Living MCF-7 Cells Research Articles

Novel Colorimetric and NIR Fluorescent Probe for Bisulfite/Sulfite Detection in Food and Water Samples and Living Cells Based on the PET Mechanism.

Despite their status of being widely used as food additives, bisulfite (HSO3-)/sulfite (SO32-) can pose serious health risks when they are excessively added. Therefore, it is vital to develop a new method for detecting HSO3-/SO32- in foodstuff. In this paper, a benzopyran-benzothiazole derivative (probe DCA-Btl) with near-infrared emission was designed and synthesized by constructing a "push-pull" electronic system. DCA-Btl can selectively recognize HSO3-/SO32- via a colorimetric and fluorescence dual channel in DMF/PBS (1:1, v/v, pH = 8.4), and the emission wavelength of DCA-Btl can reach 710 nm. The fluorescence quenching of DCA-Btl after recognition of HSO3- is attributed to the photoinduced electron transfer (PET) process of the adduct DCA-Btl-HSO3- as evaluated by the DFT/TD-DFT method. In addition, DCA-Btl has many advantages, including a large Stokes shift (95 nm), good anti-interference ability, and little cytotoxicity. What's more, DCA-Btl has been successfully applied for the detection of HSO3-/SO32- in actual water samples and food samples such as sugar, red wine, and biscuits with satisfying results, as well as for fluorescent imaging of HSO3- in living MCF-7 cells.

A fluorescent probe for monitoring sulfite in living cells with large Stokes shift and rapid response

Sulfite (SO32−) is considered as a monitor of a wide range of physiological processes. However, cells and tissues are adversely affected when the body ingests high level of sulfite. Here, we designed and synthesized a “turn on” fluorescent probe ImiSft-1 with 2-cyano-N-methylacetamide as the specific recognition site of SO32−. This probe predominantly achieved high response intensity to SO32− and desirable properties such as large Stokes shift (∼180 nm), fast response time (within 15 s), and high sensitivity (LOD = 0.12 μM). Importantly, the probe was highly selective for sulfite from other bio-species including biological thiols. Other functional properties included broad pH adaptability (5.0–10.0) and low cytotoxicity. Given these advantages and the fluorescence imaging in living MCF-7 cells, it was demonstrated that probe ImiSft-1 could monitor the changes of sulfite concentration in living cells.

Cysteine recognition by a benzothiazole-derived fluorescent probe with “AIE+ESIPT” characteristics

A series of fluorescent dyes based on 2-(2′-hydroxyphenyl)benzothiazole derivatives were designed and synthesized. Because of their structural characteristics of “AIE + ESIPT”, they have long-wavelength emission and a larger Stokes shift. The fluorescent probe HBTN-Y was prepared based on the fluorescent dye HBTN. Probe HBTN-Y can recognize cysteine (Cys) with a high selectivity, “OFF-ON” fluorescence response, a large Stokes shift (263 nm) and long-wavelength emission (637 nm) in MeCN/H2O (1:1, v/v, PBS 20 mM, pH = 8.4) solution. The probe exhibits good anti-interference ability, a low detection limit of 6.51 × 10−6 M, and is suitable for application at near neutral and weak alkaline pH (7–9) conditions. Moreover, HBTN-Y is applicable to image Cys in living MCF-7 cells.

A fluorescent probe derived from benzofuranone for turn-on detection of sulfite in living cells and mice

A novel benzofuranone fluorescent probe, BFO-SFT, for monitoring sulfite in living cells and mice is described which operates over a wide pH range and exhibits a red-shifted emission maximum. The response of the probe BFO-SFT was relatively rapid (within 20 min) and exhibited a good linear correlation of 0–10 Eq (100 μM) with reliable accuracy (R2 = 0.9934). The probe also showed high sensitivity (Limit of detection = 152 nM) and selectivity. With low cytotoxicity, BFO-SFT was successfully applied into the biological imaging of sulfite in living MCF-7 cells and in BALB/C Nude mice.

