Design a New Strategy Based on Nanoparticle-Enhanced Chemiluminescence Sensor Array for Biothiols Discrimination

Analytical Methods for Assessing Thiol Antioxidants in Biological Fluids: A Review

Redox metabolism is an integral part of the glutathione system, encompassing reduced and oxidized glutathione, hydrogen peroxide, and associated enzymes. This core process orchestrates a network of thiol antioxidants like thioredoxins and peroxiredoxins, alongside critical thiol-containing proteins such as mercaptoalbumin. Modifications to thiol-containing proteins, including oxidation and glutathionylation, regulate cellular signaling influencing gene activities in inflammation and carcinogenesis. Analyzing thiol antioxidants, especially glutathione, in biological fluids offers insights into pathological conditions. This review discusses the analytical methods for biothiol determination, mainly in blood plasma. The study includes all key methodological aspects of spectroscopy, chromatography, electrochemistry, and mass spectrometry, highlighting their principles, benefits, limitations, and recent advancements that were not included in previously published reviews. Sample preparation and factors affecting thiol antioxidant measurements are discussed. The review reveals that the choice of analytical procedures should be based on the specific requirements of the research. Spectrophotometric methods are simple and cost-effective but may need more specificity. Chromatographic techniques have excellent separation capabilities but require longer analysis times. Electrochemical methods enable real-time monitoring but have disadvantages such as interference. Mass spectrometry-based approaches have high sensitivity and selectivity but require sophisticated instrumentation. Combining multiple techniques can provide comprehensive information on thiol antioxidant levels in biological fluids, enabling clearer insights into their roles in health and disease. This review covers the time span from 2010 to mid-2024, and the data were obtained from the SciFinder® (ACS), Google Scholar (Google), PubMed®, and ScienceDirect (Scopus) databases through a combination search approach using keywords.

Use of metal nanoparticles for preconcentration and analysis of biological thiols

Metal nanoparticles (NPs) exhibit several unique physicochemical properties, including redox activity, surface plasmon resonance, ability to quench fluorescence, biocompatibility, or a high surface-to-volume ratio. They are being increasingly used in analysis and preconcentration of thiol containing compounds, because they are able to spontaneously form a stable Au/Ag/Cu-S dative bond. They thus find wide application in environmental and particularly in medical science, especially in the analysis of biological thiols, the endogenous compounds that play a significant role in many biological systems. In this review article, we provide an overview of various types of NPs that have been applied in analysis and preconcentration of biological thiols, mainly in human biological fluids. We first discuss shortly the types of NPs and their synthesis, properties, and their ability to interact with thiol compounds. Then we outline the sample preconcentration and analysis methods that were used for this purpose with special emphasis on optical, electrochemical, and separation techniques.

Pd-Fe3O4 Janus nanozyme with rational design for ultrasensitive colorimetric detection of biothiols

Although nanozyme-based colorimetric assays have been broadly used for biosensing, some limitations such as low catalytic activity of nanozyme, poor sensitivity to analytes and lack of understanding the structure-activity relationship remain unsolved. In this work, we developed an ultrasensitive colorimetric method for biothiols detection based on density functional theory-assisted design of janus Pd-Fe₃O₄ nanozyme. The Pd-Fe₃O₄ dumbbell-like nanoparticles (DBNPs) prepared by seed-mediated approach shows a uniform heterodimeric nanostructure. Ultrasensitive biothiols detection is achieved from two aspects. On one hand, due to the synergistic effect between Pd and Fe₃O₄ in the dumbbell structure, Pd-Fe₃O₄ DBNPs show enhanced peroxidase-mimic activity compared to the individual components. On the other hand, when the target biothiols molecule is present, its inhibition effect on the janus Pd-Fe₃O₄ nanozyme is also significantly enhanced. The above results are confirmed both in experiment and theoretical calculation. Based on the rational design, a simple, highly selective and urtrasensitive colorimetric and quantitative assay for biothiols is developed. The limit of detection (LOD) can reach as low as 3.1 nM in aqueous solution. This assay is also successfully applied to the detection of biothiols in real urine samples. Moreover, the Pd-Fe₃O₄ nanozyme is used to discriminate biothiols levels in normal and cancer cells with high sensitivity at the cell density of 15,000/mL, which demonstrates its great potential in biological and clinical analysis. This work not only shows the great promise of janus bimetallic nanozymes' excellent functionalities but also provides rational guidelines to design high-performance nanozymes for biosensing and biomedical applications.

