Graphene Surface Functionalization with Pyrene-, Acridine-, and Fluorenyl-Linkers for DNA Hybridization Studies Using...

Area of Science:

• Materials Science
• Nanotechnology
• Biomedical Engineering

Background:

• Electrolyte-gated graphene field-effect transistors (EG-gFETs) are promising for biosensing applications.
• Functionalization of graphene surfaces is crucial for enhancing sensor performance and specificity.
• Understanding linker molecule interactions with graphene is key to optimizing device sensitivity and dynamic range.

Purpose of the Study:

• To investigate the impact of different functionalization linkers (PBSE, FSC, AO) on EG-gFET performance for DNA hybridization biosensing.
• To analyze the sensitivity, dynamic range, and binding characteristics of EG-gFETs modified with various linker molecules.
• To elucidate the electronic interactions between linker molecules and the graphene surface using computational methods.

Main Methods:

• Fabrication and characterization of EG-gFETs functionalized with 1-Pyrenebutyric Acid Succinimidyl Ester (PBSE), Fluorenylmethylsuccinimidyl Carbonate (FSC), and Acridine Orange (AO) Succinimidyl Ester.
• DNA single-strand functionalization and subsequent hybridization biosensing experiments.
• Analysis of transfer curve shifts (ΔV_Dirac) to determine sensor sensitivity and binding parameters (Hill parameter).
• Ab initio density functional theory (DFT) simulations to study linker-graphene interactions and electronic properties.

Main Results:

• Varying sensitivities were observed: PBSE (19.02 mV/dec), FSC (12.35 mV/dec), and AO (13.19 mV/dec).
• FSC showed lower sensitivity, potentially due to weaker binding affinity.
• AO exhibited a lower Hill parameter (0.37) compared to PBSE and FSC (0.5), and induced negative charges in graphene.
• AO provided a comparable saturation signal to PBSE but with a more extensive dynamic range, attributed to nonlinear screening effects.
• DFT simulations confirmed graphene's electronic behavior (acceptor for AO, donor for PBSE/FSC) based on adsorbed molecules.

Conclusions:

• The choice of linker molecule significantly influences the sensitivity and dynamic range of graphene-based DNA biosensors.
• Acridine Orange (AO) offers a promising alternative for developing biosensors with a wider dynamic range, despite lower sensitivity compared to PBSE.
• The electronic interactions and charge transfer between linker molecules and graphene play a critical role in biosensor performance.
• Computational modeling (DFT) is valuable for understanding and predicting the behavior of functionalized graphene surfaces in biosensing applications.