(321g) Electrochemical Detection of Extracellular Bacterial Compounds Using Capillary Electrophoresis

Martin Kimani, Dr. Edgar Goluch

Department of Chemical Engineering, Northeastern University, Boston, MA

Microbiologists in the research and biotech industry still primarily depend on bacterial culture plates to identify bacterial infections. The bacterial culture plates can take 1 – 5 days before clinicians confirm a bacterial infection and provide the required antibiotic to the patient; this delay in acquiring results can hinder patient care especially with the growing impact of antibiotic resistant bacteria. Therefore, rapid detection of bacterial infections at the point of care would play a key role in improving patient care and potentially prevent bacterial antibiotic resistance. In this work, we present the use of low cost fabricated microfluidic capillary electrophoresis devices coupled with electrochemical detection to detect extracellular bacterial compounds in bodily fluids. These compounds includes electroactive molecules, sugars and proteins which have been shown to readily oxidize at gold, copper and platinum electrodes. We explore if different species of bacterial excreted molecules can be electrochemically distinguished after separation using microfluidic capillary electrophoresis. The portable microfluidic devices are capable of separation and detection under an hour which can greatly improve the time to results whereby clinicians can provide targeted antibiotics instead of awaiting 1-5 days for a culture plate to make the determination of the type of bacterial infection.

The microfluidic devices were fabricated in-house on PDMS and on glass to make 5 centimeter long capillaries at 20 – 75 µm diameters. Gold, copper or platinum electrodes were aligned and deposited on glass substrates at the end of the capillary to serve as an end channel detection and for the power supply used for conducting the capillary electrophoresis. The voltage for separation was conducted between 400V to 3000V. The fabricated microfluidic device was optimized to allow amperometric detection of excreted bacterial molecules at the end channel electrodes. Different species of pathogens were studied to determine the selectivity of the fabricated sensors. The advantage of the microfluidic setup is the low cost, portability and ease of use in which a bodily fluid sample can be analyzed with very limited sample preparation. Typical electroactive bodily fluid compositions would be separated out of the capillary by eluting at known intervals therefore allowing for specific determination of additional components in the fluids. In addition, the set-up allows for the analysis of small volumes down to the nanoliter range.

The results from this work can provide the ability to selectively differentiate bacterial species based on the elution profile from a capillary electrophoresis set-up. In addition, this set-up can be coupled with functionalized electrodes at the end of channel set-up to improve sensitivity and selectivity of targeted compounds that may not be readily electroactive on bare electrodes.