Reversible sol-gel-sol medium for enzymatic optical biosensors

In this paper we for the first time report a reversible sol-gel-sol approach to obtain optical enzymatic biosensors with improved enzyme stability and good sensitivity by using desktop inkjet printing. The developed technique is based on the bio-inorganic inks allowing for a sol-gel-sol transition of the inorganic matrix: from liquid ink to a solid alumina matrix with entrapped enzymes and a subsequent color response due to the enzymatic reaction upon the resuspension of the matrix. This approach improves the stability of the enzymes entrapped in the porous inorganic matrix, and at the same time maintains a high sensitivity of the biomolecules, whose facile release is ensured by the gel-sol transition. Rheological parameters of the developed bio-inorganic ink are highly adjustable making it suitable for the deposition on different surfaces by inkjet printing. The potential and utility of this approach is demonstrated by a successful production of optical biosensors for glucose and uric acid.