A novel bioassay for the monitoring of hydrogen peroxide in human plasma samples based on binding of horseradish peroxidase-conjugated prostate specific antigen to poly (toluidine blue) as imprinted polymer receptor

The sensor applications for prostate and lung cancer biomarkers in terms of electrochemical analysis

Prostate and lung cancers are the most common types of cancer and affect a large part of the population around the world, causing deaths. Therefore, the rapid identification of cancer can profoundly impact reducing cancer-related death rates and protecting human lives. Significant resources have been dedicated to investigating new methods for early disease detection. Cancer biomarkers encompass various biochemical entities, including nucleic acids, proteins, sugars, small metabolites, cytogenetic and cytokinetic parameters, and whole tumor cells in bodily fluids. These tools can be utilized for various purposes, such as risk assessment, diagnosis, prognosis, treatment efficacy, toxicity evaluation, and predicting a return. Due to these versatile and critical purposes, there are widespread studies on the development of new, sensitive, and selective approaches for the determination of cancer biomarkers. This review illustrates the significant lung and prostate cancer biomarkers and their determination utilizing electrochemical sensors, which have the advantage of improved sensitivity, low cost, and simple analysis. Additionally, approaches such as improving sensitivity with nanomaterials and ensuring selectivity with MIPs are used to increase the performance of the sensor. This review aims to overview the most recent electrochemical biosensor applications for determining vital biomarkers of prostate and lung cancers in terms of nanobiosensors and molecularly imprinted polymer (MIP)-based biosensors.

Conducting dyes as electro-active monomers and polymers for detecting analytes in biological and environmental samples

Currently, electrochemical sensors are regarded as an efficient tool for the biological and environmental sensing. Electrochemical sensors, such as voltammetric, amperometric, and impedimetric sensors, have gained great attention due to their simplicity, sensitivity, and selectivity. The performance of these electrochemical sensors could be enhanced by surface engineered nano/micro structured materials with conducting dyes/redox species. In this review, a great focus has been put on the redox-active dyes because of their electronic, optical, electrochromic, and conductivity properties. The mechanisms of oxidation and subsequent polymerization of different redox-active dyes at the surface of electrodes have been studied. Additionally, their role in catalyzing the oxidation or reduction of the target analytes at the surfaces of electrodes has also been highlighted. The redox-active dyes were used as electrochemical probes for detecting various analytes in biological and environmental samples. Overall, redox-active dyes are considered promising conducting polymers for the assessment of many analytes such as drugs, pesticides, surfactants, and heavy metal ions.

Construction of a sensitive and selective plasmonic biosensor for prostate specific antigen by combining magnetic molecularly-imprinted polymer and surface-enhanced Raman spectroscopy

Selective and sensitive detection of cancer biomarkers in serum samples is critical for early diagnosis of cancer. Prostate specific antigen is an important biomarker of prostate cancer, which ranks high among cancer-related deaths of men over 50 years old. Herein, a novel analytical method was introduced for detection of PSA by combining high selectivity of molecularly-imprinted polymers and high sensitivity of surface-enhanced Raman spectroscopy (SERS). Firstly, magnetic nanoparticles were grafted with an imprinted layer by using tannic acid as a functional monomer, diethylenetriamine as a cross-linker and prostate specific antigen as a template molecule. Detailed surface characterization and re-binding experiment results indicated that the imprinting of the antigen was successful with an imprinting factor of 5.58. The prepared magnetic molecularly imprinted polymers (MMIPs) were used as an antibody-free capture probe and labeled with gold nanoparticles that were modified with anti-PSA and a Raman reporter, namely 5,5'-dithiobis-(2-nitrobenzoic acid). Thus, a plasmonic structure (sandwich complex) was formed between MMIP and the SERS label. The limit of detection and limit of quantification of the designed sensor were 0.9 pg/mL and 3.2 pg/mL, respectively. The sensor also showed high recovery rates (98.0-100.1% for healthy person and 99.0-101.3% for patient) with low standard deviations (less than 4.3% for healthy person and less than 3.3% for patient) for PSA in serum samples. Compared with the traditional immunoassays, the proposed method has several advantages like low cost, reduced detection procedure, fast response, high sensitivity and selectivity. It is believed that the proposed method can be potentially used for selective and sensitive determination of tumor marker of prostate cancer in clinical applications.

