An electrochemical immunosensor based on MXene-GQD/AuNPs for the detection of trace amounts of CA-125 as specific tracer of ovarian cancer

An electrochemical immunoassay system was developed to detect CA-125 using a glassy carbon electrode (GCE) modified with MXene, graphene quantum dots (GQDs), and gold nanoparticles (AuNPs). The combined MXene-GQD/AuNPs modification displayed advantageous electrochemical properties due to the synergistic effects of MXene, GQDs, and AuNPs. The MXene-GQD composite in the modified layer provided strong mechanical properties and a large specific surface area. Furthermore, the presence of AuNPs significantly improved conductivity and facilitated the binding of anti-CA-125 on the modified GCE, thereby enhancing sensitivity. Various analytical techniques such as FE-SEM and EDS were utilized to investigate the structural and morphological characteristics as well as the elemental composition. The performance of the developed immunosensor was assessed using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), square wave voltammetry (SWV), and differential pulse voltammetry (DPV). Under optimized conditions in a working potential range of -0.2 to 0.6 V (vs. Ag/AgCl), the sensitivity, linear range (LR), limit of detection (LOD), and correlation coefficient (R2) were determined to be 315.250 µA pU.mL-1/cm2, 0.1 to 1 nU/mL, 0.075 nU/mL, and 0.9855, respectively. The detection of CA-125 in real samples was investigated using the developed immunoassay platform, demonstrating satisfactory results including excellent selectivity and reproducibility.

Biosensors; a novel concept in real-time detection of autophagy

Autophagy is an early-stage response with self-degradation properties against several insulting conditions. To date, the critical role of autophagy has been well-documented in physiological and pathological conditions. This process involves various signaling and functional biomolecules, which are involved in different steps of the autophagic response. During recent decades, a range of biochemical analyses, chemical assays, and varied imaging techniques have been used for monitoring this pathway. Due to the complexity and dynamic aspects of autophagy, the application of the conventional methodology for following autophagic progression is frequently associated with a mistake in discrimination between a complete and incomplete autophagic response. Biosensors provide a de novo platform for precise and accurate analysis of target molecules in different biological settings. It has been suggested that these devices are applicable for real-time monitoring and highly sensitive detection of autophagy effectors. In this review article, we focus on cutting-edge biosensing technologies associated with autophagy detection.

Electrochemical and optical (bio)sensors for analysis of antibiotic residuals

Antibiotic residuals in foods may lead to crucial health and safety issues in the human body. Rapid and in-time analysis of antibiotics using simple and sensitive techniques is in high demand. Among the most commonly applicable modalities, chromatography-based techniques like HPLC and LC-MS, along with immunological approaches, particularly ELISA have been exampled in the analysis of antibiotics. Despite being highly sensitive, these methods are considerably time-consuming, thus the presence of skilled personnel and costly equipment is essential. Nanomaterial-based (bio)sensors, however, are de novo analytical equipment with some beneficial characteristics, such as simplicity, low price, on-site, high accuracy, and sensitivity for the detection of analytes. This review aimed to collect the latest developments in NM-based sensors and biosensors for the observation of highly used antibiotics like Vancomycin (Van), Linezolid (Lin), and Clindamycin (Clin). The current challenges and developmental perspectives are also debated in detail for future research directions.

Detection of receptor tyrosine kinase-orphan receptor-2 using an electrochemical immunosensor modified with electrospun nanofibers comprising polyvinylpyrrolidone, soy, and gold nanoparticles

