Zinc oxide (ZnO) thin films deposited onto indium tin oxide (ITO) coated corning glass substrates using pulsed laser deposition (PLD) technique at two different oxygen pressures (50 mT and 100 mT) have been used as efficient matrix for realization of efficient urea biosensors after immobilization of urease (Urs) enzyme onto ZnO film surface. The bioelectrode Urs/ZnO/ITO/glass having ZnO matrix grown at 100 mT is found to be exhibiting an enhanced sensitivity of 36 μΑ mΜ−1 cm−2 for urea over a wide detection range of 5–200 mg/dl. The relatively low value of Michaelis–Menten constant (Km = 0.82 mM) indicates high affinity of the immobilized urease towards the analyte (urea). The prepared sensor exhibits high selectivity towards detection of urea and retains 90% of its activity for more than 12 weeks. The observed enhanced response characteristics of bioelectrode is attributed to the growth of highly c-axis oriented ZnO thin film by PLD at 100 mT oxygen pressure with desired rough and porous surface morphology besides high electron communication feature. The results confirm the promising application of PLD grown ZnO thin film as an efficient matrix for urea detection.

In this work, an artificial lipid membrane was synthesized using tetra-dodecyl ammonium bromide (TDAB) and doped with gold nanoparticles (AuNP). The taste sensor designed using artificial lipid membrane is composed of tetradodecylammonium bromide (TDAB) as a lipid, dioctylphenyl phosphonate (DOPP) as a plasticizer, and polyvinyl chloride (PVC) as a supporting polymer in the ratio of 1:3:2. The lipid/polymer membrane acts as the recognition element which transforms the taste information generated by the chemical substances into an electric potential change. The fundamental taste analytes (like fructose for sweetness, HCl for sourness, NaCl for saltiness, MgCl2 for bitterness and MSG for umami) were used to study the effect of doping on taste sensing at different concentrations (10μM to 10mM). The study was based on the open circuit potential (OCP) change of the membrane with the analytes. The observations implicate that the doping increases the specificity of the artificially synthesized lipid membrane taste sensor for the sweet analytes, particularly for fructose.

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