Antibacterial and Photocatalytic Properties of ZnO-9-Aminoacridine Hydrochloride Hydrate Drug Nanoconjugates.

The development of nanomaterial-based hybrid systems for healthcare and energy-related materials has attracted significant attention nowadays. Here, we have designed a nanocomposite of ZnO nanoparticles (NPs) with anticancer therapeutic drug 9-aminoacridine hydrochloride hydrate (9AA-HCl) for antibacterial and photocatalytic activities. Spectroscopic studies reveal that the photoinduced electron transfer from photoexcited 9AA-HCl to the conduction band of ZnO NP causes the generation of the reactive oxygen species (ROS), which is responsible for antibacterial activity and photocatalytic properties. It is seen that the efficiency of photodegradation of dye molecules increases in ZnO-9AA-HCl nanoconjugated systems than pure ZnO nanoparticles because of efficient charge separation. In addition, the antibacterial efficacy of the nanoconjugate is investigated using a strain of Gram-negative bacteria where the cell-killing activities are observed 99.99 and 100% for 20 and 21 µL/mL nanoconjugate, respectively, and very little cell-killing activity is observed for free ZnO NPs and free drug. Moreover, it is also observed that the nanoconjugate generates sufficient intracellular ROS that can hydrolyze 2',7'-dichlorodihydrofluoresceindiacetate (DCFH-DA) to highly fluorescent 2',7'-dichlorofluorescein (DCF). The outcome of the study will provide valuable information for designing new-edge nanoconjugate materials for potential applications in photocatalytic and antibacterial activities.

Fabrication of Low-Cost Flexible Superhydrophobic Antibacterial Surface with Dual-Scale Roughness.

In this work, we report a large-area fabrication of a flexible superhydrophobic bactericidal surface decorated with copper hydroxide nanowires. This involves a simple two-step method which involves growth followed by transfer of the nanowires onto the polydimethylsiloxane (PDMS) surface by mechanical peeling. Additional roughness in PDMS is obtained through incomplete wetting of the nanoscale gaps which leads to dual-scale roughness and superhydrophobicity with a contact angle of 169° and hysteresis of less than 2°. The simplicity of the process makes it low-cost and easily scalable. The process allows fabrication of nonplanar 3D surfaces. The surface shows blood repellence and antibacterial activity against Escherichia coli with more than 5 log reductions in bacterial colony. The surface also shows hemocompatible behavior, making it suitable for healthcare applications. The fabricated surface is found to be extremely robust against stretching, twisting, sandpaper abrasion, solid weight impact, and tape peel test. The surface is found to withstand human weight multiple times without losing its hydrophobicity, making it suitable for several practical scenarios in healthcare and household applications.

Correction: An efficient charge separation and photocurrent generation in the carbon dot-zinc oxide nanoparticle composite.

Correction for 'An efficient charge separation and photocurrent generation in the carbon dot-zinc oxide nanoparticle composite' by Monoj Kumar Barman et al., Nanoscale, 2017, 9, 6791-6799.

An efficient charge separation and photocurrent generation in the carbon dot-zinc oxide nanoparticle composite.

The development of light harvesting systems based on heterostructures for efficient conversion of solar energy to renewable energy is an emerging area of research. Here, we have designed heterostructures by using carbon dots (C-dots) and zinc oxide nanoparticles (ZnO NP) to develop an efficient light harvesting system. Interestingly, the conduction band and the valence band positions of ZnO NP are lower than the LUMO and HOMO positions of C-dots in this type II heterostructure of C dot-ZnO NP, which causes efficient charge separation and photocurrent generation. Steady state and time resolved spectroscopic studies reveal that an efficient photoinduced electron transfer occurs from C dots to ZnO NP and a simultaneous hole transfer occurs from the valence band of ZnO NP to the HOMO of C dots. The calculated rate of electron transfer is found to be 3.7 × 109 s-1 and the rate of hole transfer is found to be 3.6 × 107 s-1. The enhancement of photocurrent (11 fold) under solar light irradiation of the C dot-ZnO NP heterostructure opens up new possibilities to design efficient light harvesting systems.

Zinc oxide functionalized human hair: A potential water decontaminating agent.

HYPOTHESIS: Nano-ZnO is an efficient photocatalyst that can be employed for water purification but its separation from water is difficult. Immobilization of nano-ZnO on a fibrous material is expected to add practicality to its application. EXPERIMENTS: We synthesized ZnO nanostructures on a natural waste, human hair, via a cost-effective process, characterized the system and tested the efficacy of the composite for photo-decomposition of a few toxic materials in water. FINDINGS: Layers of well crystalline ZnO nanostructures grew homogeneously on hair strands, initially as thin plates that slowly turned with time into nanorods (length 400-600nm, width 28-30nm), converting the mildly hydrophobic hair (water contact angle 104°) surface into superhydrophobic (water contact angle 149°). The composite was found to effectively photodecompose toxic dyes like methylene blue, direct red, alizarin red S and aromatics (toluene), for multiple cycles without losing much efficacy.

