| Description |
Analyte-detecting sensors have been developed in many fields. Chemical sensors, and especially biomedical sensors, deserve special attention because they can simplify time-consuming, costly and site-limited medical procedures. Sensor efficiency depends on its analyte sensing material, signal transducing device and data processing system. The biggest barrier to devise biomedical sensors is the development of analyte sensing material with a high selectivity for target molecules. The motivation of this research was to develop biomolecule-sensitive polymers that can be used in biomedical sensors. Thus, this thesis covers all stages of chemical sensor development, from developing target analyte sensitive materials to merging the developed materials with a signal transducing system. First, the potential application of a zwitterionic glucose-responsive hydrogel as a body implantable continuous glucose monitoring system was examined. After using thermodynamics to confirm the glucose sensing mechanism, synthesis of the hydrogels was optimized and analyzed using statistical methods (design of experiments (DOE)). Thermodynamics study showed that mixing contribution was an important factor to glucose selectivity as well as elastic contribution. By the DOE study, we confirmed that sensitivity of the hydrogels was determined by the molar ratio of cationic and anionic functional groups, and response time depended on the amount of cross-linker. A hydrogel degradation study was also performed to determine the effect of gamma ray sterilization and neutron irradiations on the hydrogel cross-linking network for biomedical applications. Results showed that gamma ray affected cross-linking networks of UV cured hydrogels. However, the neutron irradiation effect was not considerable. In addition, ferromagnetic particles-embedded, zwitterionic glucose-responsive hydrogels were developed to enable the response processing by a magnetoresistive transducer. The hydrogel with horizontally aligned ferromagnetic particles showed good sensitivity in the physiological glucose range (~10mM). Moreover, response time was reduced by almost seven-fold with twice thicker samples (800 um) than samples (400 um) with a pressure sensor measurement. A second project optimized the synthesis of a glutathione (GSH)-sensitive polymer. The selectivity of the polymer for GSH was improved by synthesizing a GSHimprinted polymer and adopting a cobalt ion-mediated chelating binding structure as analyte binding sites. |
