A review of cellulose-based substrates for SERS: fundamentals, design principles, applications

Surface enhanced Raman spectroscopy (SERS) provides a useful sensory platform whereby target molecules at low concentration are identified, potentially detecting a single molecule. As a result, SERS has been widely applied in a variety of research endeavors using different substrates, one of which is a cellulose-based substrate. The unique properties of cellulose in its various forms make it an important component in the design of a SERS substrate. Being a flexible substrate with minimal SERS signal interference, paper-based cellulose templates are the most extensively explored form of cellulose in SERS substrate design, with innovative designs and applications. This review provides an overview of the fundamental tools of SERS enhancement, followed by a comprehensive appraisal of the various design principles associated with producing cellulose-based materials and their use as SERS substrates. Though cellulose in its various forms cannot provide the localized surface plasmon resonance required in SERS, it aids in aggregation and stabilization of plasmonic nanoparticles leading to “hot spots” for SERS signal enhancement. The unconventional techniques adopted in the designs are examined and the associated challenges are highlighted. The review demonstrates SERS applications of the substrates in diverse technologies such as bioanalysis, water quality assessment, food safety, adulteration of illicit drugs and dye identification in artworks. Ultimately, we envisage the need for a universal set standard to realize the ideal of designing SERS substrates from the perspective of end-user demand. This can be achieved through a re-evaluation of existing findings on cellulose-based SERS substrates.