Layer-by-layer assembled semipermeable membrane for amperometric glucose sensors.

Area of Science:

• Biomedical Engineering
• Materials Science
• Electrochemistry

Background:

• Implantable glucose sensor performance is critically dependent on the outer membrane's properties.
• The membrane controls glucose diffusion, directly impacting sensor sensitivity and accuracy.
• This study investigates various membrane materials to optimize device response.

Purpose of the Study:

• To evaluate the effect of different outer membrane materials on implantable glucose sensor performance.
• To analyze the diffusion characteristics of glucose and hydrogen peroxide through fabricated membranes.
• To identify membrane compositions that enhance sensor accuracy and reduce response hysteresis.

Main Methods:

• Fabrication of sensors using platinum wire and immobilized glucose oxidase (GO(X)).
• Layer-by-layer deposition of bilayers: humic acids/ferric cations (HAs/Fe(3+)), HAs/poly(diallyldimethylammonium chloride) (HAs/PDDA), and poly(styrene sulfonate)/poly(diallyldimethylammonium chloride) (PSS/PDDA).
• In vitro amperometric response measurement and diffusion coefficient calculation for glucose and hydrogen peroxide.

Main Results:

• Successful fabrication of outer membranes with HAs/Fe(3+), HAs/PDDA, and PSS/PDDA bilayers on GO(X).
• Amperometric response and reversibility were evaluated across varying glucose concentrations.
• Diffusion coefficients of glucose and H(2)O(2) were calculated and analyzed for each membrane type.

Conclusions:

• Modulating outer membrane bilayer count effectively controls glucose diffusion and sensor flux.
• Semipermeable membranes with five HAs/Fe(3+) bilayers showed superior performance.
• These HAs/Fe(3+) membranes exhibited minimal hysteresis and reduced current saturation at high glucose levels due to balanced diffusion.