Sunlight-induced covalent immobilization of proteins

Horseradish peroxidase (HRP) and glucose oxidase (GOD) were immobilized by sunlight onto the photoreactive cellulose membrane prepared by the reaction of cellulose membrane with 1-fluoro-2-nitro-4-azidobenzene (FNAB). A correlation between sunlight intensity and immobilization was studied. Sunlight intensity required for optimum immobilization was found to be 21,625 lux beyond which no appreciable increase in immobilization was observed. Around 2.5-fold increase in absorbance value was observed when HRP immobilization was carried out by sunlight than in dark or on untreated surface. Sunlight exposure gave better immobilization compared to 365 nm UV light. Thus, sunlight could be used as a potential alternative to UV light for immobilization of biomolecules such as carbohydrate, DNA or protein.