A novel isophorone-derived fluorescent probe for detecting sulfite and the application in monitoring the state of hybridoma cells

In this work, a novel isophorone-derived fluorescent probe, ISOP-SFT, was developed for the detection of sulfite, and, for the first time, it was applied into monitoring the state of hybridoma cells. ISOP-SFT could exhibit a red-emission response to sulfite with the excitation at 455 nm. It also indicated practical advantages such as wide pH tolerance within 6.0–9.0 and high storage steadiness within at least one week. The linear range was relatively long (0–20 Eq) and reliable (Pearson's correlation coefficient: 0.9989), while Limit of Detection was determined as 0.0095 Eq (95 nM). For the selectivity, ISOP-SFT could distinguish sulfite from other analytes, and the response of ISOP-SFT towards sulfite was not seriously interfered in co-existence system. With low cytotoxicity, ISOP-SFT achieved monitoring both the exogenous and endogenous sulfite in living MCF-7 cells. As a novel attempt, ISOP-SFT was applied into monitoring the state of hybridoma cells, and associated with the quality control of producing antibodies. The result preliminarily inferred the positive correlation between the production efficiency of antibodies in hybridoma cells and the intracellular sulfite level, including the conditions of serum starvation, oxidative stress, severe hypoxia and endogenous induction. We hope that the information in this work could lead to new applications of fluorescent probes in biological industry in future.

Simultaneous Discrimination of Cys/Hcy and GSH With Simple Fluorescent Probe Under a Single-Wavelength Excitation and its Application in Living Cells, Tumor Tissues, and Zebrafish.

Owing to the important physiological sits of biothiols (Cys, Hcy, and GSH), developing accurate detection methods capable of qualitative and quantitative analysis of biothiols in living systems is needed for understanding the biological profile of biothiols. In this work, we have designed and synthesized a 4′-hydroxy-[1,1′-biphenyl]-4-carbonitrile modified with NBD group-based fluorescent probe, BPN-NBD, for sensitive detection of Cys/Hcy and GSH by dual emission signals via a single-wavelength excitation. BPN-NBD exhibited an obvious blue fluorescence (λmaxem = 475 nm) upon the treatment with GSH and reacted with Cys/Hcy to give a mixed blue-green fluorescence (λmaxem = 475 and 545 nm). Meanwhile, BPN-NDB performed sufficient selectivity, rapid detection (150 s), high sensitivity (0.011 µM for Cys, 0.015 µM for Hcy, and 0.003 µM for GSH) and could work via a single-wavelength excitation to analytes and had the ability to image Cys/Hcy from GSH in living MCF-7 cells, tumor tissues, and zebrafish by exhibiting different fluorescence signals. Overall, this work provided a powerful tool for thiols visualization in biological and medical applications.

A fast-responsive fluorescent probe based on a styrylcoumarin dye for visualizing hydrogen sulfide in living MCF-7 cells and zebrafish.

As a vital antioxidant molecule, H2S can make an important contribution to regulating blood vessels and inhibiting apoptosis when present at an appropriate concentration. Higher levels of H2S can interfere with the physiological responses of the respiratory system and central nervous system carried out by mammalian cells. This is associated with many illnesses, such as diabetes, mental decline, cardiovascular diseases, and cancer. Therefore, the accurate measurement of H2S in organisms and the environment is of great significance for in-depth studies of the pathogenesis of related diseases. In this contribution, a new coumarin-carbazole-based fluorescent probe, COZ-DNBS, showing a rapid response and large Stokes shift was rationally devised and applied to effectively sense H2S in vivo and in vitro. Upon using the probe COZ-DNBS, the established fluorescent platform could detect H2S with excellent selectivity, showing 62-fold fluorescence enhancement, a fast-response time (<1 min), high sensitivity (38.6 nM), a large Stokes shift (173 nm), and bright-yellow emission. Importantly, the probe COZ-DNBS works well for monitoring levels of H2S in realistic samples, living MCF-7 cells, and zebrafish, showing that COZ-DNBS is a promising signaling tool for H2S detection in biosystems.

