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The spatial constraints imposed by the DNA structure have significant implications for the walking efficiency of three-dimensional DNA walkers. However, accurately quantifying and manipulating steric hindrance remains a challenging task. This study presents a steric hindrance-controlled DNA walker utilizing an enzymatic strand displacement amplification (ESDA) strategy for detecting microRNA-21 (miR-21) with tunable dynamic range and sensitivity. The steric hindrance of the DNA walker was precisely manipulated by varying the length of empty bases from 6.5 Å to 27.4 Å at the end of the track strand and adjusting the volumetric dimensions of the hairpin structure from 9.13 nm3 to 26.2 nm3 at the terminus of the single-foot DNA walking strand. This method demonstrated a tunable limit of detection for miR-21 ranging from 3.6 aM to 35.6 nM, along with a dynamic range from â¼100-fold to â¼166â¯000-fold. Impressively, it exhibited successful identification of cancer cells and clinical serum samples with high miR-21 expression. The proposed novel strategy not only enables tunable detection of miRNA through the regulation of steric hindrance but also achieves accurate and quantitative analysis of the steric hindrance effect, promising broader applications in personalized medicine, early disease detection, and drug development.
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The traditional preparation method of ratiometric probes faces challenges such as cumbersome preparation and low sensitivity. Thus, there is an urgent need to provide a simple method of preparing a highly sensitive ratiometric probe. Here, Eu3+-doped zinc-based organic framework (Eu/Zn-MOF) was prepared through hydrothermal method for the detection of tetracycline analogs (TCs). Under the same excitation conditions, the probe can simultaneously display valuable fluorescence and second-order scattering signals. The developed probe enabled specific identification and fast detection (1 min) of TCs, including tetracycline, oxytetracycline, doxycycline, and chlortetracycline. The linear detection ranges of tetracycline, oxytetracycline, doxycycline and chlortetracycline were respectively 100 nM - 200 µM, 100 nM - 200 µM, 98 nM - 195 µM, and 97 nM - 291 µM, and the corresponding detection limits were respectively 15.79 nM, 20.83 nM, 15.31 nM, and 28.30 nM. The developed sensor was successfully applied to detect TCs in real samples, and the recovery rate was from 92.54 % to 109.69 % and the relative standard deviation was from 0.04 % to 2.97 %. Moreover, the heterometallic Eu/Zn-MOF was designed as a ratiometric neuron for Boolean logic computing and information encryption based on the specific identification of TCs. As a proof of concept, molecular steganography was successfully employed to encode, store, and conceal information by transforming the specific identification patterns of Eu/Zn-MOF into binary strings. This study is anticipated to advance the application of metal-organic frameworks in logic detection and information security, and bridging the gap between molecular sensors and the realm of information.
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Európio , Estruturas Metalorgânicas , Espectrometria de Fluorescência , Zinco , Estruturas Metalorgânicas/química , Európio/química , Zinco/química , Zinco/análise , Corantes Fluorescentes/química , Corantes Fluorescentes/síntese química , Tetraciclinas/análise , Limite de Detecção , Antibacterianos/análise , Tetraciclina/análise , FluorescênciaRESUMO
Cascade molecular events in complex systems are of vital importance for enhancing molecular diagnosis and information processing. However, the conversion of a cascaded biosensing system into a multilayer encrypted molecular keypad lock remains a significant challenge in the development of molecular logic devices. In this study, we present a photocleavable DNA nanotube-based dual-amplified resonance Rayleigh scattering (RRS) system for detecting microRNA-126 (miR-126). The cascading dual-amplification biosensing system provides a multilayer-encrypted prototype with the functionality of a molecular computing cascade keypad lock. RRS signals were greatly amplified by using photocleavable DNA nanotubes and enzyme-assisted strand displacement amplification (SDA). In the presence of miR-126, enzyme-assisted SDA produced numerous identical nucleotide fragments as the target, which were then specifically attached to magnetic beads through the DNA nanotube by using a Y-shaped DNA scaffold. Upon ultraviolet irradiation, the DNA nanotube was released into the solution, resulting in an increase in the intensity of the RRS signal. This strategy demonstrated a low limit of detection (0.16 fM) and a wide dynamic range (1 fM to 1 nM) for miR-126. Impressively, the enzyme-assisted SDA offers a molecular computing model for generating the target pool, which serves as the input element for unlocking the system. By cascading the molecular computing process, we successfully constructed a molecular keypad lock with a multilevel authentication technique. The proposed system holds great potential for applications in molecular diagnosis and information security, indicating significant value in integrating molecular circuits for intelligent sensing.
