Protein triggered ordering transitions in poly (L-lysine)-coated liquid crystal emulsion droplets

Abstract

Bovine serum albumin (BSA), concanavalin A from Canavalia ensiformis (Jack bean) (Con A), cathepsin D from bovine spleen (CathD), lysozyme from chicken egg white (Lyz), human haemoglobin, fluorescein conjugated BSA (FITC-BSA), FITC labelled ConA (FITC-ConA), "poly-Llysine (PLL) solution 0.1 % (w/v) in H2O, 4-Cyano-4-pentylbiphenyl (5CB LC) and 5mM tris buffered saline (TBS) (pH 7.4) was obtained from Sigma-Aldrich (St. Louis,MO)" as mentioned in our earlier report. [1] "Deionization of a distilled water (DI water) source was performed using a Milli-Q-system (Millipore, Bedford, MA)" as reported earlier.[1] Glass microscopic slides (Fisher's Finest Premium grade) were purchased from Fischer Scientific (Pittsburgh, PA).

Liquid Crystal based Detection of Pb(II) Ions Using Spinach RNA as Recognition Probe

“…Thermotropic liquid crystals (LCs) associated with the long-range orientational order in the mesophase can easily amplify and transduce information at the molecular level from the interface that they are in contact with. − Such interfacial interactions of LC with various external stimuli can trigger orientational transitions in a micrometer-thick LC film (up to 100 μm). − Since LCs are birefringent materials, polarized microscopy allows the characterization of distinct director profiles through different optical appearances. This ability of LC to sensitively report the small changes in the environment via distinct optical signals has successfully led to the development of label-free LC-based sensors for over a decade. − Previously, interfaces formed between LC and aqueous phases have been successfully exploited for detection of various biochemical events like DNA hybridization and adsorption, aptamer–small molecule binding, cell adhesion, , protein adsorption, ,− antigen–antibody binding, , enzymatic reactions, , and so on. These LC-based systems are heavily based on the orientational transitions of LC triggered by macromolecular binding events occurring at these interfaces, which can be reported even at nanomolar concentrations of the target analyte.…”

Electrostatic-responsive microdroplet lasers for ultrasensitive molecular detection

“…A linear dependence can be found, the limit of detection (LOD) based on this electrostatic interaction was calculated to be 2.4 × 10 -11 g•ml -1 (0.36 pM). However, based on the method of POM images observation, only the BSA concentration above 10 -7 g•ml -1 , the changes in LC can be distinguishable by the naked eye [16]. These results present the method of WGM lasing spectrum is four orders more sensitive than that of POM images in the detection of electrostatic interactions between biomolecules.…”

Poly(α-l-lysine)-based nanomaterials for versatile biomedical applications: Current advances and perspectives

“…Polymer-stabilized LC droplets in aqueous solutions have been developed as a simple and label-free optical probe for the detection of chemical and biological species. Recently, Pal's group explored the use of PLL-coated LC droplets for the bio-sensing of the cell, DNA, and anionic proteins such as fibronectin, bovine serum albumin, concanavalin A and cathepsin D, based on the transition in the LC director induced by interfacial intermolecular interactions between PLL and the anionic biomolecules [ 264 , [273] , [274] , [275] ]. The LC droplets were formed from 4-cyano-4′-pentylbiphenyl (5CB) and coated with alternative cationic PLL and anionic poly (styrene sulfonate) via the LbL technique.…”