Strategies, challenges and opportunities of enzyme immobilization on porous silicon for biosensing applications

The use of porous silicon (PS) for biosensing applications is now emerging as it offers desired properties such as better surface-volume ratio, tunable pore size, ease of fabrication, and compatibility with the current silicon-based technology. These superior properties make PS as a promising candidate for the immobilization of biomolecules with higher retention, stability, storage, and operational ease. High specificity and catalytic activity of the enzyme for the substrate are advantageous for the detection of a particular analyte with higher accuracy in less time. Immobilization of enzyme on the PS surface alters the surface electrical and optical properties, and can conveniently be used for the sample analysis. In the present review, the strategies of enzyme immobilization on PS and various influencing factors are discussed in detail. The scope of PS for enzyme immobilization and prerequisite surface modifications has been assessed in brief. The review discusses the various methods of enzyme immobilization on PS with their benefits and bottlenecks with special emphasis on the approaches to overcome the difficulties during the immobilization process. Further, various properties of PS influencing the process of immobilization have been outlined in brief. An overall analysis of enzyme immobilization on PS surface has been given for the successful development of PS based enzymatic biosensors.