A Membrane-based Disposable Well-Plate for Cyanide Detection Incorporating a Fluorescent Chitosan-CdTe Quantum Dot

Abstract

A novel approach to building a membrane-based disposable well-plate, here applied to cyanide detection, is described. Chitosan encapsulated CdTe quantum dots with a maximum emission at 520 nm (CS-QD520) were used as fluorophores. The CS-QD520 nanoparticle was specifically quenched by copper(II), and the quenched CS-QD520 (Cu-CS-QD520) was deposited onto a glass microfiber filter (GF/B). Subsequent introduction of cyanide ion resulted in fluorescence recovery. The "signal-ON" fluorescence linearly correlated to cyanide concentrations in the range of 38.7 to 200 μM with a limit of detection of 11.6 μM. The assay was incorporated into a membrane-based well-plate format to enhance sample throughput. A three-layer paper/glass microfiber well plate design was cut using a laser cutter and assembled using a polycaprolactone (PCL) as a bonding agent in a low-cost laminator. The experimental conditions were optimized and applied to detect cyanide in drinking water with rapid, high-throughput, low-cost analysis.

Development of Fluorescent Sensors for Biorelevant Anions in Aqueous Media Using Positively Charged Quantum Dots

“…The chalcogenide QDs developed to detect anions in an aqueous medium required the surface modification of the nanocrystals with polymers, metal complexes, or other nanoparticles, introducing additional complexity to the sensor preparation and the sensing mechanism. For example, Pengpumkiat et al [ 22 ] developed a fluorescent sensor for CN − using CdTe QDs coated with chitosan and Cu 2+ ions. In the presence of the copper ions, the QDs’ emission was quenched, and it was restored upon the addition of CN − .…”

Selective laser ablation for in situ fabrication of enclosed channel porous-media microfluidic analytical devices

“…Since microfluidic devices made of patterned paper known as microfluidic paper-based analytical devices (μPADs) were introduced by Whitesides' group in 2007, 1 μPADs have gained widespread interest in academic research as a low-cost alternative to traditional analytical techniques. Currently, porous materials used for making analytical devices are not only limited to paper, but also include nitrocellulose, 2 glass microfiber, 3,4 and various textiles. 5 Advantages of porous-media analytical devices include cost-effectiveness, low mass, portability, power-free fluid transport via capillary action, and ability to store reagents in active form.…”

A Microfluidic Paper-Based Analytical Device for Type-II Pyrethroid Targets in an Environmental Water Sample

“…Fabrication techniques for paper-based devices have been extensively reviewed [ 20 , 21 ] including photolithography, wax printing, ink-jet printing, ink stamping, and plasma treatment. The device created in this study utilized stacking cut pieces of paper as the layers for vertical flow [ 7 , 22 ]. Capillary action and gravitational force facilitate the even flow of the fluid and minimize the channeling effect of the fluid flow.…”