Abstract

Printable Paper-Based Diagnostic Systems for Biomedical and Environmental Monitoring

John D. Brennan, Director, McMaster University

There is currently a great need for developing rapid and effective point-of-care (POC) diagnostics that can improve patient care in resource-limited settings. Paper-based POC diagnostic devices provide a platform for portable, low-cost, low-volume, disposable, and simple sensors, which can be developed using printing technology, making them amenable to automated fabrication or even on-site production in areas with limited resources. One major challenge in paper-based diagnostics is to integrate molecular amplification technology to allow sensitive target detection. Recently, isothermal nucleic acid amplification techniques have been widely investigated as a method to facilitate target or signal amplification in molecular biology and bioanalysis without the use of thermocycling devices. Thus the combination of isothermal nucleic acid amplification techniques with paper-based POC diagnostics should add critical functionality to these devices to make them more robust and sensitive. Herein, we describe rolling circle amplification (RCA), a simple and efficient isothermal enzymatic DNA replication process, that is performed in a wax-printed microzone plate fabricated on a paper substrate (paper-based RCA), and demonstrate an “all-in-one” paper-based POC device, in which all required reagents for amplification and detection are integrated via ink-jet printing of reagents in a polymeric sugar film formed from pullulan onto the sensor, providing improved functionality and ease of use. The resulting device is capable of carrying out target-induced rolling circle amplification (RCA) to produce massive DNA amplicons that can be easily visualized. We demonstrate that the printed “all-in-one” paper device can provide sensitive detection of viral DNA or cellular microRNA with no need for sophisticated instrumentation. Further development of this platform to include both DNA aptamers and aptazymes as recognition elements to provide analyte-triggered RCA on paper will be described.