Early stage diagnosis of programmed cell death (apoptosis) using electroanalysis: Nanomaterial and methods overview

Electrochemical approach for the analysis of DNA degradation in native DNA and apoptotic cells

The aim of this work was to develop an electrochemical approach for the analysis of DNA degradation and fragmentation in apoptotic cells. DNA damage is considered one of the major causes of human diseases. We analyzed the cleavage processes of the circular plasmid pTagGFP2-N and calf thymus DNA, which were exposed to restriction endonucleases (the restriction endonucleases BstMC I and AluB I and the nonspecific endonuclease I). Genomic DNA from the leukemia K562 cell line was used as a marker of the early and late (mature) stages of apoptosis. Registration of direct electrochemical oxidation of nucleobases of DNA molecules subjected to restriction endonuclease or apoptosis processes was proposed for the detection of these biochemical events. Label-free differential pulse voltammetry (DPV) has been used to measure endonuclease activities and DNA damage using carbon nanotube-modified electrodes. The present DPV technique provides a promising platform for high-throughput screening of DNA hydrolases and for registering the efficiency of apoptotic processes. DPV comparative analysis of the circular plasmid pTagGFP2-N in its native supercoiled state and plasmids restricted to 4 and 23 parts revealed significant differences in their electrochemical behavior. Electrochemical analysis was fully confirmed by means of traditional methods of DNA analysis and registration of apoptotic process, such as gel electrophoresis and flow cytometry.

Upconversion nanoparticles as an immunocomplexing agent for selective detection of caspases via sandwich-like supracomplexes

In this study, a nanoparticle-based sandwich-like immunoassay was designed in dispersion medium to precisely detect apoptosis over caspase antibodies in order to overcome the disadvantages of traditional apoptosis determination methods such as high cost, large sampling requirement, and appropriate laboratory and equipment conditions. For this purpose, a complementary particulate system including magnetic (MNPs) and upconversion silica (UC-SiNPs) nanoparticles while immobilizing antibodies (primary antibody to MNPs, secondary antibody to UC-SiNPs) were synthesized and characterized. Optimization and selectivity studies of the complex formed by primary antibody immobilized MNPs with standard caspase proteins were examined by the HPLC system. Within the scope of optimization studies, protein concentrations, optimal duration, and temperature parameters were evaluated. Optimal conditions were determined for pH, initial concentration, time, and temperature as 7.4, 5.6 μg/mL, 45 min, and room temperature, respectively. Furthermore, the adsorption of competitive proteins was investigated in selectivity studies as well. Moreover, the primary antibody immobilized MNPs were treated with standard caspase proteins under optimal conditions; subsequently, they were interacted with secondary antibody immobilized UC-SiNPs to demonstrate the supracomplex formation meanwhile zeta potential/size measurements and fluorescence emission spectrometry analyses were performed. As a result of these analyses, it was observed that the sandwich-like supracomplexes were successfully formed that significantly varied upconversion emission intensities of UC-SiNPs in dependence on the amounts of caspase proteins. Because this approach enabled a quantitative result, the nanoparticle-based sandwich-like immunoassay should be classified as an easy-to-handled, fast, and promising alternative to benchmark apoptosis assays.

Designing of various biosensor devices for determination of apoptosis: A comprehensive review

Apoptosis is a type of cell death caused by the occurrence of both pathological and physiological conditions triggered by ligation of death receptors outside the cell or triggered by DNA damage and/or cytoskeleton disruption. Timely monitoring of apoptosis can effectively help early diagnosis of related diseases and continuous assessment of the effectiveness of drugs. Detecting caspases, a protease family closely related to cellular apoptosis, and its identification as markers of apoptosis is a popular procedure. Biosensors are used for early diagnosis and play a very important role in preventing disease progression in various body sections. Recently, there has been a widespread increase in the desire to use materials made of paper (e.g. nitrocellulose membrane) for Point-of-Care (POC) testing systems since paper and paper-like materials are cheap, abundant and degradable. Microfluidic paper-based analytical devices (μPADs) are highly promising as they are cost-effective, easy to use, fast, precise and sustainable over time and under different environmental conditions. In this review, we focused our efforts on compiling the different approaches on identifying apoptosis pathway while giving brief information about apoptosis and biosensors. This review includes recent advantages in biosensing techniques to simply determine what happened in the cell life and which direction it would continue. As a conclusion, we believed that the review may help to researchers to compare/update the knowledge about diagnosis of the apoptosis pathway while reminding the basic definitions about the apoptosis and biosensor technologies.

Electroanalysis of Biomolecules: Rational Selection of Sensor Construction

Methods of electrochemical analysis of biological objects based on the reaction of electro-oxidation/electro-reduction of molecules are presented. Polymer nanocomposite materials that modify electrodes to increase sensitivity of electrochemical events on the surface of electrodes are described. Examples of applications electrochemical biosensors constructed with nanocomposite material for detection of biological molecules are presented, advantages and drawbacks of different applications are discussed.

