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Summary: Gelatine is obtained from the hydrolysis of collagen in bones, skin, fins, fish scales and insect bodies of cattle, pigs, camels, poultry, fish and insects. Consequently, the diversity and availability of gelatine sources, along with gelatine authentication, are concerns for those consuming gelatine products from religious, health and economic perspectives. Therefore, rapid and reliable protein‐ or DNA‐based detection methods have been developed for gelatine authentication. This review discusses and evaluates biosensor methods, comparing them with various analytical methods in terms of their popularity and precision. Additionally, the development of biosensor methods has been explored to identify a reference for a rapid, accurate, portable and simple method for gelatine detection with a low detection limit and high specificity. [ABSTRACT FROM AUTHOR]

Fast, sensitive, and easy-to-use methods for detecting DNA related to food adulteration, health, religious, and commercial purposes are evolving. In this research, a label-free electrochemical DNA biosensor method was developed for the detection of pork in processed meat samples. Gold electrodeposited screen-printed carbon electrodes (SPCEs) were used and characterized using SEM and cyclic voltammetry. A biotinylated probe DNA sequence of the Cyt b S. scrofa gene mtDNA used as a sensing element containing guanine substituted by inosine bases. The detection of probe-target DNA hybridization on the streptavidin-modified gold SPCE surface was carried out by the peak guanine oxidation of the target using differential pulse voltammetry (DPV). The optimum experimental conditions of data processing using the Box–Behnken design were obtained after 90 min of streptavidin incubation time, at the DNA probe concentration of 1.0 µg/mL, and after 5 min of probe-target DNA hybridization. The detection limit was 0.135 µg/mL, with a linearity range of 0.5–1.5 µg/mL. The resulting current response indicated that this detection method was selective against 5% pork DNA in a mixture of meat samples. This electrochemical biosensor method can be developed into a portable point-of-care detection method for the presence of pork or food adulterations. [ABSTRACT FROM AUTHOR]

The development of rapid, accurate, and efficient detection methods for Salmonella can significantly control the outbreak of salmonellosis that threatens global public health. Despite the high sensitivity and specificity of the microbiological, nucleic-acid, and immunological-based methods, they are impractical for detecting samples outside of the laboratory due to the requirement for skilled individuals and sophisticated bench-top equipment. Ideally, an electrochemical biosensor could overcome the limitations of these detection methods since it offers simplicity for the detection process, on-site quantitative analysis, rapid detection time, high sensitivity, and portability. The present scoping review aims to assess the current trends in electrochemical aptasensors to detect and quantify Salmonella. This review was conducted according to the latest Preferred Reporting Items for Systematic review and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) guidelines. A literature search was performed using aptamer and Salmonella keywords in three databases: PubMed, Scopus, and Springer. Studies on electrochemical aptasensors for detecting Salmonella published between January 2014 and January 2022 were retrieved. Of the 787 studies recorded in the search, 29 studies were screened for eligibility, and 15 studies that met the inclusion criteria were retrieved for this review. Information on the Salmonella serovars, targets, samples, sensor specification, platform technologies for fabrication, electrochemical detection methods, limit of detection (LoD), and detection time was discussed to evaluate the effectiveness and limitations of the developed electrochemical aptasensor platform for the detection of Salmonella. The reported electrochemical aptasensors were mainly developed to detect Salmonella enterica Typhimurium in chicken meat samples. Most of the developed electrochemical aptasensors were fabricated using conventional electrodes (13 studies) rather than screen-printed electrodes (SPEs) (two studies). The developed aptasensors showed LoD ranges from 550 CFU/mL to as low as 1 CFU/mL within 5 min to 240 min of detection time. The promising detection performance of the electrochemical aptasensor highlights its potential as an excellent alternative to the existing detection methods. Nonetheless, more research is required to determine the sensitivity and specificity of the electrochemical sensing platform for Salmonella detection, particularly in human clinical samples, to enable their future use in clinical practice. [ABSTRACT FROM AUTHOR]

