Bi-enzyme functionalized electro-chemically reduced transparent graphene oxide platform for triglyceride detection

Biomater Sci. 2019 Mar 26;7(4):1598-1606. doi: 10.1039/c8bm01406j.

Abstract

Recently, increased attention has been drawn to application of graphene and its derivatives for construction of biosensors, since they can be used to rapidly detect the presence of bio-analytes. Present paper establishes the preparation of a unique transducer which relies on toluidine blue (TB), absorbed by electrochemically reduced graphene oxide (ERGO) transparent thin film onto the surface of the indium tin-oxide (ITO) glass electrode. The proposed TB/ERGO/ITO electrode shows excellent reversible electro-chemical properties. The novel platform has been explored to fabricate a triglyceride (TG) biosensor via co-immobilizing of lipase (LIP) and glycerol dehydrogenase (GDH) onto TB/ERGO/ITO electrode surface. The fabricated bioelectrode (LIP-GDH/TB/ERGO/ITO) directly oxidizes glycerol (produced by catalytic hydrolysis of tributyrin acting as a model TG) in the presence of GDH. The developed bioelectrode replaces unstable biological irreversible redox mediators NAD+/NADH, involved in the triglyceride breakdown reaction. NADH causes fouling on the bioelectrode surface in bi-enzymatic estimation of TG and reduces the shelf-life of biosensor. Electrochemical response studies carried out using cyclic voltammetry reveal that the fabricated electrode can detect tributyrin in the range of 50-400 mg dL-1 with high sensitivity of 29 pA mg-1 dL, low response time of 12 s, long-term stability and a low apparent Michaelis-Menten constant (Kappm) of 0.18 mM, indicating high enzyme affinity of LIP-GDH/TB/ERGO/ITO bioelectrode towards tributyrin. Furthermore, this modified bioelectrode has been explored for estimation of TG with negligible interference in human serum samples. The proposed bi-enzymatic bioelectrode for TG analysis offers an efficient and novel interface for application of graphene and its derivatives in the field of bioelectronic devices.

MeSH terms

  • Biosensing Techniques*
  • Electrochemical Techniques*
  • Electrodes
  • Graphite / chemistry*
  • Graphite / metabolism
  • Humans
  • Lipase / chemistry
  • Lipase / metabolism*
  • Oxidation-Reduction
  • Particle Size
  • Sugar Alcohol Dehydrogenases / chemistry
  • Sugar Alcohol Dehydrogenases / metabolism*
  • Surface Properties
  • Tin Compounds / chemistry
  • Tin Compounds / metabolism
  • Tolonium Chloride / chemistry
  • Tolonium Chloride / metabolism
  • Triglycerides / analysis*
  • Triglycerides / metabolism

Substances

  • Tin Compounds
  • Triglycerides
  • graphene oxide
  • Tolonium Chloride
  • indium tin oxide
  • Graphite
  • Sugar Alcohol Dehydrogenases
  • glycerol dehydrogenase
  • Lipase