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In this paper, we report the role of surfactants in minimizing nonspecific protein adsorption in liquid crystal (LC)-based immunoassays in which LC is used as a readout system. Among all surfactants tested, only nonionic surfactant such as Tween 20 can effectively reduce the nonspecific protein adsorption, while maintaining the selectivity of the LC-based immunoassay. We also show that to minimize nonspecific protein adsorption, Tween 20 can be added directly into the antibody solution to a final concentration of 0.8 mM. After the addition of Tween 20, better correlations between the antibody concentrations and the interference colors of LCs can therefore be obtained. For example, when Cy3 antibiotin was used, black, yellow, red, and green interference colors correspond to a concentration of 5, 25, 50, and 100 μg/mL, respectively. This feature gives LC immunoassay a unique advantage over the fluorescence-based immunoassay.

In this paper, we report a method of printing uniform protein lines on glass slides by using UV-treated flat PDMS stamps. Unlike traditional microcontact printing (μCP) which requires microstructured PDMS stamps, this μCP method only requires a flat PDMS stamp, an UV lamp and a number of straight needles. Our results show that lines of bovine serum albumin (BSA), immunoglobin (IgG), anti-biotin, anti-human IgG and anti-mouse IgG can be printed evenly on glass slides by using this μCP method. We also demonstrate that the printed protein lines are suitable for applications such as microfluidic immunoassays., (Copyright © 2010 Elsevier Inc. All rights reserved.)

We report an easily visualized liquid crystal (LC)-based system to study the biophysical interactions between protein-coated gold nanoparticles (AuNPs) and LC-supported cell membrane model. The model consists of mixed phospholipid/cholesterol monolayer self-assembled at aqueous-LC interface. Protein-coated AuNPs were found to disrupt the mixed phospholipid/cholesterol monolayer. As a result, orientational transitions of LCs were triggered and optical responses of LCs from dark to bright were observed. The mixed monolayers with higher cholesterol contents were found to be more susceptible to the disruption by protein-coated AuNPs, and hydrophobic interaction played a major role in the monolayer disruption. We also found that the time for non-specific binding of fibrinogen-coated AuNPs to the mixed phospholipid/cholesterol monolayer was similar to that of specific binding of neutravidin-coated AuNPs to the mixed phospholipid/biotin-capped phospholipid monolayer. Results obtained from this study may offer new understanding in the potential nanotoxicity pathway, where the biophysical interaction between nanomaterials and cell membrane is an important step., (Copyright 2010 Elsevier Ltd. All rights reserved.)

We report an easily visualized liquid crystal (LC)-based system to study the molecular interactions between protein-coated gold nanoparticles (AuNPs) and supported phospholipid monolayer self-assembled at the aqueous-LC interface. Protein-coated AuNPs were found to disrupt the phospholipid monolayer and resulted in the orientational transitions of LCs that support the phospholipid layer. The disruption of the phospholipid monolayer depends on the type of protein (albumin, neutravidin, and fibrinogen) adsorbing onto nanoparticles. Furthermore, our results suggest that hydrophobic interaction plays a major role in the disruption of the phospholipid layer by protein-coated AuNPs. Results obtained from this study may offer new understanding in the potential cytotoxicity of nanomaterials, where the interaction between nanoparticles and cell membrane is an important step.

Protein assays are critical analytical tools performed in various biochemical laboratories to quantify the concentration of proteins. In this study, we report the optical responses of a thin layer of liquid crystals supported on glass slides decorated with proteins and the utility of this phenomenon as a new "all-or-nothing" type of protein assay. It was found that the orientations of liquid crystals are very sensitive to the concentration of protein solution applied to the surface. When the protein concentration exceeds a critical value (IgG 5.0 microg/mL, BSA 6.0 microg/mL, FTIC-anti-biotin 0.40 microg/mL, and FITC-anti-IgG 0.37 microg/mL), the thin layer of liquid crystals gives a very sharp dark-to-bright optical response within a small concentration range. This characteristic is not observed in any traditional protein assays, which are based on the adsorption of UV or visible light. The optical response is also very precise and reproducible. It is not affected by the thickness of the liquid crystal cell or the amount of organosilanes coated on the glass slides. The liquid crystal-based protein assay may be very useful for screening purposes, especially when a simple positive or negative answer is desired.

Current anti-fibrotic effect of antioxidants in vivo is disappointing due probably to the fact that once liver fibrogenesis is established it is too advanced to be reversed by anti-oxidation mechanism. We consider antioxidant may only act on the early phase of fibrogenesis. Thus, we had previously established an early liver fibrosis animal model using an inducible expression vector (pPK9a), which contains TGF-β gene and was hydro-dynamically transferred into mice to induce a transient liver fibrosis. TGF-β1 has been well documented to up-regulate the expression of α2(1) collagen (Col 1A2) gene in the liver via the reactive oxygen species (ROS); the process triggers inflammation, leading to hepatic stellate cells (HSC) activation and liver fibrogenesis. Using our animal model and ROS, cyclooxygenase-2 (Cox-2) and Col 1A2 promoter assays as screening targets, we report here that a maleic acid derivative isolated from the Antrodia camphorata mycelium strongly decreases ROS production, promoter activity of Cox-2 and Col 1A2, intracellular calcium, expression of alpha-smooth muscle actin (α-SMA), Smad4-p-Smad2/3 co-localization in cell nucleus and the DNA binding activity of Sp1. Our results suggest that the maleic acid derivative prevents liver fibrosis at an early phase both in vitro and in vivo through the inhibition of ROS, inflammation and the activation of HSC. [ABSTRACT FROM AUTHOR]