Monolithically integrated polymeric Lab-on- (Bio)Chips with photonic/electrochemical detection

Abstract

In this PhD Thesis low-cost functionalized Lab-on-(bio)Chip systems (LOC) for their use as analytical tools for environmental and biomedical applications have been developed. Based on photonic LOC approaches (PhLOC) previously defined in our group, the potential of these devices in analysis was explored first. Multiple Internal Reflection (MIR) optofluidic systems made of cost-effective polymers, such as polydimethylsiloxane (PDMS), using rapid fabrication processes were applied for the detection of different analytes (cells and heavy metal ions) and their performance compared with other more conventional analytical techniques. In order to confer selectivity to the PhLOCs, different surface modification protocols for protein immobilization on the polymeric materials used in this work were developed and compared. These methods keep the optical and structural properties of the material unaltered. Horseradish peroxidase (HRP) was chosen as a model protein in these studies, and the resulting biofunctionalized surfaces tested by measuring the enzymatic activity to hydrogen peroxide in the presence of 2,2’azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) redox mediator, whose green colored enzymatic product could be detected by absorbance measurements. The stability of the immobilized HRP was also tested for periods longer than one month. Finally, other fluidic components and functionalities were added to the previously applied PhLOCs in order to enhance their performance. Microfluidic structures such as biofunctionalized mixers (therefore also playing the role of reactors) were monolithically integrated with a MIR, resulting in a PhLOC with enhanced analytical performance. These new elements decreased the analysis time and sample / reagent volumes. With the integration of a gold electrochemical cell in the substrate, a dual readout LOC (DLOC) was developed, which enabled simultaneous optical and electrochemical transduction and made the developed system self-verifying, thereby improving its reliability. The potential of this DLOC was shown by developing an analytical tool for measuring glucose. Glucose oxidase (GOx) and HRP were immobilized following the protocol developed in this Thesis and applied as the specific receptors for the detection of glucose based on an enzymatic cascade reaction also using ABTS redox mediator. As an additional study, the applicability of the developed functionalization protocol was tested on different polymers and the immobilization of biological components other than enzymes was also carried out.

Date of Award	2013
Original language	English
Awarding Institution	Universidad Autonoma de Barcelona
Supervisor	Cesar Fernandez Sanchez (Supervisor) & Andreu Llobera (Supervisor)