Patterned Fabrication of Polyaniline Nanostructures for Ultrasensitive Biomolecule DetectionHuang, Jiyong (2014) Patterned Fabrication of Polyaniline Nanostructures for Ultrasensitive Biomolecule Detection. Doctoral Dissertation, University of Pittsburgh. (Unpublished)
AbstractWith more number of individuals becoming health conscious, the use of biosensors for medical diagnosis is rapidly growing. So far, many efforts have been made to meet this increasing demand. This work presents several routes to improve the biosensors performances and builds a sophisticated platform for sensing application. Single polypyrrole nanowire-based sensors were fabricated using a one-step electrochemical deposition method. A shadow mask was introduced to protect the biosensors from O2 plasma for the microfluidics integration. The results of nanowire resistance and fluorescence intensity indicated that the shadow mask played a key role in protecting the biosensor. The microfluidic aptasensors were consequently developed. The sensor demonstrated excellent specificity and sensitivity with faster response and rapid stabilization times. High yield polyaniline 1D nanowires and 2D nanobelts were fabricated by combining nanofabrication techniques and a chemical synthesis method. The PANI patterns possess good uniformity in morphology and electrical properties. The biosensors were found very sensitive to BNP targets, showing a response ~17% for 100 fg/mL BNP and a wide sensing range from 25 fg/mL to 5 pg/mL. Despite the reduced sensitivity compared to that in PBS, distinguishable changes in the FET sensors were observed over a range from 100 fg/mL to 5 pg/mL in serum. Significantly, the investigation about the Debye length opened an approach for further sensing performance improvement. Within the sub-threshold regime of the NWs, the sensor responses exhibited about 4 times greater than that in their linear region. Studies concentrated on the 2D PANI nanobelts revealed that they have similar rough surface and FET behavior to PANI-NWs. This suggested that the 2D PANI nanobelts would have comparable performances to 1D PANI-NWs as biosensors. A biosensor system based on the PNAI nanobelts was developed. The biosensors exhibited a good specificity and showed a linear range for BNP in buffer from 50 to 200 pg/mL. The demonstration of detecting BNP levels in human serum further confirmed that the sensor is capable of monitoring BNP in real samples. Those findings suggested that this biosensor system has a great potential for clinical use in future. Share
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