Monitoring cysteine level changes under LPS or H2O2 induced oxidative stress using a polymer-based ratiometric fluorescent probe

Cysteine (Cys) is a critical amino acid that involves in many physiological and pathological processes in the human body, and it plays an important role in maintaining redox homeostasis in living systems. The concentration of intracellular Cys is abnormal under oxidative stress thus leading to many diseases. Therefore, it is significant to develop an effective method for detection of Cys under oxidative stress. In this work, we propose a new polymer-based ratiometric fluorescent probe with good selectivity and sensitivity for detecting Cys. The bioimaging experiments results show that the novel probe has a rapid ratiometric response to Cys, which can be used to monitor Cys level changes during LPS or H₂O₂ induced oxidative stress in living cells and zebrafish.

On the Challenges for the Diagnosis of SARS-CoV-2 Based on a Review of Current Methodologies

Diagnosis of COVID-19 has been challenging owing to the need for mass testing and for combining distinct types of detection to cover the different stages of the infection. In this review, we have surveyed the most used methodologies for diagnosis of COVID-19, which can be basically categorized into genetic-material detection and immunoassays. Detection of genetic material with real-time polymerase chain reaction (RT-PCR) and similar techniques has been achieved with high accuracy, but these methods are expensive and require time-consuming protocols which are not widely available, especially in less developed countries. Immunoassays for detecting a few antibodies, on the other hand, have been used for rapid, less expensive tests, but their accuracy in diagnosing infected individuals has been limited. We have therefore discussed the strengths and limitations of all of these methodologies, particularly in light of the required combination of tests owing to the long incubation periods. We identified the bottlenecks that prevented mass testing in many countries, and proposed strategies for further action, which are mostly associated with materials science and chemistry. Of special relevance are the methodologies which can be integrated into point-of-care (POC) devices and the use of artificial intelligence that do not require products from a well-developed biotech industry.

Nanomaterial-enhanced chemiluminescence reactions and their applications

Chemiluminescence (CL) analysis is a trace analytical method that possesses advantages including high sensitivity, wide linear range, easy operation, and simple instruments. With the development of nanotechnology, many nanomaterial (NM)-enhanced CL systems have been established in recent years and applied for the CL detection of metal ions, anions, small molecules, tumor markers, sequence-specific DNA, and RNA. This review summarizes the research progress of the nanomaterial-enhanced CL systems the past five years. These CL reactions include luminol, peroxyoxalate, lucigenin, ultraweak CL reactions, and so on. The CL mechanisms of the nanomaterial-enhanced CL systems are discussed in the first section. Nanomaterials take part in the CL reactions as the catalyst, CL emitter, energy acceptor, and reductant. Their applications are summarized in the second section. Finally, the challenges and opportunities are discussed.

A fluorescein-gold nanoparticles probe based on inner filter effect and aggregation for sensing of biothiols

Cysteine (Cys), homocysteine (HCys) and glutathione (GSH) are sulfhydryl-containing amino acids known as biothiols being able to bind to gold nanoparticles (AuNPs) via sulfhydryl group, resulting in the aggregation of AuNPs. Owning to their inner filter effect, AuNPs can weaken or even quench the fluorescence of fluorescein. However, the introduction of biothiols to fluorescein-AuNPs leads to the recovery of fluorescein fluorescence. Thus, a simple and reliable turn on fluorescence method was developed for monitoring biothiols with fluorescein-AuNPs as a probe. Several factors, including AuNPs concentration, pH value and incubation time, which might influence the fluorescence reclamation of fluorescein-AuNPs probe, were optimized by taking Cys as an example at room temperature. Under the optimal conditions, sensitive sensing of Cys, HCys and GSH was achieved. The detection limits for Cys, GSH, and HCys were 0.027, 0.023, and 0.030μΜ, respectively. This method was used to the determination of Cys in human serum samples with high precision and accuracy, indicating the potential of the method in practical applications with simple operation, good accuracy and high sensitivity.