Photon Harvesting in Sunscreen-Based Functional Nanoparticles.

The ultraviolet light component in the solar spectrum is known to cause several harmful effects, such as allergy, skin ageing, and skin cancer. Thus, current research attention has been paid to the design and fundamental understanding of sunscreen-based materials. One of the most abundantly used sunscreen molecules is Avobenzone (AB), which exhibits two tautomers. Here, we highlight the preparation of spherically shaped nanoparticles from the sunscreen molecule AB as well as from sunscreen-molecule-encapsulated polymer nanoparticles in aqueous media and study their fundamental photophysical properties by steady-state and time-resolved spectroscopy. Steady-state studies confirm that the AB molecule is in the keto and enol forms in tetrahydrofuran, whereas the enol form is stable in the case of both AB nanoparticles and AB-encapsulated poly(methyl methacrylate) (PMMA) nanoparticles. Thus, the keto-enol transformation of AB molecules is restricted to a nanoenvironment. An enhancement of photostability in both the nanoparticle and PMMA-encapsulated forms under UV light irradiation is observed. The efficient excited energy transfer (60 %) from AB to porphyrin molecules opens up further prospects in potential applications as light-harvesting systems.

Synthesis of a novel cone-shaped CaAl-layered double hydroxide (LDH): its potential use as a reversible oil sorbent.

A novel cone-shaped superhydrophobic and oleophilic CaAl-LDH intercalated with dodecyl sulphate (DS(-)) anions was synthesized from calcium dodecyl sulphate as a precursor via a one-step hydrothermal method. The synthesized LDH has been successfully utilized in mopping and regeneration of oil from oil-water mixtures.

Concomitant synthesis of highly crystalline Zn-Al layered double hydroxide and ZnO: phase interconversion and enhanced photocatalytic activity.

Metal oxide/hydroxide with hierarchical nanostructures has emerged as one of the most promising materials for their unique, attractive properties and feasibility of applications in various fields. In this report, a concomitant synthesis of crystalline zinc aluminum layered double hydroxide (ZnAl-LDH) nanostructure and ZnO is presented using Al substrate as template. Studies on interconversion of ZnO to LDH phase in bulk solution under hydrothermal conditions produced Al-doped ZnO (AZO) in one case, and in other, it improves the crystallinity of LDH film templated on Al substrate. In presence of Al salt, the self-limiting growth nature of plate LDH turned to non-self-limiting. Materials obtained during phase transition, AZO in bulk solution and crystalline porous ZnAl-LDH on substrate, have been demonstrated as effective photocatalysts for decomposition of congo red in aqueous medium.

A Triad of Variable-Valent Rhenium Aldimine and Amide Systems Interrelated by Successive Oxygen Atom Transfer.

The title systems are Re(V)OCl(3)(RA), 1, Re(III)(OPPh(3))Cl(3)(RA), 2, and Re(IV)(OPPh(3))Cl(3)(RB), 3, where RA is a 2-pyridinecarboxaldimine, p-RC(6)H(4)N=CHC(5)H(4)N, and RB(-) is the corresponding 2-picolinamide, p-RC(6)H(4)NC(=O)C(5)H(4)N(-) (R = H, Me, OMe, Cl). Controlled reaction of ReOCl(3)(PPh(3))(2) with RA affords 1, which is converted to 2 upon reaction with PPh(3). The oxidation of 2 in aqueous media by Ce(4+) or H(2)O(2) furnishes 3. The X-ray structure of 1 (R = Me) has revealed meridional ReCl(3) geometry, the oxo atom lying trans to the pyridine nitrogen of chelated MeA. The metal atom is displaced by 0.35 Å toward the oxo atom from the ReCl(3)N(aldimine) plane. The couples 2(+)/2 (E(1/2) approximately 0.3 V vs SCE), 3(+)/3 (E(1/2) approximately 1.3 V), and 3/3(-) (E(1/2) approximately -0.5 V) are observable electrochemically. The conversion 1--> 2 follows a second-order rate law with a large and negative entropy of activation ( approximately -40 eu). The reaction is proposed to proceed via nucleophilic attack by the phosphine on Re=O; the observed effects of R and phosphine variation on the rate are consistent with this. In the conversion of 2 to 3, the active species is 2(+), the stoichiometry of the reaction being 32(+) + H(2)O --> 22 + 3 + 3H(+). The amide oxygen in 3 originates from the water molecule. The reaction follows a second-order law, and the entropy of activation is large and negative, approximately -30 eu. The rate-determining addition of water to the aldimine function is believed to afford an alpha-hydroxy amine intermediate which undergoes induced electron transfer and associated changes, affording 3. Crystal data for ReOCl(3)(MeA) are as follows: empirical formula C(13)H(12)Cl(3)N(2)ORe; crystal system triclinic; space group P&onemacr;; a = 7.136(4) Å, b = 8.329(5) Å, c = 14.104(9) Å, alpha = 73.88(5) degrees, beta = 76.35(5) degrees, gamma = 85.64(5) degrees; V = 782.5(8) Å(3); Z = 2.