Fabrication of alkaline phosphatase biosensor for Hg2+ determination

A colorimetric biosensor using immobilised alkaline phosphatase (AP) to detect Hg²⁺ was developed. Copolymer poly(2-hydroxyethyl methacrylate-co-butyl acrylate) (poly(HEMA-co-BA)) were use as matrix to entrap AP. It was discovered that incubation time was needed before the mixture of HEMA/BA and AP (in Tis-HCl) undergo UV-initiated photopolymerisation due to hydrophilic and hydrophobic characteristic of monomer HEMA and nBA, respectively. Sensors HB91-AP, HB82-AP and HB73-AP showed a similar optimum pH at pH 8.5. Quantitative determination of Hg²⁺ using sensor, generate a linear response range from 1 - 5 mM Hg²⁺(R² = 0.9247).