Recognition Of Biomolecules Research Articles

Utilizing Electrochemical-Based Sensing Approaches for the Detection of SARS-CoV-2 in Clinical Samples: A Review.

The development of precise and efficient diagnostic tools enables early treatment and proper isolation of infected individuals, hence limiting the spread of coronavirus disease 2019 (COVID-19). The standard diagnostic tests used by healthcare workers to diagnose severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection have some limitations, including longer detection time, the need for qualified individuals, and the use of sophisticated bench-top equipment, which limit their use for rapid SARS-CoV-2 assessment. Advances in sensor technology have renewed the interest in electrochemical biosensors miniaturization, which provide improved diagnostic qualities such as rapid response, simplicity of operation, portability, and readiness for on-site screening of infection. This review gives a condensed overview of the current electrochemical sensing platform strategies for SARS-CoV-2 detection in clinical samples. The fundamentals of fabricating electrochemical biosensors, such as the chosen electrode materials, electrochemical transducing techniques, and sensitive biorecognition molecules, are thoroughly discussed in this paper. Furthermore, we summarised electrochemical biosensors detection strategies and their analytical performance on diverse clinical samples, including saliva, blood, and nasopharyngeal swab. Finally, we address the employment of miniaturized electrochemical biosensors integrated with microfluidic technology in viral electrochemical biosensors, emphasizing its potential for on-site diagnostics applications.

Evanescent Wave Optical-Fiber Aptasensor for Rapid Detection of Zearalenone in Corn with Unprecedented Sensitivity.

Zearalenone (ZEN) is a common mycotoxin pollutant found in agricultural products. Aptamers are attractive recognition biomolecules for the development of mycotoxin biosensors. Even though numerous aptasensors have been reported for the detection of ZEN in recent years, many of them suffer from problems including low sensitivity, low specificity, tedious experimental steps, high-cost, and difficulty of automation. We report here the first evanescent wave optical-fiber aptasensor for the detection of ZEN with unprecedented sensitivity, high specificity, low cost, and easy of automation. In our aptasensor, a 40-nt ZEN-specific aptamer (8Z31) is covalently immobilized on the fiber. The 17-nt fluorophore Cy5.5-labeled complementary DNA strand and ZEN competitively bind with the aptamer immobilized on the fiber, enabling the signal-off fluorescent detection of ZEN. The coating of Tween 80 enhanced both the sensitivity and the reproducibility of the aptasensor. The sensor was able to detect ZEN spiked-in the corn flour extract with a semilog linear detection range of 10 pM-10 nM and a limit of detection (LOD, S/N = 3) of 18.4 ± 4.0 pM (equivalent to 29.3 ± 6.4 ng/kg). The LOD is more than 1000-fold lower than the maximum ZEN residue limits set by China (60 μg/kg) and EU (20 μg/kg). The sensor also has extremely high specificity and showed negligible cross-reactivity to other common mycotoxins. In addition, the sensor was able to be regenerated for 28 times, further decreasing its cost. Our sensor holds great potential for practical applications according to its multiple compelling features.

Biocompatible bonding of a rigid off-stoichiometry thiol-ene-epoxy polymer microfluidic cartridge to a biofunctionalized silicon biosensor

Attachment of biorecognition molecules prior to microfluidic packaging is advantageous for many silicon biosensor-based lab-on-a-chip (LOC) devices. This necessitates biocompatible bonding of the microfluidic cartridge, which, due to thermal or chemical incompatibility, excludes standard microfabrication bonding techniques. Here, we demonstrate a novel processing approach for a commercially available, two-step curable polymer to obtain biocompatible ultraviolet initiated (UVA)-bonding of polymer microfluidics to silicon biosensors. Biocompatibility is assessed by UVA-bonding to antibody-functionalized ring resonator sensors and performing antigen capture assays while optically monitoring the sensor response. The assessments indicate normal biological function of the antibodies after UVA-bonding with selective binding to the target antigen. The bonding strength between polymer and silicon chips (non-biofunctionalized and biofunctionalized) is determined in terms of static liquid pressure. Polymer microfluidic cartridges are stored for more than 18 weeks between cartridge molding and cartridge-to-silicon bonding. All bonded devices withstand more than 2500 mbar pressure, far exceeding the typical requirements for LOC applications, while they may also be de-bonded after use. We suggest that these characteristics arise from bonding mainly through intermolecular forces, with a large extent of hydrogen bonds. Dimensional fidelity assessed by microscopy imaging shows less than 2% shrinkage through the molding process and the water contact angle is approximately 80°. As there is generally little absorption of UVA light (365 nm) in proteins and nucleic acids, this UVA-bonding procedure should be applicable for packaging a wide variety of biosensors into LOC systems.

