Background In this label-free bioassay, an electrochemiluminescence (ECL) immunosensor was developed for the quantification of breast cancer using HER-2 protein as a metastatic biomarker. Method For this purpose, the ECL emitter, [Ru(bpy)3]2+, was embedded into biocompatible chitosan (CS) polymer. The prepared bio-composite offered high ECL reading due to the depletion of human epidermal growth factor receptor 2 (HER-2) protein. Reduced graphene oxide (rGO) was used as substrate to increase signal stability and achieve greater sensitivity. For this, rGO was initially placed electrochemically on the glassy carbon electrode (GCE) surface by cyclic voltammetry (CV) technique. Next, the prepared CS/[Ru(bpy)3]2+ biopolymer solution was coated on a drop of the modified electrode such that the amine groups of CS and the carboxylic groups of rGO could covalently interact. Using EDC/NHS chemistry, monoclonal antibodies (Abs) of HER-2 were linked to CS/[Ru(bpy)3]2+/rGO/GCE via amide bonds between the carboxylic groups of Ab molecules and amine groups of CS. The electrochemical behavior of the electrode was studied using different electrochemical techniques such as electrochemical impedance spectroscopy (EIS), differential pulse voltammetry (DPV) and square wave voltammetry (SWV) and also ECL tests. Results After passing all optimization steps, the lower limit of detection (LLOQ) and linear dynamic range (LDR) of HER-2 protein were practically obtained as 1 fM and 1 fM to 1 nM, individually. Importantly, the within and between laboratory precisions were performed and the suitable relative standard deviations (RSDs) were recorded as 3.1 and 3.5%, respectively. Conclusions As a proof of concept, the designed immunosensor was desirably applied for the quantification of HER-2 protein in breast cancer suffering patients. As a result, the designed ECL-based immunosensor has the capability of being used as a conventional test method in biomedical laboratories for early detection of HER-2 protein in biological fluids. Graphic Abstract

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Breast cancer is categorized as the most widespread cancer type among women globally. On-time diagnosis can decrease the mortality rate by making the right decision in the therapy procedure. These features lead to a reduction in medication time and socioeconomic burden. The current review article provides a comprehensive assessment for breast cancer diagnosis using nanomaterials and related technologies. Growing use of the nano/biotechnology domain in terms of electrochemical nanobiosensor designing was discussed in detail. In this regard, recent advances in nanomaterial applied for amplified biosensing methodologies were assessed for breast cancer diagnosis by focusing on the advantages and disadvantages of these approaches. We also monitored designing methods, advantages, and the necessity of suitable (nano) materials from a statistical standpoint.The main objective of this review is to classify the applicable biosensors based on breast cancer biomarkers.With numerous nano-sized platforms published for breast cancer diagnosis, this review tried to collect the most suitable methodologies for detecting biomarkers and certain breast cancer cell types.

Biopolymer films have drawn growing demand for their application in the point of care domain owing to their biocompatibility, eco-friendly, and eligibility for in vivo analyses. However, their poor conductivity restricts their sensitivity in diagnostics. For high-quality electrochemical biosensor monitoring, two vital factors to be greatly paid attention are the effective merge of amplification modifiers with transducing surface and the superior linking across the recognition interface. Here, we introduce an enzyme-free electrochemical biosensor based on electrosynthesized biocompatible WO3/poly glutamic acid nano-biocomposites to address the hardships specific to the analysis of circulating proteins clinical samples. In addition to its green synthesis route, the poor tendency of both components of the prepared nano-biocomposite to amine groups makes it excellent working in untreated biological samples with high contents of proteins. Several electrochemical and morphological investigations (SEM, EDX, and dot mapping) were fulfilled to gain a reliable and trustful standpoint of the framework. By using this nanobiosensor, the concentration of HER-2 was detectable as low as 1 fg mL−1 with a wide linear response between 1 ng mL−1 and 1 fg mL−1. Meanwhile, the protocol depicted ideal specificity, stability, and reproducibility for the detection of HER-2 protein in untreated serum samples of breast cancer patients.

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Nanoclusters are nanostructures consisting of few to tens of atoms which have attracted great interest from the scientific community due to their applications in a myriad of fields, from catalysis to biomedical applications. Due to the discrete energy levels resulting from their ultrasmall size, nanoclusters exhibit distinctly different chemical, optical, and electrical properties compared with their larger nanoparticle counterparts. Unlike previously reported nanostructures with larger dimensions (1–10 nm), which typically have a single advantage (for example, high conductivity or optical properties), nanoclusters can be used as signaling and/or reaction-accelerating materials in almost all sensing assays with enhanced properties. Nanoclusters are among the most promising luminescent emitters (electrochemiluminescent, fluorescent, chemiluminescent, and colorimetry) with high quantum yield and better biocompatibility than conventional emitters. Considering their excelent biocompatibility, tailored modification, and desirable electrochemical and optical tunability, nanoclusters have opened new horizons in designing high-performance sensing and biosensing devices. In addition, they represent excellent electrochemical and photoelectrochemical behaviors with improved functionality and environmentally friendly properties compared to traditional compounds. This review discusses the recent advances in nanoclusters, their applications in sensing and biosensing, current limitations, and prospects to overcome these challenges. The present study gives a much brighter vision of nanoclusters that discusses one by one their particular advantages and role in developing sensing frameworks.