title: Comparative study of controlled pore glass, silica gel and poraver for the immobilization of urease to determine urea in a flow injection conductimetric biosensor system.
abstract: This study compared the responses of three enzyme reactors containing urease immobilized on three types of solid support, controlled pore glass (CPG), silica gel and Poraver. The evaluation of each enzyme reactor column was done in a flow injection conductimetric system. When urea in the sample solution passed though the enzyme reactor, urease catalysed the hydrolysis of urea into charged products. A lab-built conductivity meter was used to measure the increase in conductivity of the solution. The responses of the enzyme reactor column with urease immobilized on CPG and silica gel were similar and were much higher than that of Poraver. Both CPG and silica gel reactor columns gave the same limit of detection, 0.5 mM, and the response was still linear up to 150mM. The analysis time was 4-5 min per sample. The enzyme reactor column with urease immobilized on CPG gave a slightly better sensitivity, 4% higher than the reactor with silica gel. The life time of the immobilized urease on CPG and silica gel were more than 310h operation time (used intermittently over 7 months). Good agreement was obtained when urea concentrations of human serum samples determined by the flow injection conductimetric biosensor system was compared to the conventional methods (Fearon and Berthelot reactions). These were statistically shown using the regression line and Wilcoxon signed rank tests. The results showed that the reactor with urease immobilized on silica gel had the same efficiency as the reactor with urease immobilized on CPG.
authors.affiliation: Biophysics Research Unit of Biosensors and Biocurrents, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand.
authors.forename: Warakorn
authors.initials: W
authors.lastname: Limbut
authors.forename: Panote
authors.initials: P
authors.lastname: Thavarungkul
authors.forename: Proespichaya
authors.initials: P
authors.lastname: Kanatharana
authors.forename: Punnee
authors.initials: P
authors.lastname: Asawatreratanakul
authors.forename: Chusak
authors.initials: C
authors.lastname: Limsakul
authors.forename: Booncharoen
authors.initials: B
authors.lastname: Wongkittisuksa
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D020099:Coated Materials, Biocompatible / Q000737:chemistry; D004563:Electrochemistry / Q000295:instrumentation* / Q000379:methods; D004789:Enzyme Activation; D004800:Enzymes, Immobilized / Q000737:chemistry; D004867:Equipment Design; D019544:Equipment Failure Analysis; D017022:Flow Injection Analysis / Q000295:instrumentation* / Q000379:methods; D005898:Glass / Q000737:chemistry*; D008567:Membranes, Artificial; D016062:Porosity; D011485:Protein Binding; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D058428:Silica Gel; D012822:Silicon Dioxide / Q000737:chemistry*; D014508:Urea / Q000032:analysis* / Q000737:chemistry; D014510:Urease / Q000737:chemistry*
chemical_list: D020099:Coated Materials, Biocompatible; D004800:Enzymes, Immobilized; D008567:Membranes, Artificial; D058428:Silica Gel; D012822:Silicon Dioxide; D014508:Urea; D014510:Urease