A Fluorescent Alcohol Biosensor Using a Simple microPAD Based Detection Scheme

Abstract

A paper-based microfluidic detection device for the detection of ethanol is demonstrated in this work. The method is based on a fluorophore consisting of short-chain conjugated molecular unit susceptible to the protonation of its terminal pyridine groups, along with a carboxyl-functionalized sidechain that acts as a binder and renders it water-soluble. The resulting fluorescent paper device yields large fluorescence changes when exposed to reactions that yield H2O2 in aqueous solutions. Using an enzyme-catalyzed rection that produces H2O2 from ethanol, we developed a two-zone, cut-out paper device containing a reaction zone in which the ethanol-containing analyte is placed, and an adjacent sensor zone where we observe a fluorescence color shift proportional to the ethanol concentration. The limit of detection of the fluidic ethanol biosensor was 0.05 v/v% and the dynamic range was 0.05–2 v/v%. This method was employed to detect the alcohol concentration of consumer vodkas using only a paper sensor and a smartphone camera.

Fabrication of Crescent Shaped Microparticles for Particle Templated Droplet Formation

“…The parent chromophore, sodium 6-(4-methoxy-2,5-bis((E)-2-(pyridin-4-yl)vinyl)phenoxy) hexanoate (c-P4VB), was prepared according to the previously published procedure. 47 It was further converted into N-hydroxysuccinimide-derivative (NHS-P4VB) and subsequently into MA-derivative (MA-P4VB) as follows ( Figure S10 ).…”

“…The emission spectra of blue-emitting fluorophore that we used red-shifts from blue-to-orange as the pH value was decreased from 7 to 1. [46][47][48] Since we have imaged the blue-emitting particles in the same DAPI channel, the fluorescence intensity decreased when the fluorescence spectra of particles in the acidic solution redshifts (i.e. pH decreased from 7 to 1) and vice versa.…”

“…We have systematically investigated the effect of UV intensity, flow rates of aqueous and oil streams, and concentrations of polymer precursors on the curability and dimensions of crescent-shaped particles. We separately introduced blue emitting (MA-P4VB) [46][47][48] and red-emitting (MA-RhB) dyes (see Figure S8 for the dye structures) 49 into the cured PEGDA networks. This was achieved by photo-copolymerization at different dye concentrations and resulted in covalent bonding of the dye molecules to color-code multiple crescent-shaped particles.…”

Fabrication of Crescent Shaped Microparticles for Particle Templated Droplet Formation

“…The emission spectra of blue-emitting fluorophore that we used redshifts from blue to orange as the pH value decreased from 7 to 1. [51][52][53] Since we have imaged the blue-emitting particles in the same DAPI channel, the fluorescence intensity decreased when the fluorescence spectra of particles in the acidic solution redshifts (i.e., pH decreased from 7 to 1) and vice versa. The effect of pH value on the particles that emitted red fluorescence in different pH bulk solutions was also evaluated.…”

“…We have systematically investigated the effect of UV intensity, flow rates of aqueous and oil streams, and concentrations of polymer precursors on the curability and dimensions of crescent-shaped particles. We separately introduced blue-emitting (MA-P4VB) [51][52][53] and redemitting (MA-RhB) dyes (see Figure S8 for the dye structures, Supporting Information) [54] into the cured PEGDA networks. This was achieved by photo-copolymerization at different dye concentrations and resulted in covalent bonding of the dye molecules to color-code multiple crescent-shaped particles.…”