Colorimetric Detection of ssDNA using DNA-functionalized Gold Nanoparticles

• Author / Creator

  Lam, Michael K

• Remarkable progress has been made in terms of developing gold nanoparticle (AuNP) based colorimetric systems for biodiagnostics. There are two general strategies: the target analyte triggers assembly leading to a color change from red solution to blue precipitated AuNPs; the target analyte triggers disassembly of pre-formed aggregates leading to a blue to red color change. As colorimetric detection systems suitable for point-of-care applications should be rapid, this dissertation will systematically address the effects of temperature on the rate of target DNA induced disassembly of DNA-AuNP aggregates in DNA detection. Specifically in Chapter 2, DNA-AuNP aggregates (purple) composed of two AuNP probes hybridized with a complementary linker DNA sequence are disassembled into colloidal DNA-AuNPs (red) with the addition of a target DNA sequence fully complementary to the linker. By monitoring the disassembly upon addition of target at various temperature settings, we observe an increasingly rapid disassembly as we near the melting temperature (Tm). Using the protocols developed from this system, we introduce a single-stranded overhang (toehold) into the linker to increase the rate of target-triggered disassembly and systematically varied the overhang length while monitoring the temperature-dependence of target-triggered disassembly. The length of the overhang greatly influences the temperature sensitivity of the target-triggered disaggregation process. For toehold lengths of 5 bases, rapid target-triggered disassembly occurs even at room temperature (Chapter 3). In addition, we explore strategies for making II this colorimetric process suitable for shelf storage by lyophilization of the pre-formed DNA-AuNP aggregates containing 5 base overhangs on the linker. We vary the storage temperature of the solid (lyophilized) DNA-AuNP aggregates which can be resuspended and used to detect target DNA colorimetrically.

• Subjects / Keywords

  • DNA functionalized gold nanoparticles
  • Gold nanoparticles
  • Colorimetric detection

• Graduation date

  Spring 2016

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R32Z1345Z

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.