The Effect of Silk on the Stabilization of Labile Enzyme Lipoxygenase

Enzymes, as biological catalysts, are widely used for their excellent selectivity and sensitivity, playing a crucial role in biosensors, offering significant potential for monitoring food products and health conditions. However, enzyme activity can be compromised by environmental factors like high humidity, pH, and temperature variations. This study explores the feasibility of improving the stability of the unstable enzyme lipoxygenase (LOX) through immobilization using silk, a naturally occurring fibrous protein. A linoleic acid biosensor is designed by combining silk‐entrapped LOX with poly(3,4‐ethyloxy thiophene):poly(styrene sulfonate) (PEDOT:PSS) and horseradish peroxidase (HRP). The findings demonstrate that immobilizing LOX with different molecular weight silks extends the shelf‐life of the freeze‐dried PEDOT:PSS/HRP/LOX more than tenfold, from less than 1 day to 10 days. The results of the characterization tests (e.g., Fourier transform infrared spectroscopy, rheology) highlighted the interdependency between silk properties, such as its molecular weight, the silk conformation, and the pore shape and size, and enzyme stability. Low molecular weight silk resulted in the best performance, enabling storage at room temperature. It can therefore be concluded that immobilization with silk is an efficient method to enhance the shelf‐life of enzyme‐based biosensors, for diagnostic and other applications.