An electrochemical immunosensing platform was developed for the detection of receptor tyrosine kinase-orphan receptor-2 (ROR2) at a glassy carbon electrode (GCE) modified with the electrospun nanofiber containing polyvinylpyrrolidone (PVP), soy, and Au nanoparticles (AuNPs). The PVP/soy/AuNP nanofiber exhibited good electrochemical behavior due to synergistic effects between PVP, soy, and AuNPs. The PVP/soy in the modified film provided good mechanical strength, high porosity, flexible structures, and high specific surface area. On the other hand, the presence of AuNPs effectively improved conductivity, as well as the immobilization of anti-ROR2 on the modified GCE, leading to enhanced sensitivity. Various characterization approaches such as FE-SEM, FTIR, and EDS were used for investigating the morphological and structural features, and the elemental composition. The designed immunosensor performance was investigated using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and differential pulse voltammetry (DPV). Under optimum conditions with a working potential range from -0.2 to 0.6 V (vs. SCE), sensitivity, linear range (LR), limit of detection (LOD), and correlation coefficient (R2) were acquired at 122.26 μA/cm2 dec, 0.01-1000 pg/mL, 3.39 fg/mL, and 0.9974, respectively. Furthermore, the determination of ROR2 in human plasma samples using the designed immunosensing platform was examined and exhibited satisfactory results including good selectivity against other proteins, reproducibility, and cyclic stability.

New fluorescent probe for sensing of mefenamic acid in aqueous medium: An integrated experimental and theoretical analysis

Abnormal levels of mefenamic acid (MFA) in living organisms can result in hepatic necrosis, liver, and gastrointestinal diseases. Therefore, development of accurate and effective method for detection of MFA is of great significance for the protection of public health. Herein, we designed a stilbene based sensor ECO for the sensitive and selective detection of mefenamic acid by employing fluorescence spectroscopy for the first time. The developed sensor ECO displayed fluorescence turn-off response towards MFA based on PET (photoinduced electron transfer) and hydrogen bonding. The sensing mechanism of MFA was investigated through ¹H NMR titration experiment and density functional theory (DFT) calculations. The presence of non-covalent interaction was confirmed through spectroscopic analysis and was further supported by non-covalent interaction (NCI) analysis and Bader's quantum theory of atoms in molecules (QTAIM) analysis. Additionally, the sensor ECO coated test strips were fabricated for on-site detection of mefenamic acid. Furthermore, the practical applicability of sensor ECO to detect MFA was also explored in human blood and artificial urine samples.

Early stage evaluation of colon cancer using tungsten disulfide quantum dots and bacteriophage nano-biocomposite as an efficient electrochemical platform

Background

Recently, biosensors have become popular analytical tools for small analytes due to their high sensitivity and wide analytical range. In the present work, development of a novel biosensing method based on tungsten disulfide quantum dots (WS2 QDs)-Au for rapidly and selectively detecting c-Met protein is introduced. As a proof of concept, M13 bacteriophage-based biosensors were used for the electrochemical detection of c-Met protein as a colon cancer biomarker.

Method

The M13 bacteriophage (virus), as the biorecognition element, was immobilized on glassy carbon electrodes which were modified by WS2 QDs-functionalized gold nanoparticles. The stepwise presence of the WS2 QDs, gold nanoparticles, and immobilized phage on glassy carbon electrodes were confirmed by scanning electron microscope (SEM) and square wave voltammetry (SWV) technique.

Results

The designed biosensor was applied to measure the amount of c-Met protein in standard solutions, and consequently the desirable detection limit of 1 pg was obtained. Finally, as a proof of concept, the developed platform was used for the evaluation of c-Met protein in serum samples of colon cancer-suffering patients and the results were compared with the results of the common Elisa kit.

Conclusions

As an interesting part of this study, some concentrations of the c-Met protein in colon cancer serum samples which could not be determined by Elisa, were easily analyzed by the developed bioassay system. The developed bioassay system has great potential to application in biomedical laboratories.

Graphical Abstract

Ultrasensitive and label free electrochemical immunosensor for detection of ROR1 as an oncofetal biomarker using gold nanoparticles assisted LDH/rGO nanocomposite

In the present article, we developed a highly sensitive label-free electrochemical immunosensor based on NiFe-layered double hydroxides (LDH)/reduced graphene oxide (rGO)/gold nanoparticles modified glassy carbon electrode for the determination of receptor tyrosine kinase-like orphan receptor (ROR)-1. In this electrochemical immunoassay platform, NiFe-LDH/rGO was used due to great electron mobility, high specific surface area and flexible structures, while Au nanoparticles were prepared and coated on the modified electrodes to improve the detection sensitivity and ROR1 antibody immobilizing (ROR1Ab). The modification procedure was approved by using cyclic voltammetry and differential pulse voltammetry based on the response of peak current to the step by step modifications. Under optimum conditions, the experimental results showed that the immunosensor revealed a sensitive response to ROR1 in the range of 0.01-1 pg mL^-1, and with a lower limit of quantification of 10 attogram/mL (10 ag mL^-1). Furthermore, the designed immunosensor was applied for the analysis of ROR1 in several serum samples of chronic lymphocytic leukemia suffering patients with acceptable results, and it also exhibited good selectivity, reproducibility and stability.

