A hydrogel-based sensor for screening protease specificity has been developed by scientists in the UK.

Simon Webb and colleagues from the University of Manchester have, for the first time, combined solid-phase synthesis (SPS) and liquid crystal display (LCD) technology, to develop a simple and cheap sensor system for protease activity.

Proteases have a huge medical and commercial importance and so versatile screening and detection methods are therefore in demand. There is a need for low-cost, portable sensors that will allow the detection of proteases using the naked eye, without requiring specialist equipment.

Webb's system uses a polyethylene glycol acrylamide (PEGA) hydrogel as the SPS support, which is compatible in both organic and aqueous solvents. The SPS support is functionalised with Fmoc-protected peptides, which can only be cleaved from the hydrogel SPS support by specific proteases. Successful peptide cleavage is shown by the LCD as a visible, light-to-dark, response.

Webb and co-workers have shown that by careful design and synthesis of the peptide sequences on the SPS surface, they can generate a light-to-dark response on the LCD for three common proteases; trypsin, elastase and thermolysin. The ultimate goal for this work would be to develop this sensor to detect proteases in the disease state.

'We hope that our proof-of-principle studies will encourage the expansion and development of LCD technology in biosensors. We will build upon these studies on model proteases and develop our methodology further to detect physiological concentrations of medically relevant proteases, such as viral proteases like HIV protease,' explained Webb.

Emma Shiells