Ultra-high-sensitive biosensor based on SrTiO3 and two-dimensional materials: ellipsometric concepts

We propose a new Kretschmann configuration-based SPR biosensor using the combination of SrTiO3 (STO) and two-dimensional (2D) materials. Using STO and single-layer graphene (SLG) enhanced the sensitivity by about 187% compared to conventional SPR biosensors in the angle interrogation method. This enhancement is related to the 44 nm of silver/13 nm of STO/SLG structure with a sensitivity of 333.2 °/RIU and conventional Ag-based SPR biosensor has a sensitivity of 116 °/RIU. Although the highest achieved sensitivity is 409 °/RIU for the 40 nm of Ag/14 nm of STO but for biosensor applications, 2D materials are needed to act as a Biomolecule Recognition Element (BRE). Furthermore, numerical modeling of ellipsometry integrated with the SPR technique is used, and it showed extraordinary enhancement in the overall performance of the proposed biosensor. Firstly, using Ψ can help to enhance the quality factor (QF) of the 2D materials-based SPR biosensor by more than 50%. Furthermore, using differential phase from numerical modeling of ellipsometry, by providing the extraordinary sensitivity of about 32140 °/RIU, improve the sensitivity more than 270-fold compared to conventional Ag-based SPR biosensors. These results show that our proposed structure and method will be beneficial in biomedical applications.

Coding recognition of the dose-effect interdependence of small biomolecules encrypted on paired chromatographic-based microassay arrays.

The discovery of small biomolecules has suffered from the lack of a comprehensive framework to express the intrinsic correlation between bioactivity and the contribution from small molecules in complex samples with molecular and bioactivity diversity. Here, by mapping a sample’s 2D-HPTLC fingerprint to microplates, paired chromatographic-based microassay arrays are created, which can be used as quasi-chips to characterize multiple attributes of chromatographic components; as the array differential expression of the bioactivity and molecular attributes of irregular chromatographic spots for dose–effect interdependent encoding; and also as the automatic-collimated array mosaics of the multi-attributes of each component itself encrypted by its chromatographic fingerprint. Based on this homologous framework, we propose a correlating recognition strategy for small biomolecules through their self-consistent chromatographic behavior characteristics. In the approach, the small biomolecule recognition in diverse compounds is transformed into a constraint satisfaction problem, which is addressed through examining the dose–effect interdependence of the homologous 2D code pairs by an array matching algorithm, instead of preparing diverse compound monomers of complex test samples for identification item-by-item. Furthermore, considering the dose–effect interdependent 2D code pairs as links and the digital-specific quasimolecular ions as nodes, an extendable self-consistent framework that correlates mammalian cell phenotypic and target-based bioassays with small biomolecules is established. Therefore, the small molecule contributions and the correlations of bioactivities, as well as their pathways, can be comprehensively revealed, so as to improve the reliability and efficiency of screening. This strategy was successfully applied to galangal, and demonstrated the high-throughput digital preliminary screening of small biomolecules in a natural product.Graphical abstract Supplementary InformationThe online version contains supplementary material available at 10.1007/s00216-022-04162-9.