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Tunable detection of microRNA is crucial to meet the desired demand for sample species with varying concentrations in clinical settings. Herein, we present a DNA walker-based molecular circuit for the detection of miRNA-21 (miR-21) with tunable dynamic ranges and sensitivity levels ranging from fM to pM. The phosphate-activated fluorescence of UiO-66-NH2 metal-organic framework nanoparticles was used as label-free fluorescence tags due to their competitive coordination effect with the Zr atom, which significantly inhibited the ligand-to-metal charge transfer. To achieve a tunable detection performance for miR-21, the ultraviolet sensitive o-nitrobenzyl was induced as a photocleavable linker, which was inserted at various sites between the loop and the stem of the hairpin probe to regulate the DNA strand displacement reaction. The dynamic range can be precisely regulated from 700- to 67,000-fold with tunable limits of detection ranging from 2.5 fM to 36.7 pM. Impressively, a Boolean logic tree and complex molecular circuit were constructed for logic computation and cancer diagnosis in clinical blood samples. This intelligent biosensing method presents a powerful solution for converting complex biosensing systems into actionable healthcare decisions and will facilitate early disease diagnosis.
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Técnicas Biossensoriais , Nanopartículas Metálicas , Estruturas Metalorgânicas , MicroRNAs , Nanopartículas , DNA , MicroRNAs/genética , Técnicas Biossensoriais/métodos , Limite de DetecçãoRESUMO
Conventional electrochemical detection of microRNA (miRNA) encounters issues of poor sensitivity and fixed dynamic range. Here, we report a DNA tile and invading stacking primer-assisted CRISPR-Cas12a multiple amplification strategy to construct an entropy-controlled electrochemical biosensor for the detection of miRNA with tunable sensitivity and dynamic range. To amplify the signal, a cascade amplification of the CRISPR-Cas12a system along with invading stacking primer signal amplification (ISPSA) was designed to detect trace amounts of miRNA-31 (miR-31). The target miR-31 could activate ISPSA and produce numerous DNAs, triggering the cleavage of the single-stranded linker probe (LP) that connects a methylene blue-labeled DNA tile with a DNA tetrahedron to form a Y-shaped DNA scaffold on the electrode. Based on the decrease of current, miR-31 can be accurately and efficiently detected. Impressively, by changing the loop length of the LP, it is possible to finely tune the entropic contribution while keeping the enthalpic contribution constant. This strategy has shown a tunable limit of detection for miRNA from 0.31 fM to 0.56 pM, as well as a dynamic range from â¼2200-fold to â¼270,000-fold. Moreover, it demonstrated satisfactory results in identifying cancer cells with a high expression of miR-31. Our strategy broadens the application of conventional electrochemical biosensing and provides a tunable strategy for detecting miRNAs at varying concentrations.