Rational Design of Amphiphilic Diblock Copolymer/MWCNT Surface Modifiers and Their Application for Direct Electrochemical Sensing of DNA

We demonstrate the application of amphiphilic ionic poly(n-butylmethacrylate)-block- poly(2-(dimethylamino)ethyl methacrylate) diblock copolymers (PnBMA₄₀-b-PDMAEMA₄₀, PnBMA₄₀-b-PDMAEMA₁₂₀, PnBMA₇₀-b-PDMAEMA₁₂₀) for dispersing multiwalled carbon nanotubes (MWCNTs) in aqueous media, a subsequent efficient surface modification of screen-printed electrodes (SPEs), and the application of the modified SPEs for DNA electrochemistry. Stable and fine aqueous dispersions of MWCNTs were obtained with PnBMA_x-b-PDMAEMA_y diblock copolymers, regardless of the structure of the copolymer and the amount of MWCNTs in the dispersions. The effect of the diblock copolymer structure was important when the dispersions of MWCNTs were deposited as modifying layers on surfaces of SPEs, resulting in considerable increases of the electroactive surface areas and great acceleration of the electron transfer rate. The SPE/(PnBMA_x-b-PDMAEMA_y + MWCNT) constructs were further exploited for direct electrochemical oxidation of the guanine (G) and adenine (A) residues in a model salmon sperm double-stranded DNA (dsDNA). Two well-defined irreversible oxidation peaks were observed at about +600 and +900 mV, corresponding to the electrochemical oxidation of G and A residues, respectively. A multi-parametric optimization of dsDNA electrochemistry enables one to get the limits of detection (LOD) as low as 5 μg/mL (0.25 μM) and 1 μg/mL (0.05 μM) for G and A residues, respectively. The achieved sensitivity of DNA assay enables quantification of the A and G residues of dsDNA in the presence of human serum and DNA in isolated human leukocytes.

Application of DNA nanodevices for biosensing

Deoxyribonucleic acid (DNA), the carrier of genetic information in living life, is an essential biomacromolecule in almost all living systems. DNA has advantages including, programmability, predictability, high rigidity, and stability. Through self-assembly or combination with other nanomaterials (such as gold nanoparticles, graphene oxides, quantum dots, and polymers), DNA can be applied to construct specific, stable, biocompatible, and functional nanodevices. DNA nanodevices have made greater contributions in a plethora of fields. In this review, we discuss the recent progress of DNA nanodevices in molecular detection and analysis. Meanwhile, we prospect the development of various DNA devices in biological analysis, clinical diagnosis and biomedical research.

DNA-based bioassay of legionella pneumonia pathogen using gold nanostructure: A new platform for diagnosis of legionellosis

The specific diagnosis of hard-growing bacteria is one of the most important concerns of medical bacteriology. Legionella pneumophila is one of the most important bacteria in hard growth. In spite remarkable trends in bacteriology, now day, culture is the gold standard for detection of L. pneumophila. This work is an attempt to quantification of L. pneumophila bacteria using a bioassay. The fabrication of a new electrochemical DNA-based bioassay using gold nano architecture combined with as a transducer substrate combined with toluidine blue (TB) as a redox marker was performed successful. Also, the mixture of beta‑cyclodextrin and dopamine as Poly (dopamine‑β‑Cyclodextrin) was used to proper a biointerface for stabilization of gold nanoparticles optimum immobilize of pDNA sequence (5-SH-TCGA TAC TCT CCC CGC CCC TT T TGTATCGACG-3). So, a specific thiolated pDNA was immobilized on the transducer substrate and DNA hybridization was followed by C-DNA sequence (5-ACA AAA GGG GCG GGG AGA GTA-3) using square wave voltammetry and differential pulse voltammetry. At the optimum conditions, linear range was 1 μM to 1 ZM and low limit of quantification (LLOQ) was 1 Zepto-molar. L. pneumophila were sensitively distinguished by the planned DNA sensor. Finally, the engineered DNA based bioassay could be used for identifying the L. pneumophila samples from patients or environments.

Bioassay of saliva proteins: The best alternative for conventional methods in non-invasive diagnosis of cancer

Non-invasive diagnosis of cancer is often the key to effective treatment and patient survival. Saliva as a multi-constituent oral fluid comprises various disease signaling biomarkers, holds great potential for early-stage cancer diagnostics with cost-effective and easy collection, storage, transport and processing. Therefore, detection of biomarkers and proteins in the saliva samples is highly demand. The current review was performed using reliable internet database (mainly PubMed) to provide an overview of the most recent developments on non-invasive diagnosis of cancers in saliva and highlights main challenges and future prospects in sensing of the salivary biomarkers. The conventional detection methods of cancer biomarkers in saliva is discussed in the paper, however, the main focus is on non-invasive diagnosis of cancers in saliva using immunosensing (electrochemical, optical, piezoelectric), DNA based sensors, aptasensors and peptide based bio-assays The reviewed literature revealed that non-invasive cancer detection methods using the mentioned biosensors and without any processing of saliva sample offers a quick, sensitive, specific and cost effective analytical tool. Besides, salivary based detection methods can be used for simultaneous detection of panels of disease specific biomarkers in a real time manner or as home testing kits in near future.

