A transmission electron microscopy (TEM) grid filled with 4-cyno-4-pentylbiphenyl (5CB) on the octadecyltrichloro silane-coated glass in an aqueous medium was developed to construct a urea biosensor by coating poly(acrylicacid-b-4-cynobiphenyl-4-oxyundecylacrylate) (PAA-b-LCP) at the aqueous/5CB interface and immobilizing urease covalently to the PAA chains. The urea was detected from a planar to homeotropic (P-H) orientational transition of 5CB by polarized optical microscopy under crossed polarizers. This TEM grid sensor with the maximum immobilization density of urease, 0.17 molecules/nm2 enabled the detection of urea at concentrations as low as 5 mM by a P-H change with a half time of full P-H change of 250 seconds. This TEM grid sensor could detect urea in blood without inference of hemoglobin and ascorbic acid. This new and sensitive urea biosensor has the merits of low production cost and easy detection through the naked eye, and might be useful for screening the urea level in the human body.

Real-time liquid crystal-based biosensor for urea detection

248th National Meeting (2014)

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