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Sistemas CRISPR-Cas , MicroRNAs , Entropia , Sistemas CRISPR-Cas/genética , DNA/genética , Eletrodos , MicroRNAs/genéticaRESUMO
Organophosphate pesticides are used in agriculture due to their high effectiveness and low persistence in eradicating insects and pests. However, conventional detection methods encounter the limitation of undesired detection specificity. Thus, screening phosphonate-type organophosphate pesticides (OOPs) from their analogues, phosphorothioate organophosphate pesticides (SOPs), remains a challenge. Here, we reported a d-penicillamine@Ag/Cu nanocluster (DPA@Ag/Cu NCs)-based fluorescence assay to screen OOPs from 21 kinds of organophosphate pesticides, which can be used for logic sensing and information encryption. Acetylthiocholine chloride was enzymatically split by acetylcholinesterase (AChE) to produce thiocholine, which reduced the fluorescence of DPA@Ag/Cu NCs due to the transmission of electrons from DPA@Ag/Cu NCs donor to the thiol group acceptor. Impressively, OOPs acted as an AChE inhibitor and retained the high fluorescence of DPA@Ag/Cu NCs due to the stronger positive electricity of the phosphorus atom. Conversely, SOPs possessed weak toxicity to AChE, which led to low fluorescence intensity. By setting 21 kinds of organophosphate pesticides as the inputs and the fluorescence of the resulting products as the outputs, DPA@Ag/Cu NCs could serve as a fluorescent nanoneuron to construct Boolean logic tree and complex logic circuit for molecular computing. As a proof of concept, by converting the selective response patterns of DPA@Ag/Cu NCs into binary strings, molecular crypto-steganography for encoding, storing, and concealing information was successfully achieved. This study is expected to advance the progress and practical application of nanoclusters in the area of logic detection and information security while also enhancing the relationship between molecular sensors and the world of information.
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Antígenos de Grupos Sanguíneos , Inseticidas , Nanopartículas Metálicas , Organofosfonatos , Praguicidas , Penicilamina , Acetilcolinesterase , Compostos Organofosforados , Corantes , Organofosfatos , Lógica , Cobre , Praguicidas/análiseRESUMO
The widespread presence of tetracyclines in the environment has raised concerns about the potential risks to ecosystems and human health. The ratiometric fluorescence sensor for detecting tetracyclines was developed using europium-doped carbon dots (Eu-CDs) as probes under alkaline conditions. The sensing mechanism of sensor for tetracyclines was considered as inner filter effect (IFE), antenna effect (AE), and self-quenching effect (SQE). The sensor had a wide linear detection range than the reported europium ions-based tetracyclines sensors. The linear detection ranges of oxytetracycline (OTC), tetracycline (TC), doxycycline (DC) and chlorotetracycline (CTC) were respectively 0.00-603.75 µM, 0.00-623.82 µM, 0.00-594.61 µM and 0.00-601.54 µM, and the corresponding detection limits were respectively 9.50 nM, 15.80 nM, 10.40 nM and 90.30 nM. The smartphone with RGB Color Picker was further employed to analyze the concentration of tetracyclines, which provided a new method for visual tetracyclines detection. The application of Eu-CDs test paper was also explored, and the results showed that the Eu-CDs test paper has great potential application in the visual detection of tetracyclines. In addition, the accuracy of the established tetracyclines sensor was compared with that of the China national standard method by high-performance liquid chromatography (HPLC), and the results showed that the established method in this work has similar accuracy to the China national standard method. The sensor has been employed to detect tetracyclines in the actual samples with satisfactory results, which indicated that this method has promising applications in the real-time monitoring tetracyclines of food and environment.
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Pontos Quânticos , Tetraciclinas , Humanos , Tetraciclinas/análise , Carbono/química , Európio/química , Smartphone , Colorimetria , Ecossistema , Pontos Quânticos/química , Corantes Fluorescentes/química , Antibacterianos/análise , Espectrometria de Fluorescência/métodos , Limite de DetecçãoRESUMO
Although some ratiometric fluorescent sensors have been reported to detect tetracyclines, most of ratiometric fluorescent sensors were established based on europium ion with a narrow linear range. In this work, a ratiometric fluorescent sensor for tetracyclines detection was established based on the dual-emission lanthanum-doped carbon dots (La-CDs) as probes combining with the characteristic pH-response of tetracyclines. The fluorescence intensity of tetracyclines will be enhanced in high pH, and the emission peak of tetracyclines overlapped with the peak of probes. The superposition effect of tetracyclines and probes at 515 nm greatly improved the sensitivity of the ratiometric fluorescent sensor and widened the detection range, and linear ranges for oxytetracycline (OTC) and tetracycline (TC) were respectively 0.00-805.20 µM and 0.00-1039.50 µM. Moreover, the preparation procedure of the La-CDs was simple and time saving and the coupling agent was not required. A comparison of La-CDs with undoped carbon dots (un-CDs) showed that the optical performance and sensing performance of La-CDs were improved. In addition, a portable paper sensor with La-CDs as probes was preliminarily explored in this work, and the sensor has been applied to detect OTC and TC in pork and fish with satisfactory results.
