Facile Preparation Method of a Disposable Capillary Biosensor Using an Ion-selective Optode Membrane and a Dissolvable Enzyme Membrane and Its Application to Urea Sensing

Abstract

A facile preparation method of a disposable capillary biosensor immobilizing a plasticized poly(vinyl chloride) (PVC) membrane ion-selective optode containing a lipophilic pH indicator dye and an ionophore, and a dissolvable poly(ethylene glycol) (PEG) membrane containing an enzyme is developed. The method involves the sequential introduction of membrane cocktail solution followed by air introduction. Repeating this process allowed facile preparation of a capillary biosensor comprised of two layer structure, which can be used for single-step biosensing just by sipping the sample with capillary action. Here a urea biosensor was prepared as a proof-of-concept.

Advancements in Capillary-Assembled Microchip (CAs-CHIP) Development for Multiple Analyte Sensing and Microchip Electrophoresis

“…4). 39 Further development of additional ion-sensing capillaries based on the same mechanism have been characterized, and multiple ion sensing on a single microchip has been demonstrated. 38 The hydrophobic nature of the ionselective optode membrane, however, could limit the application of the simple "drop-and-sip" fluid handling technique, which requires introduction of sample solutions into the capillary via capillary action.…”

“…This capillary is stable for at least 15 days when stored at temperatures of about -18 C. 41 The combination of an ionselective optode membrane and an ERC has been explored for urea analysis, according to the sensing mechanism as described in the previous section of this review. 39 Most recently, we have successfully analyzed both glucose and cholesterol in serum samples by using the ERC technology. 42 Furthermore, an electrochemical detection system embedded into the CAs-CHIP system has been demonstrated for glucose analysis.…”

Fabrication and packaging of a mass-producible capillary-assembled microchip for simple and multiplexed bioassay

“…We have developed various glass capillary biosensors to be integrated into CAs-CHIP, to measure various analytes such as proteins [25][26][27][28], ions [29,30], enzymes [30,31], and metabolites [32,33] Among many capillary biosensors developed, dry reagentrelease capillary (dRRC) which allows spontaneous dissolution of analytical reagents and selective reaction to give fluorescence response by sample introduction via capillary action, played an important role for the simplicity in capillary biosensor preparation and biosensing [30]. However, both the first (CAs-CHIP-1G) [23,30,31] and second (CAs-CHIIP-2G) [35] generations of CAs-CHIP requires the meticulous one-by-one capillary embedding onto a PDMS microchannel.…”

Enzyme-responsive Fluorescent Ionic Liquid

“…The response mechanism of an optode is based on the ion extraction equilibrium of an analyte between the organic phase (membrane) and the aqueous phase (sample solutions). [1][2][3] We have investigated the application of the functional PVC membrane to capillary-based micro-analytical devices that include ion sensing, 4,5 enzyme biosensing, 6 and enzyme immunoassay (EIA). 7 Among these, a plasticized PVC membrane containing a fluorescent alkaline phosphatase (ALP) substrate facilitated single-step EIA by using a water-soluble membrane containing enzyme-labeled antibodies and a hydrogel membrane possessing the molecular sieving function.…”