Development of an Oligopeptide Functionalized Surface Plasmon Resonance Biosensor for Online Detection of Glyphosate

We report a surface plasmon resonance (SPR) biosensor for online detection of glyphosate. The surface of the sensing element is decorated with an oligopeptide, TPFDLRPSSDTR, which is identified by using phage display library. This oligopeptide shows high binding specificity for glyphosate (<i>K</i>_D = 8.6 μM), probably because of the presence of R and D in the oligopeptide. To detect glyphosate in buffer solution, an SPR gold sensor chip is modified by using the oligopeptide with a surface density of 0.6 1/nm². The sensitivity of this oligopeptide-functionalized SPR biosensor is 1.02 RU/μM whereas the limit of detection (LOD) is 0.58 μM. This oligopeptide functionalized SPR biosensor also shows good specificity against other analytes such as glycine, thiacloprid, and imidacloprid

Antibody-free Detection of Human Chorionic Gonadotropin by Use of Liquid Crystals

Human chorionic gonadotropin (hCG) is an important biomarker for the diagnosis of pregnancy and cancers. In this study, we report an antibody-free and label-free mechanism for detecting hCG. To replace enzyme-labeled antibodies, we use a short oligopeptide as an hCG receptor to bind hCG. The short oligopeptide sequence, (N-)­PPLRINRHILTR­(-C), is identified after 5 rounds of screening by use of a phage library. After binding, liquid crystal (LC) is used to transduce the binding event into optical signals. The captured hCG can disrupt a thin layer (∼6 μm) of LC covered on the surface. Depending on the initial concentration of hCG, LC gives distinct optical signals visible to the naked eye. The limit of detection (LOD) for this method is approximately 1 IU/mL (2 nM) in both phosphate-buffered saline and urine samples, and only 0.6 μL of hCG solution is required. This means that as little as 45.5 pg of hCG can be detected by this method. Compared to other detection methods for hCG, this detection method does not require the use of antibody and is label-free. It has the potential to become a portable diagnostic kit for hCG

Surfactant-Driven Assembly of Poly(ethylenimine)-Coated Microparticles at the Liquid Crystal/Water Interface

Microparticles sitting at interfaces formed by a liquid crystal (LC) and water are known to self-assemble into distinct patterns. In this study, we observed that poly­(ethylenimine)- (PEI-) coated microparticles are able to self-assemble at LC/water interfaces decorated with surfactants such as Tween 20 and sodium dodecyl sulfate (SDS). Interestingly, assemblies of microparticles strongly depend on the types of surfactants used and how surfactants adsorb on the PEI-coated microparticles. For example, adsorption of Tween 20 on the PEI-coated microparticles causes the microparticles to form short chains that follow the director field of the LC. In contrast, adsorption of SDS causes the microparticles to assemble into circular rings that encompass domains saturated with SDS. Such surfactant-driven assembly of microparticles offers a possible method for directing the assembly of microparticles. It can also be applied for the visual detection of lipases that hydrolyze Tween 20 in water

Inkjet Printing and Release of Monodisperse Liquid Crystal Droplets from Solid Surfaces

Recently, liquid crystal (LC) droplets in aqueous solutions have become a new platform for chemical and biological sensing applications. In this work, we present a two-step method to generate monodisperse LC droplets in aqueous solutions for sensing applications. In the first step, we exploit inkjet printing to dispense uniform LC droplets on a solid surface. Uniform LC droplets, ranging from 35 to 136 μm in diameter, can be prepared by printing multiple times on the same spot. In the second step, we flush the LC droplets with a stream of aqueous solution in an open rectangular channel. Factors that determine the polydispersity of the LC droplets include flow rates and surface wettability. Under appropriate experimental conditions (i.e., when the surface is glass and the flow rate is sufficiently high), the LC droplets can be lifted off completely and carried away by the solution, forming free LC droplets (15–62 μm in diameter). These free LC droplets can respond to a chemical reaction and change their optical textures uniformly

Detecting Proteins in Microfluidic Channels Decorated with Liquid Crystal Sensing Dots

In this paper, we report the integration of liquid crystal (LC) dots on microfluidic channels as microscopic protein sensors. Flexibility of patterning LC dots on a surface to fit small microfluidic channels is achieved by using inkjet printing technology. These LC dots (1 pL) remain stable when they are subjected to flowing buffer solution at a high flow velocity (<i>v</i> ≥ 0.198 cm/s). When the buffer solution contains protein, such as bovine serum albumin (BSA), it causes a change in the orientational ordering of the LC dots as indicated by a distinct dark-to-bright transition in the optical appearance of the LC dots. Moreover, we are able estimate the concentration of BSA by simply counting the number of bright LC dot sections. This microscopic protein sensor has potential applications in the real-time detection and quantification of proteins in aqueous solutions. This detection method is advantageous because protein labeling and complex instrumentation are not required

Prevention of TGF-β-induced early liver fibrosis by a maleic acid derivative anti-oxidant through suppression of ROS, inflammation and hepatic stellate cells activation

<div><p>Current anti-fibrotic effect of antioxidants <i>in vivo</i> 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 <i>Antrodia camphorata</i> 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 <i>in vitro</i> and <i>in vivo</i> through the inhibition of ROS, inflammation and the activation of HSC.</p></div

Effects of compound 2 on Smad4 and p-Smad2/3 localization in HSC-T6 cells.

<p>HSC-T6 cells were treated with TGF-β only (I), TGF-β + 30 nM compound 2 (II), TGF-β + 150 nM compound 2 (III), and TGF-β + 300 nM compound 2 (IV). Smad4 and p-Smad2/3 are showed in green and red colors, respectively.</p

Schematic diagram of blocking targets of TGF-β1 signaling pathways in liver fibrosis.

<p>Schematic diagram of blocking targets of TGF-β1 signaling pathways in liver fibrosis.</p

Effects of compound 2 on histopathology of liver fibrosis.

<p>Forty-eight hours after hydrodynamics-based injection of pPK9a, the mice were sacrificed and the liver sections were subjected to Masson’s trichrome staining (A) and immunohistochemistry (B). (A) Detection of ECM and collagen by Masson’s trichrome staining. The cytoplasm is red and collagen fiber is blue-green. The collagen signals were indicated by arrows. (B) Detection of α-SMA by immunohistochemistry. Dark brown granules represent α-SMA signals stained by α-SMA-specific antibody and were indicated by arrows. Representative liver sections of collagen (A) or α-SMA (B) from experimental I-VI groups: (I) Ringer’s solution + pPK9a + ZnSO₄ 48 h, (II) Ringer’s solution + pPK9a + ZnSO₄ + 30 μg/kg/day compound 2, (Ⅲ) Ringer’s solution + pPK9a + ZnSO₄ +50 μg/kg/day compound 2, and (IV) Ringer’s solution + pPK9a + ZnSO₄ + 300 μg/kg/day compound 2. Original magnification: I-IV, 200x.</p

Effects of compound 2 on [Ca²⁺]_i in HSC-T6 cells.

<p>Observation of [Ca²⁺]_i under the treatment of TGF-β1 and compound 2. Cells were first pretreated with various concentrations of compound 2 (30, 150 or 300 nM) for 4 h then loaded with the fluorescent calcium indicator fura-3/AM before the addition of TGF-β1 (2ng/ml). (A) TGF-β only, (B) w/o TGF-β, (C) TGF-β + 30 nM compound 2, (D) TGF-β + 150 nM compound 2, and (E) TGF-β + 300 nM compound 2.</p