Hierarchal polyaniline-folic acid nanostructures act as a platform for electrochemical detection of tumor cells

Label-free electrochemical assessment of human serum and cancer cells to determine the folate receptor cancer biomarker

The folate receptor (FR) is a well-known biomarker that is overexpressed in many cancer cells, making it a valuable target for cancer diagnostics and therapeutic strategies. However, identifying cancer biomarkers remains a challenge due to factors such as lengthy procedures, high costs, and low sensitivity. This study presents the development of a novel, cost-effective biosensor designed for the detection of FR. To overcome the limitations of traditional immunological methods, which rely on antigen-antibody interactions, we utilized a charge-based affinity approach. Folic acid (FA) was conjugated with poly (diallyl dimethylammonium chloride) (PDDA) using an EDC-NHS linker on the surface of multi-walled carbon nanotubes. The biosensor enabled electrochemical detection of FR through differential pulse voltammetry (DPV), achieving an impressive detection limit of 1.6 pg/mL and a dynamic range of 1-10,000 ng/mL. Additionally, the biosensor exhibited excellent stability (30 days), high selectivity, and repeatability (RSD = 3.14 %, n = 5). This work presents a promising strategy for developing ligand-receptor-based biosensors. It paves the way for future applications in cancer diagnostics and biosystem interfaces, offering high performance and practical advantages.

Ag nanorod@PEI-Ag nanohybrid as an excellent signal label for sensitive and rapid detection of serum HER2

The accurate detection of Human epidermal growth factor receptor-2 (HER2) as a critical breast cancer biomarker can be essential for the early selection of therapeutic approaches. HER2 is a prominent component of a signaling network. Overexpression of the HER2 protein due to amplification of its gene leads to the development of an aggressive subtype of breast cancer. Patients with tumors that overexpress HER2 are eligible for treatment that significantly reduces mortality rates. Herein, we present a fast and simple method for detecting serum HER2. A new electrochemical label has been developed using charged Ag nanorod@ polyethylenimine-Ag (Ag NR@ PEI-Ag) nanohybrid. The synthesized Ag NR@PEI-Ag nanohybrid simultaneously has the electroactive property of silver and the large surface area of the PEI, which results in the enhancement of the detection signal. So, using Ag NR@PEI-Ag nanohybrid as the electrochemical label, a simple, fast, and sensitive electrochemical biosensor was designed to detect HER2. This way, after immobilizing HER2 aptamer on the Au electrode surface, HER2 or human serum was exposed to the aptamer. Then, the positively charged Ag NR@PEI-Ag nanohybrid was adsorbed onto the negatively charged aptamer-HER2 complex, and the current that was produced due to the Ag/AgCl reaction was measured as the electrochemical signal. The aptasensor shows a broad linear response from 10-12 to 10-7 g, a low detection limit (LOD) of 10 pg, and a total assay time of ~ 30 min.