Multifunctional cellulose based substrates for SERS smart sensing: Principles, applications and emerging trends for food safety detection

Food safety issues leading to severe healthy, economic and even social problems and detection of food contaminants has been attracting remarkable attention in recent decades. Surface-enhanced Raman scattering (SERS) is one of the most promising techniques to enable detecting contaminants at trace levels. Besides, with the emergence of global resource shortages and environmental problems, there is a growing demand for environmentally friendly and renewable resources. As a sustainable and biodegradable raw material, cellulose has aroused great interest and stimulated researchers to develop cellulose-based SERS substrates with novel functions. The review focuses on the utilizing of cellulosic materials for the design and preparation of various SERS substrates, including cellulose-papers, cellulose fabrics (CFs) and membranes, cellulose nanofibrils (CNFs), bacterial cellulose (BC), nanocrystalline cellulose (NCC), and surface-modified cellulose. The applications, challenges and potential solutions of these cellulose-based substrates in food safety detection are also presented, proposed and evaluated. For the complexity and diversity of multitudinous food systems, multiple approaches have been successfully employed to manufacture cellulose-based SERS substrates. Various types of cellulose with diverse morphology and mechanical properties make them customizable and integratable with multiple technologies in certain realistic applications. The explorations of SERS detections displaying excellent performances especially for the complex system/surface analysis with the capability of extraction, swabbing, transferring and concentrating target molecules from complexing food systems. The widespread application and prominent performance demonstrating the huge potential for cellulose-based materials to realize commercially viable, sustainable, flexible and green substrates in the near future.