Supramolecular Approach to Enzyme Sensing on Paper Discs Using Lanthanide Photoluminescence

A paper based photoluminescent biosensor has been developed, with green Tb-luminescence as the output, for the rapid detection of beta-glucosidase and lipase, both in purified form and in biological/natural fluids. A Tb Cholate hydrogel doped with specially designed, specific enzyme substrates (''pro''-sensitizers) was integrated on filter paper discs. The addition of small volumes(similar to 5 mu L) of enzyme solutions on these discs led to enhanced green emission (UV lamp, lambda(ex) 365 nm), allowing qualitative detection of the enzymes-when needed, the intensity enhancement can be quantified using image processing software, or for multiple samples using a commercial plate reader. This simple technique allowed the detection of beta-glucosidase in almond extract and lipase in blood serum. Easy identification of the inhibition of beta-glucosidase was also demonstrated. The paper based sensor is inexpensive, user-friendly and needs low volumes of biological sample for analysis. This strategy has the potential to be useful for possible clinical applications