Date of Graduation
Statler College of Engineering and Mineral Resources
Mechanical and Aerospace Engineering
Early detection of malignant disease is crucial for timely diagnosis and effective medical intervention, which significantly increases survival rates and reduce financial burden on patients. Biomarkers are becoming increasingly important in detection of malignant diseases, because they can be employed for indicating diseases, predicting risks and monitoring the progression of diseases. In addition, biomarkers show up at early stages of diseases in human tissues and fluids (e.g., blood, urine and saliva), which shows great promise for early disease detection. In this dissertation, paper-based lateral flow strips (PLFSs) have been developed for the detection of disease biomarkers, including protein biomarkers and microRNA (miRNA) biomarkers from clinical samples and whole blood samples. Among most of the reported biosensors, PLFSs appear to be an effective tool for providing access to point-of-care (POC) applications, due to low cost, fast response, portability and ease of use. In addition, paper is compatible with biological samples, which allows its application in analyzing various biomolecules. However, conventional PLFSs exhibit insufficient sensitivity and poor interference resistance. In particular whole blood samples, which contain numerous interference biomolecules, substantially affect detection accuracy and specificity.
In this dissertation, several strategies have been employed to solve the problems, including introducing PLFSs with ultrasensitive techniques, meanwhile modifying PLFSs with functional nanomaterials and paper accessory unit to reduce the interference biomolecules from human fluids. In summary, five chapters will be demonstrated:
(1) Surface-enhanced Raman scattering (SERS) technique modified PLFSs for protein biomarker detection in clinical blood plasma samples. In this chapter, silica coated SERS nanoparticles (NPs) have been developed for improving Raman signal and detection sensitivity, at the same time, silica coating of the SERS NPs substantially improve the stability of the NPs in complex human fluids. As a result, the developed SERS-PLFS can realize direct detection of neuron-specific enolase (NSE) from clinical blood plasma samples of traumatic brain injury (TBI) patients. The test results of the SERS-PLFSs were compatible with those from the standard enzyme-linked immunospecific assay (ELISA) method;
(2) Blood plasma separation unit (PSU) integrated PLFS for cancer protein biomarker detection from whole human blood sample. In this chapter, a paper based PSU was fabricated to efficiently retain red blood cells (RBCs) inside the unit to block their migration and meanwhile push the target protein contained plasma to the detection area of the PLFS. As a result, cancer protein biomarker-carcinoembryonic antigen (CEA) was successfully detected by the PSU-PLFS from whole blood samples;
(3) Plasmonic chip and PSU integrated PLFS for protein biomarker detection from whole blood. In order to meet the high sensitivity demand, a gold nanopyramid array functionalized chip was integrated into a PLFS for amplifying Raman signal and ultrasensitive detection of TBI protein biomarker s-100β; while the PSU was utilized to reduce the RBCs interference from whole blood. As a result, compared with the result of the SERS-PLFS in Chapter 2, an improvement in LOD with two-order of magnitude was obtained;
(4) Near-infrared fluorophores (NIRFs) functionalized PLFS for miRNA detection from blood plasma. In this chapter, NIRFs encapsulated silica nanoparticles were synthesized and incorporated into a PLFS for stroke biomarker miRNA-34 detection. Compared with a single fluorescent dye, the synthesized NIRF NPs encapsulated numerous fluorophores into one single silica nanoparticle, exhibiting amplified luminescent intensity. Moreover, the NIRF nanoparticles minimized the fluorescent background from biological matrices and test strip materials, which elevates signal-to-noise ratio and anti-interference capacity;
(5) Duplex specific nuclease (DSN) based signal amplification strategy modified PLFS for ultrasensitive miRNA detection in blood plasma. In order to meet the high sensitivity demand of miRNA-34 measurement from the clinical blood plasma of stroke patient, the developed NIRFs-PLFS in Part 4 was further elevated with DSN modification for amplifying fluorescent signal. As a result, the DSN-PLFS exhibited an improvement in detection sensitivity with two-orders of magnitude in blood plasma.
Gao, Xuefei, "Paper-Based Point-of-Care Tools for Blood Testing" (2020). Graduate Theses, Dissertations, and Problem Reports. 7620.