Abstract

Microfluidic devices offer important benefits for forensic applications, in particular for fast tests at a crime scene. A large portion of forensic applications require microfluidic chip material to show compatibility with biochemical reactions (such as amplification reactions), and to have high transparency in the visible region and high chemical resistance. Also, preferably, manufacturing should be simple. The characteristic properties of cyclic olefin copolymer (COC) fulfills these requirements and offers new opportunities for the development of new forensic tests. In this work, the versatility of COC as material for lab-on-a-chip (LOC) systems in forensic applications has been explored by realizing two proof-of-principle devices. Chemical resistance and optical transparency were investigated for the development of an on-chip presumptive color test to indicate the presence of an illicit substance through applying absorption spectroscopy. Furthermore, the compatibility of COC with a DNA amplification reaction was verified by performing an on-chip multiple displacement amplification (MDA) reaction.

Highlights

  • Lab-on-a-chip (LOC) technology can be used to decrease analysis time, the amount of reagents and analyte, and can add to the development of portable devices that can be used directly on the crime scene

  • Concentration for uncoated chips was well above 200 ng/μL, which was in accordance with the run concentration for uncoated chips was well above 200 ng/μL, which was in accordance with the run in the thermocycler (Figure 7) and the literature [37,38,59]

  • The coating of a cyclic olefin copolymer (COC) chip with bovine serum albumin (BSA) has been described in the literature to prevent non-specific binding to a COC surface in biological applications (e.g., polymerase chain reaction (PCR) or immunosensors) [7,54,61], in our experiments, a BSA coating clearly resulted in an inhibitory effect on the multiple displacement amplification (MDA) reaction

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Summary

Introduction

Lab-on-a-chip (LOC) technology can be used to decrease analysis time, the amount of reagents and analyte, and can add to the development of portable devices that can be used directly on the crime scene. Silicon is widely used as chip material because of its good thermal conductivity, which makes it suitable for the fast heating and cooling required in (well-based) polymerase chain reaction (PCR) cycling [1,2,3]. It is not transparent for UV-VIS light. Because of its transparency in the visible range and, the possibility for optical detection, glass is widely used as chip material for (forensic) DNA analysis on-chip. Two forensically relevant reactions within COC chips were studied in this research, namely the spot test for illicit drug analysis and DNA amplification. Bovine serum albumin (BSA) is widely used to coat the channel walls in order to prevent absorption of the polymerase [50,54]

Chip Fabrication
Design of the Presumptive Color Test Chips
Milling depth
Design of the MDA Chips
Reagents and Analytes
UV-VIS Spectroscopy
MDA Protocol
DNA Quantification
Food Dyes
Absorbance
The standardChip
Drug Chips
MDA Chips
Conclusions
Objective

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