Comparative analysis of the efficacy of bulk and membrane nanoporous materials in biological sensing

Abstract

Nanoporous materials possess significant potential in biological sensing applications due to their unique pore structures and high surface-area-to-volume ratios. Two common types of nanoporous materials are bulk and membrane-based. The differences in the structural and dimensional properties of nanopores are expected to impact the efficiency of biomolecule interactions during immobilization and hybridization, thereby influencing the overall performance of biological sensors. This study aims to investigate which type of nanoporous material offers enhanced sensitivity in detecting DNA targets. In this context, activated rice husk carbon (ARHC) and anodic aluminum oxide (AAO) were used to represent bulk and membrane nanoporous materials, respectively. Chitosan was mixed with ARHC to improve conductivity and provide better adhesion to the electrode substrate. ARHC and AAO thin films were characterized using SEM, XRD, and FTIR. Their performance in biological sensing was evaluated using Electrochemical Impedance Spectroscopy (EIS). Compared to chitosan/ARHC, the charge transfer resistance (Rct) at the AAO/electrolyte interfaces was three times higher due to the smaller pore size and narrow, long nanoporous tunnel structure. Consequently, the sensitivity of the AAO thin film electrode in detecting DNA hybridization was lower (0.1312 Ω·M⁻¹) compared to the chitosan/ARHC electrode (0.0343 Ω·M⁻¹), which has a larger pore size and interconnected nanopore structures. The limit of detection (LOD) was also affected, with the AAO thin film electrode exhibiting a higher LOD of 3.0 × 10⁻¹³ M, while the chitosan/ARHC electrode demonstrated a lower and better LOD of 8.0 × 10⁻²⁵ M. This study demonstrates that the type of nanoporous material significantly impacts sensitivity performance in biological sensing.