Poster Z1 - Quantification of Hydrogen Peroxide using Single Walled Carbon Nanotube Based Optical Sensors

Introduction: Hydrogen peroxide (H2O2), a reactive oxygen species (ROS), plays a vital role in cellular processes, including regulation of protein metabolism, redox signaling, inflammation, apoptosis, and cell proliferation. Understanding changes in H2O2 concentrations at a sub-cellular level could lead to improved disease detection/identification and optimization of drug treatments in the presence of increased or decreased levels of ROS. Many H2O2 detection methods face challenges such as low sensitivity, complex operational procedures, extended processing times, lack of spatial/temporal detection, and elevated expenses, which restricts their broad utilization. Optical sensors based on single walled carbon nanotubes (SWNT) have shown the potential to provide high-quality spatial and temporal information regarding a wide range of cellular signaling molecules, including H2O2. Herein, we detect and quantify H2O2 based on changes in SWNT fluorescence intensity, the first step towards quantifying intracellular and extracellular H2O2 concentrations at the sub-cellular level.

Materials and

Methods: The SWNT-based H2O2 sensors are prepared by wrapping SWNT with single-stranded DNA, specifically (GT)15. Briefly, the SWNT and DNA mixture are sonicated then centrifuged, followed by collection of the supernatant. The wrapped SWNT’s concentration is determined using UV/Vis spectrometry. To determine SWNT’s response to H2O2, various concentrations of H2O2 were recorded in 5-minute intervals for 60 minutes using a custom-built hyperspectral microscope.

Results, Conclusions, and Discussions:

Results: The fluorescence spectrum of SWNT-based H2O2 sensors in the presence of different H2O2 concentrations was successfully acquired. The fluorescence quenching of the sensor was used to create a calibration curve. It was observed that the quenching was rapid for 35 minutes, after which it began to slow down, eventually reaching a plateau at 60 minutes. Hence, we have the calibration curves for both time points with R² values of 0.969 and 0.991 respectively for 35 and 60 minutes.

Conclusion: The concentration of H2O2 was successfully quantified through the utilization of the SWNT sensors. This ability to quantify H2O2 will allow for investigation into H2O2 concentrations in bodily fluids, which could help in early disease detection and improved treatments.

Discussion: We demonstrated that the fluorescence intensity quenching increased with increasing concentration of H2O2 in the solution. Acquisition of the spectrum for 60 minutes allowed us to explore the gradual quenching rate of SWNT sensors, however after 35 minutes the quenching rate was observed to be slower. The calibration curve provides a linear positive regression relationship between H2O2 concentration and percent quenching of SWNT fluorescence.

Acknowledgements (Optional): We would like to thank NSF for their support through CAREER Grant and all members of Iverson lab.