An electrochemical sensor based on AuPd@FexOy nanozymes for a sensitive and in situ quantitative detection of hydrogen peroxide in real samples.

The hydrogen peroxide (H2O2) levels in living organisms and environment have strong effects on many biological processes inducing cell apoptosis/cell necrosis and wound disinfection. Therefore, it is important to have an accurate and in situ detection of H2O2. Herein, an AuPd@FexOy nanozyme-based electrochemical (EC) sensor (termed as AuPd@FexOy NPs/GCE) with good stability and anti-interference ability has been prepared for the detection of H2O2 by differential pulse voltammetry (DPV) and chronoamperometry dual-measurement modes. The AuPd@FexOy NPs/GCE exhibits good linear relationships in the ranges from 13.0 to 6.0 × 103 μM (DPV measurement) and 50 to 1.0 × 103 μM (chronoamperometry measurement), low detection limits (LODs) of 1.6 μM (DPV measurement) and 3.0 μM (chronoamperometry measurement) and high sensitivities of 83.8 nA μM-1 cm-2 (DPV measurement) and 120.7 nA μM-1 cm-2 (chronoamperometry measurement). The practicability of the as-prepared AuPd@FexOy NPs/GCE has been demonstrated by an in situ real-time detection of H2O2 released from adherent living MCF-7 cells triggered by varying amounts of N-formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP) from 0.5 to 3.0 μM and the quantitative determination of H2O2 in commercial disinfectants.

A pH-applicative fluorescent probe with long measuring range for monitoring hydrazine in water samples and Arabidopsis thaliana

In this work, a fluorescent probe, RhodCl-Hz, with pH-applicative capability and long measuring range, was developed to serve the topic on the enrichment process of hydrazine. It was practical due to the clear acid-base boundary and the sectioned linear ranges. With the excitation wavelength of 515 nm and the emission peak at 565 nm, the detecting system was steady. It exhibited a clear cut-off point at pH 7.0 and steady fluorescence signals within the range of 7.0–10.0. As a whole, the linear range of 10.0–500 µM (1.0–50.0 equivalent) was long. The Limit of Detection value was calculated as 0.64 μM. With high selectivity, RhodCl-Hz was applied to suit water samples and biological imaging in both Arabidopsis Thaliana root tips and living MCF-7 cells. The information here might be helpful for revealing the enrichment process of hydrazine.

An ESIPT-based NIR-emitting ratiometric fluorescent probe for monitoring hydrogen peroxide in living cells and zebrafish

Hydrogen peroxide (H2O2) is closely related to a variety of human diseases. It is a challenge to dynamically monitor biological H2O2 activity. Hence, we design and prepare a NIR-emitting ratiometric fluorescent probe (HBQ-B) for detecting H2O2 according to the excited-state intramolecular proton transfer (ESIPT) mechanism using the benzyl boronic pinacol ester group as a recognition unit. HBQ-B displayed specificity toward H2O2 over other bioactive analytes. Meanwhile, HBQ-B exhibited a good linear relationship between the fluorescence ratio (I656/I538) changes and the concentrations of H2O2 (0–10 μM). HBQ-B also showed a large Stokes shift (234 nm) and a marked detection limit (40.2 nM). HBQ-B was utilized to image the intracellular H2O2 in living MCF-7 cells, HeLa cells and macrophages (RAW 264.7 cells), respectively. In addition, HBQ-B was used to monitor the dynamics of H2O2 level changes during zebrafish development.

