Hybrid Nanofilms Research Articles

One-step electrodeposited hybrid nanofilms in amperometric biosensor development.

This review summarizes recent developments in amperometric biosensors, based on one-step electrodeposited organic-inorganic hybrid layers, used for analysis of low molecular weight compounds. The factors affecting self-assembly of one-step electrodeposited films, methods for verifying their composition, advantages, limitations and approaches affecting the electroanalytical performance of amperometric biosensors based on organic-inorganic hybrid layers were systemized. Moreover, issues related to the formation of one-step organic-inorganic hybrid functional layers with different structures in biosensors produced under the same electrodeposition parameters are discussed. The systemized dependencies can support the preliminary choice of functional sensing layers with architectures tuned for specific biotechnology and life science applications. Finally, the capabilities of one-step electrodeposition of organic-inorganic hybrid functional films beyond amperometric biosensors were highlighted.

In-situ fabrication of MOF@CoP hybrid bifunctional electrocatalytic nanofilm on carbon fibrous membrane for efficient overall water splitting

Construction of metal-organic framework@cobalt phosphide (MOF@CoP) hybrid materials with enriched structures and excellent synergistic electrocatalytic properties for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is still highly desirable. Herein, a new series of Co-MOF@CoP hybrid nanofilms with controllable content ratio are successfully fabricated on carbon fibrous membrane (CFM) for electrocatalytic overall water splitting. Multiple characterization techniques verify the partial phosphorization of Co-MOF to CoP for an unique hybrid structure, where the remained Co-MOF with an interconnected porous structure not only provides efficient and fast channels for reactants/products transportation but also stabilizes the resulted CoP species in Co-MOF with an intimate interaction. As a result, the optimized Co-MOF@CoP@CFM catalyst exhibits remarkable electrocatalytic activity both for HER and OER, which only requires a voltage of 1.58 V to achieve the current density of 10 mA cm−2 for the overall water splitting. The results provide some inspiration for the design and construction of advanced porous nanofilm catalysts.

Combinatorial non-covalent assembly of graphene oxide and chromophores into hybrid nanofilms for organic electronics

Functionally different 2D hybrids were assembled by using the same starting set of components comprising graphene oxide, perylene chromophore, polydiacetylene surfactant and divalent ions to modulate the properties of resulting systems.

One-Step Interfacial Integration of Graphene Oxide and Organic Chromophores into Multicomponent Nanohybrids with Photoelectric Properties.

A one-step protocol for interfacial self-assembly of graphene oxide (GO), glutamine-substituted perylene diimide (PDI-glu), 10,12-pentacosadiynoic acid (PCDA), and zinc acetate into three- and four-component hybrid nanofilms through hydrogen and coordination bonding was developed. The hybrids deposited onto solid supports were studied after polymerization of PCDA by UV-vis absorption, fluorescence, and Raman spectroscopies, scanning electron microscopy (SEM), and atomic force microscopy (AFM). The results of spectroscopic studies suggest that the hybrids assembled through H-bonds can maintain the light-induced Förster energy transfer from the PDI-glu chromophore to the conjugated polymer and then to GO leading to fluorescence quenching. In the hybrids assembled through coordination bonding with zinc clusters, the energy transfer proceeds from PDI-glu to the PDA polymer, whereas the transfer from PDA to GO is quenched completely. Another important characteristic of these ultrathin hybrids is their stability with respect to photobleaching of chromophores due to the acceptor properties of GO. The as-assembled hybrid nanofilms were integrated with conventional photovoltaic planar architectures to study their photoelectric properties. The zinc-containing hybrids integrated with a hole transport layer exhibited photovoltaic properties. The cell with the integrated four-component hybrid comprising both PDI-glu and PDA showed a photocurrent/dark current ratio almost an order higher than that of the three-component hybrid assembled with PDA only. The supramolecular method based on the interfacial self-assembly can be extended to a wide variety of organic chromophores and polymerizable surfactants for integrating them into multicomponent functional GO-based nanohybrids with targeted properties for organic electronics.