Cross-linked chitosan/thiolated graphene quantum dots as a biocompatible polysaccharide towards aptamer immobilization

Chitosan has a number of commercial and possible biomedical uses. Chitosan as a polysaccharide is a bioactive polymer with a variety of applications due to its functional properties such as antibacterial activity, non-toxicity, ease of modification, and biodegradability. In this work, cross-linked chitosan/thiolated graphene quantum dot as a biocompatible polysaccharide was modified by gold nanoparticle and used for immobilization of ractopamine (RAC) aptamer. A highly specific DNA-aptamer (5'-SH-AAAAAGTGCGGGC-3'), selected to RAC was immobilized onto thiolated graphene quantum dots (GQDs)-chitosan (CS) nanocomposite modified by gold nanostructures (Au NSs) and used for quantification of RAC. Different shapes of gold nanostructures with various sizes from zero-dimensional nanoparticles to spherical structures were prepared by one-step template-assistant green electrodeposition method. Fully electrochemical methodology was used to prepare a new transducer on a glassy carbon surface which provided a high surface area to immobilize a high amount of the aptamer. Therefore, a label free electrochemical (EC) apta-assay for ultrasensitive detection of RAC was developed. A special immobilization media consisting of Au NSs/GQDs-CS/Cysteamine (CysA) was utilized to improve conductivity and performance of the biosensor. The RAC aptamer was attached on the Au NSs of the composite membrane via AuS bond. The fabrication process of the EC aptamer based assay was characterized by some electrochemical techniques. The peak currents obtained by differential pulse voltammetry decreased linearly with the increasing of RAC concentrations and the apta-assay responds approximately over a wide dynamic range of RAC concentration from 0.0044 fM to 19.55 μM. The low limit of quantification was 0.0044 fM.

Bioassays: The best alternative for conventional methods in detection of Legionella pneumophila

Fastidious bacteria are group of bacteria that not only grow slowly but also have complex nutritional needs. In this review, recent progress made on development of biosensing strategies towards quantification of Legionella pneumophila as fastidious bacteria in microbiology was investigated. In coincidence with medical bacteriology, it is the most widely used bio-monitoring, biosensors based on DNA and antibody. Also, all of legionella pneumophila genosensors and immunosensors that developed in recent years were collected analyzed. This review is meant to provide an overview of the various types of bioassays have been developed for determination of Legionella Legionella, along with significant advances over the last several years in related technologies. In addition, this review described: i) Most frequently applied principles in bioassay/biosensing of Legionellaii) The aspects of fabrication in the perspective of bioassay/biosensing applications iii) The potential of various electrochemical and optical bioassay/biosensing for the determination of Legionella and the circumvention of the most serious problem in immunosensing/immunoassay was discussed. iv) Some of bioassay/biosensing has been discussed with and without labels. v) We also summarize the latest developments in the applications of bioassay/biosensing methods for detection of Legionella. vi) The development trends of optical and electrochemical based bioassay/biosensing are also introduced.

A review on visible-light induced photoelectrochemical sensors based on CdS nanoparticles

Discovering the distinctive photophysical properties of semiconductor nanoparticles (NPs) has made these a popular subject in recent advances in nanotechnology-related analytical methods.

Aptamer based assay of plated-derived grow factor in unprocessed human plasma sample and MCF-7 breast cancer cell lysates using gold nanoparticle supported α-cyclodextrin