Optical nanoprobes for chiral discrimination

Chiral recognition can be achieved by exploiting chiral properties of nanoparticles within various colorimetric and luminescent sensing systems.

Direct Determination of Redox Statuses in Biological Thiols and Disulfides with Noncovalent Interactions of Poly(ionic liquid)s

The three most important redox couples, including cysteine (Cys)/cystine (Cyss), homocysteine (Hcys)/homocystine (Hcyss), and reduced glutathione (GSH)/glutathione disulfide (GSSG), are closely associated with human aging and many diseases. Thus, it is highly important to determine their redox statuses at the following two levels: (i) the redox identity in different thiols/disulfides and (ii) the redox ratio in a mixture of a specific couple. Herein, by using one single AIE-doped (AIE, aggregation-induced emission) photonic-structured poly(ionic liquid) (PIL) sphere as a virtual sensor array, we realize a direct determination of the redox status without a reducing pretreatment of disulfides, which will greatly promote the development of high-throughput and simple procedures. The pattern-recognition method uses the multiple noncovalent interactions of imidazolium-based PILs with these redox species to produce differential responses in both the photonic crystal and fluorescence dual channels. On the one hand, a single sphere enables the direct and simultaneous discrimination of the redox identities of Cys, Cyss, Hcys, Hcyss, GSH, and GSSG under the interference of other five commonly occurring thiols. On the other hand, this sphere also allows for not only a direct quantification of the GSH/GSSG ratios without previously determining the individual concentrations of GSH and GSSG but also the accurate prediction of the ratios in unknown redox samples. To further demonstrate applications of this method, redox mixtures in a biological sample are differentiated. Additionally, quantum calculations further support our assignments for interactions between the imidazolium-based PILs and these redox species.

Pt NPs catalyzed chemiluminescence method for Hg2+ detection based on a flow injection system

Establishing a simple and accurate method for Hg²⁺ detection is of great importance for the environment and human health. In this work, platinum nanoparticles (Pt NPs) with different capped agents and morphologies were synthesized. It was found that Pt NPs exhibited peroxidase-like activity that can catalyze the chemiluminescence (CL) of the luminol system without H₂ O₂ . The most intensive CL signals were obtained by using PVP-capped Pt NPs as catalysis. Based on the fact that Hg²⁺ could further enhance the CL intensity in the Pt NPs-luminol CL system, a Pt NPs-catalyzed CL method based on a flow injection system is developed for the sensitive analysis of Hg²⁺ . When the concentration of Hg²⁺ in the system increases, the CL intensity would together increase, thereby achieving sensitive Hg²⁺ detection. The limit of detection (LOD) was calculated to be 8.6 nM. This developed method provides a simple and rapid approach for the sensitive detection of Hg²⁺ and shows great promise for applications in other complex systems.

Array-based "Chemical Nose" Sensing in Diagnostics and Drug Discovery

Array-based sensor "chemical nose/tongue" platforms are inspired by the mammalian olfactory system. Multiple sensor elements in these devices selectively interact with target analytes, producing a distinct pattern of response and enabling analyte identification. This approach offers unique opportunities relative to "traditional" highly specific sensor elements such as antibodies. Array-based sensors excel at distinguishing small changes in complex mixtures, and this capability is being leveraged for chemical biology studies and clinical pathology, enabled by a diverse toolkit of new molecular, bioconjugate and nanomaterial technologies. Innovation in the design and analysis of arrays provides a robust set of tools for advancing biomedical goals, including precision medicine.

