Analysis of Correlation Between Contrast and Component of Polylatic Acid Composite for Fused Deposition Modeling 3D Printing.

Additive manufacturing or three-dimensional (3D) printing is considered a disruptive technology for producing components with topologically optimized complex geometries as well as functionalities that are not achievable by traditional methods. 3D printing is expected to revolutionize the manufacturing of components. While several 3D printing systems are available, printing based on fused-deposition modeling (FDM) using thermoplastics is particularly widespread because of the simplicity and potential applicability of the method. In this study, we report the analysis of correlation between contrast and component of polylactic acid (PLA) based composite for FDM 3D printing. The pre-fabricated white composite and black composite were mixed in the fraction of 100:0, 90:10, 75:25, 50:50, 25:75, and 0:100% (v/v) and the obtained mixture was extruded using HX-35 3D filament extrusion line. The samples in different contrast were printed in disk like shape, and the gray scale filaments and 3D printed samples were measured the morphology and components using a field emission scanning electron microscope and energy dispersive X-ray spectroscopy. The CIE-lab values of the samples were measured using a colorimeter and the correlation between CIE-lab values and the components were analyzed. Although the component of Ti was linearly increased, the CIE-lab values show a clear exponential increase by increasing the white composite.

Detection of Amyloid ß Using a Poly-L-Lysine Mediated Nanobiosensor.

Amyloid ß (Aß) peptide is secreted from the outside of neural cell by a neural signal pathway and it accumulated each other results in the highly toxicity amyloid plaque which is a critical causative factor in the pathogenesis of Alzheimer's Disease (AD). The peptide is considered to be a potential biomarker to diagnose AD. Here we introduce a novel poly-L-lysine (PLL) mediated nanobiosensor to detect Aß in vitro. The PLL molecules were utilized as a signal amplifier of Aß detection. The indirect enzyme-linked immunosorbent assay (ELISA) method and the sandwich ELISA method have tried to the detection of Aß. A commercially available ELISA plate was modified by PLL using a chemical agent and the amplified amino groups were activated by a functional group for the binding of Aß. The bound Aß was further modified with a primary antibody and fluorescence molecules conjugated secondary antibody by the traditional immunochemistry. In the result, the fluorescence intensity was increased by the increasing concentration of Aß, and the best Aß detection results were obtained in the PLL mediated indirect ELISA nanobiosensor. We expected that the present method would be optimized and applied for the detection of Aß in human fluid.

Development of Chemically Signal Amplified Nano-Biosensor Mediated by Poly-L-Lysine.

Amyloid ß (Aß) is considered to be one of a potential biomarker to monitor Alzheimer's Disease (AD) not only for diagnostic purposes but for early detection. Here we describe a novel nano-biosensor for Aß mediated by poly-L-lysine (PLL) which was used for the amplification of detection signal for Aß. The indirect enzyme-linked immunosorbent assay (ELISA) method was modified using PLL for the amplification of the Aß detection signal. A commercially available ELISA plate was modified by PLL using chemical agent and the amplified amino groups were activated by a chemical agent for the detection of Aß. The detection was carried out by the traditional immunochemistry using primary antibody and fluorescence molecules conjugated secondary antibody. In the result, the fluorescence intensity was increased by the increasing treated Aß amount, and the sensitivity was approximately 2 times higher in the concentration of 2 ng/mL Aß treatment, and approximately 4 times higher in the concentration of 200 ng/mL Aß treatment compare with that of indirect ELISA detection method. We suggest our novel signal amplification method for the Aß early detection.

Detection of Actin Filament and Cofilin Interaction Change by Actin Filament Curvature Decreasing.

Actin filament senses mechanical forces and it is transduced into biochemical signals during many cellular processes. In the disassembling process of actin filaments, cofilin plays a central role as the actin filament depolymerization. In this study, we evaluated a quantitative analysis of the actin filament-cofilin interaction change dependent upon the actin filament curvature decrease using atomic force microscopy (AFM) and a fabricated wave-like substrate. A wave-like substrate was fabricated by a maskless photo-lithography of a spin coated film on a glass substrate, and graphene oxide sheet was used for the decreasing of non-specific interaction between protein and the substrate. By single-molecule force spectroscopy, we determined rupture force of actin filament-cofilin binding on the wave-like substrate and a flat substrate. The rupture force of actin filament-cofilin binding at the curvature of -1.35 µm-1 showed a value approximately 4 times higher than the rupture force at the curvature of -0.15 µm-1. The present study will provide the possibility and quantitative evidence that mechanical stress on cytoskeletal filaments can modulate how they interact with their binding proteins.

Probing Amyloid ß and the Antibody Interaction Using Atomic Force Microscopy.

Amyloid ß (Aß) peptide is considered to be the critical causative factor in the pathogenesis of Alzheimer's disease (AD) because the hydrophilic molecules accumulated outside of the neural cells and results in the formation of highly toxicity amyloid plaque. In this study, we probed the interaction between Aß and the antibody using atomic force microscopy (AFM). We compared two kinds of antibodies which are the antibody for Aß 1-42 (antibody42) and the antibody for Aß 1-16 (antibody16). To detect the interaction between Aß and the antibodies, the single molecular force spectroscopy was carried out using Aß modified glass substrate and the antibodies modified AFM probes. In the results, the single Aß-antibody42 dissociation constant was estimated to be 5.2 × 10-3 s-1 and the single Aß-antibody16 dissociation constant was 2.8×10-2 s-1. The Aß-antibody42 showed 5.3 times longer bond life time compare with Aß-antibody16. It suggested that antibody42 is better choice for the Aß sensor development.