Mazhar-ul-Haque, ZA Ansari, SG Ansari
Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, India 110025, India.
The demand for fast, inexpensive and reliable methods to detect very low concentration of various analytes in clinical, industrial and environmental areas are increasing every day. During the last few decades, development of enzyme based biosensors different techniques has been a topic of considerable interest due to their potential applications with intrinsic selectivity to enzymatic reactions, reliability and possibility of commercialization. Amongst different bio-analytes, urea ((NH 2 ) 2 CO) is basically an organic compound of carbon, nitrogen, hydrogen and oxygen; is one of the important analyte to be analyzed and controlled as most organisms’ deal with the excretion of nitrogen waste originating from protein and amino acid catabolism in the form of urea or uric acid. The normal level of urea in serum is 3 mM to 7 mM (15 to 40 mg/dl). In patients suffering from the renal insufficiency, urea concentration present in the serum is raised from 30 mM to 80 mM (180 to 480 mg/dl) and if the level is raised above 180 mg/dl, hemodialysis is required. Therefore, urea analysis is of considerable importance. Here we present urea sensing properties of Cu-doped titanate nanostructure. Cu-doped nanomaterial was prepared using hydrothermal method at 150°C for 48 hours followed by calcination at 350°C. From the morphological study, we learnt that during hydrothermal process, spherical particles are transformed to the mixed structure of particles and flakes. Thick films were deposited using screen printing technique on electropolished aluminum substrates. Urease; used as receptor for urea; was immobilized on the films by soaking in urease solution for 5 h which is covalently attached on the surface of films. Urease immobilization was confirmed from IR spectroscopy analysis of the films with few additional peaks. The conductivity of the urease-immobilized films was recorded in buffer and different urea concentration. In general, conductivity of film increased after urease immobilization as observed in the buffer solution and the conduction linearly increases over the wide range of urea concentration i.e. 1mM to 500 mM, as shown in the graph. Read more…