Nano-sized Beads Research Articles

Multifunctional Tannic Acid-Alendronate Nanocomplexes with Antioxidant, Anti-Inflammatory, and Osteogenic Potency.

In the current study, we fabricated tannic acid-alendronate (TA-ALN) nanocomplexes (NPXs) via self-assembly. These TA-ALNs were characterized by dynamic light scattering, zeta potential, transmission electron microscopy, and FT-IR spectroscopy. The TA-ALNs were evaluated for antioxidant, anti-inflammatory, and osteogenesis-accelerating abilities in osteoblast-like cells (MC3T3-E1 cells). All TA-ALNs displayed nano-sized beads that were circular in form. Treatment with TA-ALN (1:0.1) efficiently removed reactive oxygen species in cells and protected osteoblast-like cells from toxic hydrogen peroxide conditions. Moreover, TA-ALN (1:0.1) could markedly decrease the mRNA levels of pro-inflammatory mediators in lipopolysaccharide-stimulated cells. Furthermore, cells treated with TA-ALN (1:1) exhibited not only significantly greater alkaline phosphatase activity and calcium collection, but also outstandingly higher mRNA levels of osteogenesis-related elements such as collagen type I and osteocalcin. These outcomes indicate that the prepared TA-ALNs are excellent for antioxidant, anti-inflammatory, and osteogenic acceleration. Accordingly, TA-ALN can be used latently for bone renovation and regeneration in people with bone fractures, diseases, or disorders.

Design of an optofluidic diffusion sensor by transient grating using dielectrophoresis.

An optofluidic diffusion sensor using laser-induced dielectrophoresis in a device with a sputtered a-Si:H layer is presented. Diffusion sensors enabling high-speed measurement have important potential uses as bio-sensors and for quantitative analysis of nano-sized products. The present sensor was developed for measurement in a few seconds by optic observations of the sample diffusion from transient grating formed by laser-induced dielectrophoresis. As a photoconductive layer for the proposed device, we used a sputtered a-Si:H film. The optical (refractive index and extinction coefficient), structural (Raman and IR spectroscopy), and optoelectronic properties of this film, as well as its applicability to the proposed device are characterized. Nano-sized beads were measured by the fabricated device, and its performance as a diffusion sensor was validated.

Targeted Therapy for Acute Autoimmune Myocarditis with Nano-Sized Liposomal FK506 in Rats.

Immunosuppressive agents are used for the treatment of immune-mediated myocarditis; however, the need to develop a more effective therapeutic approach remains. Nano-sized liposomes may accumulate in and selectively deliver drugs to an inflammatory lesion with enhanced vascular permeability. The aims of this study were to investigate the distribution of liposomal FK506, an immunosuppressive drug encapsulated within liposomes, and the drug’s effects on cardiac function in a rat experimental autoimmune myocarditis (EAM) model. We prepared polyethylene glycol-modified liposomal FK506 (mean diameter: 109.5 ± 4.4 nm). We induced EAM by immunization with porcine myosin and assessed the tissue distribution of the nano-sized beads and liposomal FK506 in this model. After liposomal or free FK506 was administered on days 14 and 17 after immunization, the cytokine expression in the rat hearts along with the histological findings and hemodynamic parameters were determined on day 21. Ex vivo fluorescent imaging revealed that intravenously administered fluorescent-labeled nano-sized beads had accumulated in myocarditic but not normal hearts on day 14 after immunization and thereafter. Compared to the administration of free FK506, FK506 levels were increased in both the plasma and hearts of EAM rats when liposomal FK506 was administered. The administration of liposomal FK506 markedly suppressed the expression of cytokines, such as interferon-γ and tumor necrosis factor-α, and reduced inflammation and fibrosis in the myocardium on day 21 compared to free FK506. The administration of liposomal FK506 also markedly ameliorated cardiac dysfunction on day 21 compared to free FK506. Nano-sized liposomes may be a promising drug delivery system for targeting myocarditic hearts with cardioprotective agents.

Liposomal Amiodarone Augments Anti-arrhythmic Effects and Reduces Hemodynamic Adverse Effects in an Ischemia/Reperfusion Rat Model

Although amiodarone is recognized as the most effective anti-arrhythmic drug available, it has negative hemodynamic effects. Nano-sized liposomes can accumulate in and selectively deliver drugs to ischemic/reperfused (I/R) myocardium, which may augment drug effects and reduce side effects. We investigated the effects of liposomal amiodarone on lethal arrhythmias and hemodynamic parameters in an ischemia/reperfusion rat model. We prepared liposomal amiodarone (mean diameter: 113 ± 8 nm) by a thin-film method. The left coronary artery of experimental rats was occluded for 5 min followed by reperfusion. Ex vivo fluorescent imaging revealed that intravenously administered fluorescent-labeled nano-sized beads accumulated in the I/R myocardium. Amiodarone was measurable in samples from the I/R myocardium when liposomal amiodarone, but not amiodarone, was administered. Although the intravenous administration of amiodarone (3 mg/kg) or liposomal amiodarone (3 mg/kg) reduced heart rate and systolic blood pressure compared with saline, the decrease in heart rate or systolic blood pressure caused by liposomal amiodarone was smaller compared with a corresponding dose of free amiodarone. The intravenous administration of liposomal amiodarone (3 mg/kg), but not free amiodarone (3 mg/kg), 5 min before ischemia showed a significantly reduced duration of lethal arrhythmias (18 ± 9 s) and mortality (0 %) during the reperfusion period compared with saline (195 ± 42 s, 71 %, respectively). Targeting the delivery of liposomal amiodarone to ischemic/reperfused myocardium reduces the mortality due to lethal arrhythmia and the negative hemodynamic changes caused by amiodarone. Nano-size liposomes may be a promising drug delivery system for targeting I/R myocardium with cardioprotective agents.