Prostate cancer biomarker citrate detection using triaminoguanidinium carbon dots, its applications in live cells and human urine samples

Citrate is a tricarboxylate, plays vital role in prostate cancer (PC) and the level of citrate is an indicator for PC identification. Herein, triaminoguanidine carbon dots (TAG-CDs) prepared by one step hydrothermal method and used as a citrate receptor. Notably the TAG-CDs without alkaline treatment were highly fluorescent at pH 7 with high quantum yield (11.3%). TAG-CDs were characterized through TEM, XRD, FT-IR, UV–vis and spectrofluorimetry. It is noted that the average size was of 2.8 nm, the presence of highly disordered carbon, retain the functionality of TAG. The absorbance maxima obtained at 294 nm and good emitting response observed at 396 nm. The Y-aromaticity of receptor guanidinium moiety acts as Lewis acid and have peculiar interaction with Lewis base citrate via electrostatic interaction and also protons in the TAG participate hydrogen bonds with citrate, which causes quenching of TAG-CDs. From the obtained linear quenching equation the LOD was found to be 4 nM. The probe expressed high selectivity, high interference tolerance (500 – fold), fast response in 15 mins and good biocompatible. Finally, TAG-CDs utilized for the intracellular imaging of citrate in live MCF-7 cells, it showed good cytotoxicity and delivered contrast images in presence, absence of citrate. TAG-CDs detected the citrate level in human urine samples, the obtained results are validated with HPLC method.

A fluorescent Rhodol-derived probe for rapid and selective detection of hydrogen sulfide and its application

H2S has been reported to play essential roles in a variety of physiological and pathological procedures. In this work, a novel fluorescent probe, Rho-HS, for detecting H2S was developed by introducing the ortho-halogen to activate the least reactive recognition group 2,4-dinitrophenyl moiety. In combination of the structures from both Rhodamine B and fluorescein, Rho-HS could generate both the colorimetric and fluorescent responses. This feature was not frequently achieved and could lead to the quantitative and convenient for the end-user. In comparison with recent probes for H2S, the major advantages of Rho-HS included suiting wide pH range (6.0–10.0), relatively rapid response (within 15 min) and the high selectivity among the competing species including the biothiols. With low cytoxicity, Rho-HS was further applied in the biological imaging in living MCF-7 cells and Caenorhabditis elegans. We hope that the designing strategy in this work might provide useful information for more preferable implements in this field.

AND molecular logic gates based on host-guest complexation operational in live cells

We report supramolecular AND logic gates based on host-guest complexation between acid-labile acyclic cucurbit[n]uril (CB[n]) molecular container and NaClO-responsive dye. Supramolecular AND logic gate is turned on due to acid-triggered degradation of molecular container and the release of the dye, followed by NaClO-induced fluorescence “switch on” effect of the dye. The reason for AND molecular logic gate is discovered to be the combination of oxidation inhibition and fluorescence “switch off” effect. Supramolecular AND logic gate is confirmed to be operational in live MCF-7 and HeLa cancer cells.

A novel selective probe for detecting glutathione from other biothiols based on the concept of Fluorescence Fusion

Biological thiols importantly regulate the intracellular redox activity and metabolic level, but many of the developed probes for biothiols are facing difficulty in effectively distinguishing GSH from Cys/Hcy due to the similarity in mechanism. In this work, despite the previous pattern of “Logic Gate”, we reported the concept of “Fluorescence Fusion” for the first time to achieve only one excitation-emission process. The exploited the probe, MZ-NBD, could quickly measure GSH in 10 min with a large Stokes shift (130 nm). Though the reacting mechanism was similar, only GSH could cause the “Fluorescence Fusion” with only one strong fluorescence response while Cys/Hcy caused two peaks. Adjusting the excitation wavelength could hardly split the fused peak into two. Though image recognition by artificial intelligence could easily distinguish the patterns of peaks, here we used the signal-treating method to realize the high selectivity towards GSH. Moreover, MZ-NBD could be utilized for rapid detection of GSH in living MCF-7 cells, which was more suitable for GSH than using the “Logic Gate” strategy. More than introducing a novel probe with the new concept, this work was meaningful as the linker of traditional reaction-based fluorescent probes and potential image recognition by artificial intelligence, thus led to various future researches in inter-disciplines.