The authors describe a gold nanocage-based lateral flow strip biosensor (LFSB) for low-cost and sensitive detection of IgG. This protein was used as a model analyte to demonstrate the proof-of-concept. The method combines the unique optical properties of gold nanocages (GNCs) with highly efficient chromatographic separation. A sandwich-type of immunoreactions occurs on the GNC-based LFSB which has the attractive features of avoiding multiple incubation, separation, and washing steps. The captured GNCs on the purple test zone and control zone of the biosensor are producing characteristic purple bands, and this enables IgG even to be visually detected. Quantitatation was accomplished by reading the intensities of the bands with a portable strip reader. The LFSB fabrication and assay parameters were optimized. The biosensor displays a linear response in the 0.5 to 50 ng⋅mL IgG concentration range, and it has a 15 min assay time. The detection limit is 0.1 ng⋅mL of IgG, which is 2.5 times lower than that when using a gold nanoparticle-based LFSB. In our perception, this assay has a wide potential for the detection of other proteins and species for which respective antibodies are available. [ABSTRACT FROM AUTHOR]

Biomarkers are described as characteristics that provide information about biological conditions whether normal or pathological. Detection of biomarkers at the earliest stage of the cancer is of utmost importance for clinical diagnosis. Electrochemical biosensors allow detecting the low levels of specific analytes in blood, urine or saliva and providing a sensitive approach for direct measurement for cancer biomarker detection. Moreover, the integration of electrochemical devices with nanomaterials, such as carbon nanotubes, gold and magnetic particles offer amplification and multiplexing capabilities for simultaneous measurements of cancer biomarkers very sensitively. This review summarizes the recent developments of electrochemical biosensors systems for the detection of cancer biomarkers with emphasis on voltammetric, amperometric and impedimetric biosensors. A special attention is paid to aptamers and miRNAs that are very promising for the ultra-sensitive and specific cancer biomarker detection. [ABSTRACT FROM AUTHOR]

An electrochemical nucleic acid (NA)-based biosensor is a biosensor that integrates a nucleic acid as the biological recognition element and an electrode as the electrochemical signal transducer. The present report provides concepts, terms, and methodology related to biorecognition elements, detection principles, type of interactions to be addressed, and construction and performance of electrochemical NA biosensors, including their critical evaluation, which should be valuable for a wide audience, from academic, biomedical, environmental, and food-testing, drug-developing, etc. laboratories to sensor producers. [ABSTRACT FROM AUTHOR]

Abstract: Electrochemical DNA biosensors have become strong candidates for DNA based analysis. Allele-specific genotyping is also one of the important research areas, where electrochemical approaches provide promising advances. Recently reported two methods based on electrochemical guanine and colloidal gold (Au) nanoparticle oxidation signals are reviewed and compared with the existing genotyping methods in this report. [Copyright &y& Elsevier]

Presents a study that examined an electrochemical biosensor for the voltammetric detection of DNA sequences related to the bloomforming genera of Microcystis. Background on the uses of DNA biosensor technologies; Functions of microcystin polypeptides; Analysis of the hybrids formed on the electrode surface.

As being the most extensively studied, non-coding, evolutionary conserved, post-transcriptional gene regulators of genome, microRNAs (miRNAs) have taken great attention among various disciplines due to their important roles in biological processes and link with cancer. Due to their diagnostic value, there have been many conventional methods used in detection of miRNAs including northern blotting, quantitative real time PCR (qRT-PCR) and microarray technology besides novel techniques based on various nanotechnology approaches and molecular biology tools including miRNA biosensors. The aim of this review is to explain the importance of miRNAs in biomedical field with an emphasis on early cancer diagnosis by overviewing both research based and commercially available miRNA detection methods in the last decade considering their strengths and weakness with an emphasis on miRNA biosensors. [ABSTRACT FROM AUTHOR]

