title: Ionophore-based ion-selective optical nanosensors operating in exhaustive sensing mode.
abstract: Ion selective optical sensors are typically interrogated under conditions where the sample concentration is not altered during measurement. We describe here an alternative exhaustive detection mode for ion selective optical sensors. This exhaustive sensor concept is demonstrated with ionophore-based nanooptodes either selective for calcium or the polycationic heparin antidote protamine. In agreement with a theoretical treatment presented here, linear calibration curves were obtained in the exhaustive detection mode instead of the sigmoidal curves for equilibrium-based sensors. The response range can be tuned by adjusting the nanosensor loading. The nanosensors showed average diameters of below 100 nm and the sensor response was found to be dramatically faster than that for film-based optodes. Due to the strong binding affinity of the exhaustive nanosensors, total calcium concentration in human blood plasma was successfully determined. Optical determination of protamine in human blood plasma using the exhaustive nanosensors was attempted, but was found to be less successful.
authors.affiliation: Department of Inorganic and Analytical Chemistry, University of Geneva , Quai Ernest-Ansermet 30, CH-1211 Geneva, Switzerland.
authors.forename: Xiaojiang
authors.initials: X
authors.lastname: Xie
authors.forename: Jingying
authors.initials: J
authors.lastname: Zhai
authors.forename: Gastón A
authors.initials: GA
authors.lastname: Crespo
authors.forename: Eric
authors.initials: E
authors.lastname: Bakker
mesh_terms: D015374:Biosensing Techniques / Q000592:standards; D002118:Calcium / Q000032:analysis* / Q000097:blood / Q000592:standards; D002138:Calibration; D002623:Chemistry Techniques, Analytical / Q000295:instrumentation* / Q000379:methods*; D006801:Humans; D007476:Ionophores / Q000737:chemistry*; D036103:Nanotechnology; D011479:Protamines / Q000032:analysis* / Q000097:blood / Q000592:standards
chemical_list: D007476:Ionophores; D011479:Protamines; D002118:Calcium