Crumpled Graphene/Poly (azure I) Modified Electrode for Non-enzymatic Detection of Hydrogen Peroxide Secreted from Tumor Cells.

Hydrogen peroxide (H2O2), an important representatives of reactive oxygen species, its aberrant expression is related to many diseases, including cancers. Therefore, it is very significant to design a reliable method for the real-time detection of endogenous H2O2. Herein, we describe preparing a poly (azure I)/crumpled graphene (cGN) modified electrode by an electro-polymerization method. The results showed that this electrode presented obvious electrocatalytic effect on the reduction of H2O2. Amperometric method was employed to monitor H2O2, and the amperometric response exhibited a good linear relationship with its concentration in the range of 8.0 × 10-6 - 1.25 × 10-3 mol/L; the detection limit reached to 6.7 × 10-7 mol/L (S/N = 3). Furthermore, this modified also displayed good selectivity, long-term stability and a high anti-interference ability. Excitingly, the established method could be successfully used to detect H2O2 in human serum samples, and measured H2O2 secreted from living MCF-7 cells. It could have potential use in cancer diagnosis.

Label-Free Multivariate Biophysical Phenotyping-Activated Acoustic Sorting at the Single-Cell Level.

Biophysical markers of cells such as cellular electrical and mechanical properties have been proven as promising label-free biomarkers for studying, characterizing, and classifying different cell types and even their subpopulations. Further analysis or manipulation of specific cell types or subtypes requires accurate isolation of them from the original heterogeneous samples. However, there is currently a lack of cell sorting ability that could actively separate a large number of individual cells at the single-cell level based on their multivariate biophysical makers or phenotypes. In this work, we, for the first time, demonstrate label-free and high-throughput acoustic single-cell sorting activated by the characterization of multivariate biophysical phenotypes. Electrical phenotyping is implemented by single-cell electrical impedance characterization with two pairs of differential sensing electrodes, while mechanical phenotyping is performed by extracting the transit time for the single cell to pass through microconstriction from the recorded impedance signals. A real-time impedance signal processing and triggering algorithm has been developed to identify the target sample population and activate a pulsed highly focused surface acoustic wave for single-cell level sorting. We have demonstrated acoustic single-particle sorting solely based on electrical or mechanical phenotyping. Furthermore, we have applied the developed microfluidic system to sort live MCF-7 cells from a mixture of fixed and live MCF-7 population activated by a combined electrical and mechanical phenotyping at a high throughput >100 cells/s and purity ∼91.8%. This demonstrated ability to analyze and sort cells based on multivariate biophysical phenotyping provides a solution to the current challenges of cell purification that lack specific molecular biomarkers.

PKa modulation of rhodamine alkylamides by hydrogen-bond and application in bio-imaging

To confirm the pKa regulation by hydrogen bond, a series of rhodamine alkylamides were developed, and their pKa values were measured in aqueous solution. For Rh-APD, intramolecular hydrogen bond derived from hydroxyl of 2-amino-1,3-propanediol between carbonyl of spirolactam was favorable to the increase of pKa values (pKa 5.7). Gaussian stimulation demonstrated a moderate intramolecular hydrogen bond in Rh-APD at DFT/B3LYP/6–31 G(d) level. Except for pH, neither protic/aprotic solvents nor metal ions induced ring-opening transformation of Rh-APD. Bio-imaging showed that Rh-APD could specifically accumulate in lysosomes and evaluate lysosomal pH fluctuation in living MCF-7 cells. Moreover, Rh-APD also can indicate the acidity of gut and ovary of Daphnia magna. Rh-APD would be a potential reagent for water-quality monitoring with the help of its pH indication in living cells and water fleas.