Methyl ester and aromatic ether modification of mitragynine for generation of mitragynine-specific polyclonal antibodies

Mitragynine is an alkaloid from Mitragyna speciosa Korth. (kratom), a native tropical plant in Southeast Asia. It could render psychotropic effects and is often misused in substitution for commercial drugs. In recent years, the consumption of kratom has grown rapidly and has led some countries to ban its use. The misuse of kratom can be detected and monitored through the determination of mitragynine from biological samples of the users. Therefore, the development of a rapid and effective detection method is needed. In this study, polyclonal antibodies were produced using mitragynine coupled to a carrier protein (cationic bovine serum albumin, cBSA) as an immunogen, which was prepared with coupling agents (i.e., N, N- dicyclohexylcarbodiimide, DCC and N-hydroxysuccinimide, NHS). It was conjugated to different mitragynine structure, 16-COOCH3 (methyl ester) and 9-OCH3 (aromatic ether). 2,4,6-Trinitrobenzenesulfonic acid (TNBS) method showed that 45 and 46 amino groups were bound to C22-MG-cBSA and C9-MG-cBSA, respectively. Fourier-transform infrared spectroscopy (FTIR) spectral changes at C22- and C9-hydroxymitragynine indicated reduction and demethylation process. In UV–Vis spectra, conjugated mitragynine to cBSA and OVA were displayed at a spectral region at 240–300 nm. For the antibody titre, the C22-MG-cBSA anti-serum showed a significantly higher titre than the C9-MG-cBSA at 1/128000 and 1/32000 dilutions, respectively. The detection range of the developed competitive indirect ELISA (CI-ELISA) was 0.01 to 10.00 μg/mL (R2 = 0.9964). The assay exhibited a limit of detection (LOD) and limit of quantification (LOQ) at 0.041 and 0.124 μg/mL, respectively. The antibody produced is a high-value biorecognition molecule that can be further used in developing immuno-based detection methods such as immunosensors and immunochromatographic lateral flow assays. This will benefit the task force or forensic agencies for toxicological screening with high speed and efficiency.

In-situ preparation of hollow CdCoS2 heterojunction with enhanced photocurrent response for highly photoelectrochemical sensing of organophosphorus pesticides

In this study, a porous hollow CdCoS2(2) microsphere was synthesized based on the ZIF-67-S MOFs derived method of sulfurization reaction and calcination process. Under visible light irradiation, the resulting CdCoS2(2) composite showed a markedly enhanced photoelectrochemical (PEC) response. The photocurrent value of the CdCoS2(2) modified ITO electrode was 93-fold and 41-fold than that of CoS and CdS materials, respectively. Promoting the photo-absorption ability by internal multilight scattering/reflection was due to the porous and hollow nature of CdCoS2(2). Furthermore, obtained CdCoS2(2) heterostructure in-situ with a close contact interface could facilitate the separation/migration of photo-induced carriers. The CdCoS2(2) was also mixed with Ag nanoparticles (NPs) to further improve the PEC response. Acetylcholinesterase (AChE) as a bio-recognition molecule was immobilized on the glutaraldehyde-chitosan (GLD-CS) modified CdCoS2(2)@Ag electrode surface by cross-linking effect. AChE could hydrolyze the acetylcholine chloride (ATCl) to produce an electron donor of thiocholine which led to the elevated photocurrent output. When the bioactivity of AChE was inhibited by the organophosphate pesticides (chlorpyrifos as substrate), the reduced production of thiocholine resulted in a decline in photocurrent. Under optimal conditions, the structured AChE/GLD-CS/CdCoS2(2)@Ag/ITO sensing platform was successfully achieved for chlorpyrifos detection. The wide linear response range was from 0.001 to 270 μg mL−1 and with a low detection limit of 0.57 ng mL−1. The proposed PEC biosensor also exhibited excellent selectivity and good stability, demonstrating the designed porous hollow CdCoS2(2)@Ag heterostructured composite promised to be a great application in the PEC sensors.

Current Advances in Aptamer-based Biomolecular Recognition and Biological Process Regulation.

