Comparative study between organic and inorganic entrapment matrices for urease biosensor development

An essential step in biosensors development is the bonding of the biological components to the transduction element. Here, we present some matrices used as support materials for urease immobilization based on organic and inorganic matrices including in many cases glutaraldehyde as cross-linking agent. Organic matrices were designed through the use of four latex polymers; neutral hydroxy polymer, three polycationic derivatives polynorbornene with different non-cytotoxic counter ions and a biopolymer obtained under chemical oxidation step of biotinylated pyrrole monomers. Inorganic matrices were based on Zn–Al layered double hydroxide nanohybrid materials (LDH). UV–vis and permeability techniques were carried out, respectively, in order to control the immobilized urease activity and to determine the permeability of the various biomembranes. All these support matrices containing urease biomolecules were deposited on insulator semiconductor (IS) transducers for further urea biosensors development. Biochemical responses of these modified IS electrodes to urea addition were examined using the electrochemical capacity-potential measurements C(V). Developed urea electrodes exhibit a linear response in the range from 10−4 to 10−1 M. For all matrices the Michaelis–Menten constant, Km (0.67 ≤ Km (mM) ≤ 5) was obtained from the Lineweaver–Burk representation and was compared with values obtained using other immobilization strategies.