Ultrasensitive bioassaying of HER-2 protein for diagnosis of breast cancer using reduced graphene oxide/chitosan as nanobiocompatible platform

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

A highly sensitive electrochemiluminescence cytosensor for detection of SKBR-3 cells as metastatic breast cancer cell line: A constructive phase in early and precise diagnosis

Ultrasensitive monitoring of cancer cells, especially metastatic ones, has a great interest in human medicine. Despite the early diagnosis of diseases, there is an essential need for any prediction in the severity of side effects for therapeutic outcomes like metastasis. Therefore, the inhibition of cancer cells metastasis to other organs is of utmost importance for cancer suffering patients. In this regard, we developed an electrochemiluminescence (ECL)-based cytosensor for the quantification of metastatic breast cancer cells, namely SKBR-3. Silica-based mesoporous materials have a great potential for application in ECL biosensors due to their high loading capacity and mechanical strength. Herein, a silica-based electrode was prepared via in situ electrosyntheses of mesoporous silica as an environmentally friendly approach. In this protocol, luminol (as luminophore) was combined with chitosan (as attachment biomolecule) to produce a stable lumino-composite film on the electrode surface. At the optimum experimental conditions, the lower limit of quantitation (LLOQ) and linear dynamic range (LDR) were obtained as 20 cells/mL and 20 to 2000 cells/mL, individually. The specificity was desirably examined in the presence of other breast cancer cell lines such as MCF-7 and MDA-MB-231, as a model of early-stage and invasive phases of breast cancer cells. The repeatability was successfully examined for five repetitive measurements and the acceptable relative standard deviation (RSD) was calculated as about 1.6% for 500 cells/mL. As a proof of concept, the presented cytosensor has a high ability to use in clinical laboratories for the detection and separation of metastatic cells via the combination with microfluidic systems.

Multiplex bioassaying of cancer proteins and biomacromolecules: Nanotechnological, structural and technical perspectives

Since the specific proteins (carbohydrate antigens, ligands and interleukins) get raised up in body tissue or fluids in cancer cases, early detection of them will provide an effective treatment and survival rate. Sensitive and accurate determination of multiple cancer proteins can be engaged in chorus by simultaneous/multiplex detection in the biomedical fields. Bioassaying technology is one of the non-invasive, high-sensitive, and economical methods. Currently, extensive application of nanomaterial (biocompatible polymers, metallic and metal oxide) in bioassays resulted in ultra-high sensitive and selective diagnosis. This review article focuses on types of multiplex bioassays for delicate and specific determination of cancer proteins for diagnostic aims. It also covers two modes of multiplex bioassays as multi labeled bioassays and spatially-separated test zones (multi-electrode mode). In this review, the nanotechnological, structural, and technical perspectives in the multiplex analysis of cancer proteins were discussed. Finally, the use of different types of nanomaterials, polysaccharides, biopolymers and their advantages in signal amplification are discussed.

Natural polypeptides-based electrically conductive biomaterials for tissue engineering

Fabrication of an appropriate scaffold is the key fundamental step required for a successful tissue engineering (TE). The artificial scaffold as extracellular matrix in TE has noticeable role in the fate of cells in terms of their attachment, proliferation, differentiation, orientation and movement. In addition, chemical and electrical stimulations affect various behaviors of cells such as polarity and functionality. Therefore, the fabrication approach and materials used for the preparation of scaffold should be more considered. Various synthetic and natural polymers have been used extensively for the preparation of scaffolds. The electrically conductive polymers (ECPs), moreover, have been used in combination with other polymers to apply electric fields (EF) during TE. In this context, composites of natural polypeptides and ECPs can be taken into account as context for the preparation of suitable scaffolds with superior biological and physicochemical features. In this review, we overviewed the simultaneous usage of natural polypeptides and ECPs for the fabrication of scaffolds in TE.

