if you are using glass substrate, the most usual immobilization method will be to do silanization. You can use silane which has amino functional group, e.g. aminopropyltriethoxysilane (APTS) that can bind by replacing some amino functional group in the enzyme.

For reference, please have a look at this book:

T. Cass and F.S. Ligler (eds.), "Immobilized Biomolecules in Analysis", Oxford University Press.1998 (or newer edition).

If your are planning to use reflective-mode optical sensing, e.g. colorimetric, then other types substrates may be considered, and various other immobilization techniques may be explored.

Dear Prof. Dedy,

Thank you very much for your nice answer and valuable reference. I'll go through this. Thank you once again as you always support me for knowledge sharing. I remember, previously, you gave me one of your paper which was so interesting. I hope to continue this bridge.

Have a nice time.

Dear Christina,

Thank you very much for your nice idea. It seems to be very interesting. I'll go through your reference. Actually, I don't want to lose any property of enzyme and want to accumulate as many molecules as possible in the reaction area. Some groups have tried with APTES with coating buffer. But, sometimes, it is tricky. Anyway, I hope to find fruitful solution from your reference. If I have any query, I'll ask you.

Wish you nice time.

Regards