Label-free Electrochemical Aptasensor For Detection Research Articles

Label-free electrochemical aptasensor for detection of Acinetobacter baumannii: Unveiling the kinetic behavior of reduced graphene oxide v/s graphene oxide

In this study, we introduce an electrochemical aptasensor for the sensitive detection of Acinetobacter baumannii. This method, based on impedance and current analysis, represents a first-of-its kind platform in the field of A. baumannii detection. We employed a screen-printed carbon electrode modified with both graphene oxide (GO) and reduced graphene oxide (rGO) as the immobilization platform, and the bacteria specific aptamer was employed as the biorecognition element. The aptamer selectively interacts with A. baumannii, causing a decrease in the peak current of the redox complex because the binding biomolecules on the electrode surface hinder the electron transfer of the redox probe. This initial point-of-care-compatible rGO electrochemical aptasensor demonstrated an exceptional sensing performance with an impressive limit of detection of 10 CFU/mL for detecting A. baumannii. This enhanced sensitivity can be attributed to several key factors including structural defects during reduction, increased surface area and improved electron transfer kinetics. The findings of this study highlight the potential of the developed aptasensor as a rapid and reliable detection platform for various pathogenic diseases. By further ensuring seamless integration into clinical practice, these label-free graphene-based aptasensors, with their π-π interactions and other favorable attributes, hold great promise for sensitive and specific pathogen detection, thereby contributing to advancements in healthcare diagnostics.

Label-free electrochemical aptasensor for GPC3 detection based on RGO-CS-Fc/Pt NPs

Glypican-3 (GPC3) is a promising biomarker of early detection of hepatocellular carcinoma (HCC). Herein, an label-free electrochemical aptasensor for the detection of GPC3 was developed based on reduced graphene oxide-chitosan-ferrocene/platinum nanoparticles (RGO-CS-Fc/Pt NPs). GPC3 aptamer (GPC3-Apt) was immobilized onto the surface of the modified screen-printed carbon electrode (SPE) by RGO-CS-Fc/Pt NPs. When the GPC3 was added to the platforms of aptasensor, the specific recognition reaction between the GPC3-Apt and GPC3 produced aptamer-antigen complex and arranged on the electrode surface, which made the change of electrochemical signals of Fc obtained by differential pulse voltammetry (DPV). Hence, the calibration graph (peak current vs GPC3 concentration) can be used for quantification of GPC3. The measured peak current and GPC3 concentration have a good linearity in the range of 0.05-10.0 μg/mL, a correlation coefficient of 0.9805 and a low detection limit of 0.018 μg/mL (S/N=3). Moreover, the designed aptasensor showed good performance with excellent selectivity, acceptable reproducibility and stability. Thus, this label-free electrochemical aptasensor has promising applications for the early detection of HCC.

Design of a facile and label-free electrochemical aptasensor for detection of atrazine

A facile and label-free electrochemical aptasensor for detection of atrazine (ATZ) was designed based on nickel hexacyanoferrate nanoparticles (NiHCF NPs) and electrochemically reduced graphene oxide (ERGO). Because of ERGO perfect electrochemical conductivity and large surface area, it was first modified on glassy carbon electrode (GCE) surface by electrochemical reduction. NiHCF NPs were immobilized on ERGO/GCE as a signal probe with well-defined peaks and good stability. Subsequently, gold nanoparticles (Au NPs) were electrodeposited on NiHCF NPs/ERGO to anchored aptamer and increase the conductivity and stability of the electrode. When ATZ was added, ATZ-aptamer complexes generated with poor conductivity on the sensor surface increased the hindrance of electron transfer, leading to electrochemical signal decrease. The signal change was used to detect ATZ quantitatively. The designed aptasensor exhibited good analytical performance for determining ATZ. A linear curve was obtained in the range of 0.25–250 pM with a low detection limit of 0.1 pM, and it showed perfect selectivity for ATZ in the presence of diverse interferents. Meanwhile, the electrochemical aptasensor was employed to evaluate ATZ content in the samples.

Fabrication of a novel and ultrasensitive label-free electrochemical aptasensor for detection of biomarker prostate specific antigen

In this study, a novel and efficient aptasensor based on immobilization of thiol terminated prostate specific antigen (PSA) binding DNA aptamer onto Au nanoparticles/fullerene C60-chitosan-ionic liquid/multiwalled carbon nanotubes/screen printed carbon electrode has been fabricated for ultrasensitive aptasensing of biomarker PSA. Formation of PSA-aptamer complex caused a variation in electrochemical impedance spectroscopic (EIS) and differential pulse voltammetric (DPV) responses of the aptasensor which enabled us to aptasensing of the PSA by EIS and DPV methods. Morphology and electrochemical properties of the fabricated aptasensor were examined by scanning electron microscopy (SEM), cyclic voltammetry (CV) and EIS. The aptasensor was successfully applied to the determination of PSA by EIS and DPV in the range of 1–200 pg mL−1 with a limit of detection (LOD) of 0.5 pg mL−1 and 2.5–90 ng mL−1 with a LOD of 1.5 ng mL−1, respectively. This aptasensor exhibited outstanding anti-interference ability towards co-existing molecules with good stability, sensitivity, repeatability and reproducibility. Practical application of the aptasensor was examined with analysis of the PSA levels in serum samples obtained from patients with prostate cancer using both the aptasensor and a reference method. The results revealed the proposed system to be a promising candidate for clinical analysis of PSA.

Label-free electrochemical aptasensor for detection of alpha-fetoprotein based on AFP-aptamer and thionin/reduced graphene oxide/gold nanoparticles

Sensitive and accurate detection of tumor markers is critical to early diagnosis, point-of-care and portable medical supervision. Alpha fetoprotein (AFP) is an important clinical tumor marker for hepatocellular carcinoma (HCC), and the concentration of AFP in human serum is related to the stage of HCC. In this paper, a label-free electrochemical aptasensor for AFP detection was fabricated using AFP-aptamer as the recognition molecule and thionin/reduced graphene oxide/gold nanoparticles (TH/RGO/Au NPs) as the sensor platform. With high electrocatalytic property and large specific surface area, RGO and Au NPs were employed on the screen-printed carbon electrode to load TH molecules. The TH not only acted as a bridging molecule to effectively capture and immobilize AFP-aptamer, but as the electron transfer mediator to provide the electrochemical signal. The AFP detection was based on the monitoring of the electrochemical current response change of TH by the differential pulse voltammetry. Under optimal conditions, the electrochemical responses were proportional to the AFP concentration in the range of 0.1–100.0 μg/mL. The limit of detection was 0.050 μg/mL at a signal-to-noise ratio of 3. The proposed method may provide a promising application of aptamer with the properties of facile procedure, low cost, high selectivity in clinic.