Multiplexed optical barcoding of cells via photochemical programming of bioorthogonal host-guest recognition.

Modern chemical and biological studies are undergoing a paradigm shift, where understanding the fate of individual cells, in an apparently homogeneous population, is becoming increasingly important. This has inculcated a growing demand for developing strategies that label individual cells with unique fluorescent signatures or barcodes so that their spatiotemporal trajectories can be mapped in real time. Among various approaches, light-regulated methods employing photocaged fluorophores have received particular attention, owing to their fine spatiotemporal control over labelling. However, their multiplexed use to barcode large numbers of cells for interrogating cellular libraries or complex tissues remains inherently challenging, due to the lack of multiple spectrally distinct photoactivated states in the currently available photocaged fluorophores. We report here an alternative multiplexable strategy based on optically controlled host–guest recognition in the cucurbit[7]uril (CB[7]) system that provides spatial control over the positioning of fluorophores to generate distinct barcodes in ‘user-defined’ cells. Using a combination of three spectrally distinct CB[7]-conjugated fluorophores and by sequentially performing cycles of photoactivation and fluorophore encoding, we demonstrate 10-color barcoding in microtubule-targeted fixed cells as well as 7-color barcoding in cell surface glycan targeted live MCF7 cells.

Organic-inorganic photoelectrochemical sensor based on aza-cope rearrangement reaction for formaldehyde

Abstract A photoelectrochemical (PEC) sensor was designed by connecting an organic recognize group 1-(4-(3-aminopropoxy)phenyl)-N-(4-nitrobenzyl)but-3-en-1-amine (FOP-1) to a modified photoelectric nanomaterial Pt-BiVO4 nano flowers (NFs) for ultra-sensitive and highly selective detection of formaldehyde (FA). The steric hindrance of the FOP-1 and the strong electron-withdrawing group nitro blocked the transfer of electrons excited to the electrode under illumination, resulting in a decrease in photocurrent. With the addition of FA, it triggered a specific aza-cope remake reaction (2-aza-cope sigmatropic rearrangement), leading to N-(4-nitrobenzyl)but-3-en-1-amin (NBEA) group removed, the steric hindrance weakened, the electron-withdrawing effect decreased, and the photocurrent signal recovered obviously. The entire sensor shows good stability and repeatability, excellent selectivity for FA, its detection limit is 0.4 μM, and the linear range is 1–1000 μM, Moreover, endogenous FA released from live MCF-7 cells and the real mice serum samples were monitored successfully by the PEC sensor, indicating its practicality potential in biological cytology and pathophysiology.

A new cascade reaction-based colorimetric and fluorescence “turn on” dual-function probe for cyanide and hydrazine detection

Selective detection of cyanide (CN−) and hydrazine (N2H4) are highly desirable owing to the highly toxic properties of these species. We report herein a new cascade reaction-based colorimetric and fluorescence “turn on” dual-function probe (HBTM-HC) for CN− and N2H4 detection with long wavelength emission (620 nm) and a large Stokes shift (122 nm). In DMSO/H2O (3/7, v/v, PBS 10 mM, pH = 9.1) solution, HBTM-HC displays highly selective and sensitive detection of CN− and N2H4 with the assistance of masking agents (acetone was used to mask N2H4, and Fe2+ was used to mask CN−). The detection limits of HBTM-HC for CN− and N2H4 were calculated to be 1.38 × 10−6 M and 5.47 × 10−6 M, respectively. The sensing mechanisms for CN− and N2H4 were proved to undergo cascade reactions, which results in deprotection of levulinate group and releasing of compound HBTM. In addition, probe HBTM-HC has been successfully applied to fluorescence imaging of N2H4 in live MCF-7 cells, detect CN− in sprouting potatoes and apple seeds, and detect CN− and N2H4 in real water samples with high recovery rates (92.0%–104.5%) and small relative standard deviations (≤7.15%).