Carbon nanohorn modified platinum electrodes for improved immobilisation of enzyme in the design of glutamate biosensors

• Published in: Analyst (London) Vol. 144; no. 17; pp. 5299 - 537
• Main Authors: Ford, Rochelle, Devereux, Stephen. J, Quinn, Susan. J, O'Neill, Robert. D
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 16.08.2019
• Subjects: Amino Acid Oxidoreductases - chemistry; Biocompatibility; Biosensing Techniques - methods; Biosensors; Brain; Carbon; Carbon - chemistry; Design; Design modifications; Electrical measurement; Electrochemical Techniques - instrumentation; Electrochemical Techniques - methods; Electrodes; Enzymes; Enzymes, Immobilized - chemistry; Glutamic Acid - analysis; Glutamic Acid - chemistry; Hybrid systems; Hydrogen peroxide; Hydrogen Peroxide - chemistry; Immobilization; Limit of Detection; Nanostructures - chemistry; Neurotransmitters; Oxidation; Oxidation-Reduction; Platinum; Platinum - chemistry; Polyethyleneimine; Polyethyleneimine - chemistry; Response time; Sensitivity
• ISSN: 0003-2654; 1364-5528
• DOI: 10.1039/c9an01085h

Electrochemical enzymatic biosensors are the subject of research due to their potential for in vivo monitoring of glutamate, which is a key neurotransmitter whose concentration is related to healthy brain function. This study reports the use of biocompatible oxidised carbon nanohorns ( o-CNH ) with a high surface area, to enhance the immobilization of glutamate oxidase (GluOx) for improved biosensor performance. Two families of biosensors were designed to interact with the anionic GluOx. Family-1 consists of covalently functionalised o-CNH possessing hydrazide (HYZ) and amine (PEG-NH 2 ) terminated surfaces and Family-2 comprised non-covalently functionalised o-CNH with different loadings of polyethyleneimine (PEI) to form a cationic hybrid. Amperometric detection of H 2 O 2 formed by enzymatic oxidation of glutamate revealed a good performance from all designs with the most improved performance by the PEI hybrid systems. The best response was from a o-CNH  : PEI ratio of 1 : 10 mg mL −1 , which yielded a glutamate calibration plateau, J MAX , of 55 ± 9 μA cm −2 and sensitivity of 111 ± 34 μA mM −1 cm −2 . The low K M of 0.31 ± 0.05 mM indicated the retention of the enzyme function, and a limit of detection of 0.02 ± 0.004 μM and a response time of 0.88 ± 0.13 s was determined. The results demonstrate the high sensitivity of these biosensors and their potential for future use for the detection of glutamate in vivo . This work reports the use of biocompatible carbon nanohorns, with a high surface area, to enhance the immobilization of glutamate oxidase for improved biosensor performance.