Abstract: Janus Kinase 2 (JAK2) gene single point mutations, which have been reported to be associated with myeloproliferative disorders, are usually detected through conventional methods such as melting curve assays, allele-specific and quantitative Polymerase Chain Reactions (PCRs). Herein, an electrochemical biosensor for the detection of a Guanine (G) to Thymine (T) transversion at nucleotide position 1849 of the JAK2 gene was reported. Due to clinical importance of this mutation, easy and sensitive tests are needed to be developed. Our aim was to design a biosensor system that is capable of detecting the mutation within less than 1h with high sensitivity. For these purposes, an electrochemical sensing system was developed based on detecting hybridization. Hybridization between probe and its target and discrimination of single point mutation was investigated by monitoring guanine oxidation signals observed at +1.0V with Differential Pulse Voltammetry (DPV) by using synthetic oligonucleotides and Polymerase Chain Reaction (PCR) amplicons. Hybridization between probe and PCR amplicons was also determined with Electrochemical Impedance Spectroscopy (EIS). We successfully detect hybridization first in synthetic samples, and ultimately in real samples involving blood samples from patients as well as additional healthy controls. The limit of detection (S/N=3) was calculated as 44pmol of target sequence in a 40-μl reaction volume in real samples. [Copyright &y& Elsevier]

Abstract: microRNA (miRNA) has drawn a great attention in biomedical research due to its functions on biological processes. Detection of miRNAs is a big challenge since the amount present in real samples is very low and the length of them is short. In this study, for the first time an electrochemical biosensor for detection of mir21 using the oxidation signal of protein 19 (p19) as a molecular caliper was designed. The proposed method enables detection of mir21 in direct, rapid, sensitive, inexpensive and label-free way. Binding specificity of the p19 to 20–23 base pair length double stranded RNA (dsRNA) and direct/water-mediated intermolecular contacts between the fusion protein and miRNA allows detection of miRNA–antimiRNA hybrid structure. The detection of mir21 was achieved in picomole sensitivity through the changes of intrinsic p19 oxidation signals observed at +0.80V with Differential Pulse Voltammetry (DPV) and the specifity of the designed sensor was proved by control studies. [Copyright &y& Elsevier]

• CRISPR/Cas could enhance nucleic acid-based detection in biosensors field. • CRISPR/Cas12 increase sensitivity and selectivity of electrochemical biosensors. • CRISPR/Cas12 EC biosensors has the potential in diagnostic and food monitoring. Each organism has a unique sequence of nitrogenous bases in in the form of DNA or RNA which distinguish them from other organisms. This characteristic makes nucleic acid-based detection extremely selective and compare to other molecular techniques. In recent years, several nucleic acid-based detection technology methods have been developed, one of which is the electrochemical biosensor. Electrochemical biosensors are known to have high sensitivity and accuracy. In addition, the ease of miniaturization of this electrochemical technique has garnered interest from many researchers. On the other hand, the CRISPR/Cas12 method has been widely used in detecting nucleic acids due to its highly selective nature. The CRISPR/Cas12 method is also reported to increase the sensitivity of electrochemical biosensors through the utilization of modified electrodes. The electrodes can be modified according to detection needs so that the biosensor's performance can be improved. This review discusses the application of CRISPR/Cas12-based electrochemical biosensors, as well as various electrode modifications that have been successfully used to improve the performance of these biosensors in the clinical and food monitoring fields. [ABSTRACT FROM AUTHOR]

Abstract: An electrochemical genosensor for the detection of hypermethylation of the glutathione S-transferase P1 (GSTP1) gene, a specific marker of prostate cancer, was reported. This new sensor was used in combination with a single-use carbon graphite working electrode and differential pulse voltammetry, with the results of sample analysis based on the guanine oxidation signals obtained at +1.0V before and after hybridization between probe and synthetic target or denatured PCR samples. The detected DNA hybridization was also characterized by electrochemical impedance spectroscopy with potassium ferri/ferrocyanide as a redox probe. The protocol consisted of 2 different modes: (i) capture probes selective for methylation-specific and unmethylated GSTP1 sequences were immobilized onto the sensor directly, and hybridization was formed on the electrode surface; (ii) probe/target or probe/noncomplementary target couples were mixed in solution phase, and the transducer was modified through simple adsorption. The limit of detection (S/N=3) was calculated as 2.92pmol of target sequence in a 100-μl reaction volume. The optimum analytical detection parameters for the biosensor, as well as its future prospects, were also presented. [Copyright &y& Elsevier]

