Layer-by-Layer Self-Assembled Ferrite Multilayer Nanofilms for Microwave Absorption

We demonstrate a simple method for fabricating multilayer thin films containing ferrite (Co0.5Zn0.5Fe2O4) nanoparticles, using layer-by-layer (LbL) self-assembly. These films have microwave absorbing properties for possible radar absorbing and stealth applications. To demonstrate incorporation of inorganic ferrite nanoparticles into an electrostatic-interaction-based LbL self-assembly, we fabricated two types of films: (1) a blended three-component LbL film consisting of a sequential poly(acrylic acid)/oleic acid-ferrite blend layer and a poly(allylamine hydrochloride) layer and (2) a tetralayer LbL film consisting of sequential poly(diallyldimethylammonium chloride), poly(sodium-4-sulfonate), bPEI-ferrite, and poly(sodium-4-sulfonate) layers. We compared surface morphologies, thicknesses, and packing density of the two types of ferrite multilayer film. Ferrite nanoparticles (Co0.5Zn0.5Fe2O4) were prepared via a coprecipitation method from an aqueous precursor solution. The structure and composition of the ferrite nanoparticles were characterized by X-ray diffraction, energy dispersive X-ray spectroscopy, transmission electron microscopy, and scanning electron microscopy. X-ray diffraction patterns of ferrite nanoparticles indicated a cubic spinel structure, and energy dispersive X-ray spectroscopy revealed their composition. Thickness growth and surface morphology were measured using a profilometer, atomic force microscope, and scanning electron microscope

Spontaneous Biomacromolecule Absorption and Long-Term Release by Graphene Oxide

Biomacromolecule loading is the popular research in the biomedical field. To control the loading amount and releasing profile, various materials and fabrication techniques were developed. In this study, layer-by-layer assembly of multilayer films between collagen (Col) and graphene oxide (GO) was used to control the release of the loading molecule. By mixing GO into the system, ovalbumin (OVA) can be spontaneously adsorbed onto the GO sheet (denoted as GO/OVA) via the hydrophobic interaction. Two kinds of multilayer films (Col/GO/OVA and Col/GO/OVA) were fabricated. The thickness growth curve, quantitative of each layer adsorption, film morphology, stability, cell viability, and OVA release from multilayer films were investigated. The result has shown excellent film stability, macromolecule loading, and sustained release because of GO ability

Studies on the Drug Loading and Release Profiles of Degradable Chitosan-Based Multilayer Films for Anticancer Treatment

This study demonstrates the possibility of developing a rapidly degradable chitosan-based multilayer film for controlled drug release. The chitosan (CHI)-based multilayer nanofilms were prepared with three different types of anions, hyaluronic acid (HA), alginic acid (ALG) and tannic acid (TA). Taking advantage of the Layer-by-Layer (LBL) assembly, each multilayer film has different morphology, porosity and thickness depending on their ionic density, molecular structure and the polymer functionality of the building blocks. We loaded drug models such as doxorubicin hydrochloride (DOX), fluorescein isothiocyanate (FITC) and ovalbumin (Ova) into multilayer films and analyzed the drug loading and release profiles in phosphate-buffered saline (PBS) buffer with the same osmolarity and temperature as the human body. Despite the rapid degradation of the multilayer film in a high pH and salt solution, the drug release profile can be controlled by increasing the functional group density, which results in interaction with the drug. In particular, the abundant carboxylate groups in the CHI/HA film increased the loading amount of DOX and decreased rapid drug release. The TA interaction with DOX via electrostatic interaction, hydrogen bonding and hydrophobic interaction showed a sustained drug release profile. These results serve as principles for fabricating a tailored multilayer film for drug delivery application

Joint Attention Virtual Classroom: A Preliminary Study.

ObjectivePrevious studies have suggested that a virtual classroom is immersive and ecologically valid neuropsychological assessment, but those studies have limited components for social attentions. Therefore, the objective in the current study is the development of a joint attention virtual reality (JA-VR) classroom to incorporate social attentions between a participant and a virtual avatar teacher.MethodsFifty-eight participants were recruited for current study (25 for pilot and 33 for main studies; 32.8% female, n=19; age: M=24.5, SD=4.0). We suggested a JA-VR classroom, and compared it with previous methods including a VR classroom without JA components. We conducted attention experiments with AX-version of continuous performance tasks.ResultsOur results suggest that the new JA-VR classroom had convergent validity with previous methods, and that the JA-VR classroom promoted attentional processing among participants better than both old VR and non-VR measures.ConclusionWe add an important social attention concept to the virtual classroom, and believe that this work is an methodological foundation for the study of social attention in school life. We hope it ultimately help people with mental handicaps in social attention

Inkjet Printing-Based Patchable Multilayered Biomolecule-Containing Nanofilms for Biomedical Applications

Thin films including biocompatible polymers and biological materials as building blocks can be produced with a variety of critical film characteristics, including various materials, thicknesses, roughnesses, amounts of compound released, and release rates for biomedical purposes. We developed a multilayer fabrication system via high-throughput layer-by-layer (LbL) assembly of a nanofilm with inkjet printing to facilitate practical biomedical applications. Our system was used to generate biomolecule (ovalbumin and basic fibroblast growth factor)-containing printed LbL films. This is the first demonstration of the clinical benefits of nanofilm-type nanobiomaterials based on molecular organization, suggesting that novel therapeutic human skin patches could be realized without the need for conventional surgical practices

Intrinsic Hydrophobic Cairnlike Multilayer Films for Antibacterial Effect with Enhanced Durability

One important aspect of nanotechnology includes thin films capable of being applied to a wide variety of surfaces. Indispensable functions of films include controlled surface energy, stability, and biocompatibility in physiological systems. In this study, we explored the ancient Asian coating material lacquer to enhance the physiological and mechanical stability of nanofilms. Lacquer is extracted from the lacquer tree and its main component called urushiol, which is a small molecule that can produce an extremely strong coating. Taking full advantage of layer-by-layer assembly techniques, we successfully fabricated urushiol-based thin films composed of small molecule/polymer multilayers by controlling their molecular interaction. Unique cairnlike nanostructures in this film, produced by urushiol particles, have advantages of intrinsic hydrophobicity and durability against mechanical stimuli at physiological environment. We demonstrated the stability tests as well as the antimicrobial effects of this film.OAIID:oai:osos.snu.ac.kr:snu2015-01/102/0000002410/13ADJUST_YN:YEMP_ID:A002014DEPT_CD:458CITE_RATE:6.723DEPT_NM:화학생물공학부SCOPUS_YN:YCONFIRM:

Drug Loading and Release Behavior Depending on the Induced Porosity of Chitosan/Cellulose Multilayer Nanofilms

The ability to control drug loading and release is the most important feature in the development of medical devices. In this research, we prepared a functional nanocoating technology to incorporate a drug-release layer onto a desired substrate. The multilayer films were prepared using chitosan (CHI) and carboxymethyl cellulose (CMC) polysaccharides by the layer-by-layer (LbL) method. By using chemical cross-linking to change the inner structure of the assembled multilayer, we could control the extent of drug loading and release. The cross-linked multilayer film had a porous structure and enhanced water wettability. Interestingly, more of the small-molecule drug was loaded into and released from the non-cross-linked multilayer film, whereas more of the macromolecular drug was loaded into and released from the cross-linked multilayer film. These results indicate that drug loading and release can be easily controlled according to the molecular weight of the desired drug by changing the structure of the film