assembly in aqueous medium at neutral pH. Further, the presence of defects in the thus-morphogenized ZnO structures leads to blue luminescence and efficient photoinduced activity, assisted by the surface-hole-trapping effect of polyamines.