The interaction between biomolecules with their target ligands plays a great role in regulating biological functions. Aptamers are short oligonucleotide sequences that can specifically recognize target biomolecules via structural complementarity and thus regulate related biological functions. In the past ten years, aptamers have made great progress in target biomolecule recognition, becoming a powerful tool to regulate biological functions. At present, there are many reviews on aptamers applied in biomolecular recognition, but few reviews pay attention to aptamer-based regulation of biological functions. Here, we summarize the approaches to enhancing aptamer affinity and the advancements of aptamers in regulating enzymatic activity, cellular immunity and cellular behaviors. Furthermore, this review discusses the challenges and future perspectives of aptamers in target recognition and biological functions regulation, aiming to provide some promising ideas for future regulation of biomolecular functions in a complex biological environment.

Single Molecule Level and Label-Free Determination of Multibiomarkers with an Organic Field-Effect Transistor Platform in Early Cancer Diagnosis.

The single molecule level determination with a transistor (SiMoT) platform has attracted considerable attention in the recognition of various ultralow abundance biomolecules, while complicated labeling and testing processes limit its further applications. Recently, organic field-effect transistor (OFET)-based biosensors are good candidates for constructing an advanced label-free SiMoT platform due to their facile fabrication process, rapid response time, and low sample volume with a wide range of detection. However, the sensitivity of most OFET-based biosensors is in the order of nM and pM, which cannot meet the detection requirements of ultralow abundance protein. Herein, a label-free SiMoT platform is demonstrated by integrating pillar[n]arene as a signal amplifier, and the detection limit can reach 4.75 aM. Besides, by simultaneous determination of α-fetoprotein, carcinoembryonic antigen, and prostate antigen, the proposed multiplexed OFET-based SiMoT platform provides a key step in reliable early cancer diagnosis.

Monitoring of Microbial Safety of Foods Using Lectins: A Review

Food-borne diseases are on the rise, and these will likely continue as a public health concern into the coming decades. Majority of foodborne outbreaks are linked to infections by emerging foodborne pathogens such as Campylobacter, Salmonella, Listeria monocytogenes, and Escherichia coli O157:H7. Foodborne pathogen identification becomes crucial in such scenarios to control these pathogens, associated outbreaks, and diseases. Pathogen detection systems have evolved as essential food safety tools to combat microbial threats and experts are striving to develop robust, accurate and ergonomic rapid pathogen-detection kits. Lectin, a ubiquitous biomolecule (sugar binding proteins) present in almost all domains of life is a promising alternative to molecular based methods as a bio-recognition molecule in detection of foodborne pathogens for biosensor applications, owing to its multivalency and spatial organization of ligands. Due to their extensive prevalence, lectin-based biosensors have become the most sought-after bio-recognition molecules in biosensor applications because of increased sensitivity and reduced cost when compared to immune-based biosensors. The current paper discusses the claimed benefits of lectin as a superior bio-recognition molecule, as well as its numerous applications in biosensor creation.

Recent Advances of Point-of-Care Devices Integrated with Molecularly Imprinted Polymers-Based Biosensors: From Biomolecule Sensing Design to Intraoral Fluid Testing.

Recent developments of point-of-care testing (POCT) and in vitro diagnostic medical devices have provided analytical capabilities and reliable diagnostic results for rapid access at or near the patient’s location. Nevertheless, the challenges of reliable diagnosis still remain an important factor in actual clinical trials before on-site medical treatment and making clinical decisions. New classes of POCT devices depict precise diagnostic technologies that can detect biomarkers in biofluids such as sweat, tears, saliva or urine. The introduction of a novel molecularly imprinted polymer (MIP) system as an artificial bioreceptor for the POCT devices could be one of the emerging candidates to improve the analytical performance along with physicochemical stability when used in harsh environments. Here, we review the potential availability of MIP-based biorecognition systems as custom artificial receptors with high selectivity and chemical affinity for specific molecules. Further developments to the progress of advanced MIP technology for biomolecule recognition are introduced. Finally, to improve the POCT-based diagnostic system, we summarized the perspectives for high expandability to MIP-based periodontal diagnosis and the future directions of MIP-based biosensors as a wearable format.

