The development of rapid, affordable, and reliable diagnostic tools is essential for combating HIV, particularly in early-stage detection where timely intervention significantly improves outcomes. This study introduces a disposable aptasensor platform based on screen-printed electrodes (SPEs) modified with graphene quantum dots (GQDs), engineered to detect the p24-HIV protein with high sensitivity and specificity. The key innovation lies in utilizing GQDs not only as a stable immobilization matrix for aptamers but also as an electrochemical signal amplifier, enhancing the sensor’s performance without requiring enzymatic labels.
GQDs were synthesized through a straightforward citric acid pyrolysis method at 200 °C, resulting in small, water-soluble nanoparticles with tunable optical and electronic properties. Characterization via transmission electron microscopy (TEM), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FTIR) confirmed their size (~7 nm average diameter), morphology, and presence of carboxylic and hydroxyl functional groups—critical for bioconjugation.CEA Antibody Autophagy These surface functionalities enabled efficient covalent attachment of amine-modified p24-specific DNA aptamers via EDC/NHS coupling chemistry after GQD deposition on SPEs.
Electrodeposition of GQDs was performed using cyclic voltammetry in the potential range of −1.4 V to 0.0 V (vs. Ag/AgCl), which reduced oxygen-containing groups and promoted strong adhesion to the graphite working electrode. This process significantly enhanced the electron transfer kinetics, as evidenced by a reduction in charge transfer resistance from 38.4 kΩ in unmodified SPEs to 2.43 kΩ in GQD-modified ones, according to electrochemical impedance spectroscopy (EIS). Cyclic voltammetry further revealed that three electrodeposition cycles yielded optimal aptamer loading, maximizing signal suppression upon target binding.
The aptasensor operates on a label-free principle: when p24-HIV binds to the immobilized aptamer, it induces a conformational change that hinders electron transfer between the redox probe (K₃[Fe(CN)₆]) and the electrode, leading to a measurable decrease in peak current. This signal response was linear over a broad concentration range—from 0.93 ng mL⁻¹ to 93 μg mL⁻¹—with a correlation coefficient (R²) of 0.996. The limit of detection (LOD) was determined to be 51.7 pg mL⁻¹, surpassing many existing methods and enabling detection at clinically relevant levels.
The sensor demonstrated excellent selectivity against p24-HTLV, a structurally similar viral protein, showing no significant signal interference. In addition, the device maintained consistent performance in spiked human serum samples diluted 1:100, with clear distinction between positive and negative controls. Signal variation remained below 10% across replicates, indicating high reproducibility.Resorufin β-D-glucuronide supplier
Stability tests revealed minimal degradation after four weeks of refrigerated storage, with less than 8% deviation in baseline signal.PMID:34889017 The system retained 91% of its original response after two weeks, confirming its suitability for real-world deployment. These results highlight the robustness and practicality of the GQD-SPE platform for field applications.
This work establishes a scalable, low-cost strategy for developing point-of-care diagnostics using readily available materials and simple fabrication protocols. By combining the unique electrochemical properties of GQDs with the disposability and ease of use of SPEs, this aptasensor offers a promising solution for early HIV screening, especially in regions with limited access to advanced laboratory infrastructure.MedChemExpress (MCE) offers a wide range of high-quality research chemicals and biochemicals (novel life-science reagents, reference compounds and natural compounds) for scientific use. We have professionally experienced and friendly staff to meet your needs. We are a competent and trustworthy partner for your research and scientific projects.Related websites: https://www.medchemexpress.com