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Pontos Quânticos , Tetraciclinas , Animais , Carbono , Corantes Fluorescentes , Concentração de Íons de Hidrogênio , Lantânio , CarneRESUMO
pH-responsive DNA motifs have attracted substantial attention attributed to their high designability and versatility of DNA chemistry. Such DNA motifs typically exploit DNA secondary structures that exhibit pH response properties because of the presence of specific protonation sites. In this review, we briefly summarized second structure-based pH-responsive DNA motifs, including triplex DNA, i-motif, and A+-C mismatch base pair-based DNA devices. Finally, the challenges and prospects of pH-responsive DNA motifs are also discussed.
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In this work, the water-soluble fluorescent Ag nanoclusters (DPA@Ag NCs) were first prepared based on D-Penicillamine (DPA) as a stabilizer, however, the fluorescence quantum yield (QY) of DPA@Ag NCs was very low, then Cu2+ was employed to improve the fluorescence QY and the doped Ag nanoclusters with Cu2+ (DPA@Ag/Cu NCs) were obtained. The study showed that the QY increased fourfold and the emission of nanoclusters changed from red to yellow after addition of Cu2+. The reasonfor change of fluorescent properties wasattributed to the change of self-assembly structures caused by adding Cu2+ into reaction system, leading to the aggregation-induced emission enhancement (AIEE) effect and enhancing the band gap (Eg) between the HOMO and LUMO in nanoclusters. Subsequently, a fluorescent Ag+ sensor with high sensitivity and selectivity was established based on the DPA@Ag/Cu NCs as probes in aqueous solution. Experiments showed that the Ag+ could significantly quench the fluorescence of DPA@Ag/Cu NCs under experimental conditions, and there was a good linear relationship between the fluorescent intensity quenching value and Ag+ concentration in the range of 0.05-800 µM, and the limit of detection (LOD) was 0.03 µM (3σ/k). Meanwhile, most of common ions had no effect on the experimental results under the same conditions. In addition, the sensor was successfully applied on the detection of Ag+ in real water samples, and the recovery rate was 80.3-99.0%.
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Ammonia concentration together with pH values are important and closely linked indexes for aqueous systems. Rapid on-site determination of ammonia or pH is of great significance to environmental monitoring. In this work, a pH-switchable nanoprobe based on biomass carbon dots (CDs) is developed using a smartphone as a simple and handy instrument. The CDs demonstrate sensitive pH response in wide linear ranges of 6.1-13.6, and 2.0-13.6 with colorimetric and fluorescent channels, respectively. It is the pH-induced aggregation that governs the color and fluorescence switch. With the pH evolution caused by the dissolution of ammonia, the smartphone-integrated nanoprobe is applied to ammonia detection with a broad range of 0.5-300â¯mM. Moreover, the headspace single drop microextraction strategy can concentrate ammonia from matrix, offering a remarkably high selectivity for ammonia determination. Finally, the practical applications of this method for ammonia analysis obtained satisfactory results.
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In this work, a facile and label-free ratiometric sensor is constructed for selective determination of norepinephrine (NE) by coupling second-order scattering (SOS) and fluorescence, two different and independent optical signals. Herein, polyethyleneimine (PEI) dilute solution medium shows an intensive SOS signal without any fluorescence response. Interestingly, NE can be selectively induced by PEI to emit bright fluorescence, and meanwhile causes an observable decrease in the SOS signal due to the interactions between NE and PEI. The simultaneous variation of the two independent signals can be used for ratiometric sensing of NE. Under the optimal conditions, the resultant ratiometric sensor displays high sensitivity and selectivity toward NE by simultaneously monitoring fluorescence and SOS signals with the same excitation wavelength. The proposed sensor exhibits a good linear relationship versus NE concentration in the range of 10.0 nM-45.0 µM with a detection limit of 2.0 nM (S/N = 3) and has been successfully applied to the determination of NE in real samples without the use of any extra reagent. The combination of fluorescence and SOS signals provides a new scheme for ratiometric sensor design, greatly simplifying experimental procedure and effectively enhancing detection accuracy. Moreover, the proposed analytical strategy further broadens the application of dilute solutions of polymers in research into optical sensor and green analytical chemistry. Graphical abstract.
