The Selective Measurement Method Of Glucose Concentration In Interstitial Fluid

Comprehensive blood glucose information of the diabetics was obtained throughcontinuous blood glucose monitoring. And it was essential to control and treatdiabetes through accurate insulin injection based on the whole blood glucoseinformation. Now human blood glucose detection method includes invasive,minimally-invasive and non-invasive. Minimally-invasive detection method can avoidinvasive detection’s limitation, meanwhile it is easier to realize clinically thannon-invasive detection. Our group studies minimally-invasive blood glucose detectionwith following two steps, extracting interstitial fluid through transdermal extractionand measuring glucose concentration with surface plasmon resonance technique.Because of the tiny volume and complex components of the interstitial fluid, onehigh-precision specific measurement method is needed.The selective measurement method of glucose concentration in interstitial fluidbased on SPR surface modification was studied in this paper. GGBP and boratepolymer PAA-ran-PAAPBA which can specifically adsorb glucose were researched.Firstly GGBP was site-directed mutated and then immobilized on the gold surfacethrough thiol coupling method. Two key factors during binding process were studied,and results showed optimal PBS pH and GGBP concentration were4.5and40μg/mL.The glucose concentration measuring experiment suggested the limited measuringrange was0.1~1mg/dL and resolution was0.2mg/dL, which well met the experimentrequirement of glucose concentration in diluted interstitial fluid.As GGBP was unstable, expensive, and complex to immobilize, borate polymerPAA-ran-PAAPBA was introduced as an alternative that was stable, cheap, andsimple to be bound through layer-by-layer (LBL) self-assembly technique. Initialglucose measurement was conducted, and results showed the limited measuring rangewas2~10mg/dL and resolution was1mg/dL. Since the LBL technique was easy tocontrol binding layers, polymer layers’ effect on the glucose measurement was carriedon.6,12and20layers of polymer were bound on the surface of sensors respectively,and the experiment results showed12-layer-polymer sensor was better than6-layersensor in1~10mg/dL and10~100mg/dL, suggesting properly increasing polymerlayers can improve measuring accuracy;20-layer-polymer sensor’s results showed limited measuring range was0.1~1mg/dL and resolution was0.1mg/dL, which canreach the accuracy to measure glucose concentration in diluted interstitial fluid.