betadex and 2-naphthoic-acid

We demonstrate the selective detection of endocrine disruptor chemicals (EDCs) from river water using surface enhanced Raman scattering (SERS). By means of nanosphere lithography, the SERS substrate was prepared via the initial deposition of a monolayer of silica nanospheres (with diameter of ∼330 nm) on a silicon substrate as the template. Subsequently, a 180 nm thick layer of silver followed by a 20 nm layer of gold was deposited. This surface was modified with mono-6-deoxy-6-((2-mercaptoethyl)amino)-beta-cyclodextrin (β-CD) in order to produce a selective capture surface suitable for EDC capture and their detection by means of SERS. We show that EDC model compounds, including 3-amino-2-naphthoic acid (NAPH), potassium hydrogen phthalate (PHTH) and the EDC β-estradiol (ESTR), were captured by the β-CD decorated surface. This surface facilitated SERS detection with limits of detection of 3.0 μM (NAPH), 10 μM (PHTH) and 300 nM (ESTR), all 10-100 times lower than that without the surface modification with β-CD. Individual and simultaneous detection of NAPH and PHTH from their mixture was achieved as evidenced using the bianalyte Raman technique.

Topics: beta-Cyclodextrins; Endocrine Disruptors; Nanospheres; Nanostructures; Naphthalenes; Phthalic Acids; Silicon Dioxide; Spectrum Analysis, Raman; Substrate Specificity

A highly anionic cyclomaltooligosaccharide (cyclodextrin, CD) derivative containing sulfopropyl functional groups on the primary face of the CD was synthesized. Heptakis(2,3-di-O-methyl)cyclomaltoheptaose [heptakis(2,3-di-O-methyl)-beta-cyclodextrin] was reacted with 1,3-propane sultone and potassium hydride (KH) in anhydrous tetrahydrofuran in the presence of 18-crown-6 to yield highly substituted potassium heptakis(2,3-di-O-methyl-6-O-sulfopropyl)cyclomaltoheptaose [heptakis(KSPDM)-beta-CD] with an average degree of substitution (DSCE) of 6.9 as determined by inverse detection capillary electrophoresis (CE). The principal species in the product is the fully substituted heptakis(KSPDM)-beta-CD. Complete NMR assignments of the hydrogen and carbon atoms are made using a combination of gCOSY and gHSQC. In the absence of 18-crown-6, the reaction generates a mixture of multiply charged derivatives with average DSCE of 4.1. The possible roles of the crown ether in the reaction are discussed. The ROESY NMR spectrum of the inclusion complex that forms between heptakis(KSPDM)-beta-CD and 2-naphthoic acid in D2O reveals that 2-naphthoic acid inserts with the carboxyl group toward the derivatized primary rim of the cyclodextrin.

Topics: Anions; beta-Cyclodextrins; Carbohydrate Conformation; Carbon; Deuterium Oxide; Electrophoresis, Capillary; Hydrocarbons; Hydrogen; Magnetic Resonance Spectroscopy; Methane; Models, Chemical; Naphthalenes; Potassium; Thiophenes; Ultraviolet Rays