Lateral Flow Nucleic Acid Biosensor for the Detection of Sexually Transmitted Diseases

Nucleic acid detection is of central importance for the diagnosis and treatment of genetic diseases, infectious agents, bio-warfare agents, and drug discovery. Nucleic acid testing for diseases is exclusively performed in laboratories using high-end instrumentation and personnel. However, this has developed the need for point of care diagnostics which can provide near-patient testing in a clinic, doctor?s office, or home. Such diagnostic tools can prove advantageous when rapid response is required or when suitable facilities are unavailable. Compared to equivalent methods used in laboratories, point of care testing is more affordable, as it eliminates the need for expensive instrumentation and skilled labor. One option involves the use of lateral flow assays. Pre-fabricated strips of dry reagents activated upon fluid application are already used in diagnostics, such as to ascertain pregnancy. Nucleic acid based detection assays on lateral flow offer several advantages over traditional microbiological detection methods. In this work we introduce a lateral flow biosensor that can combine the optical properties of nanoparticles (such as gold nanoparticles) with conventional immunoassay techniques to deliver a simple platform for rapid analysis of DNA with high sensitivity and selectivity. The quick 30 minute assay provides a platform to detect multiple nucleic acids with high efficiency achieved via chromatographic separation sandwich-type DNA hybridization reactions. Captured gold nanoparticles on the device can provide qualitative analysis by observing the color change to red and a semi-quantitative analysis via a strip reader. The biosensor was applied to the detection of human genomic DNA directly with high sensitivity and selectivity. The work was further expanded to detect Chlamydia trachomatis and Neisseria gonorrhoeae samples using nucleic acid amplification to generate large numbers of target copies. Improvements were made in the preparation of the biosensor to enable detection of Human Papilloma Virus Type-16. The clinical samples obtained were amplified using PCR for direct detection on the lateral flow biosensor without interference from other HPV types (e.g. HPV 18). The feasibility of the biosensor shows great potential for further development to assure its use in point of care diagnosis. The promising properties of the biosensor are reported in this dissertation