MicroRNAs (miRNAs) are short non-coding RNA sequences with a length of 18 to 24 nucleotides and are known to modulate protein expression by binding to complementary sequences of messenger RNA (mRNA). Despite being discovered only recently, there is growing evidence that miRNAs are involved in key biological processes. Recent studies have shown a correlation between circulating miRNA biomarkers and many diseases including type 2 diabetes. The development of a method for miRNA detection is of great importance as it could allow for early detection of type 2 diabetes, and therefore may have the potential to reduce the number of people with undiagnosed diabetes. Many methods can be used for miRNA detection, however surface enhanced Raman scattering (SERS) is an ideal candidate as it is considered to be a fast, highly sensitive and an extremely effective technique for miRNA detection when applied with bio-functionalised metallic nanoparticles. In addition, it offers the capability for the simultaneous detection of multiple targets, which provides SERS with major advantages over other techniques. The research began with the functionalization of silver nanoparticles using DNA oligonucleotide sequences and successive testing of their ability to detect miRNA biomarkers with a clinical relevance to type 2 diabetes in a solution-based assay. The silver nanoparticle conjugates were functionalised using thiol modified oligonucleotides and a Raman reporter to aid SERS detection. When the sample was exposed to a complementary strand of miRNA target, the nanoparticles aggregated and increased the SERS signal. Using a similar sandwich assay format, miRNA targets were also detected using a solid phase assay incorporating lateral flow strips. Lateral flow devices (LFDs) are already established for the detection of nucleic acids, and by using SERS, the detection sensitivity for targets in biological samples may be increased. Here we have been able to detect miRNA by direct visualisation of the lateral flow strips, and by SERS detection at very low concentrations difficult to see by the naked eye. These two approaches, towards using SERS for miRNA detection, are very promising and could allow biologists and clinicians to measure and monitor miRNA levels, for use in medical diagnosis and early detection of many diseases, not just type 2 diabetes.
|Date of Award||4 May 2018|
- University Of Strathclyde
|Supervisor||Duncan Graham (Supervisor) & Karen Faulds (Supervisor)|