Halloysite nanotubes as nano-support matrix to tailor cellulase and acetylcholinesterase-based ‘nano-biocatalysts’ for waste degradation and electrochemical sensing

Enzyme immobilization has always remained in huge demand because of industrial appeal of enzymes, and their ability to be reused several times. Therefore, in present study, 3-aminopropyltriethoxysilane (APTES) grafted halloysite nanotubes (f-Hal), were utilized to develop nano-biocatalysts using enzymes, viz. cellulase (Cel) and acetylcholinesterase (AChE). During immobilization studies, it was found that in comparison to Hal, f-HAL had better loading% for Cel (72.27 ± 0.21%) and AChE (97.34 ± 0.16%). Properties of the nano-biocatalysts, viz. Cel@f-Hal and AChE@f-Hal were studied using advanced characterization tools. During stability studies, it was found that f-Hal provided better resistance to enzymes against variations in pH, temperature and storage time (up to 20 days). Nano-biocatalysts also exhibited excellent reusability for up to 5 cycles. Cel@f-Hal was further used for degrading cellulose wastes such as bagasse, bamboo leaf, blotting paper, orange peel and wheat bran; where orange peel showed maximum saccharification. AChE@f-Hal was used for the electrochemical sensing of malathion (R ² = 0.99). The biosensor had LOD and LOQ of 3.35 and 10.14 mM for AtChI with a sensitivity of 0.1786 mA mM ⁻¹ cm ⁻². These research findings reveal that nano-biocatalysts developed here have real-time applications and can be effectively used in environmental industry.