Polyethyleneglycol diacrylate microspheres: a novel carrier for laccase immobilisation

Laccase was immobilised on polyethyleneglycol diacrylate (PEGDA) microspheres. The optimal preparation conditions of PEGDA microspheres were as follows: 3.0% (w/v) 2,2-azobisisobutyro-nitrite (AIBN), 4.0-5.0% (w/v) polyvinylpyrrolidone (PVP), 5.0-8.0% (w/v) glucose and 4.0% (w/v) PEGDA in glucose solution. The volume ratio of PEGDA solution, glucose/PVP solution and AIBN solution was 25: 100: 1. Microspheres obtained exhibited good characteristics with small sizes (1-4 µm). The immobilised laccase showed a higher stability in a wide pH range. Thermal stability and storage stability of immobilised laccase were enhanced. The activity of immobilised laccase was 45.0% after six cycles uses. Only 62.7% of the activity remained for free laccase while there was a 60.4% increased for immobilised laccase with storage at 4 °C for 25 d. The Km value of laccase increased from 21.9 to 114.0 µmol/l after immobilisation.