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Norepinefrina/análise , Óptica e Fotônica/instrumentação , Espalhamento de Radiação , Espectrometria de Fluorescência/métodos , Estudos de Viabilidade , Fluorescência , Luz , Limite de Detecção , Norepinefrina/normas , Norepinefrina/urina , Tamanho da Partícula , Polietilenoimina/química , Portulaca/química , Padrões de ReferênciaRESUMO
A simple and label-free fluorescence turn-on method is proposed for the discrimination and detection of epinephrine (Ep) and dopamine (DA) via polyethyleneimine (PEI)-initiated in situ copolymerization and excitation wavelength switch. The PEI solution in the presence of Ep, DA and the mixture of Ep and DA are denoted as PEp-PEI, PDA-PEI and MEp+DA, respectively. In this study, PEI aqueous solution medium initiates the auto-oxidization of Ep and DA and the bioinspired copolymerization. These resultant copolymers emit yellow-green fluorescence color with a fluorescence emission maximum at 515â¯nm. Interestingly, these fluorescent copolymers exhibit distinct different excitation spectra, although Ep and DA are structurally very similar. PDA-PEI exhibits only one excitation peak at 385â¯nm, and PEp-PEI shows dual-excitation mode with two significant excitation peaks at 328â¯nm and 405â¯nm, respectively. MEp+DA also shows dual-excitation mode with two excitation peaks at 330â¯nm and 395â¯nm, respectively. Thus, individual Ep, DA, and their mixture can be discriminated based on the different excitation spectral shapes and peak locations of PEp-PEI, PDA-PEI and MEp+DA. Furthermore, the quantitative analysis of Ep and DA in mixture can also be achieved by switching excitation wavelength between 330 and 395â¯nm and monitoring the fluorescence emission intensity of MEp+DA at 515â¯nm. The fluorescence intensity of MEp+DA only related to the concentration of Ep when excited at 330â¯nm. Moreover, the concentration of DA can also be calculated by subtracting the fluorescence intensity of PEp-PEI from the total fluorescence intensity when excited at 395â¯nm. The resultant method has been used to simultaneously detect Ep and DA in human urine samples. The proposed fluorescence system is facile, eco-friendly, low-cost, and time-saving, and also provides a new and simple path for discriminating analogues.
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Materiais Biomiméticos/química , Dopamina/urina , Epinefrina/urina , Polímeros/química , Urinálise/métodos , Dopamina/química , Epinefrina/química , Estudos de Viabilidade , Humanos , Polietilenoimina/química , Polimerização , Espectrometria de Fluorescência , Fatores de TempoRESUMO
Following research on two-dimensional (2D) transition metal dichalcogenides (TMDs), zero-dimensional (0D) TMDs nanostructures have also garnered some attention due to their unique properties; exploitable for new applications. The 0D TMDs nanostructures stand distinct from their larger 2D TMDs cousins in terms of their general structure and properties. 0D TMDs possess higher bandgaps, ultra-small sizes, high surface-to-volume ratios with more active edge sites per unit mass. So far, reported 0D TMDs can be mainly classified as quantum dots, nanodots, nanoparticles, and small nanoflakes. All exhibited diverse applications in various fields due to their unique and excellent properties. Of significance, through exploiting inherent characteristics of 0D TMDs materials, enhanced catalytic, biomedical, and photoluminescence applications can be realized through this exciting sub-class of TMDs. Herein, we comprehensively review the properties and synthesis methods of 0D TMDs nanostructures and focus on their potential applications in sensor, biomedicine, and energy fields. This article aims to educate potential adopters of these excitingly new nanomaterials as well as to inspire and promote the development of more impactful applications. Especially in this rapidly evolving field, this review may be a good resource of critical insights and in-depth comparisons between the 0D and 2D TMDs.
