Labeling materials with special functional groups are very valuable for the creation of novel probes. Hence, a novel fluorescent probe was constructed by conjugating 4-butyl-3-thiosemicarbazide ...(BTSC) with carbon dots (CDs). The CDs labeled by BTSC (BTSC-CDs) displayed a strong capability for recognition of Cu
and Cu
could quench the emission of BTSC-CDs significantly. The fluorescence quenching was proved to be a static quenching which was resulted from the interaction between BTSC-CDs and Cu
to form a ground-state BTSC-CDs/Cu
complex, and the fluorescence intensities showed a good linear correlation with Cu
concentrations in the range of 0.20-30 μM. What is more important, by adding glyphosate into the sensor system of BTSC-CDs/Cu
the fluorescence of the probe turned on again owing to the stronger chelating between glyphosate and Cu
than between BTSC-CDs and Cu
. This could realize the specific detection of glyphosate and the limit of detection was low to 0.27 μM. Detecting glyphosate using the complex BTSC-CDs/Cu
system in actual samples with satisfactory outcomes indicated that a novel fluorescent probe for Cu
and subsequent glyphosate detections has been provided.
In the diagnosis of genetic diseases and disorders, nanomaterials-based gene detection systems have significant advantages over conventional diagnostic systems in terms of simplicity, sensitivity, ...specificity, and portability. In this review, we describe the application of nanomaterials for disease-related genes detection in different methods excluding PCR-related method, such as colorimetry, fluorescence-based methods, electrochemistry, microarray methods, surface-enhanced Raman spectroscopy (SERS), quartz crystal microbalance (QCM) methods, and dynamic light scattering (DLS). The most commonly used nanomaterials are gold, silver, carbon and semiconducting nanoparticles. Various nanomaterials-based gene detection methods are introduced, their respective advantages are discussed, and selected examples are provided to illustrate the properties of these nanomaterials and their emerging applications for the detection of specific nucleic acid sequences.
•The current and future trends about application of nanomaterials in disease-related gene were reviewed.•The most used nanomaterials, such as gold, silver, carbon and semiconducting nanoparticles, were discussed mainly.•Different bioanalytical methods excluding the PCR-related method were discussed.
•C3G and the SPP form complexes mainly through hydrophobic interactions.•C3G degradation rate constant decreased after SPP preheated at 80 °C.•C3G-SPP thermal stability increased effectively after ...SPP preheated at 80 °C.•C3G-SPP oxidative stability increased effectively after SPP preheated at 80 °C.
In this paper, the interaction of silkworm pupae protein (SPP) with cyanidin-3-O-glucoside (C3G) was studied the protective anthocyanins stability. Characterization experiments suggested that C3G-SPP complexes mainly through hydrophobic interactions, with a decrease in the α-helix content and increases in the β-sheet and β-turn contents. Fluorescence results revealed that C3G quenched the intrinsic fluorescence of SPP by static quenching. The highest quenching constant, Kq, was recorded to be1.26 × 1012 M−1s−1 for the SPP preheated at 80 °C. Following the C3G-SPP complexes, the degradation rate constant decreased, and the half-life of C3G was prolonged from 64.81 ± 1.07 to 261.99 ± 13.32 min at 80 °C (p < 0.05). The SPP preheated at 80 °C exhibited the highest binding affinity towards C3G and also effectively increased the thermal and oxidative stability of the C3G. The obtained results suggest that the novel protein proposed in this study could expand the application of anthocyanins as stable, functional food ingredients.
A new red-emissive bioprobe TPE-red-2AP2H was developed by taking advantage of the unique emission feature of tetraphenylethylene and a cancer cell-specific peptide. By responding to the target ...protein and the acidic microenvironment of tumor cells, activated fluorescence bioimaging was achieved with high signal-to-noise ratio and without involving mutiple washing steps. Apart from targeting the membrane-anchored LAPTM4B proteins, TPE-red-2AP2H was successfully utilized to trace the intracellular movement of LAPTM4B protein. The generation of (1)O2 under visible light irradiation makes this bioprobe also promising for targeted-photodynamic therapy. By discriminating the expression level of the target protein, TPE-red-2AP2H can respond to the progression status of tumors with different photodynamic therapy effect.
An innovative and green strategy to synthesize carbon dots (CDs) with a quantum yield (QY) of nearly 19.8% has been successfully established for the first time. Subsequently, the possible ...fluorescence (FL) mechanism was elucidated by fluorescence, UV–vis, high resolution transmission electron microscope (HR-TEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses. Significantly, not only the precursor of CDs and whole synthesis procedure was green, but also the CDs obtained here exhibited various advantages including high fluorescent QY, excellent photostability, non-toxicity and satisfactory stability. Additionally, the CDs were employed for assaying Fe3+ based on direct interactions between Fe3+ and COOH, OH and NH2 of CDs, resulting in aggregations that facilitate to quench their fluorescence. The decrease of fluorescence intensity permitted detections of Fe3+ in a linear range of 5.0×10−9–1.0×10−4mol/L, with a detection limit of 1.7×10−9mol/L at a signal-to-noise ratio of 3, suggesting a promising assay for Fe3+. Eventually, the CDs were applied for cell imaging and coding, demonstrating their potential towards diverse applications.
•A green, novel, one-pot strategy for synthesizing carbon dots was established.•A simple, sensitive and cost-effective quantification of Fe3+ was developed.•The carbon dots could serve for fluorescent staining, coding and bioimaging.
