Introduction to Fluorescence Response

Then, a ratiometric fluorescence sensor was constructed by in situ growth of CsPb(BrI)3@Asp-Cs4Pb(BrI)6 in metal organic framework (NH2-MIL-53) for the detection of BDE-3, in which the orange fluorescence of CsPb(BrI)3@Asp-Cs4Pb(BrI)6 (614 nm) was regarded as the reference signal and the cyan fluorescence of NH2-MIL-53 (494 nm) was used as the fluorescence response signal.

To address this, herein, we report a new hydrolytically stable luminescent Zn(ii) based cationic metal organic framework (MOF), iMOF-4C, which further successfully exhibited a rare dual "turn off/on" fluorescence response toward Cr(vi), As(v) and As(iii) based oxo-anions respectively in water medium.

Metal detection in living cells will be highlighted with representative examples together with fluorescence response mechanisms such as photoinduced electron transfer (PET), intramolecular charge transfer (ICT), and fluorescence resonance energy transfer (FRET).

Interestingly, the probe BP gave a turn-on fluorescence response by shutting the photoinduced electron transfer (PET) effect and extending the coplanar conjugated π-system.

However, in the presence of Zinc (II) ion, C N isomerization and ESIPT processes are inhibited due to its coordination to metal ion by triggering CHEF (chelation-enhanced fluorescence) giving turn-on fluorescence response.

The sensor R1 showed an obvious "turn-on" fluorescence response toward Ag+ due to the inhibition of both C-N single bond free rotation, internal charge transfer (ICT) and the formation of chelation enhanced fluorescence (CHEF) effects.

Operating via ring opening reaction, the probe molecule (RhP) offered extensive properties such as “turn-on” fluorescence response, naked-eye detection, low detection limit (15 nM) and fast response time (.

Moreover, the product polymer showed highly sensitive fluorescence response to Fe3+, with low detection limit to 0.

These probes showed good fluorescence response to viscosity with twisted intramolecular charge transfer mechanism, among them, the probes with diethylamino (TOB), dibutylamino (TOC) and pyrrolidin (TOE) side chains showed better response to the viscosity with 78-fold, 55-fold, and 88-fold fluorescence enhancement in 95% glycerol solution respectively.

Probe ANI-DP displayed a distinctive ratiometric fluorescence response toward ONOO− with a red-shifted emision in far-red to NIR region owing to the cleavage of a phosphinate group and change of intramolecular charge transfer (ICT) efficiency induced by ONOO−.

In order to explore the effects of high temperature stress on photosynthetic apparatus of kiwifruit leaves and establish a heat injury identification index based on chlorophyll fluorescence response, the variation characteristics of the FO(minimal recorded fluorescence intensity), Fm(maximal recorded fluorescence intensity), Fa(maximal photochemistry efficiency), ΔWK(relative variable fluorescence difference at 300 μs), Tr(trapped energy flux per area at t=0), Et(electron transport flux per area at t=0), Dd(dissipated energy flux per area at t=0), Rm (density of QA-reducing PSⅡ reaction centers) in kiwifruit leaves under 30 ℃, 33 ℃, 36 ℃, 39 ℃, 42 ℃, 45 ℃, 48 ℃, 50 ℃, 52 ℃, 54 ℃ condition are studied by using the technique of fast chlorophyll fluorescence induction dynamics analysis(JIP-test).

Importantly, CPA-1 and CPA-2 shows ratiometric fluorescence response towards SO2 with highly sensitive and selective.

In this work, we combine these two groups organically to construct a rapid response site (within 30 s) for H2S, and at the same time, a ratiometric fluorescence response is presented throughout the process of H2S detection.

By taking advantage of their strong solid-state emission, excellent photostability, fast and sensitive fluorescence responses, and good biocompatibility, materials with AIE attributes are widely employed in pre-clinical diagnosis and mechanistic studies on biological processes.

In particular, the fluorophore with the benzoselenadiazole groups can form stronger chalcogen bonding with trimethyl arsine than the fluorophore with the benzothiadiazole groups, which in turn triggers much faster and more sensitive fluorescence responses.

In addition, this viscosity-selective fluorescence response covers a wide pH range from 2.

In EtOH/H2O (15/1, V/V), L showed selective fluorescence response to Zn2+, when the excitation wavelength was set to 425 nm.

Both the probes exhibited a good fluorescence response for HOCl in vitro and in mammalian cells.

The probe shows a good fluorescence response to Hg2+ in THF-H2O (fw=5%) mixed system.

This causes rapid fluorescence response and thus ensures the fast and continuous monitoring of SDM.

Additionally, based on the rapid fluorescence response of CBO to Fe2+, a simple test strip-based detector was designed for boosting practical applicability.

The separation of the fluorophore and quencher produces a high fluorescence response for BPA detection.