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Fontes de Energia Bioelétrica , Tecnologia Biomédica , Técnicas Biossensoriais , Calcogênios/química , Metais/química , Elementos de Transição/química , Tecnologia Biomédica/instrumentação , Tecnologia Biomédica/métodos , Técnicas Biossensoriais/instrumentação , Técnicas Biossensoriais/métodos , Química Verde/instrumentação , Humanos , Nanoestruturas/química , Pontos Quânticos/químicaRESUMO
A resonance Rayleigh scattering (RRS) aptasensor was fabricated for detection of Pb2+via hairpin-like label-free substrate and G-wire for signal amplification. A hairpin-like DNA substrate contains a sequence in the loop labeled with ribonucleobase A and c-myc sequence in the stem. When hybridized with 8-17 DNAzyme in the presence of Pb2+, the sequence in the loop was activated and cleaved. Hundreds of c-myc sequences departing from the 8-17 DNAzyme yield nanowires superstructure called G-wire in the presence of Mg2+. The polymer G-wire was demonstrated by the RRS spectrum, polyacrylamide gel electrophoresis, and AFM. The RRS intensity was enhanced by the product G-wires, and the RRS signal at 370nm was linear with the logarithm of Pb2+ concentration in the range of 2.0nM to 5.0µM. This method was selective for Pb2+ even coexisting with other metal ions at high concentrations and was successfully applied to the determination of Pb2+ in real samples. The aptasensor holds a great promise for universal RRS sensing platform for sensitive detection of various metal ions just by changing the sequence of the probe in the loop and DNAzyme.
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Aptâmeros de Nucleotídeos/química , Técnicas Biossensoriais , Quadruplex G , Chumbo/análise , Nanofios , Espalhamento de Radiação , Cátions Bivalentes/análise , DNA/química , DNA Catalítico/química , Eletroforese em Gel de Poliacrilamida , Genes myc , Manganês/química , Microscopia de Força Atômica , Polímeros/química , Ribonuclease Pancreático/químicaRESUMO
A stable silver nanoparticles/carbon quantum dots (Ag/CQDs) composite was prepared by using CQDs as reducing and stabilizing agent. The CQDs synthesized with polyethyleneimine (PEI) showed an extraordinary reducibility. When Hg2+ was presented in the Ag/CQDs composite solution, a color change from yellow to colorless was observed, accompanied by a shift of surface plasmon resonance (SPR) band and decrease in absorbance of the Ag/CQDs composite. On the basis of the further studies on TEM, XPS and XRD analysis, the possible mechanism is attributed to the formation of a silver-mercury amalgam. Hence, a two dimensional sensing platform for Hg2+ detection was constructed upon the Ag/CQDs composite. Based on the change of absorbance, a good linear relationship was obtained from 0.5 to 50µM for Hg2+. And the limit of detection for Hg2+ was as low as 85nM, representing high sensitivity to Hg2+. More importantly, the proposed method also exhibits a good selectivity toward Hg2+ over other metal ions. Besides, this strategy demonstrates practicability for the detection of Hg2+ in real water samples with satisfactory results.
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A bidimensional optical sensing platform which combines the advantages of fluorescence and colorimetry has been designed for arginine (Arg) detection. The system was established by monitoring the influence of Arg on the growth of gold nanoparticles/carbon quantum dots (Au/CQDs) composite, and the CQDs synthesized by ethylene glycol were used as the reducing and stabilizing agent in this paper. Considering that Arg is the only amino acid with guanidine group and has the highest isoelectric point (pI) value at 10.76, Arg would carry positive charges at pH 7.4. Consequently, the positively charged guanidine group of Arg could attract AuCl4- and CQDs through electrostatic interaction, which inhibited the growth of Au/CQDs composite. Thereby, the color of the system almost did not change and the fluorescence quenching of CQDs was prevented in the presence of Arg. Based on the color change a low detection limit for Arg was 37nM, and a detection limit of 450nM was obtained by fluorescence spectroscopy. Moreover, this dual-signal sensor also revealed excellent selectivity toward Arg over other amino acids. Besides, Arg can be detected in urine samples with satisfactory results, which demonstrate the potential applications for real analysis.