Platelet-derived growth factor (PDGF), a protein biomarker, is directly involved in many cell transformation processes, such as tumor growth and progression. Elevation platelet-derived growth factor (PDGF-BB) concentration in plasma could indicate the accelerating growth of metastatic breast tumors and angiogenesis. The development of an apta-assay for detection of PDGF-BB in is presented in this work. A highly specific DNA-aptamer, selected to PDGF-BB was immobilized onto a gold nanoparticles supported α-cyclodextrin and electrochemical measurements were performed in a solution containing the phosphate buffer solution with physiological pH. Variety of shapes of gold nanostructures with different sizes from zero-dimensional nanoparticles to spherical structures were prepared by one-step template (α-cyclodextrin)-assistant green electrodeposition method. Fully electrochemical methodology was used to prepare a new transducer on a gold surface which provided a high surface area to immobilize a high amount of the aptamer. The surface morphology of electrode was characterized by high-resolution field emission scanning electron microscope (FE-SEM) and energy dispersive spectroscopy (EDX). The prepared aptasensors represented different electrochemical activities toward the redox processes of PDGF-BB attributing to the size and shape of the gold nanoparticles. The aptasensor was employed for the detection of PDGF using square wave voltammetry (SWV) and Cyclic voltammetry (CV) techniques. Under optimized condition the calibration curve for PDGF-BB was linear in 0.52-1.52nM with low limit of quantification of 0.52nM. Also, under the optimized experimental conditions, the proposed aptasensor of GNPs_-cubic-α-CD-Apt-Au electrode exhibited excellent analytical performance for MCF-7 cells determination, ranging from 328 TO 593 cells mL^-1 with low limit of quantification of 328 cells mL^-1. As a result, the electrochemical aptasensor was able to detect cancer-related targets in unprocessed human plasma samples.

Ensuring food safety using aptamer based assays: Electroanalytical approach

Aptamers, are being increasingly employed as favorable receptors for constructing highly sensitive biosensors, for their remarkable affinities towards certain targets including a wide scope of biological or chemical substances, and their superiority over other biologic receptors. The selectivity and affinity of the aptamers have been integrated with the wise design of the assay, applying suitable modifications, such as nanomaterials on the electrode surface, employing oligonucleotide-specific amplification strategies or, their combinations. After successful performance of the electrochemical aptasensors for biomedical applications, the food sector with its direct implication for human health, which demands rapid and sensitive and economic analytical solutions for determination of health threatening contaminants in all stages of production process, is the next field of research for developing efficient electrochemical aptasensors. The aim of this review is to categorize and introduce food hazards and summarize the recent electrochemical aptasensors that have been developed to address these contaminants.

An innovative immunosensor for detection of tumor suppressor protein p53 in unprocessed human plasma and cancer cell lysates

An innovative mediator-free electrochemical immunosensor for quantitation of p53 tumor suppressor protein based on signal amplification strategy was fabricated. In this work, biotin conjugated p53-antibody (anti-p53) was immobilized onto a green and biocompatible nanocomposite containing poly l-cysteine (P-Cys) as conductive matrix and 3D gold nanoparticles (GNPs) as signal amplification element. Therefore, a novel nanocomposite film based on P-Cys and GNPs was exploited to develop a highly sensitive immunosensor for detection of p53 protein. Importantly, GNPs prepared by sonoelectrodeposition method which lead to compact morphology. Fully electrochemical methodology was used to prepare a new transducer on a gold surface which provided a high surface area to immobilize a high amount of the anti-p53. The surface morphology of electrode was characterized by high-resolution field emission scanning electron microscope (FE-SEM) and energy dispersive spectroscopy (EDX). The immunosensor was employed for the detection of p53 in physiological pH using square wav voltammetry and differential pulse voltammetry (DPVs) techniques. Under optimized condition the calibration curve for p53 concentration by SWV and DPV was linear in 0.0369-50pM and 0.018-2.5pM with lower limit of quantification of 48fM and 18fM, respectively. The method was successfully applied assay of the p53 in unprocessed human plasma samples. Also, the method was applied to the assay of p53 in human plasma sample and normal and malignant cell line lysates such as (L929 normal cell Line from mouse C3H (L929), colon cancer cell-HCT, prostate cancer cell line PC-3, and human breast adenocarcinoma cell line-MCF7).

Highly sensitive immunosensing of prostate specific antigen using poly cysteine caped by graphene quantum dots and gold nanoparticle: A novel signal amplification strategy

A mediator-free electrochemical immunosensor for quantitation of prostate specific antigen (PSA) based on dual signal amplification strategy was fabricated. In this work, PSA-antibody (anti-PSA) was immobilized onto a green and biocompatible nanocomposite containing poly l-cysteine (P-Cys) as conductive matrix and graphene quantum dots (GQDs)/gold nanoparticles (GNPs) as dual signal amplification elements. Therefore, a novel multilayer film based on P-Cys, GQDs, and GNPs was exploited to develop a highly sensitive amperometric immunosensor for detection of PSA. Fully electrochemical methodology was used to prepare a new transducer on a gold surface which provided a high surface area to immobilize a high amount of the anti-PSA. Importantly, GNPs prepared by soft template synthesized method lead to compact morphology was achieved. The surface morphology of electrode surface was characterized by high-resolution field emission scanning electron microscope (FE-SEM) and energy dispersive spectroscopy (EDX). Chemical compositions of the gold nanoparticles were analysed by an EDX. The immunosensor was employed for the detection of PSA in physiological pH. Under optimized condition the calibration curve for PSA concentration was linear up to 2-9pgmL^-1 with lower limit of quantification of 1.8pgmL^-1.