Development of amperometric biosensor in modified carbon paste with enzymatic preparation based on lactase immobilized on carbon nanotubes

• Published in: Journal of food science and technology 2020-04, Vol.57 (4), p.1342-1350
• Main Authors: de Brito, Aila Riany, dos Santos Reis, Nadabe, Oliveira, Polyany Cabral, Rezende, Denilde Vilas Bôas, Monteiro, Gabriel Pereira, Soares, Glêydison Amarante, de Jesus, Rodrigo Sá, Santos, Antônio Santana, Salay, Luiz Carlos, de Oliveira, Julieta Rangel, Franco, Marcelo
• Format: Article
• Language: English
• Subjects: Amperometry; Biosensors; Carbon; Carbon nanotubes; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Detection limits; Electrical measurement; Electrochemical cells; Electrochemistry; Electrodes; Electron microscopy; Electrons; Food Science; Lactase; Lactose; Microscopy; Milk; Morphology; Nanotechnology; Nanotubes; Nutrition; Original; Original Article; Platinum; Quality control; Scanning electron microscopy; Silver chloride; Transmission electron microscopy
• ISSN: 0022-1155; 0975-8402
• DOI: 10.1007/s13197-019-04168-9

The variety of products derived from milk, without or with lactose, encourages the development of more effective analytical techniques that can be applied to the quality control of both the production line and the final products. Thus, in this work an efficient and minimally invasive method for the detection of lactose was proposed, using a biosensor containing the enzyme lactase (LAC) immobilised on carbon nanotubes (CNTs) that, when reacting with lactose, emit an electrochemical signal. This biosensor was connected to a potentiostat, and its electrochemical cell was composed of the following three electrodes: reference electrode (Ag/AgCl), auxiliary electrode (platinum wire), and working electrode (biosensor) on which graphite (carbon) paste (CP), CNTs, and LAC were deposited. The transmission electron microscopy and scanning electron microscopy were used in the characterisation of the composite morphology, indicating excellent interactions between the CNTs and LAC. The sensitivity of the CP/LAC/CNT biosensor was determined as 5.67 μA cm −2 .mmol −1  L and detection limits around 100 × 10 −6  mol L −1 (electrode area = 0.12 cm 2 ) and an increase in the stability of the system was observed with the introduction of CNTs because, with about 12 h of use, there was no variation in the signal (current). The results indicate that the association between the CNTs and LAC favoured the electrochemical system. Graphic Abstract