Efficient Electrochemical Sensor Based on Gold Nanoclusters/Carbon Ionic Liquid Crystal for Sensitive Determination of Neurotransmitters and Anti-Parkinson Drugs

Purpose: Herein we introduce a simple and sensitive sensor for the electrochemical determination of neurotransmitters compounds and anti-Parkinson drugs.

Methods: The electrochemical sensor (Au/CILCE) based on gold nanoclusters modified carbon ionic liquid crystal (ILC) electrode was characterized using scanning electron microscopy and voltammetry measurements.

Results: The effect of ionic liquid type in the carbon paste composite for the electro-catalytic oxidation of L-dopa was evaluated. Highest current response was obtained in case of ILC compared to other studied kinds of ionic liquids. The effective combination of gold nanoclusters and ILC resulted in extra advantages including large surface area and high ionic conductivity of the nanocomposite. L-dopa is considered one of the most important prescribed medicines for treating Parkinson’s disease. Moreover, a binary therapy using L-dopa and carbidopa proved effective and promising as it avoids the short comings of L-dopa mono-therapy for Parkinson’s patients. The Au/CILCE can detect L-dopa in human serum in the linear concentration range of 0.1 μM to 90 μM with detection and quantification limits of 4.5 nM and 15.0 nM, respectively. Also, the Au/CILCE sensor can simultaneously and sensitively detect L-dopa in the presence of carbidopa with low detection limits.

Conclusion: The sensor is advantageous to be applicable for electrochemical sensing of other biologically electroactive species.

Design a highly specific sequence for electrochemical evaluation of meat adulteration in cooked sausages

A specific and unique sequence probe was designed for detection of donkey adulteration in cooked sausages and its species specificity was confirmed bioinformatically in the common software and website (ClustalX and NCBI). Subsequently, a novel species-specific electrochemical DNA probe (locked nucleic acid, LNA) was synthesized and implemented in a construction of DNA-based electrochemical genosensor for sensitive, convenient and selective detection of donkey adulteration. The electrochemical behavior of the fabricated genosensor was studied by linear sweep, square wave, differential pulse voltammetry and electrochemical impedance spectroscopy techniques. Due to inherent optimal hybridization conditions, the lower limit of quantification (LLOQ) was obtained as 148 pM with a relative standard deviation of 0.16%. Eventually, as a proof of concept, the designed biosensor was successfully used for detection of donkey genetic element in consumable beef sausages preparations, as a real sample. It is predicted that the proposed biosensor will provide a sensitive, inexpensive, fast, and reliable bioassay for application in food analysis, forensic investigations, genetic screening and biodiagnostics. As a prominent feature of this study, the recorded results were confirmed by quantitative real time-polymerase chain reaction (QRT-PCR) as a standard method in adulteration analysis. Our future perspective is minutralization of the development bioassay for making on-desk device and specially merging the designed system by microfluidic systems for accelerating the analysis time.

Advances in nanomaterial based optical biosensing and bioimaging of apoptosis via caspase-3 activity: a review

Caspase-3 plays a vital role in intrinsic and extrinsic pathways of programed cell death and in cell proliferation. Its detection is an important tool for early detection of some cancers and apoptosis-related diseases, and for monitoring the efficacy of pharmaceuticals and of chemo- and radiotherapy of cancers. This review (with 72 references) summarizes nanomaterial based methods for signal amplification in optical methods for the determination of caspase-3 activity. Following an introduction into the field, a first large section covers optical assays, with subsections on luminescent and chemiluminescence, fluorometric (including FRET based), and colorimetric assays. Further section summarize methods for bioimaging of caspase-3. A concluding section covers current challenges and future perspectives. Graphical Abstract ᅟ.

Electro-sensing base for mefenamic acid on a 5% barium-doped zinc oxide nanoparticle modified electrode and its analytical application

In the present work, surface enhanced electro-oxidation of mefenamic acid (MFA) at a glassy carbon electrode modified with 5% barium doped ZnO nanoparticles was studied.