Quantitative and label free determination of bacteria in nanoliter droplets with a 3D printed microfluidic device by using a contactless conductivity detector

FIGUEREDO, FEDERICO; COLTRO, WENDELL K.T.; DUARTE, LUCAS C.; CORTÓN, EDUARDO; RIBEIRO, LUIZ E.B.

Bruselas

Conferencia; SLAS EUROPE 2018; 2018

SLAS

For the detection of cells inside droplets, fluorescent labelling is a technology accessible and well established inconventional methods of microbiology that have been widely used1,2. Fluorescent markers, when added to the sample as a reagent canbe used for a wide range of microorganisms, but some relevant problems associated to them are high cost, disposal problems (most ofthem are toxic) and instability (photo bleaching). This study presents an electrochemical and label free approach to quantify E. coliK12 cells in droplets by means of a C4D system. The microdevice was fabricated with a 3D printer, containing integrated electrodesof PLA doped with CNT3 (Figure 1). It was found that the conductivity signal decreases since bacteria cells change the conductivityof the droplet. A linear relationship was found between conductivity variation and log10(CFU droplet-1) in a range between 86.5-8650CFU droplet-1 with a LOD of 64.42 CFU droplet-1.