Then, by integrating Cas12a system and GO-based post-quenching strategy, a DNA biosensor was developed with extremely high fluorescence response and low initial background.

In the presence of the target mecA gene, the recognition and hybridization between HP1 and mecA can trigger Exo III and DNAzyme-mediated signal amplification and further release numerous ATMND, resulting in an enhanced fluorescence response, which serves as a response signal for the fluorescence detection of mecA gene.

Herein, a fluorescent amplification strategy based on catalyzed hairpin assembly indirectly covalent on Fe3O4@C nanoparticles via short single-stranded DNA was investigated for cellular miRNA detection in living cells, integrating non-enzyme target-active releasing for amplifying the signal output, highly quenching efficiency of Fe3O4@C nanoparticles with low background, ssDNA assisted fluorescent group-fueled chain releasing from Fe3O4@C nanoparticles with enhanced fluorescence response.

The binding mechanism studies suggested that the distinct fluorescence response was caused by electrostatic and π-π stacking interactions of HPTA-1 with the pocket between two G-quadruplex units of telomeric dimeric G-quadruplex TTA45.

The three fluorescent probes exhibit different binding affinities toward metal ions, resulting in diverse fluorescence behaviors and distinct fluorescence response patterns.

The SCN-PMO possessed high selectivity and sensitivity toward Cu2+ based on the specific fluorescence response.

The formation of these complexes with L not only triggers luminescence of lanthanides, but also produces specific fluorescence responses to antibiotics in aqueous solution, successfully demonstrating a new type of application for this supramolecular system.

The sensing properties can be applied in HEPES buffer to show strong fluorescence responses.

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.

Moreover, because of the diverse fluorescence properties of the eight compounds in various aggregated forms, they exhibit reversible fluorescence response to the transition of solid phases between crystalline and amorphous states under the mechanical force stimuli through breaking the multi-intermolecular interactions.

The nanoaggregates of the diethylamino-substituted polymer show remarkable and reversible fluorescence response to acid and base, and the acid-fumed polymer thin film can be used as a sensitive and reusable fluorescent probe for detecting seafood spoilage.

In order to explore the effects of high temperature stress on photosynthetic apparatus of kiwifruit leaves and establish a heat injury identification index based on chlorophyll fluorescence response, the variation characteristics of the FO(minimal recorded fluorescence intensity), Fm(maximal recorded fluorescence intensity), Fa(maximal photochemistry efficiency), ΔWK(relative variable fluorescence difference at 300 μs), Tr(trapped energy flux per area at t=0), Et(electron transport flux per area at t=0), Dd(dissipated energy flux per area at t=0), Rm (density of QA-reducing PSⅡ reaction centers) in kiwifruit leaves under 30 ℃, 33 ℃, 36 ℃, 39 ℃, 42 ℃, 45 ℃, 48 ℃, 50 ℃, 52 ℃, 54 ℃ condition are studied by using the technique of fast chlorophyll fluorescence induction dynamics analysis(JIP-test).

The cold tolerance of three Dendrocalamus farinosus strains (seedling plant and two somaclone mutants) which have been cold-acclimated were compared in terms of their chlorophyll fluorescence responses.

The different fluorescence responses make HBT-FS a fluorescent probe to discriminatorily detect F− and SO32–.

With the addition of metal ions, three sensor components can generate different fluorescence response patterns for discriminating 11 heavy metal ions via principal component analysis (PCA).

0, with a robust fluorescence response to extracellular ATP when expressed in several cell types.

Upon H2 supply, the Frex reporter reveals a robust fluorescence response and allows for monitoring rapid changes in cellular [NADH].

Hitherto, the development of fluorescent probes for UGTs was severely restricted due to the poor isoform selectivity, on-off or blue-shifted fluorescence response.

Unlike their 4-dibutylaminophenyl congeners that exhibited dynamic hypsochromic or bathochromic shifts in response to Lewis and Brønsted acids, the current class of compounds simply showed quenched fluorescence upon protonation; only AlCl3 elicited a red-shifted fluorescence response.

In the present strategy, the designed BZA-BOD@ZIF-90 showed excellent fluorescence response to protamine with a low detection limit of 0.

6-fold from methanol to glycerol exhibiting an excellent fluorescence response.

Interestingly, it effectively restored the red fluorescence of Eu3+ (593, 618 and 699 nm) and showed a dual-emission fluorescence response at 506 and 593 nm when the DPA existed.

Based on a single excitation–double emission fluorescence response of liberated fluorophores caused by enzymatic cleavage, the presence of a single or both proteases in a mixture was unambiguously determined in an experimentally established concentration range.

A higher fluorescence response was achieved using two capture probes tethered to magnetic beads using a biotin/streptavidin linkage, targeting two specific sites in the ORF1a and S genes.

Compared with the control experiment using a probe without NO prodrug loading, higher fluorescence response of NO was detected in the cell (3.