Chemiluminometric fingerprints for identification of plasmonic nanoparticles

Development of a convenient and inexpensive method for identification and detection of nanoparticles (NPs) is of great interest. In this work, we have developed a novel and simple chemiluminescence based sensor array, with its sensing mechanism mimicking that of olfactory and gustatory systems for discriminating a set of NPs. The proposed method is based on the enhancement effect of NPs on luminol-oxidant CL intensity by their catalytic effect. Three kinds of oxidant including H₂O₂, AgNO₃, and K₃Fe(CN)₆ were used as sensor elements and NPs exhibited diverse enhancing responses to different oxidant-luminol CL systems producing unique response patterns that were identified through heat map and chemometric methods, including linear discriminant analysis (LDA) and hierarchical cluster analysis (HCA). Five NPs have been well distinguished at various concentrations. In addition, this method clearly revealed a linear relationship between CL signal values and the concentrations of NPs for the quantitative detection of NPs. We believe that this type of CL sensor array can open a new way for facile discrimination and detection of different kinds of NPs.

Nanoparticle-based Chemiluminescence for Chiral Discrimination of Thiol-Containing Amino Acids

The ability to recognize the molecular chirality of enantiomers is extremely important owing to their critical role in drug development and biochemistry. Convenient discrimination of enantiomers has remained a challenge due to lack of unsophisticated methods. In this work, we have reported a simple strategy for chiral recognition of thiol-containing amino acids including penicillamine (PA), and cysteine (Cys). We have successfully designed a nanoparticle-based chemiluminescence (CL) system based on the reaction between cadmium telluride quantum dots (CdTe QDs) and the enantiomers. The different interactions of CdTe QDs with PA enantiomers or Cys enantiomers led to different CL intensities, resulting in the chiral recognition of these enantiomers. The developed method showed the ability for determination of enantiomeric excess of PA and Cys. It has also obtained an enantioselective concentration range from 1.15 to 9.2 mM for PA. To demonstrate the potential application of this method, the designed platform was applied for the quantification of PA in urine and tablet samples. For the first time, we presented a novel practical application of nanoparticle-based CL system for chiral discrimination.

Aptasensors as the future of antibiotics test kits-a case study of the aptamer application in the chloramphenicol detection

Antibiotics are a type of antimicrobial drug with the ubiquitous presence in foodstuff that effectively applied to treat the diseases and promote the animal growth worldwide. Chloramphenicol as one of the antibiotics with the broad action spectrum against Gram-positive and Gram-negative bacteria is widely applied for the effective treatment of infectious diseases in humans and animals. Unfortunately, the serious side effects of chloramphenicol, such as aplastic anemia, kidney damage, nausea, and diarrhea restrict its application in foodstuff and biomedical fields. Development of the sufficiently sensitive methods to detect chloramphenicol residues in food and clinical diagnosis seems to be an essential demand. Biosensors have been introduced as the promising tools to overcome the requirement. As one of the newest types of the biosensors, aptamer-based biosensors (aptasensors) are the efficient sensing platforms for the chloramphenicol monitoring. In the present review, we summarize the recent achievements of the accessible aptasensors for qualitative detection and quantitative determination of chloramphenicol as a candidate of the antibiotics. The present chloramphenicol aptasensors can be classified in two main optical and electrochemical categories. Also, the other formats of the aptasensing assays like the high performance liquid chromatography (HPLC) and microchip electrophoresis (MCE) have been reviewed. The enormous interest in utilizing the diverse nanomaterials is also highlighted in the fabrication of the chloramphenicol aptasensors. Finally, some results are presented based on the advantages and disadvantages of the studied aptasensors to achieve a promising perspective for designing the novel antibiotics test kits.

