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    Device Technologies and Biomedical Robotics

    Enzymatic Glucose Biosensor- based on Prussian Blue-Modified Laser-Induced Graphene Electrochemical Sensor.

    (K-413) Enzymatic Glucose Biosensor- based on Prussian Blue-Modified Laser-Induced Graphene Electrochemical Sensor.

    Saturday, October 14, 2023
    9:30 AM – 10:30 AM PDT
    Location: Exhibit Hall - Row K - Poster # 413
    Introduction:: SUBTRACK: Biosensors

    The primary focus for medical sensing technology has recently shifted towards lower cost and higher sensitivity materials for point-of-care devices. Biosensors have become an increasingly popular option for monitoring countless diseases through biomarker concentrations within the body due to their heightened sensitivity and accessibility. Laser-induced graphene (LIG) sensors are particularly appealing due to their high surface area, electroanalytical capability, and conductivity. LIG-based enzymatic biosensors additionally offer high specificity to certain biomarkers such as glucose, alcohol, and lactate, allowing them to detect minute concentration imbalances that may arise in prevalent health conditions. Previous studies have highlighted the efficacy of Prussian Blue (PB) in catalyzing the reduction of hydrogen peroxide on regular biosensors, which is the product of the reaction between the enzyme and the targeted analytes. Our study proposes the development of enzymatic LIG sensors modified by PB for enhanced sensitivity and specificity. Glucose sensing was used as the basis of the investigation due to its well-known properties, enabling the establishment of a clear head-to-head comparison between our sensors and currently used products.

    Materials and Methods:: LIGs were modified by ablating polyimide films with a CO2 laser at 10% power and 5% speed. The LIG sensor was modified from a solution of 5mM K3[Fe(CN)6], 5mM Fe(NO3)3, and 0.1 M KCl in 0.1 M HCl. Cyclic voltammetry was performed before and after the deposition of PB to examine its effects on the surface area of the LIG. The enzymatic membrane was prepared by mixing a BSA solution, glutaraldehyde, and Nafion in a 1:1:0.33 ratio. The BSA solution consisted of 40 mg/mL of GOx. 4 µL of the enzymatic membrane solution were added drop-sense to the modified LIG sensor, then incubated for one hour. The sensors were then tested using amperometry to measure the current at a fixed potential of 0 V and varying concentrations of glucose within 50 µL of phosphate buffered saline (PBS).

    Results, Conclusions, and Discussions:: Figure A shows the successful production of porous graphene using laser engraving on the polyimide film. In Figure B, the 0.26 and 0.16 V peaks represent the electron transfer between Prussian Blue and Prussian White on the electrode surface. The increase in peak separation signifies a higher surface area, as the modification allowed the sensor to initiate electron transfer at a higher rate. Following the incubation period, the sensor achieved a linear response toward glucose in the concentration range of 0 mM to 4 mM and stabilized in 60 seconds (Figure C, D). The difference in current between the 1 mM concentration of glucose and the control at 60 seconds was 14.4 x 10-4 mA, indicating a statistically significant difference in detection. Since the range coincides with clinically-relevant glucose levels in blood samples, our results show that the electrode could be implemented in medical devices as a functional but significantly cheaper and potentially more effective product. Prussian Blue-modified LIGs demonstrated an outstanding performance as a platform for developing enzymatic biosensors. Future directions for our study involve optimizing the fabrication process of the LIGs to minimize error, and analyzing the effects of varying the incubation time and concentration of PB  on the electrode’s sensitivity.

    Acknowledgements (Optional): : We thank the Women in Science and Engineering Chapter at USC for their support and funding.

    References (Optional): :