"THERMAL STABILITY AND UV RESISTANCE OF NANOCELLULOSE/TANNIN HYBRID FILMS"

"Nanofibrillated cellulose can be used as a robust scaffold filled with tannin particles. Such reinforcement may confer particular chemical features needed for the production of hybrid films used as active packaging. Based on this hypothesis, powdered tannin particles were incorporated into nanocellulose-based films at two different weight fractions. The chemical, thermal and mechanical properties of these films were determined. Also, their resistance to UV exposure was evaluated in terms of colorimetric and mechanical characteristics. Neither chemical nor thermal noticeable adverse effects could be ascribed to the tannin insertion. On the other hand, the insertion of 1 wt% tannin induced an increase of 60% in tensile strength, although this effect was not retained after UV exposure. Meanwhile, the film that incorporated 3 wt% tannin appeared to present stable mechanical properties after UV exposure. This mechanical stability over UV exposure was not obtained with the inclusion of 1 wt% tannin content. The hybrid nanofilms acquired brown shades, which were not retained when the films were exposed to UV radiation."

Hybrid nanofilms as topical anesthetics for pain-free procedures in dentistry

Topical anesthetics are widely applied in order to relieve the discomfort and anxiety caused by needle insertion and other painful superficial interventions at the oral cavity. So far, there are no commercially available effective topical anesthetic formulations for that purpose, and the most of developments are related to hydrophilic and low mucoadhesive forms. Therefore, we have prepared different hybrid nanofilms composed of biopolymer matrices (chitosan, pectin, and chitosan-pectin) blended with nanostructured lipid carriers (NLC) loading the eutectic mixture of 5% lidocaine–prilocaine (LDC–PLC), in order to fulfill this gap in the market. These dual systems were processed as hybrid nanofilms by the solvent/casting method, and its mucoadhesive, structural and mechanical properties were detailed. The most appropriate hybrid nanofilm combined the advantages of both pectin (PCT) and NLC components. The resultant material presented sustained LDC–PLC release profile for more than 8 h; permeation across porcine buccal mucosa almost twice higher than control and non-cytotoxicity against 3T3 and HACAT cell lines. Then, the in vivo efficacy of PCT/NLC formulation was compared to biopolymer film and commercial drug, exhibiting the longest-lasting anesthetic effect (> 7 h), assessed by tail flick test in mice. These pectin-based hybrid nanofilms open perspectives for clinical trials and applications beyond Dentistry.

Physico-chemical properties and surface characterization of renewable hybrid nanofilms interacting with model proteins

A comprehensive characterization of physical-chemical properties and biological interactions of ca. 200-nm-thick hybrid films based on silylated (inorganic part) castor oil (organic part) is proposed. A series of such nanofilms was fabricated and cross-linked by a sol-gel procedure, and their properties such as hydrophilicity, hardness and water vapour transmission rate were systematically studied as a function of the ratio of silylated agent to castor oil. It was found that the nanofilms have contact angles always below 90°, tunable Young modulus and hardness in the MPa range. Moreover, their water vapour transmission rates are increased by decreasing the silica ratio. The protein adsorption and cytocompatibility were evaluated using model proteins and cells. The adsorption of the proteins bovine serum albumin (BSA) and lysozyme was characterized using a quartz crystal microbalance in energy dissipation mode (QCM-D), and atomic force microscopy (AFM). The combination of the latter provided evidence for the different affinities of the proteins with the films. It was found that BSA and lysozyme form rigid layers on the surface with surface coverage close to 30%, and that both protein layers decrease their thickness after their dehydration. Finally, cell culture experiments exhibited a good viability of the fibroblasts compared to ultra-low adhesion surfaces, which makes them potential candidates for biomedical applications.

Laser-induced luminescence in hybrid nanofilms

Tris(8-hydroxyquinoline) boron (Bq3) was synthesized by a high-temperature exchange reaction. Bq3 powders containing various polymorphous modifications were synthesized, and their photoluminescent characteristics were analyzed. Films of Alq3/B2O3/Al hybrid materials (HMs) were deposited on glass substrates by vacuum thermal evaporation. It is shown that local heating by a diode laser (785 nm) with an intensity of 150 W/cm2 for one second causes irreversible transformation in the HM film structure. The chromaticity coordinates of the photoluminescence of laser-irradiated regions considerably differ from those of the initial HM film luminescence.

Sandwiched confinement of quantum dots in graphene matrix for efficient electron transfer and photocurrent production.