A Novel Chemosensor for Selective Detection of L‐Arginine and L–Cysteine via Macroscopic Sol‐Gel Transition

AbstractTo develop chemosensors for biomolecule recognition, a multi stimuli responsive supramolecular gelator, [(E)‐4‐((4‐(benzyloxy)phenyl)diazenyl)benzaldehyde], comprised of azo and formyl units, was designed and synthesized from readily available starting materials. The gelator was found to be capable of forming gels in light alcohols and alcohol/water mixtures at low concentrations (0.7–1.5 g/100 mL). The gel rheological analyses showed the dominance of storage modulus (G′) values (ca 5000 Pa) within the range of analysis, confirming the gel stiffness. The xerogel scanning electron microscopy (SEM) studies showed a flake‐like pattern of thin sheets. Our investigations on the gelator sensing abilities revealed that, in addition to the photo‐responsive function due to the presence of azo moiety, its ethanol/water gel exhibited excellent ability to detect l‐arginine among 19 various amino acids, via gel to sol transition and colour change. Furthermore, the gelator could successfully recognize l‐cysteine among 19 amino acids, through macroscopic sol to gel transition and colour change of its alkaline methanolic solution. Moreover, the photo‐ and chemo‐responsive functions of the gelator were demonstrated as two combinational logic gates.

Recent Progress in Rapid Determination of Mycotoxins Based on Emerging Biorecognition Molecules: A Review.

Mycotoxins are secondary metabolites produced by fungal species, which pose significant risk to humans and livestock. The mycotoxins which are produced from Aspergillus, Penicillium, and Fusarium are considered most important and therefore regulated in food- and feedstuffs. Analyses are predominantly performed by official laboratory methods in centralized labs by expert technicians. There is an urgent demand for new low-cost, easy-to-use, and portable analytical devices for rapid on-site determination. Most significant advances were realized in the field bioanalytical techniques based on molecular recognition. This review aims to discuss recent progress in the generation of native biomolecules and new bioinspired materials towards mycotoxins for the development of reliable bioreceptor-based analytical methods. After brief presentation of basic knowledge regarding characteristics of most important mycotoxins, the generation, benefits, and limitations of present and emerging biorecognition molecules, such as polyclonal (pAb), monoclonal (mAb), recombinant antibodies (rAb), aptamers, short peptides, and molecularly imprinted polymers (MIPs), are discussed. Hereinafter, the use of binders in different areas of application, including sample preparation, microplate- and tube-based assays, lateral flow devices, and biosensors, is highlighted. Special focus, on a global scale, is placed on commercial availability of single receptor molecules, test-kits, and biosensor platforms using multiplexed bead-based suspension assays and planar biochip arrays. Future outlook is given with special emphasis on new challenges, such as increasing use of rAb based on synthetic and naïve antibody libraries to renounce animal immunization, multiple-analyte test-kits and high-throughput multiplexing, and determination of masked mycotoxins, including stereoisomeric degradation products.

Aptamer-Based Lateral Flow Assays: Current Trends in Clinical Diagnostic Rapid Tests.

The lateral flow assay (LFA) is an extensively used paper-based platform for the rapid and on-site detection of different analytes. The method is user-friendly with no need for sophisticated operation and only includes adding sample. Generally, antibodies are employed as the biorecognition elements in the LFA. However, antibodies possess several disadvantages including poor stability, high batch-to-batch variation, long development time, high price and need for ethical approval and cold chain. Because of these limitations, aptamers screened by an in vitro process can be a good alternative to antibodies as biorecognition molecules in the LFA. In recent years, aptamer-based LFAs have been investigated for the detection of different analytes in point-of-care diagnostics. In this review, we summarize the applications of aptamer technology in LFAs in clinical diagnostic rapid tests for the detection of biomarkers, microbial analytes, hormones and antibiotics. Performance, advantages and drawbacks of the developed assays are also discussed.

