Development of Electrical Readouts for Amplified Single Molecule Detection
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Molecular diagnostics is a fast growing field with new technologies being developed constantly. There is a demand for more sophisticated molecular tools able to detect a multitude of molecules on a single molecule level with high specificity, able to distinguish them from other similar molecules. This becomes very important for infectious diagnostics with the increasing antibiotic resistant viruses and bacteria, in gene based diagnostics and for early detection and more targeted treatments of cancer. For increased sensitivity, simplicity, speed and user friendliness, novel readouts are emerging, taking advantage of new technologies being discovered in the field of nanotechnology.
This thesis, based upon four papers, examines two novel electrical readouts for amplified single molecule detection. Target probing is based upon the highly specific amplification technique rolling circle amplification (RCA). RCA enables localized amplification resulting in a long single stranded DNA molecule containing tandem repeats of the probing sequence as product. Paper I demonstrates sensitive detection of bacterial genomic DNA using a magnetic nanoparticles-based substrate-free method where as few as 50 bacteria can be detected. Paper II illustrates a new sensor concept based on the formation of conducting molecular nanowires forming a low resistance circuit. The rolling circle products are stretched to bridge an electrode gap and upon metallization the resistance drops by several orders of magnitude, resulting in an extremely high signal to noise ratio. Paper III explores a novel metallization technique, demonstrating the efficient incorporation of boranephosphonate modified nucleotides during RCA. In the presence of a silver ion solution, defined metal nanoparticles are formed along the DNA molecule with high spatial specificity. Paper IV demonstrates the ability to manipulate rolling circle products by dielectrophoresis. In the presence of a high AC electric field the rolling circle products stretch to bridge a 10 µm electrode gap.
Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2015. , 46 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 1091
Rolling circle amplification, metallization, electrical DNA detection, magnetic nanoparticles, dielectrophoresis, boranephosphonate modified nucleotides, DNA elongation
Biochemistry and Molecular Biology
Research subject Biochemistry
IdentifiersURN: urn:nbn:se:uu:diva-247945ISBN: 978-91-554-9219-9OAI: oai:DiVA.org:uu-247945DiVA: diva2:798020
2015-05-22, B41, BMC, Husargatan 3, Uppsala, 13:15 (English)
Högberg, Björn, Associate professor
Nilsson, Mats, Professor
List of papers