Xanth-NPr showed linear fluorescence response as a function of pH in the range of 1 to 4.

The results showed that the addition of Fe3+ makes the fluorescence emission spectra of A quenched and displayed a linear fluorescence response to Fe3+ with a detection limit of 1.

The as-obtained COFs exhibited a sensitive pH-dependent fluorescence response compared to their building blocks.

The fluorescence intensity of CD-4a exhibited a two-stage, concentration-dependent fluorescence response in the range 0.

5% of Hg2+ from aqueous solution with significant fluorescence response and colorimetric change.

Both of them demonstrated a significant fluorescence response to bisulfite in Tris-HCl buffer solutions (5 mM, pH = 7.

After embedding FA-CDs in Eu-MOFs, owing to the robust self-calibration function and excellent accumulation effect of Eu-MOFs, the developed FA-CDs@Eu-MOFs-based ratiometric fluorescence (RF) probe has a more prominent selectivity toward Ag+ with an ultrasensitive fluorescence response across a broad range of 0.

For instance, TP-QG could exhibit ultrasensitive fluorescence response for Fe3+ and F- in water via the fluorescence "ON-OFF-ON" pathway; the lowest detection limit (LOD) of TP-QG for Fe3+ was 2.

Herein, an unprecedented Cd-MOF-based sensor, [CdL]n [1, H2L = 4-(2-methyl-1H-benzo[d]imidazol-1-yl) isophthalic acid] with multiple fluorescence response behaviours towards antibiotics and bacteria was developed.

To overcome the sensing limitation of available mitophagy probes to only lysosome fusion or degradation, a molecular logic gate probe showing multiple fluorescence responses to different mitophagy stages was proposed in this study to sense the oxidative stress-induced mitophagy via a dual-channel mode.

In particular, it showed the best fluorescence response to 2,4,6-trinitrophenol (TNP) and 2,4-dinitrophenol (DNP), and the KSV values were 2.

Oxytetracycline (OTC) with the best fluorescence response of tetracycline antibiotics was coated on Zn-MOF to synthesize OTC@Zn-MOF fluorescent probe.

Additionally, PC-800 stimulated the secretion of redox-active humic substances (HSs), and excitation emission matrix spectra analysis indicated that the largest increase in percent fluorescence response of HSs occurred in the tightly bound EPS (TB-EPS) with addition of PC-800.

According to FRI, the C/N ratio had a significant impact on Regions III, IV, and V of EPS, Region V (34%~63%) was the dominant fraction in both types of EPS fractions and TB-EPS and LB-EPS contained similar functional groups, furthermore, the percent fluorescence response (Pi,n) of humic acid in TB-EPS was dramatically lower than LB-EPS.

In detail, PA signal is employed to trace the in vivo delivery with high spatial resolution, meanwhile the glutathione (GSH)-triggered dual-channel fluorescence response could real-timely monitor drug distribution and release without “blind spot”.

Dual-channel fluorescence response of RHI for Zn2+ and Hg2+ ensured a chance to apply them for build simple or complex molecular logic circuits.

In cellular imaging, time-resolved photoluminescence imaging microscopy clearly showed the independent fluorescence response toward hypochlorite and phosphorescence response toward oxygen in separated time intervals.

Importantly, CPA-1 and CPA-2 shows ratiometric fluorescence response towards SO2 with highly sensitive and selective.

The fluorescence response patterns were characteristic for each PFAS because of their different adsorption affinities toward different PCNs.

The three fluorescent probes exhibit different binding affinities toward metal ions, resulting in diverse fluorescence behaviors and distinct fluorescence response patterns.

The fluorescence response mechanism was discussed in detail.

Metal detection in living cells will be highlighted with representative examples together with fluorescence response mechanisms such as photoinduced electron transfer (PET), intramolecular charge transfer (ICT), and fluorescence resonance energy transfer (FRET).

Then, a ratiometric fluorescence sensor was constructed by in situ growth of CsPb(BrI)3@Asp-Cs4Pb(BrI)6 in metal organic framework (NH2-MIL-53) for the detection of BDE-3, in which the orange fluorescence of CsPb(BrI)3@Asp-Cs4Pb(BrI)6 (614 nm) was regarded as the reference signal and the cyan fluorescence of NH2-MIL-53 (494 nm) was used as the fluorescence response signal.

The unique probe exhibits excellent spectral properties including ratiometric fluorescence response signals to OCl- (within 7 s), high selectivity and sensitivity, and a large Stokes shift (278 nm).

Thus AP-1 site-mCherry-based biosensors were constructed, optimized, and then tested for their applicability and stable fluorescence response activities.

Fluorescence selectivity experiments revealed that it exhibited higher ratiometric fluorescence response activity toward NAD(P)H than other commonly coexisting compounds in the cell microenvironment, in accord with the fluorescence shift from red to blue.