The Chemistry of Europium(III) Encountering DNA: Sprouting Unique Sequence-Dependent Performances for Multifunctional Time-Resolved Luminescent Assays

Screening functional DNA that can fruitfully interact with metal ions is a long-standing hot topic in the fields of biotechnology, medicine, and DNA-based sensors. In this paper, we focus on the chemistry of europium(III) (Eu) coupled with single-stranded DNA (ssDNA), and we innovatively unveil that cytosine- and thymine-rich ssDNA oligomers (e.g., C₁₆ and T₁₆) can be effective antenna ligands to sensitize the luminescence of Eu. Luminescence lifetime spectroscopy, circular dichroic (CD) spectroscopy, and isothermal titration calorimetry (ITC) have been used to systematically characterize the interaction involved between Eu and ssDNA. In light of the resultant sequence-dependent performances, the long luminescence lifetime Eu/ssDNA-based label-free and versatile probes are further devised as a pattern distinction system for time-resolved luminescent (TRL) sensing applications. The interactions of metal ions and ssDNA can distinctively shift the antenna effect of ssDNA toward Eu as accessible pattern signals. As a result, as few as two Eu/ssDNA label-free TRL probes can discriminate 17 metal ions via principal component analysis (PCA). In addition, thiols can readily capture metal ions to switch the luminescence of Eu/ssDNA probes initially altered by metal ions. Hence, four Eu/ssDNA-metal ion ensembles are demonstrated to be a powerful label-free TRL sensor array for pattern differentiation of eight thiols and even chiral recognition of cysteine enantiomers with different concentrations. Moreover, the sensitive TRL detection of thiols in biofluids can be successfully realized by using our method, promising its potential practical usage. This is the first report of a ssDNA-sensitized Eu-based TRL platform for label-free yet multifunctional background-free sensing and would open a door for sprouting of more novel lanthanide ion/DNA-relevant strategies toward widespread applications.

A nanopaper-based artificial tongue: a ratiometric fluorescent sensor array on bacterial nanocellulose for chemical discrimination applications

In the present study, a ratiometric fluorescent sensor array as an artificial tongue has been developed on a nanopaper platform for chemical discrimination applications. The bacterial cellulose (BC) nanopaper was utilized for the first time as a novel, flexible, and transparent substrate in the optical sensor arrays for developing high-performance artificial tongues. To fabricate this platform, the hydrophobic walls on the BC nanopaper substrates were successfully created using a laser printing technology. In addition, we have used the interesting photoluminescence (PL) properties of an immobilized ratiometric probe (carbon dot-Rhodamine B (CD-RhB) nanohybrids) on the nanopaper platform to improve the visual discrimination analysis. Heavy metal ions were utilized as model analytes to verify the applicability of the fabricated nanopaper-based ratiometric fluorescent sensor array (NRFSA). Using the color variation of the NRFSA platform upon the addition of heavy metal ions, which have been obtained by a smartphone (under an UV irradiation), five heavy metal ions (i.e., Hg(ii), Pb(ii), Cd(ii), Fe(iii), and Cu(ii)) have been well-distinguished through the RGB analysis via production of the characteristic PL fingerprint-like response patterns for each of them. Moreover, the developed optical sensor array was successfully exploited to identify the heavy metal ions in the water and fish samples. We have also found that the PL spectra, which have been obtained by a spectrofluorometer, of the developed NRFSA can be exploited for discrimination applications. We believe that the nanopaper-based artificial tongues will provide innovative insights into the development of optical sensor arrays towards advanced (bio)chemical discrimination applications and can revolutionize the conventional optical sensor array technology.

Enhanced SIA-chemiluminescence probes for angiotensin II receptor antagonist detection using silver and gold nanoparticles: applications in pharmaceutical formulations

The present work describes three different sequential injection chemiluminescence systems for the detection of some angiotensin II receptor antagonists, such as candesartan cilexetil, valsartan and telmisartan.

A rainbow ratiometric fluorescent sensor array on bacterial nanocellulose for visual discrimination of biothiols

The crucial role of biothiols in many biological processes, which turns them into important biomarkers for the early diagnosis of various diseases, the development of an affordable, sensitive and portable probe for the detection and discrimination of these compounds is of great importance.