Synthetic approaches for BF2-containing adducts of outstanding biological potential. A review

Organic compounds containing the F or B elements in their structures have recently attracted the interest of the chemists and medicinal chemists because their improved biological properties displayed in comparison to their non-fluorinated or non-borinated parent structures. It is widely been documented that curcumine (CUR) have a high biological potential as antioxidant, anti-inflammatory and anticancer agent, among others, but some drawbacks related to its unfavorable bio-physicochemical properties have prevented its applicability as chemotherapeutic drug. Nevertheless, recent studies have shown that the introduction of the BF 2 functionality in its structure (i.e. CUR-BF 2 adducts) and analogues have significantly improved their biological properties, mainly, their anticancer and antibiotic activities. On the other hand, the BF 2 -adduct BODIPY (i.e. 4,4-difluoro-4-bora-3a-azonia-4a-aza- s -indacene) and derivatives are widely known by their outstanding photophysical properties displayed. However, recently it have increased the interest in such structures, but this time, for the biological properties that these fluorescent compounds are also shown, as convenient probes for diverse biological targets. Focusing on the above findings, we were interested into compile, in this review article, the literature documented since 2000–2020 exclusively engaged with the synthetic strategies established for the synthesis of curcumine-BF 2 adducts, BODIPY and their related derivatives, in which the biological properties displayed by such structures have been highlighted. Remarkably, the biological activities displayed by the aforementioned BF 2 -based compounds are mainly related with cell imaging studies, biomolecules recognition and labels, antibiotic properties and antiproliferative agents, which were conveniently used to organize them in concise Tables and Schemes to facilitate their comparisons, and to underscore the key points of the present review.

Advances in quantum dots as diagnostic tools.

Quantum dots (QDs) are crystalline inorganic semiconductor nanoparticles a few nanometers in size that possess unique optical electronic properties vs those of larger materials. For example, QDs usually exhibit a strong and long-lived photoluminescence emission, a feature dependent on size, shape and composition. These special optoelectronic properties make them a promising alternative to conventional luminescent dyes as optical labels in biomedical applications including biomarker quantification, biomolecule targeting and molecular imaging. A key parameter for use of QDs is to functionalize their surface with suitable (bio)molecules to provide stability in aqueous solutions and efficient and selective tagging biomolecules of interest. Researchers have successfully developed biocompatible QDs and have linked them to various biomolecule recognition elements, i.e., antibodies, proteins, DNA, etc. In this chapter, QD synthesis and characterization strategies are reviewed as well as the development of nanoplatforms for luminescent biosensing and imaging-guided targeting. Relevant biomedical applications are highlighted with a particular focus on recent progress in ultrasensitive detection of clinical biomarkers. Finally, key future research goals to functionalize QDs as diagnostic tools are explored.

Highly Sensitive Electrochemical Aptasensor for Detection of Glypican-3 Using Hemin-Reduced Graphene Oxide-Platinum Nanoparticles Coupled with Conductive Reduced Graphene Oxide-Gold Nanoparticles.

An electrochemical aptasensor for quantitatively detecting glypican-3 (GPC3) was constructed by combining hemin-reduced graphene oxide-platinum (H-rGO-Pt) nanoparticles (NPs) with reduced graphene oxide-gold (rGO-Au) nanoparticles (NPs). Herein, the rGO-Au NPs deposited onto screen-printed electrodes resulted in signal amplification due to their large surface areas. Meanwhile, highly conductive H-rGO-Pt NPs acted as a sensing medium that improved electrical conductivity and as an indicator for monitoring peak current for determination. A GPC3 aptamer (GPC3apt) with a low equilibrium dissociation constant was used as a bio-recognition molecule. GPC3apt specifically captured GPC3 proteins and formed aptamer-GPC3 complexes, which impeded electron transfer and thus hampered the redox signal of hemin in H-rGO-Pt NPs. This developed electrochemical aptasensor showed a linear response to GPC3 (from 0.001 μg/mL to 10 μg/mL) and had a detection limit of 0.001 μg/mL. This work provides a low-cost and highly sensitive detection with and good recovery for GPC3 and holds great promise for the clinical diagnosis of hepatocellular carcinoma.

