Copper (Cu2+) is physiologically essential, but excessive Cu2+ may cause potential risk to plants and animals due to the bioaccumulative properties. Hence, sensitive recognition is crucial to avoid overintake of Cu2+, and visual recognition is more favored for practical application. In this work, a dual-emission ratiometric fluorescent nanoprobe was developed possessing the required intensity ratio, which can facilitate the sensitive identification of Cu2+ by the naked eye. The probe hybridizes two fluorescence nanodots (quantum dots (QDs) and carbon dots (CDs)). Although both of them can be viable fluorescence probes for metal ion detection, rarely research has coupled this two different kinds of fluorescence material in one nanosensor to fabricate a selectively ratiometric fluorescence probe for intracellular imaging. The red emitting CdTe/CdS QDs were capped around the silica microsphere to serve as the response signal label, and the blue-emitting CDs, which is insensitive to the analyte, were covalent...

Carbon-Dot and Quantum-Dot-Coated Dual-Emission Core–Satellite Silica Nanoparticles for Ratiometric Intracellular Cu2+ Imaging

In recent years, it has become a trend to employ organic molecular fluorescent probes with multireaction sites for the distinguishable detection and biological imaging of similar substances. However, the introduction of multireaction sites brought great challenges to organic synthesis, and at the same time, often destroyed the conjugated structure of the molecules, leading to an unsatisfactory fluorescence emission wavelength not conducive to practical application. As the eternal theme of life, metabolism goes on all the time. Metabolism is a series of ordered chemical reactions that occurs in the organism to maintain life. Chemical reactions in metabolism can be summarized as metabolic pathways. Simultaneous monitoring of different metabolic pathways of the same substance poses a lofty challenge to the probe. Here, we developed a new strategy: to construct new sites through the preliminary reactions between probes and some targets, which can be used to further distinguish among targets or detect their metabolites, so as to realize the simultaneous visualization tracer of multiple metabolic pathways. By intravenous injection, it revealed that the probe containing benzopyrylium ion can target tumors efficiently, and thiols are highly expressed in tumors compared to other tissues (heart, lung, kidney, liver, etc.). The consumption of thiols by the probe could not prevent tumor growth, suggesting that the tumor cure was not correlated with thiol concentration. The construction of new sites in the reaction process is a novel idea in the pursuit of multiple reaction sites, which will provide more effective tools for solving practical problems.

A New Strategy: Distinguishable Multi-substance Detection, Multiple Pathway Tracing Based on a New Site Constructed by the Reaction Process and Its Tumor Targeting

In recent years, publications from this laboratory (Snyder and Lichstein, 1940; Lichstein and Snyder, 1941; Lichstein, 1941) have indicated the value of sodium azide (NaN3) as an aid in the isolation of streptococci from clinical material containing \"spreaders\" and other interfering gram-negative organisms. The use of blood-infusion agar containing 0.02 per cent sodium azide for the cultivation of fecal samples holds in abeyance the rich flora of gram-negative bacilli, thus making possible the isolation of streptococci. The present paper is concerned with a comprehensive study of the action of sodium azide on pure cultures of selected strains of bacteria directed primarily at an understanding of the mechanism of action of the chemical.

IV. The Effect of Sodium Azide on Glucose Fermentation and Lactic Acid Production by Streptococci and Lactobacilli.

Recent advances in chemical proteomics have begun to characterize the reactivity and ligandability of lysines on a global scale. Yet, only a limited diversity of aminophilic electrophiles have been evaluated for interactions with the lysine proteome. Here, we report an in-depth profiling of >30 uncharted aminophilic chemotypes that greatly expands the content of ligandable lysines in human proteins. Aminophilic electrophiles showed disparate proteomic reactivities that range from selective interactions with a handful of lysines to, for a set of dicarboxaldehyde fragments, remarkably broad engagement of the covalent small-molecule–lysine interactions captured by the entire library. We used these latter ‘scout’ electrophiles to efficiently map ligandable lysines in primary human immune cells under stimulatory conditions. Finally, we show that aminophilic compounds perturb diverse biochemical functions through site-selective modification of lysines in proteins, including protein–RNA interactions implicated in innate immune responses. These findings support the broad potential of covalent chemistry for targeting functional lysines in the human proteome. A deep chemical proteomic investigation of diverse aminophilic electrophiles has identified ligandable lysines across a wide range of human proteins. The proteins cover different functional and structural classes, and the aminophilic electrophiles include compounds that disrupt protein–protein and protein–RNA interactions. This dataset provides a proteome-wide atlas of lysine-reactive chemistry.

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A proteome-wide atlas of lysine-reactive chemistry.