Nanoparticle-based optical sensor arrays

As in many other methods that have integrated nanoparticles (NPs), the chemical nose/tongue strategy has also progressed greatly since the entrance of NPs into this field. The fascinating tunable physicochemical properties of NPs have made them powerful candidates for array-based sensing platforms and have enabled the development of real-time, sensitive and portable systems that are able to target complex mixtures of analytes. In particular, the unique optical properties of NPs have a key role in providing promising array-based sensing approaches. This review will describe the main aspects and processes of most common NP-based optical sensor arrays. The fundamental steps in the design of a sensor array together with details of each step would be provided. The review begins with the principles of optical sensor arrays and presents the concept of cross-reactivity as the main criterion in the selection of sensing elements. Changes in the absorption and emission properties of the assembled sensing elements are categorized into two main classes of optical signals (colorimetric and fluorometric). Popular chemometric methods used for analyzing the data acquired by a sensor array have also been briefly introduced. On the basis of the objective and the desired application, different types of plasmonic and fluorescent NP that possess unique opto-physical properties have been presented as available choices in the design of sensing elements. The vast number of applications of NP-based optical sensor arrays published throughout the literature have then been reviewed according to their mechanism of interaction and the type of optical signal. Finally, the remaining challenges and future directions in this topic have been highlighted.

Colorimetric Fingerprints of Gold Nanorods for Discriminating Catecholamine Neurotransmitters in Urine Samples

Catecholamine neurotransmitters, generally including dopamine (DA), epinephrine (EP) and norepinephrine (NE) are known as substantial indicators of various neurological diseases. Simultaneous detection of these compounds and their metabolites is highly recommended in early clinical diagnosis. To this aim, in the present contribution, a high performance colorimetric sensor array has been proposed for the detection and discrimination of catecholamines based on their reducing ability to deposit silver on the surface of gold nanorods (AuNRs). The amassed silver nanoshell led to a blue shift in the longitudinal localized surface plasmon resonance (LSPR) peak of AuNRs, creating a unique pattern for each of the neurotransmitters. Hierarchical cluster analysis (HCA) and linear discriminate analysis (LDA) pattern recognition techniques were employed to identify DA, EP and NE. The proposed colorimetric array is able to differentiate among individual neurotransmitters as well as their mixtures, successfully. Finally, it was shown that the sensor array can identify these neurotransmitters in human urine samples.

A Simple and Rapid Turn On ESIPT Fluorescent Probe for Colorimetric and Ratiometric Detection of Biothiols in Living Cells

Biothiols, such as cysteine (Cys), homocysteine (Hcy), and glutathione (GSH), play a key role in an extensive range of physiological processes and biological functions. Therefore, the selective and sensitive detection of intracellular thiols is important for revealing cellular function. In this study, ethyl 2-(4-(acryloyloxy)-3-formylphenyl)-4-methylthiazole-5-carboxylate (NL-AC) was designed and synthesized as a colorimetric and ratiometric fluorescent probe that can be utilized to rapidly, sensitively and selectively detect biothiols in physiological media. The fluorescence intensity of this probe using the three target biothiols at a concentration of 20 equiv. of the probe increased by approximately 6~10-fold in comparison to that without the biothiols in aqueous solution. The limits of detection (LOD) for Cys, Hcy and GSH were 0.156, 0.185, and 1.838 μM, respectively. In addition, both ¹H-NMR and MS analyses suggested the mechanism of fluorescence sensing to be excited-state intramolecular proton transfer (ESIPT). The novel colorimetric and ratiometric probe is structurally simple and offers detection within 20 min. Furthermore, this probe can be successfully applied in bioimaging. The results indicate high application potential in analytical chemistry and diagnostics.

The improved sensitive detection of C-reactive protein based on the chemiluminescence immunoassay by employing monodispersed PAA-Au/Fe3O4 nanoparticles and zwitterionic glycerophosphoryl choline

Monodispersed PAA-Au/Fe₃O₄ NPs were engineered for highly sensitive CRP assay with zwitterionic glycerophosphoryl choline as the co-blocking agent.