title: Potentiometric determination of trypsin using a polymeric membrane polycation-sensitive electrode based on current-controlled reagent delivery.
abstract: A potentiometric biosensor for the determination of trypsin is described based on current-controlled reagent delivery. A polymeric membrane protamine-sensitive electrode with dinonylnaphthalene sulfonate as cation exchanger is used for in situ generation of protamine. Diffusion of protamine across the polymeric membrane can be controlled precisely by applying an external current. The hydrolysis catalyzed with trypsin in sample solution decreases the concentration of free protamine released at the sample-membrane interface and facilitates the stripping of protamine out of the membrane surface via the ion-exchange process with sodium ions from the sample solution, thus decreasing the membrane potential, by which the protease can be sensed potentiometrically. The influences of anodic current amplitude, current pulse duration and protamine concentration in the inner filling solution on the membrane potential response have been studied. Under optimum conditions, the proposed protamine-sensitive electrode is useful for continuous and reversible detection of trypsin over the concentration range of 0.5-5UmL(-1) with a detection limit of 0.3UmL(-1). The proposed detection strategy provides a rapid and reagentless way for the detection of protease activities and offers great potential in the homogeneous immunoassays using proteases as labels.
authors.affiliation: We Key Laboratory of Coastal Zone Environmental Processes, Yantai Institute of Coastal Zone Research (YIC), Chinese Academy of Sciences (CAS), Shandong Provincial Key Laboratory of Coastal Zone Environmental Processes, YICCAS, Yantai, Shandong 264003, PR China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Chen
authors.forename: Jiawang
authors.initials: J
authors.lastname: Ding
authors.forename: Wei
authors.initials: W
authors.lastname: Qin
mesh_terms: D000818:Animals; D015374:Biosensing Techniques / Q000379:methods*; D002417:Cattle; D004553:Electric Conductivity; D004566:Electrodes; D007202:Indicators and Reagents / Q000737:chemistry; D008567:Membranes, Artificial; D011073:Polyamines / Q000737:chemistry*; D000071228:Polyelectrolytes; D011108:Polymers / Q000737:chemistry*; D011199:Potentiometry / Q000379:methods*; D011479:Protamines / Q000737:chemistry / Q000378:metabolism; D013997:Time Factors; D014357:Trypsin / Q000032:analysis* / Q000378:metabolism
chemical_list: D007202:Indicators and Reagents; D008567:Membranes, Artificial; D011073:Polyamines; D000071228:Polyelectrolytes; D011108:Polymers; D011479:Protamines; D014357:Trypsin