For the hundreds of millions of worldwide diabetic patients, glucose test strips are the most important and commonly used tool for monitoring blood glucose levels. Commercial test strips use glucose oxidases as recognition agents, which increases the cost and reduces the durability of test strips. To lower the cost of glucose sensors, we developed a paper-based electrical sensor with molecularly imprinted glucose recognition sites and demonstrated the determination of various glucose concentrations in bovine blood solutions. The sensing electrode is integrated with molecular recognition sites in the conductive polymer. A calibration graph as a function of glucose concentration in aqueous solution was acquired and matched with a correlation coefficient of 0.989. We also demonstrated the determination of the added glucose concentrations ranging from 2.2 to 11.1 mM in bovine blood samples with a linear correlation coefficient of 0.984. This non-enzymatic glucose sensor has the potential to reduce the health care cost of test strips as well as make glucose sensor test strips more accessible to underserved communities.
Perfluorinated compounds like perfluorooctanesulfonic acid (PFOS) are synthetic water pollutants and have accumulated in environments for decades, causing a serious global health issue. Conventional assays rely on liquid chromatography and mass spectroscopy that are very expensive and complicated and thus limit the large-scale monitoring of PFOS in wastewater. To achieve low-cost and accurate detection of PFOS, we designed a paper-based sensor with molecularly imprinted polyaniline electrodes that have recognition sites specific to PFOS. The calibration curve of resistivity ratios as a function of PFOS concentrations has a linear range from 1 to 100 ppt with a coefficient of determination of 0.995. The estimated limit of detection is 1.02 ppt. We also investigated attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) spectra of the surface of the polyaniline (PANI) electrodes to propose the potential recognition sites in polyaniline matrix and the detection mechanism. This electrical paper sensor with low cost and excellent sensitivity and selectivity provides the potential for large-scale monitoring of wastewater.
Silver nanoparticles (AgNPs) exhibit size-dependent bactericidal activity. They are, however, subject to aggregation when added to most hydrophobic polymers. In this study, a surfactant-modified delaminated clay (surfactant-capped nanosilicate platelets, or "NSQ") was employed to be a nanocarrier for AgNPs. The nanohybrid of AgNPs and NSQ ("AgNP/NSQ") in aqueous solution showed remarkable bactericidal effect as well as negligible cytotoxicity and immune response at a concentration of 10 ppm.Poly(carbonate)urethane (PCU) with different hard/soft segment ratios was synthesized and used in the preparation of the nanocomposites, PCU-AgNP/NSQ. Based on TEM observation, AgNP/NSQ was well dispersed in the resulting nanocomposites. The reinforcing effects of AgNP/NSQ in nanocomposites were distinct for PCU with different hard/soft segment ratios. The phase-separated structure of PCU-AgNP/NSQ nanocomposites was investigated by small-angle X-ray scattering (SAXS). PCU-AgNP/NSQ containing 75 ppm of Ag demonstrated superior microbiostatic effect, as well as better biodurability and lower foreign body reaction than the commercial Pellethane 2363-80A.
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