Sol-gel encapsulated enzyme arrays for high-throughput screening of biocatalytic activity

We developed versatile low-cost arrays of sol-gel-encapsulated enzymes (referred to as solzymes) suitable for repeated assays of bioactivity or enzyme inhibition. Sol-gel microstructures containing active enzymes were stabilized on glass at moderate pH and room temperature without harsh calcination. A multi-well bilayer of polydimethylsiloxane was used to support the solzyme array and contain the reaction medium. Each of the 147 microwells has a working volume of 5 muL and contains 50 mug of immobilized enzyme. The solzyme arrays maintained high activity through repeated applications and exhibited superior thermostability compared to soluble enzymes. Among the enzymes used were lipases, glucose oxidase, and horseradish peroxidase. Twenty different lipases and proteases were also used to prepare a hydrolase array, for which bromthymol blue served as a generic indicator of activity. The relative activities of the encapsulated hydrolases correlated closely with those of the soluble hydrolases, illustrating that sol-gel encapsulation preserved the hierarchy of enzyme activity. The development of solzyme arrays paves the way to higher throughput screening of diverse proteins and enzymes, including those that are available only in trace amounts. (C) 2002 Wiley Periodicals, Inc.