Quantum dots (QDs) and graphene are both promising materials for the development of new-generation optoelectronic devices. Towards this end, synergic assembly of these two building blocks is a key step but remains a challenge. Here, we show a one-step strategy for organizing QDs in a graphene matrix via interfacial self-assembly, leading to the formation of sandwiched hybrid QD-graphene nanofilms. We have explored structural features, electron transfer kinetics and photocurrent generation capacity of such hybrid nanofilms using a wide variety of advanced techniques. Graphene nanosheets interlink QDs and significantly improve electronic coupling, resulting in fast electron transfer from photoexcited QDs to graphene with a rate constant of 1.3 × 109 s−1. Efficient electron transfer dramatically enhances photocurrent generation in a liquid-junction QD-sensitized solar cell where the hybrid nanofilm acts as a photoanode. We thereby demonstrate a cost-effective method to construct large-area QD-graphene hybrid nanofilms with straightforward scale-up potential for optoelectronic applications.

Formation of Silica/Graphene Oxide Hybrid Nano Films by Layer-by-Layer Self-Assembly and Biomimetic Silicification.

Silica/graphene oxide hybrid thin films were formed by layer-by-layer self-assembly and biomimetic silicification, and the thickness and structure of hybrid thin films were finely controlled at the nanometer scale, by tuning number of the layer-by-layer process. The physical properties of thin films were characterized by infrared spectroscopy, atomic force microscopy, and scanning electron microscopy. In addition, silica/graphene oxide hybrid thin films were successfully utilized for cell culture platforms.

A high-performance UV/visible photodetector of Cu2O/ZnO hybrid nanofilms on SWNT-based flexible conducting substrates

A Cu2O/ZnO nanofilm photodetector was fabricated on flexible SWNT-coated substrates, which demonstrates excellent responsiveness under UV/visible illumination without external bias.

Graphitic carbon nitride solid nanofilms for selective and recyclable sensing of Cu2+ and Ag+ in water and serum.

Herein we report the fabrication of g-C3N4 nanofilms and their application as a solid fluorescence sensor. The as-prepared films are capable of convenient, sensitive, selective, rapid and recyclable sensing of Cu(2+) and Ag(+) in water and serum, indicating the sensor's potential application in disease diagnosis. Attractively, our sensor is able to differentiate Cu(2+) and Ag(+) by making use of their different adsorption and desorption kinetics during the interaction with g-C3N4 nanofilms.

Hysteresis phenomena in permalloy–niobium bilayer films

Kinetics of magnetization reversal is studied in bilayer permalloy–niobium hybrid nanofilms by means of a magneto-optic visualization technique. The Nb-sublayer is found to affect the width of magnetic domain walls, the type of the walls, the orientation of the walls, and the kinetics of magnetization reversal in permalloy. Moreover, the low temperature magnetization reversal dependence upon the high temperature prehistory is revealed for a permalloy layer with domain walls of Bloch type. The niobium retains the information about a magnetic pattern freezed in permalloy and causes its reproduction during magnetization reversal. The “memory” is intact under magnetic field cycling as well as under a current flow. The effect demonstrates the efficiency of magnetic pinning and opens a new method for reversible variation of electromagnetic properties of hybrid devices.

One-pot synthesis of fluorescent hybrid nanoparticles and their assembly into transparent and multi-coloured nanofilms

We developed a route for one-pot synthesis of fluorescent hybrid nanoparticles and their assembly into a nanofilm by utilizing a fusion and fission-triggered nanoreactor system based on water-in-oil “mini-emulsion”. A fluorescent nanocrystal, ZnS:Mn2+, was produced in a confined system via fusion and fission of nanodroplets induced by ultrasonication and the amount of nanocrystals formed in each nanoreactor was easily controlled. Then, in situ polymerisation allowed for encapsulation of nanocrystals inside polymer nanoparticles, leading to an efficient surface capping of nanocrystals with polymers and hence a strong light emission under UV irradiation. Also, hybrid nanoparticles with different colours could be created by tuning of Mn2+ doping into ZnS nanocrystals, which can give rise to an energy transfer from carboxylic groups of surface capping polymers to the Mn2+. These hybrid nanoparticles were then spin-coated to form hybrid nanofilms where nanocrystals were uniformly distributed. The multicolour tuning of nanofilms was achieved simply by mixing nanoparticles with ZnS-derived blue emission and those with ZnS:Mn2+-derived orange emission. We believe that our nanoreactor system would offer a viable way in creating fluorescent nanomaterials.