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Arginina/urina , Carbono/química , Ouro/química , Nanopartículas Metálicas/química , Pontos Quânticos/química , Técnicas Biossensoriais/métodos , Colorimetria/métodos , Humanos , Limite de Detecção , Nanopartículas Metálicas/ultraestrutura , Pontos Quânticos/ultraestrutura , Espectrometria de Fluorescência/métodosRESUMO
In this paper, a simple sensor platform is presented for highly selective and sensitive detection of dissolved ammonia in aqueous solutions without pretreatment based on temperature gradient headspace single drop microextraction (HS-SDME) technique, and fluorescence and UV-vis spectrophotometry are utilized with the Ag nanoclusters (Ag NCs) functioned by citrate and glutathione as the probe. The sensing mechanism is based on the volatility of ammonia gas and the active response of Ag NCs to pH change caused by the introduction of ammonia. High pH can make the Ag NCs agglomerate and lead to the obvious decrease of fluorescence intensity and absorbance of Ag NCs solution. Moreover, the presented method exhibits a remarkably high selectivity toward dissolved ammonia over most of inorganic ions and amino acid, and shows a good linear range of 10-350µM (0.14-4.9mgNL-1) with a low detection limit of 336nM (4.70µgNL-1) at a signal-to-noise ratio of 3. In addition, the practical applications of the sensor have been successfully demonstrated by detecting dissolved ammonia in real samples.
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Amônia/análise , Corantes Fluorescentes/química , Lagos/análise , Nanopartículas Metálicas/química , Prata/química , Poluentes Químicos da Água/análise , Limite de Detecção , Nanopartículas Metálicas/ultraestrutura , Razão Sinal-Ruído , Espectrometria de Fluorescência/métodos , Espectrofotometria Ultravioleta/métodos , TemperaturaRESUMO
Developing probes with good biocompatibility and realizing intracellular detection in living cells are of great significance for biomedicine and life sciences, but remain a challenge presently. In this paper, we describe a rapid and highly selective biosensor for Fe3+ detection in living cells based on the Maillard reaction fluorescent products (MRFPs) of glutathione and ascorbic acid as a probe. Experiments show that the MRFPs are non-cytotoxic and possess excellent biocompatibility. Moreover, the MRFPs show a rapid response and good selectivity towards Fe3+ over other metal ions under physiological pH conditions in vitro. The introduction of Fe3+ can quench the fluorescence of MRFPs, and the fluorescence intensity of system decreases linearly with the increasing concentration of Fe3+ in the range of 0.05-50 µM with the detection limit of 4.6 nM at a signal-to-noise ratio of 3. Moreover, the recognition mechanism has been discussed, which is attributed to the charge transfer from excited-state MRFPs molecules to metal ions. In addition, the MRFPs have been successfully demonstrated to be a good imaging probe for Fe3+ sensing in living cells. This study shows that the biocompatible MRFPs might hold great potential for applications in bioimaging, diagnosis, and therapy of intracellular diseases.
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Maillard reactions and their fluorescent products have drawn much attention in the fields of food and life science, however, the application of fluorescent products separated from the reaction as an indicator for detection of certain substances in sensor field has not been mentioned. In this article, we report on an easy-to-synthesize and water-soluble fluorescent probe separated from the typical Maillard reaction products of glutathione and ascorbic acid, with excellent stability and high quantum yield (18.2%). The further application of the probe has been explored for dual detection of Hg(2+) and biothiols including cysteine, homocysteine, and glutathione, which is based on Hg(2+)-induced fluorescence quenching of the Maillard reaction fluorescent products (MRFPs) and the fluorescence recovery as the introduction of biothiols. This sensing system exhibits a good selectivity and sensitivity, and the linear ranges for Hg(2+), cysteine, homocysteine, and glutathione are 0.05-12, 0.5-10, 0.3-20, and 0.3-20µM, respectively. The detection limits for Hg(2+), cysteine, homocysteine, and glutathione are 22, 47, 96, and 30nM at a signal-to-noise ratio of 3, respectively. Furthermore, the practical applications of this sensor for Hg(2+) and biothiols determination in water samples and human plasma sample have been demonstrated with satisfactory results.