Colourimetric detection of triglycerides using porcine pancreatic lipase immobilized nanocomposite biosensor

Polymeric nanoconjugates have shown great potential in the adaptability and acceptability of nanofillers. They combine nano and micrometric matter characters with advanced applications across diverse fields. One such polymeric nanocomposite material chitosan is readily available, costs less and is biodegradable. In this study, we analysed eight different nanoconjugates, formed by immobilisation of porcine pancreatic lipase (PPL) onto chitosan-nanocomposites fabricated based on different combinations using graphene oxide, cupric oxide and magnetite with chitosan, coupled with a chromophore for their application as a colourimetric biosensor to detect triglyceride (TG) contaminants. The (10 mg/mL) lipase immobilized magnetic graphene oxide–cupric oxide biosensor exhibited exemplary colourimetric biosensor properties, showing a response time of 6 to 7 min and compatibility with a sample pH range of 6 to 9 with a local working temperature of 25 to 55°C. The biosensor tolerates up to 500 times the BIS standard for Fe contamination in water. The detectable TG contamination in the sample ranges between 1 and 500 μg/mL, where the least and the highest detectable sample quantity were 5 and 250 μg/mL, respectively. The biosensor showed a relative standard deviation (RSD) value of 0.0089% with a limit of detection (LOD) at 0.2 μg/mL and a sensitivity of 6.01/U/μg/cm². The biosensor showed overall stability for 5 days when stored at 37°C, while it retained 70% of its original activity for 7 days and 50% for more than 10 days when stored under cold conditions.