Detection of Nanometer Magnetic Labels' Concentration Via the Movement of Micrometer Superparamagnetic in Application of Magnetic Field

Research on medical diagnostics for point of care treatment (POCT) is driven by demand for rapid, high sensitivity, and inexpensive point of care diagnosis of heart disease, infection, allergies and cancer. Demands to improve quantification and affinity necessitate magnetic labels with sizes comparable to target molecules. However, it is extremely challenging to detect small concentrations of sub-200 nm functionalized magnetic labels using magnetoresistive-based sensors. In order to overcome these limitations we have developed a simple procedure for detecting ~ 130 nm sized magnetic labels via magnetically induced capture of micrometer sized superparamagnetic beads by several 130 nm-diameter target beads immobilized on substrates. Here we demonstrate a new method to improve the quantification of our protocol that exploits magnetically induced frictional forces between micro-sized beads and target magnetic labels. By reducing the external magnetic field, the magnetically captured micro-sized beads restart to flow due to electrostatic forces and the strength of the critical external magnetic field for release depends on the number of nano-sized beads immobilized on substrate. Our protocol has the possibility for quantitative biomaterial detection.

A novel and rapid assay for HIV-1 protease detection using magnetic bead mediation

A simple sensing assay was established for label-free detection of HIV-1 protease. HIV-1 protease peptide substrate conjugated to magnetic beads via its N-terminus is directly fixed onto the sensor gold surface through the sulphur atom of cysteine. Surface plasmon resonance (SPR) was used to study the peptide substrate cleavage efficiency of the protease with magnetic beads of different sizes (1μm and 30nm). Cyclic voltammetry and faradic impedance spectroscopy were employed in order to characterize the functionalized gold electrode. It was found that the nano-sized beads are a more efficient sensing probe for the protease. Electrochemical biosensing showed a gradual decrease in charge transfer resistance after injection of the HIV-1 protease. The experimental data established a detection limit of 10pg/ml, as well as demonstrated a drug screening assay. This HIV-1 protease biosensor represents a new detection approach which will lead to low-cost point-of-care devices for sensitive HIV-1 diagnosis, as well as high-throughput drug screening platforms.

Superparamagnetic bead interactions with functionalized surfaces characterized by an immunomicroarray

Magneto-resistive sensors capable of detecting superparamagnetic micro-/nano-sized beads are promising alternatives to standard diagnostic assays based on absorbance or fluorescence and streptavidin-functionalized beads are widely used as an integral part of these sensors. Here we have developed an immunomicroarray for systematic studies of the binding properties of 10 different micro-/nano-sized streptavidin-functionalized beads to a biotin substrate immobilized on SiO(2) with or without surface modification. SiO(2) surface cleaning, immobilized substrate concentration and surface blocking conditions were optimized. Polyethylene glycol-based surfaces with different end groups on the anchor molecule, 2,4,6-trichloro-1,3,5-triazine (TsT), were synthesized and compared with the standard (3-aminopropyl)triethoxysilane (APTS)/glutaraldehyde chemistry. APTS/glutaraldehyde, directly linked TsT and bare H(2)O(2)-activated SiO(2) performed better than polyethylene glycol-modified surfaces. Two beads, Masterbeads and M-280 beads, were found to give superior results compared with other bead types. Antibody/antigen interactions, illustrated by C-reactive protein, were best performed with Masterbeads. The results provide important information concerning the surface binding properties of streptavidin-functionalized beads and the immunomicroarray can be used when optimizing the performance of bead-based biosensors.

Improving neuronal adhesion on chip using a phagocytosis-like event

Efficient integration of neuronal cells and electronic devices could result in hybrid bi-directional communication systems that would enable us to interact at fundamental levels with biological structures and gain insight in the mechanisms governing their functions. Such systems require a very tight coupling between the neuronal cell membrane and the surface of an electronic chip. In this paper we report an approach where the combination of specialized surface chemistry and the manipulation of biological processes, like a phagocytosis-like process, might improve this coupling. As a model, we used coated micro- and nano-sized beads and induced phagocytosis-like events by adding them to cultured cells. The development of the surface chemistry and the results obtained with beads functionalized with a laminin derived peptide are presented.

Nano-sized beads and porous fiber constructs of Poly(ε-caprolactone) produced by electrospinning

Nano-sized beads and non-woven porous fiber constructs of poly(e-caprolactone) were produced by electrospinning. Nearly spherical beads with diameters between 900 nm and 5 μm were produced with dilute solutions with less than 3 wt% PCL. In this case, the initial jet of solution may split into many mini jets almost at the end of the needle and each minijet gradually disintegrates into small droplets. Beyond a critical solution concentration of about 4 wt% PCL, the jet may undergo extensional flow, splitting and splaying to produce a web of interconnected fibers with mean diameters on the order of 300 to 900 nm. Intermolecular entanglements play a dominant role in stabilizing the fibrous structure. A uniform fibrous structure was obtained at 40 kV while at 20 kV a large fraction of beads were present in the electrospun polymer. The fiber diameter in the PCL deposited on the collector typically exhibits a bimodal distribution. Electrospinning lowers the degree of crystallinity in the polymer.