Clay-protein ultrathin films: Design and bio-catalytic performance study

In recent years, immense interest has been paid to the biomolecular architecture with the aim of protein assembly in two dimensions on solid substrates, and the constructions of clay-protein ultrathin films (CPUFs) are particularly concerned. This paper gives an overview of the recent research concerning the protein molecules (lysozyme, papain, protamine, bovine serum albumin) immobilized on clay mineral (Na-saponite) platelets and assembled in monolayered or multilayered hybrid ultrafilms or nanofilms. Two techniques including alternate layer-by-layer (LbL) assembly and the Langmuir-Blodgett (LB) are described in detail. A variety of means, including UV-vis absorption, attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, XRD, AFM and surface chemistry techniques, have been described for characterization of the films in terms of quantification of protein and clay. The result reveals that electrostatic interaction is a prominent but not the only driving force in CPUF construction. In the case of LB technique, we managed to manipulate the elementary clay mineral platelets (1.3 nm in thickness) and assemble proteins into CPUFs with the aid of surfactants, and the formation of CPUFs was monitored via surface pressure vs. time ( π-t) kinetics curves and surface pressure vs. area (π-A) isotherms. The factors that influence protein adsorption on the clay layer, such as surfactants, the concentration of clay, equilibrium time, categories of protein, and injection methods, were investigated. The parameters such as protein amount (n S ), packing density (Θ), and average surface area per molecule (Ω) of deposited CPUFs were measured via method of surface chemistry and spectroscopy. By comparing the results of surface chemistry with those of adsorption experiments, we demonstrate that the surface chemistry method is a useful tool in investigating CPUFs. We also found that the water soluble protein molecules could form protein-clay hybrid monolayer over the dilute clay dispersions without addition of surfactants, and CPUFs containing elementary clay sheets and protein with great homogeneity were easily prepared by controlling certain surface pressure. To investigate the bio-catalytic performance of the immobilized lysozyme in CPUFs, we deposited CPUFs onto a cover glass, and installed the cover glass in a flow cell-grown reactor for Comamonas testosteroni (WDL7-GFP) incubation. The results show that the proliferation of WDL7-GFP is greatly suppressed by lysozyme, which demonstrates that lysozyme still retains its bioactivity after it is immobilized in the CPUFs.

Bio-inspired nanoreactor based on a miniemulsion system to create organic–inorganic hybrid nanoparticles and nanofilms

We developed a novel route to control both mineralization and polymerization inside a nanoreactor based on a miniemulsion system to create organic–inorganic hybrid nanomaterials with diverse structures and morphologies. Nanodroplets of calcium nitrate (Ca(NO3)2)/monomer and nanodroplets of sodium carbonate (Na2CO3) were separately prepared and suspended in the oil phase. They were mixed through the fusion and fission process triggered by ultrasonication to precipitate a biomineral only inside the nanodroplets. In the presence of monomer, 2-hydroxyethyl methacrylate (HEMA), we could obtain unique structures of nano-sized CaCO3 particles, which were crystalline with spherical or rod-like shapes or amorphous. By subsequent polymerization, we could encapsulate nano-CaCO3 inside the polymeric nanoparticles at a desired stage of crystal growth. The preincubation period for CaCO3 nucleation and growth and the polymerization rate were important factors to manipulate the structures and polymorphs of nano-CaCO3 inside the hybrid nanoparticles, owing to inhibition of crystal growth and transformation by polymerization of HEMA. Also, the growth of rod-like CaCO3 inside the nanoparticles led to formation of spheroidal hybrid nanoparticles. By using hybrid nanoparticles as building blocks, we could produce nanofilms containing nano-CaCO3 with a variety of sizes and structures. Crystal transformation of amorphous CaCO3 was induced inside the nanofilm by increasing the temperature to above the Tg of PHEMA.

