Rapid Electromechanical Transduction on a Single-Walled Carbon Nanotube Film: Sensing Fast Mechanical Loading via Detection of Electrical Signal Change

Carbon nanotubes (CNTs) have been widely explored as next generation embedded-strain-pressure sensors. However, most investigations of CNT sensors did not consider the response time as a critical factor, although the ultrafast sensing of mechanical deformation is very important for the detection of dynamic loading or impact, such as in reactive armor systems. Owing to the low capacitance that shortens the response time of the electrical resistance changes induced by mechanical deformation, CNTs are expected to detect rapid electromechanical transduction without delay. Herein, we fabricate single-walled carbon nanotube (SWNT) films on diverse substrates, and evaluate their applications as sensors to detect rapid electromechanical transduction on a macroscopic scale. Under repetitive, high-speed mechanical loading, the SWNT films generate consistent electrical signal changes, which are accurately synchronized with their strain and the beginning of the deformation

Multilayered Controlled Drug Release Silk Fibroin Nanofilm by Manipulating Secondary Structure

Many studies of drug delivery nanoplatforms have explored drug loading affinity and controlled release. The nanoplatforms can be influenced by their inherent building blocks. Natural polypeptide silk fibroin (SF) is an excellent nanoplatform material because of its high biocompatibility and unique structural properties. SF secondary structures have different properties that can be changed by external stimuli. Thus, the characterization of SF-containing platforms is strongly affected by secondary structure transformations. Structural changes can occur spontaneously, which hinders the control of structural variation in aqueous conditions. Herein, we successfully prepared a controllable secondary structure composed of SF/heparin (HEP) layer-by-layer assembled nanofilms using simple solvents (glycerol and methanol). SF in the SF/HEP nanofilms takes up than 90%, which means configurations of SF have a strong effect on the character of the nanofilms. We investigated the degradation profiles of SF/HEP nanofilms depending on their β-sheet contents and demonstrated an immediate correlation between the transformation of secondary structures inside the nanofilms and the degree of degradation of nanofilms. Finally, SF/HEP nanofilms were used as a delivery platform for incorporating the anticancer drug epirubicin (EPI). We could control the loading efficiency and release profile of EPI with various β-sheet contents of the nanofilms

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

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

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

Multifunctional Collagen and Hyaluronic Acid Multilayer Films on Live Mesenchymal Stem Cells

Cell encapsulation has been reported to convey cytoprotective effects and to better maintain cell survival. In contrast to other studies, our report shows that the deposition of two major biomacromolecules, collagen type I (Col) and hyaluronic acid (HA), on mesenchymal stem cells (MSCs) does not entirely block the cell plasma membrane surface. Instead, a considerable amount of the surface remained uncovered or only slightly covered, as confirmed by TEM observation and by FACS analysis based on quantitative surface labeling. Despite this structure showing openness and flexibility, the multilayer Col/HA films significantly increased cell survival in the attachment-deprived culture condition. In terms of stem cell characteristics, the MSCs still showed functional cell activity after film deposition, as evidenced by their colony-forming activity and in vitro osteogenic differentiation. The Col/HA multilayer films could provide a cytoprotective effect and induce osteogenic differentiation without deteriorating effect or inhibition of cellular attachment, showing that this technique can be a valuable tool for modulating stem cell activities

Efficient Encapsulation and Sustained Release of Basic Fibroblast Growth Factor in Nanofilm: Extension of the Feeding Cycle of Human Induced Pluripotent Stem Cell Culture

Basic fibroblast growth factor (bFGF) has an established pivotal function in biomedical engineering, especially for the human pluripotent stem cells (iPSCs). However, the limitation of bFGF is the ease of denaturation under normal physiological conditions, inducing loss of its activity. In this study, we designed multi-trilayered nanofilm composed of a repeating polycation/polyanion/bFGF structure, which has high loading efficiency and short buildup time. We also investigated that the loading and release of bFGF from the nanofilm with two parameters (counter-polyanion and film architectures). Then, we prepared the optimized nanofilm which maintains a sustained bFGF level in physiological condition to apply the nanofilm to human iPSCs culture. The amount of bFGF release from 12 trilayer nanofilm was 36.4 ng/cm², and activity of bFGF encapsulated into the nanofilm was maintained (60%) until 72 h during incubation at 37 °C. As a result, the iPSCs grown in the presence of the nanofilm with tridaily replacement of growth medium maintained undifferentiated morphology and expression levels of pluripotency marker proteins

Durable Urushiol-Based Nanofilm with Water Repellency for Clear Overlay Appliances in Dentistry

With increased esthetic needs, orthodontics is an indispensable medical treatment in dentistry, and transparent clear overlay appliances (COAs) are in general use to fix teeth. However, COAs are easily worn out because of the lack of durability. Here, we applied a nanofilm onto COAs using urushiol (U), a durable coating material from plant via a layer-by-layer assembly technique. In particular, polymerized urushiol (PU) provided COAs with higher mechanical strength in the large-scale assessment, lower cytotoxicity, and intrinsic hydrophobicity for antimicrobial use. In this report, we inceptively attempted to functionalize COAs with nanofilm for advanced biomedical use

Synthesis and Characterization of Functional Nanofilm-Coated Live Immune Cells

Layer-by-layer (LbL) assembly techniques have been extensively studied in cell biology because of their simplicity of preparation and versatility. The applications of the LbL platform technology using polysaccharides, silicon, and graphene have been investigated. However, the applications of the above-mentioned technology using living cells remain to be fully understood. This study demonstrates a living cell-based LbL platform using various types of living cells. In addition, it confirms that the surplus charge on the outer surface of the coated cells can be used to bind the target protein. We develop a living cell-based LbL platform technology by stacking layers of hyaluronic acid (HA) and poly-l-lysine (PLL). The HA/PLL stacking results in three bilayers with a thickness of 4 ± 1 nm on the cell surface. Furthermore, the multilayer nanofilms on the cells are completely degraded after 3 days of the application of the LbL method. We also evaluate and visualize three bilayers of the nanofilm on adherent (AML-12 cells)-, nonadherent (trypsin-treated AML-12 cells)-, and circulation type [peripheral blood mononuclear cells (PBMCs)] cells by analyzing the zeta potential, cell viability, and imaging via scanning electron microscopy and confocal microscopy. Finally, we study the cytotoxicity of the nanofilm and characteristic functions of the immune cells after the nanofilm coating. The multilayer nanofilms are not acutely cytotoxic and did not inhibit the immune response of the PBMCs against stimulant. We conclude that a two bilayer nanofilm would be ideal for further study in any cell type. The living cell-based LbL platform is expected to be useful for a variety of applications in cell biology

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