Abstract: A label-free bioelectronic detection of aptamer–thrombin interaction based on electrochemical impedance spectroscopy (EIS) technique is reported. Multiwalled carbon nanotubes (MWCNTs) were used as modifiers of screen-printed carbon electrotransducers (SPCEs), showing improved characteristics compared to the bare SPCEs. 5′amino linked aptamer sequence was immobilized onto the modified SPCEs and then the binding of thrombin to aptamer sequence was monitored by EIS transduction of the resistance to charge transfer (Rct) in the presence of 5mM [Fe(CN)6]3−/4−, obtaining a detection limit of 105pM. This study represents an alternative electrochemical biosensor for the detection of proteins with interest for future applications. [ABSTRACT FROM AUTHOR]

The interaction of mitomycin C (MC) with fish sperm or calf thymus DNA immobilized onto carbon screen-printed electrodes (CSPE) and carbon paste electrode (CPE) have been studied by using electrochemical techniques as square wave voltammetry (SWV) and differential pulse voltammetry (DPV). After the interaction was occurred between DNA and MC on electrode surface, it was observed that the guanine signal was higher with bare electrode than DNA-modified one. The changes in the experimental parameters such as the concentration of MC, and the accumulation time of MC were studied by using SWV and DPV. In addition, reproducibility, and detection limit parameters were determined using both electrodes. The partition coefficient of MC was also calculated before and after interaction of MC with dsDNA at CPE surface. These results showed that these two different DNA biosensors could be used for the sensitive, rapid and cost effective detection of MC–DNA interaction. [Copyright &y& Elsevier]

The interaction of lycorine (LYC) with calf thymus double stranded DNA (dsDNA) and calf thymus single stranded DNA (ssDNA) was studied electrochemically based on the oxidation signals of guanine and adenine by using differential pulse voltammetry (DPV) at carbon paste electrode (CPE) and pencil graphite electrode (PGE). As a result of the interaction of LYC with DNA, the voltammetric signal of guanine and adenine greatly decreased. The changes in the experimental parameters such as the concentration of LYC, and the accumulation time of LYC were studied by using DPV with PGE. The interaction of LYC with synthetic polynucleotides, such as poly[G] was also observed. The interaction of LYC with dsDNA was also observed at PGE in solution phase. In addition, the detection limit and the reproducibility was determined by using both electrochemical transducers. The application of electrochemical methods on the interactions between DNA and DNA targeted agent were explored. [Copyright &y& Elsevier]

Describes an electrochemical genosensor for the genotype detection of allele-specific factor V Leiden mutation from polymerase chain reaction amplicons using the intrinsic guanine signal. Immobilization of the oligonucleotide capture probes related to the wild-type amplicons; Extent of hybridization between the probe and target sequences; Discrimination between the homozygous and heterozygous mutations.

The interaction of an alkylating agent, 4,4′-dihydroxy chalcone (DHC) with calf thymus double stranded DNA (dsDNA) and calf thymus single stranded DNA (ssDNA) was studied electrochemically based on the oxidation signals of guanine and adenine by using differential pulse voltammetry (DPV) at carbon paste electrode (CPE). As a result of the alkylation of DHC between the base pairs in dsDNA, the voltammetric signal of guanine and adenine greatly decreased. After the interaction of DHC with ssDNA, a higher decrease in the oxidation signals of guanine and adenine was observed under the same conditions. The partition coefficients of DHC at dsDNA and ssDNA modified CPEs were calculated. The interactions of DHC with synthetic polynucleotides, such as polyguanylic acid and polyadenylic acid were also observed. In addition, the detection limit and the reproducibility were determined by using DPV. The interaction of DHC with dsDNA in solution-phase was also investigated and the results were compared with the ones obtained by surface immobilized dsDNA. The application of electrochemical DNA biosensor for monitoring the DNA–alkylating agent interactions was explored. [Copyright &y& Elsevier]

