Preparation of Nanosensors for Detecting the Activity of Glycosaminoglycan Cleaving Enzymes.

Glycosaminoglycans (GAGs) play crucial roles in several biological processes including cell division, angiogenesis, anticoagulation, neurogenesis, axon guidance and growth, and viral and bacterial infections among others. The GAG cleaving hydrolases/lyases play a major role in the control of GAG structures, functions, and turn over. Dysregulation of GAG cleaving enzymes in vivo are linked to a number of human diseases including cancer, diabetes, atherosclerosis, arthritis, inflammation, and cardiovascular diseases. Several GAG cleaving enzymes are widely used for studying GAG glycobiology: heparitinases, chondroitinases, heparanases, hyaluronidases, and keratanases. Herein, we describe a method to synthesize four distinct nanometal surface energy transfer (NSET)-based gold-GAG-dye conjugates (nanosensors). Heparin, chondroitin sulfate, heparan sulfate, and hyaluronic acid are covalently linked with distinct fluorescent dyes and then immobilized on gold nanoparticles (AuNPs) to build nanosensors that serve as excellent substrates for GAG cleaving enzymes. Upon treatment of nanosensors with their respective GAG cleaving enzymes, dye-labeled oligosaccharides/disaccharides are released from AuNPs resulting in enhanced fluorescence recovery. These nanosensors have a great promise as diagnostic tools in various human pathophysiological conditions for detecting dysregulated expression of GAG cleaving enzymes and also as a sensitive analytical tool for assessing the quality control of pharmaceutical grade heparin polysaccharides that are produced in millions of small- and medium-sized animal slaughter houses worldwide.