Layered Double Hydroxides/Trypsin Based Conductometric Biosensors

The work presented here deals with the encapsulation of trypsin in bidimensional Lamellar Double Hydroxides (LDH) (M2Al)-Al-II(OH)6Cl center dot nH(2)O (M-II = Zn and Mg abbreviated M2Al-Cl) through coprecipitation and adsorption methods. Nanomaterials were deposited on interdigital electrodes for further polypeptide biosensor development. Due to the more basic surface of the Mg2Al-Cl phase, its affinity of retention of trypsin is higher compared to that of Zn2Al-Cl phase, respectively 44% of immobilisation rate for Mg2Al-Cl and 15% for Zn2Al-Cl. The amount of trypsin on the Zn-2-Al-Cl/LDH is more important for the coprecipitation methods than for adsorption reaction. Trypsin immobilized onto Zn2Al-Cl phases retained 70% and 40% of its initial activity by adsorption and coprecipitation method respectively. The LDH-Trypsin biosensors display a decrease in sensibility S = 1.68 mu S/mM for Zn2Al-Tryp cop (Q = 1.0) compared to Trypsin Biosensor (S = 8.10 mu S/mM), however the calibration linearity range is extended up to 6 mM against 3-5 mM respectively. The stability of Zn-2-Al-Cl/Tryp cop (0 = 1.0) biosensor is remarkable, more than 60 days.