Nanocomposites of nanocrystalline cellulose for enzyme immobilization

We describe the synthesis, characterization and use of a composite material made of a renewable source and metallic nanoparticles for biosensing applications. Nanocrystalline cellulose (NCC) is a product isolated from natural cellulose fibers, which is of approximately 100 nm long and 10 nm wide in size. We augmented the surface area and tailored the chemical affinity of NCC by optimally dressing it with gold nanoparticles (AuNPs). The deposition of AuNPs on NCC was controlled by using cationic polyethylenimine (PEI) at different pHs. AuNPs were thiol-functionalized using different linkers prior to enzyme immobilization. The enzyme (glucose oxidase or GOx) was conjugated on the composite by carbodiimide coupling, and subsequent activation of linker-carboxylic acid group. Our results showed that GOx was attached to the surface of the NCC nanocomposite. Moreover, the amount of GOx loaded onto the support depended on the length of the thiol-linker used. The lower value (20.3 mg/mg of support) was obtained with the longer thiol-linker (11 carbon chain) compared to 25.2 mg/mg of support for the smaller thiol-linker (3 carbon chain).