POSS/TiO<sub>2</sub> Nanohybrids as Sun Protection Ingredients for Greenhouse Covers

Based on (3-methacryloxypropyl)-Polyhedral oligomeric silsesquioxane (MP-POSS) (MP), vinyl-POSS (VP), (3-glycidoxypropyl)-POSS (GP) and modified with 10, 20 and 30 wt-% titanium tetrabutoxide (TTB), three hybrid nanofilms (f-MPT, f-VPT and f-GPT) were prepared using hydrolytic condensation and crosslinking. The average transparency (AT) and absorption coefficients (AC) of the films were measured in the ranges of 280-2500 nm. The average transparency (AT) values of three films were about 10-11% (280-320 nm), 78-80% (320-400 nm) and 85-89% (750-2500 nm), which implies that these films indeed can provide a physical barrier for blocking the UV-B absorbed into greenhouse, indicating functionality of the POSS/TiO2 materials as the sun protection ingredients. The AT values of three films were in the order of f-MPT>f-GPT>f-VPT due to complete-cage structures of building blocks (POSS) and the size of organic branches covalently bonded to the silica network in the molecular structures. This indicates that VPT powder might be significantly better to selected for the sun protection factor (SPF). Lower mtransparency of the films containing 30 wt-% TTB fractions is ascribed to more amounts of TTB in the modified films.

Ultrathin films of clay–protein composites

In recent years, immense interest has been paid to biomolecular architecture with the aim of protein assembly in two dimensions on solid substrates, and the construction of clay–protein ultrathin films (CPUFs). An overview is provided of recent research on hybrid ultrafilms or nanofilms of clay mineral layers and protein molecules. Two techniques, layer-by-layer (LbL) assembly and Langmuir–Blodgett (LB), are presented. The films are characterised by UV–visible spectroscopy and atomic force microscopy (AFM). The amount of proteins incorporated in the films is obtained from UV–visible spectra. Film formation in the LB trough is studied by following the surface pressure versus time curves and the surface pressure versus area isotherms. With AFM the individual clay mineral layers and aggregates of protein molecules are resolved.

Optical, structural and adsorption properties of zinc peroxide/hydrogel nanohybrid films

Hybrid nanofilms from zinc-peroxide/poly(acrylamide) (ZnO 2/PAAm) and zinc-peroxide/poly(N-isopropyl-acrylamide) (ZnO 2/PNIPAAm) were prepared using the photopolymerization procedure. The thin layers were prepared by the combination of the Layer-by-Layer (LbL) self-assembly method and photopolymerization using UV light in every step of the procedure. The hybrid multilayer films consisting of layers of zinc peroxide nanoparticles and hydrogel alternating in a sandwich-like fashion with thicknesses of 65–246 nm. The chemical structures of the hybrid films were investigated by FTIR spectroscopy, their morphology was studied by atomic force microscopy (AFM). The build up of the films was studied by measuring the optical reflection spectrum, and we have calculated the refractive index and layer thickness of the hybrid layers using simulating software. The adsorption properties of the ZnO 2/hydrogel nanohybrid composite networks were investigated by measuring water and ethanol vapour adsorption by a quartz crystal microbalance (QCM). It was established that on partially hydrophobic ZnO 2/PNIPAAm hybrids the adsorbed amounts were lower, against the hydrophilic ZnO 2/PAAm film the vapour amount was higher. These results correspond to those of the bulk gel swelling results.

Structure and Sensor Properties of Thin Ordered Solid Films

Miniaturized gas sensors and biosensors based on nanostructured sensing elements have attracted considerable interest because these nanostructured materials can be used to significantly improve sensor sensitivity and the response time. We report here on a generic, reversible sensing platform based on hybrid nanofilms. Thin ordered Langmuir-Blodgett (LB) films built of fluorene derivatives were used as effective gas sensors for both oxidative and reductive analytes. A novel immobilization method based on thin LB films as a matrix has been developed for construction of sensing protein layers. Biomolecules can often be incorporated into and immobilized on Langmuir-Blodgett films using adsorption methods or by covalent immobilization of proteins. The sensor sensitisation was achieved by an amphiphilic N-alkyl-bis(thiophene)arylenes admixed into the film. The interlaced derivative was expected to facilitate the electron transfer, thereby enhancing the sensor sensitivity. The results suggest that this may be very promising approach for exploring the interactions between proteins and high throughput detection of phenol derivatives in wastewater.