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•Fluorescence quenching process has been introduced for the determination of Mirabegron by quenching tyrosine and L-tryptophan fluorophores.•The developed methods were validated as ...per ICH guidelines and the obtained results were statistically analyzed.•Stern-Volmer relationship was studied at different temperatures for the quenching mechanism recognition which is static or dynamic.•The double log plots were constructed to evaluate binding sites and binding constants.•Greenness of the proposed methods has been assessed to clarify the extent of environmental safety.
Green spectrofluorimetric methods have been adopted for the determination of Mirabegron (MG) in pure drug and pharmaceutical dosage form. The developed methods based on fluorescence quenching of tyrosine and L-tryptophan amino acids fluorophores by the effect of Mirabegron as a quencher. Experimental conditions of the reaction were studied and optimized. The Fluorescence quenching (ΔF) values were proportional to the concentration range of MG 2–20 μg/ml for the tyrosine-MG system in buffered media pH 2 and 1–30 μg/ml for L-tryptophan-MG system pH 6. Good correlation coefficients with low detection limits of 0.163 and 0.234 μg/ml for the two systems respectively. Method validation was applied according to ICH guidelines. The cited methods were successively applied for MG determination in tablet formulation. No statistically significant difference between the results of the cited and the reference methods regarding t and F tests. The proposed spectrofluorimetric methods are simple, rapid, eco-friendly and can contribute to MG’s methodologies in quality control labs. Stern-Volmer relationship, the effect of temperature, quenching constant (Kq), and UV spectra were studied to identify the mechanism by which the quenching might occur. The results demonstrated that fluorescence quenching of tyrosine was a dynamic quenching process and L-tryptophan was static. The double log plots were constructed to determine the binding constants and binding sites. The greenness profile of the developed methods has been assessed by Green Analytical procedure index (GAPI) and Analytical Greenness Metric Approach (AGREE).
We have developed a fluorescence correlation spectroscopy (FCS) setup for performing single-molecule measurements on samples inside regular cuvettes. The cuvette FCS uses a horizontally mounted ...extra-long working distance, 0.7 NA, air objective with a working distance of >1.8 mm instead of a high NA water or oil immersion objective. The performance of the cuvette FCS is found to be highly sensitive to the quality and alignment of the cuvette. The radial resolution and effective observation volume obtained using the optimized setup are ∼340 nm and 1.8 fL, respectively. The highest molecular brightness and the signal/noise ratio in the autocorrelation data achieved using an aqueous solution of rhodamine B are greater than 44 kHz and 110, respectively. Here, we demonstrate two major advantages of cuvette FCS. For example, the cuvette FCS can be used for measurements over a wide range of temperatures that is beyond the range permitted in the microscope-based FCS. Furthermore, cuvette FCS can be coupled to automatic titrators to study urea-dependent unfolding of proteins with unprecedented accuracy. The ease of use and compatibility with various accessories will enable applications of cuvette FCS in the experiments that are regularly performed in spectrofluorometers but are generally avoided in microscope-based FCS.
The construction of microenvironment-sensitive probes with good cell membrane-targetability can reveal the fundamental properties of cell membranes. Herein, two polarity-sensitive probes, termed
were ...reported for the first time to specifically light up cancer cell membranes. Both probes were designed with tetrahydroquinoxaline coumarin amide as the fluorophore, and quaternary ammonium groups were appended to increase water solubility and target cell membranes. In vitro studies showed that the fluorescence of both probes displayed strong polarity dependence and had a wide linear range to polarity (Δ
).
also displayed excellent cell membrane targeting ability and could long-term light up cell membranes with red fluorescence and a wash-free process. More excitingly,
could specifically light up cancer cell membranes, revealing that cancer cells might have lower cell membrane polarity than normal cells. In vivo studies showed that
could also effectively distinguish tumors from normal tissues. Overall, this work has not only developed two polarity-sensitive probes with good cell membrane targetability, but also provided new insights and methods for an in-depth understanding of cancer cells and cancer diagnosis.
Alkaline phosphatase (ALP) activity is regarded as an important biomarker in medical diagnosis. A ratiometric fluorescent probe is developed based on a phosphorylated chalcone derivative for ALP ...activity assay and visualization in living cells. The probe is soluble in water and emits greenish-yellow in aqueous buffers. In the presence of ALP, the emission of probe changes to deep red gradually with ratiometric fluorescent response due to formation and aggregation of enzymatic product, whose fluorescence involves both excited-state intramolecular proton transfer and aggregation-induced emission processes. The linear ratiometric fluorescent response enables in vitro quantification of ALP activity in a range of 0-150 mU/mL with a detection limit of 0.15 mU/mL. The probe also shows excellent biocompatibility, which enables it to apply in ALP mapping in living cells.
A novel selective fluorescent chemosensor based on an 8-hydroxyquinoline-appended fluorescein derivative (L1) was synthesized and characterized. Once combined with Cu(2+), it displayed high ...specificity for sulfide anion. Among the various anions, only sulfide anion induced the revival of fluoresecence of L1, which was quenched by Cu(2+), resulting in "off-on"-type sensing of sulfide anion. What's more, the sensor was retrievable to indicate sulfide anions with Cu(2+), and S(2-), in turn, increased. With the addition of Cu(2+), compound L1 could give rise to a visible pink-to-yellow color change and green fluorescence quenching. The resulting yellow solution could change to pink and regenerate to green fluorescence immediately upon the addition of sulfide anion; however, no changes were observed in the presence of other anions, including CN(-), P(2)O(7)(4-), and other forms of sulfate, making compound L1 an extremely selective and efficient sulfide chemosensor. The signal transduction occurs via reversible formation-separation of complex L1Cu and CuS. What's more, the biological imaging study has demonstrated that the chemosensor can detect sulfur anions in biological systems at a relatively low concentration.
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