Conducting Polymer-Based Electrochemical Aptasensor for the Detection of Adenosine

Emerging research in the area of conducting polymer-based electrochemical biosensors has revealed the need for the development of techniques that can enable easy functionalization with biorecognition molecules and enhance biosensor stability. In this work, an electrochemical biosensor for the detection of the small molecule adenosine was developed utilizing a conducting copolymer as a transducing agent. First, a method was developed to modify the surface of indium tin oxide-coated glass slides to enable robust copolymer deposition. A 3,4-ethylenedioxythiophene (EDOT) and 2H-thieno[3,4-b][1,4]dioxepin-3,3(4H)-diacetic acid (ProDOT–(COOH)2) copolymer was then electrochemically grown on the surface of the modified slides. This copolymer was used to covalently attach an aptamer specific to adenosine to the biosensing platform to provide the system with target selectivity. The electroactivity of the conducting polymer before and after aptamer attachment in aqueous electrolyte solutions was studied. The attachment of the aptamers to the conducting polymer was confirmed using fluorescence microscopy and cyclic voltammetry. The fabricated aptamer-based sensors were then used for the electrochemical detection of adenosine, and the performance of the sensor was investigated. The adenosine aptasensor had a limit of detection of 2.33 nM and a linear range from 9.6 nM to 600 μM. The adenosine aptasensor showed good selectivity against competing interfering agents and specificity relative to scrambled oligonucleotide stands. In addition, the sensor showed good stability for up to 6 days when stored in 0.1 M phosphate-buffered saline or argon.

Antibodies as Biosensors’ Key Components: State-of-the-Art in Russia 2020–2021

The recognition of biomolecules is crucial in key areas such as the timely diagnosis of somatic and infectious diseases, food quality control, and environmental monitoring. This determines the need to develop highly sensitive display devices based on the achievements of modern science and technology, characterized by high selectivity, high speed, low cost, availability, and small size. Such requirements are met by biosensor systems—devices for reagent-free analysis of compounds that consist of a biologically sensitive element (receptor), a transducer, and a working solution. The diversity of biological material and methods for its immobilization on the surface or in the volume of the transducer and the use of nanotechnologies have led to the appearance of an avalanche-like number of different biosensors, which, depending on the type of biologically sensitive element, can be divided into three groups: enzyme, affinity, and cellular/tissue. Affinity biosensors are one of the rapidly developing areas in immunoassay, where the key point is to register the formation of an antigen–antibody complex. This review analyzes the latest work by Russian researchers concerning the production of molecules used in various immunoassay formats as well as new fundamental scientific data obtained as a result of their use.

Aptamer biosensing based on metal enhanced fluorescence platform: A promising diagnostic tool

Diagnosis of disease at an early, curable, and reversible stage allows more conservative treatment and better patient outcomes. Fluorescence biosensing is a widely used method to detect biomarkers, which are early indicators of disease. Importantly, biosensing requires a high level of sensitivity. Traditionally, these sensors use antibodies or enzymes as biorecognition molecules; however, these can lack the specificity required in a clinical setting, limiting their overall applicability. Aptamers are short, single stranded nucleotides that are receiving increasing attention over traditional recognition molecules. These exhibit many advantages, such as high specificity, making them promising for ultrasensitive biosensors. Metal enhanced fluorescence (MEF) utilizes plasmonic materials, which can increase the sensitivity of label-based fluorescent biosensors. The fluorescence enhancement achieved by placing metallic nanostructures in close proximity to fluorophores allows for detection of ultra-low biomarker concentrations. Plasmonic biosensors have been successfully implemented as diagnostic tools for a number of diseases, such as cancer, yet reproducible systems exhibiting high specificity and the ability to multiplex remain challenging. Similarly, while aptasensors have been extensively reported, few systems currently incorporate MEF, which could drastically improve biosensor sensitivity. Here, we review the latest advancements in the field of aptamer biosensing based on MEF that have been explored for the detection of a wide variety of biological molecules. While this emerging biosensing technology is still in its infant stage, we highlight the potential challenges and its clinical potential in early diagnosis of diseases.