title: SPR imaging biosensor for aspartyl cathepsins: sensor development and application for biological material.
abstract: A Surface Plasmon Resonance Imaging (SPRI) sensor has been developed for highly selective determination of cathepsin D (Cat D) or/and E (Cat E). The sensor contains immobilised pepstatin A, which binds aspartyl proteases from solution. Pepstatin A activated with N-Hydroxysuccinimide (NHS) and N-Ethyl-N'-(3-dimethylaminopropyl) carbodiimide (EDC) was immobilized on an amine-modified gold surface. Cysteamine was used for modification of the gold surface. Pepstatin A concentration and pH of interaction were optimised. A concentration of pepstatin equal to 0.5 microg mL(-1) and a pH of 3.75 were selected as optimal. The sensor's dynamic response range is between 0.25 and 1.0 ng mL(-1), and the detection limit is 0.12 ng mL(-1). However, the sensor cannot distinguish between Cat D and Cat E. In order to demonstrate the sensor's potential, Cat E was determined in human red blood cells, Cat D in human saliva, as well as total concentration of Cat D and Cat E in human nasal polyps.
authors.affiliation: Department of Electrochemistry, Institute of Chemistry, University of Bialystok, Al.J.Pilsudskiego11/4, 15-443 Bialystok, Poland. ewka@uwb.edu.pl
authors.forename: Ewa
authors.initials: E
authors.lastname: Gorodkiewicz
authors.forename: Elzbieta
authors.initials: E
authors.lastname: Regulska
mesh_terms: D000818:Animals; D015374:Biosensing Techniques / Q000379:methods*; D002402:Cathepsin D / Q000032:analysis; D020059:Cathepsin E / Q000032:analysis; D002403:Cathepsins / Q000032:analysis*; D004912:Erythrocytes / Q000737:chemistry; D006801:Humans; D009298:Nasal Polyps / Q000737:chemistry; D010436:Pepstatins / Q000032:analysis; D012463:Saliva / Q000737:chemistry; D020349:Surface Plasmon Resonance / Q000379:methods*
chemical_list: D010436:Pepstatins; D002403:Cathepsins; D020059:Cathepsin E; D002402:Cathepsin D; C031375:pepstatin