Theoretical Analysis of the Performance of Glucose Sensors with Layer-by-Layer Assembled Outer Membranes

Sensors

Robert A. Croce³  Santhisagar Vaddiraju¹  Fotios Papadimitrakopoulos² 

[1] Biorasis Inc., Technology Incubation Program, University of Connecticut, Storrs, CT 06269, USA;Nanomaterials Optoelectronics Laboratory, Polymer Program, Institute of Materials Science, University of Connecticut, Storrs, CT 06269, USA; E-Mails:;Electrical and Computer Engineering, University of Connecticut, 371 Fairfield Way, Storrs, CT 06269, USA; E-Mail:

关键词: amperometric glucose sensors;    mathematical modeling;    biosensors;    Michaelis-Menten constant;    enzyme kinetics;    layer-by-layer assembly;    polymer chemistry;    finite difference schemes;    differential equations;    analyte diffusion;   

DOI  :  10.3390/s121013402

来源: mdpi

【 摘 要 】

The performance of implantable electrochemical glucose sensors is highly dependent on the flux-limiting (glucose, H₂O₂, O₂) properties of their outer membranes. A careful understanding of the diffusion profiles of the participating species throughout the sensor architecture (enzyme and membrane layer) plays a crucial role in designing a robust sensor for both in vitro and in vivo operation. This paper reports the results from the mathematical modeling of Clark's first generation amperometric glucose sensor coated with layer-by-layer assembled outer membranes in order to obtain and compare the diffusion profiles of various participating species and their effect on sensor performance. Devices coated with highly glucose permeable (HAs/Fe³⁺) membranes were compared with devices coated with PSS/PDDA membranes, which have an order of magnitude lower permeability. The simulation showed that the low glucose permeable membrane (PSS/PDDA) sensors exhibited a 27% higher amperometric response than the high glucose permeable (HAs/Fe³⁺) sensors. Upon closer inspection of H₂O₂ diffusion profiles, this non-typical higher response from PSS/PDDA is not due to either a larger glucose flux or comparatively larger O₂ concentrations within the sensor geometry, but rather is attributed to a 48% higher H₂O₂ concentration in the glucose oxidase enzyme layer of PSS/PDDA coated sensors as compared to HAs/Fe³⁺ coated ones. These simulated results corroborate our experimental findings reported previously. The high concentration of H₂O₂ in the PSS/PDDA coated sensors is due to the low permeability of H₂O₂ through the PSS/PDDA membrane, which also led to an undesired increase in sensor response time. Additionally, it was found that this phenomenon occurs for all enzyme thicknesses investigated (15, 20 and 25 nm), signifying the need for a holistic approach in designing outer membranes for amperometric biosensors.

【 授权许可】

CC BY   
© 2012 by the authors; licensee MDPI, Basel, Switzerland.