Enzymatic recognition of hydrogen peroxide (H2 O2 ) in human plasma samples using HRP immobilized on the surface of poly(arginine-toluidine blue)- Fe3 O4 nanoparticles modified polydopamine; A novel biosensor

In this study, an innovative strategy was proposed for the electrocatalytical reduction and enzymatic biosensing of hydrogen peroxide (H₂ O₂ ) using chronoamperometry technique. For the first time, immobilization of horseradish peroxidase (HRP) in polydopamine-modified magnetic nanoparticles (PDA-MNPs) was successfully performed. Also, poly(l-arginine/toluidine blue) film-modified glassy carbon electrode was constructed through co-electropolymerization of l-arginine and toluidine blue on the surface of GCE using cyclic voltammetry technique. The engineered hybrid thin film provides strong functionalities for efficient grafting of PDA-MNPs which, in turn, enable the covalent immobilization of HRP. The proposed biosensor was used for the detection of H₂ O₂ in the range of 0.5-30 μM with a low limit of quantification 0.23 μM. It also was successfully applied for the investigation of hydrogen peroxide in human plasma samples.

Sensitive monitoring of doxorubicin in plasma of patients, MDA-MB-231 and 4T1 cell lysates using electroanalysis method

In the present work, an innovative electrochemical sensor was fabricated based on poly toluidine blue modified glassy carbon electrode (PTB-GCE). So, PTB-GCE was used for the detection and determination of doxorubicin hydrochloride (DOX) in cell lysate, and whole human plasma samples. PTB could enhance the rate of electrochemical reaction for the electro oxidation and detection of DOX in real samples. Cyclic voltammetry (CV) technique was used for the electro polymerization of toluidine blue on the surface of GCE with the applied potential ranging from -0.6 to 0.2 V. The sensor construction steps were approved by field emission scanning electron microscopy (FE-SEM), Energy dispersive X-ray spectroscopy (EDX) and electrochemical methods. Also, CV results indicated that the DOX is oxidized via two electrons and two protons process at the optimum pH of 6.5 using PTB modified GCE. Under optimized conditions, differential pulse voltammetry (DPV) technique response exhibited linear relationship between the oxidative peak current and concentration of DOX in the range of 17 nM - 8.6 μM with low limit of quantification (LLOQ) of 17 nM for untreated and treated human plasma samples. Also, determination of DOX in MDA-MB-231 and 4T1cell lysates were performed based on its direct electrochemical oxidation on PTB-GCE. Finally, analytical validation of DOX in human bio-fluids using FDA guideline were done successfully. Results suggested that the proposed electrochemical sensor can be used to the sensitive and selective determination of DOX in biological samples. The interaction results of DOX with cancer cells indicate the developed probe can easily detect candidate drug in cancer cells with high accuracy. To the best of our knowledge this is the first report of the determination of DOX based on the direct electrochemical oxidation on PTB-GCE and determination in MDA-MB-231 and 4T1 cell lysates. It is anticipated that this research open new horizons on the design of new class of electrochemical sensors for determination drugs, and therapeutic drug monitoring (TDM) in human bio-fluids.

Development of a reliable bioanalytical method based on prostate specific antigen trapping on the cavity of molecular imprinted polymer towards sensing of PSA using binding affinity of PSA-MIP receptor: A novel biosensor

In this study, electrically-conducting poly [Toluidine Blue (PTB)] was applied as artificial receptor. It was organized by molecular imprinting approaches and via electrochemical technique for the sensitive monitoring of prostate-specific antigen (PSA). The protein-imprinted PTB was electropolymerized in a pre-formed glutaraldehyde-cysteamine (GA-Cys A) matrix on the surface of gold electrode, which significantly boosted the stability against degradation of the Molecular Imprinted Polymer (MIP) on the surface of pre-modified gold electrode. Moreover, the MIP bio-receptor ability towards protein recognition was explored by some electrochemical techniques. The binding affinity of MIP system was considerably upper than that of non-imprinted polymer (NIP) system, indicating the success of the method in generating imprinted materials that was specifically use to PSA protein. The incubation of the MIP modified electrode in various concentration of PSA (from 1-60 μg/L) resulted in the increase of the Fe (CN)₆^3-/4- redox peak current. The bio-device also showed linear response from 1-60 μg/L and LLOQ of 1 μg/L by using DPV technique, leading to PSA monitoring in clinical samples. The proposed MIP-based biosensor was satisfactorily applied to the determination of PSA in human plasma samples. Therefore, the developed bio-device provides a new approach for sensitive, simple, rapid, and cost-effective monitoring of 1 μg/L of PSA. Notably, this approach could appear as an appropriate candidate for point-of-care (POC) use in clinical and biomedical analyses.