An easily accessible colorimetric and fluorescence probe 4-((3-chloro-1,4-dioxo-1,4-dihydronaphthalen-2-yl)amino)benzenesulfonamide (4CBS) was successfully developed for the selective and sensitive detection of Sn2+ in an aqueous solution. The sensing mechanism involves reduction of -C═O into -C-OH groups in 4CBS upon the addition of Sn2+, which initiates the fluorescence turn-on mode. A better linear relationship was achieved between fluorescence intensity and Sn2+ concentration in the range of 0-62.5 μM, with a detection limit (LOD) of 0.115 μM. The binding mechanism of 4CBS for Sn2+ was confirmed by Fourier transform infrared analysis, NMR titrations, and mass (electrospray ionization) spectral analysis. Likewise, the proposed sensing mechanism was supported by quantum chemical calculations. Moreover, bioimaging studies demonstrated that the chemosensing probe 4CBS is an effective fluorescent marker for the detection of Sn2+ in living cells and zebrafish. Significantly, 4CBS was able to discriminate between Sn2+ in human cancer cells and Sn2+ in normal live cells.

Simple Colorimetric and Fluorescence Chemosensing Probe for Selective Detection of Sn2+ Ions in an Aqueous Solution: Evaluation of the Novel Sensing Mechanism and Its Bioimaging Applications.

Rapid detection of aspartic acid and glutamic acid in water by BODIPY-Based fluorescent probe: Live-cell imaging and DFT studies

A 4-(naphthalen-1-ylethynyl) aniline appended rhodamine based fluorescent chemosensor ‘NAP-RD’ is synthesized which undergoes through bond energy transfer in the presence of Sn2+ ions in mixed aqueous media. NAP-RD is an excellent colorimetric and fluorescence ratiometric probe which recognizes traces of Sn2+ in real samples and a fluorescence indicator in living RAW264.7 cells. The new sensing probe NAP-RD shows higher sensitivity as well as faster response compared to the reported systems. The detection limit of NAP-RD is 5 × 10−9 M. DFT studies strongly support the experimental results.

A through bond energy transfer based ratiometric probe for fluorescent imaging of Sn2+ ions in living cells

4-Hydroxy-5-isopropyl-2-methylisophthalaldehyde anchored rhodamine B derivative, RDDFT experiences Fe3+ assisted inhibition of photoinduced electron transfer (PET), chelation-enhanced fluorescence (CHEF) and fluorescence resonance energy transfer (FRET) process in aqueous buffered acetonitrile media. RDDFT is an excellent colorimetric Fe3+ probe that undergoes ratiometric fluorescence change to recognize and determine traces of Fe3+ in presence of Fe2+ in real sample, thus allowing speciation studies of iron. It detects as low as 2 × 10−8 M Fe3+ with an association constant, 3.7025 × 106 M−1. Common ions do not show any significant interference in the detection of Fe3+ ion. RDDFT efficiently images intracellular Fe3+ in HeLa cells under fluorescence microscope. DFT studies strongly support experimental findings.

Ratiometric sensing of Fe3+ through PET-CHEF-FRET processes: Live cell imaging, speciation and DFT studies

A 2-(1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl)acetaldehydeanchored rhodamine B based probe, RDNAP detects Cr3+ ion by fluorescence resonance energy transfer (FRET) process in aqueous buffered acetonitrile media (7:3, v/v). Conversely, conjugation of 2-(1,3-dioxo-6-(piperidin-1-yl)-1H-benzo[de]isoquinolin-2(3H)-yl)acetaldehyde with rhodamine B provides another probe, RDNAP-PY that undergoes Cr3+assisted ratiometric fluorescence and colorimetric change in the same media. RDNAP-PY provides higher FRET efficiency and detects as low as 1.81×10−6 M Cr3+with an association constant, 15.9 × 104 M−1. Other common ions do not interfere. RDNAP-PY efficiently images intracellular Cr3+ in live Hep3B, MCF-7, HeLa, SiHa and HEK 293T cells under fluorescence microscope in a ratiometric and time dependent manner. 1H NMR titration and DFT studies strongly support experimental findings.

A 1,8 naphthalimide anchor rhodamine B based FRET probe for ratiometric detection of Cr3+ion in living cells

The recognition of a specific protein in blood serum amidst similar proteins is a challenging and vital endeavor in clinical diagnostics. Herein, we have described a small-molecule probe (DFPAC-OH)...

Small-Molecule Probe for Sensing Serum Albumin with Consequential Self-Assembly as a Fluorescent Organic Nanoparticle for Bioimaging and Drug-Delivery Applications

Subhajit Guria

Papers

Rapid detection of aspartic acid and glutamic acid in water by BODIPY-Based fluorescent probe: Live-cell imaging and DFT studies

A through bond energy transfer based ratiometric probe for fluorescent imaging of Sn2+ ions in living cells

Ratiometric sensing of Fe3+ through PET-CHEF-FRET processes: Live cell imaging, speciation and DFT studies

A 1,8 naphthalimide anchor rhodamine B based FRET probe for ratiometric detection of Cr3+ion in living cells

Small-Molecule Probe for Sensing Serum Albumin with Consequential Self-Assembly as a Fluorescent Organic Nanoparticle for Bioimaging and Drug-Delivery Applications