Described here are the electrochemical parameters for MB on binding to DNA at hanging mercury drop electrode (HMDE), glassy carbon electrode (GCE), and carbon paste electrode (CPE) in the solution and at the electrode surface. MB, which interacts with the immobilized calf thymus DNA, was detected by using single-stranded DNA-modified HMDE or CPE (ssDNA-modified HMDE or CPE), bare HMDE or CPE, and double-stranded DNA-modified HMDE or CPE (dsDNA-modified HMDE or CPE) in combination with adsorptive transfer stripping voltammetry (AdTSV), differential pulse voltammetry (DPV), and alternating current voltammetry (ACV) techniques. The structural conformation of DNA and hybridization between synthetic peptide nucleic acid (PNA) and DNA oligonucleotides were determined by the changes in the voltammetric peak of MB. The PNA and DNA probes were also challenged with excessive and equal amount of noncomplementary DNA and a mixture that contained one-base mismatched and target DNA. The partition coefficient was also obtained from the signal of MB with probe, hybrid, and ssDNA-modified GCEs. The effect of probe, target, and ssDNA concentration upon the MB signal was investigated. These results demonstrated that MB could be used as an effective electroactive hybridization indicator for DNA biosensors. Performance characteristics of the sensor are described, along with future prospects. [Copyright &y& Elsevier]

An electrochemical hybridization biosensor based on peptide nucleic acid (PNA) probes is presented. PNA probes were attached covalently through a competition of free amines on the guanine bases and also at the 5′ end of the probe, using N-(3-dimethylamino)propyl)-N′-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) onto a carboxylate terminated alkanethiol self-assembled monolayer (SAM) preformed on a gold electrode (AuE). The covalently immobilized probe could selectively hybridize with the target DNA to form a hybrid on the surface despite the bases being attached to the SAM. The changes in the peak currents of methylene blue (3,7-bis(dimethylamino)phenothiazin-5-ium chloride, MB), an electroactive label, were observed upon hybridization of probe with the target. Effective discrimination against point mutation was also obtained. Performance characteristics of the sensor are described, along with future prospects. [Copyright &y& Elsevier]

An electrochemical DNA biosensor based on the recognition of single stranded DNA (ssDNA) by hybridization detection with immobilized complementary DNA oligonucleotides is presented. DNA and oligonucleotides were covalently attached through free amines on the DNA bases using N-hydroxysulfosuccinimide (NHS) and N-(3-dimethylamino)propyl-N′-ethylcarbodiimide hydrochloride (EDC) onto a carboxylate terminated alkanethiol self-assembled monolayers (SAM) preformed on a gold electrode (AuE). Differential pulse voltammetry (DPV) was used to investigate the surface coverage and molecular orientation of the immobilized DNA molecules. The covalently immobilized probe could selectively hybridize with the target DNA to form a hybrid on the surface despite the bases being attached to the SAM. The changes in the peak currents of methylene blue (MB), an electroactive label, were observed upon hybridization of probe with the target. Peak currents were found to increase in the following order: hybrid-modified AuE, mismatched hybrid-modified AuE, and the probe-modified AuE which indicates the MB signal is determined by the extent of exposed bases. Control experiments were performed using a non-complementary DNA sequence. The effect of the DNA target concentration on the hybridization signal was also studied. The interaction of MB with inosine substituted probes was investigated. Performance characteristics of the sensor are described. [Copyright &y& Elsevier]

DNA biosensors based on nucleic acid hybridization processes are rapidly being developed towards the goal of rapid and inexpensive diagnosis of genetic and infectious diseases. Electrochemical transducers are often being used for detecting the DNA hybridization event, due to their high sensitivity, small dimensions, low cost, and compatibility with microfabrication technology. In this study, an electrochemical biosensor for the voltammetric detection of DNA sequences related to the Hepatitis B virus (HBV) and TT virus (TTV) from polymerase chain reaction (PCR) amplified real samples is described for the first time. The biosensor relies on the immobilization of the 21- or 24-mer single stranded oligonucleotides (probe) related to the HBV and TTV sequences and hybridization of these oligonucleotides with their complementary sequences (target) at carbon paste electrode (CPE). The extent of hybridization between the probe and target sequences was determined by using square wave voltammetry (SWV) with moving average baseline correction and methylene blue (MB) as the hybridization indicator. As a result of the interaction between MB and the bound guanine bases of hybrid at CPE surface, the MB signal decreased, when it was compared with the MB signal, which was observed with probe modified CPE. The difference between the MB signals, obtained from the hybrid modified and the probe modified CPE is used to detect the DNA sequences of the infectious diseases from PCR amplified real samples. Numerous factors affecting the target hybridization and indicator binding reactions are optimized to maximize the sensitivity. [Copyright &y& Elsevier]