Study the fluorescent and conductivity properties of a 4-hydroxy-3-nitro-1,8-naphthalic anhydride

The compound of (4-hydroxy-3-nitro-1,8-naphthalic anhydride) and the dopant material (4-hydroxy-m-benzene-disulfonic acid) were synthesized. The UV-Vis absorption and fluorescence spectra of the compound were recorded. The bathochromic shifts in absorption due to the changes in the solvent polarity was observed, in DMSO solvent, the compound shows different peaks, three bands in the UV region and one band in the visible region, one absorption peak at 402 nm, which might be attributed to the (ICT) band. The emission spectra of this compound were sensitive to the solvent polarity. They moved to lower energies with increasing the polarity of the solvent. The influence of the solvent polarity on the fluorescence maximum was more pronounced compared with the absorption maximum, showing ca. 3 nm red shift on moving from butanol to DMSO. The effect of the dopant material on the conductivities (ionic and specific) of the compound was studied, the ionic conductivity was increased as the weight of the dopant material increases, and the ionic conductivity (G) was measured in water as a solvent. the (G) of the compound was 2.4X10-6 Siemens at 0.01 gm of the dopant material, and was 2.62X10-4 Siemens after the dopant material was added (0.1 gm).

A Facile Strategy for the Ion Current and Fluorescence Dual-Lock in Detection: Naphthalic Anhydride Azide (NAA)-Modified Biomimetic Nanochannel Sensor towards H2S

Inspired by biological channels, the electric signal-based artificial nanochannel system exhibits high sensitivity in various analyses. However, ion current may be affected by many other factors, leading to false-positive signals. For reliable detection, in this work, we apply a facile strategy to combine both current signal and fluorescence. Fluorescent probes were conjugated to the nanochannel surface by covalent bonds. By utilizing the specific reduction of azide groups in the probe to amino groups by H2S, a synchronizing change in fluorescence and nanochannel surface charge was established. As a result, both transmembrane ion current and fluorescence intensity showed significant changes. The photoelectric double-checked locking from temporal and spatial variation validly confirmed the response process and protected detection accuracy. The work may provide new ideas for the development of more sophisticated current and fluorescence dual-index nanochannel systems.

A Nitronaphthalimide Probe for Fluorescence Imaging of Hypoxia in Cancer Cells

The bioreductive enzymes typically upregulated in hypoxic tumor cells can be targeted for developing diagnostic and drug delivery applications. In this study, a new fluorescent probe 4−(6−nitro−1,3−dioxo−1H−benzo[de]isoquinolin−2(3H)−yl)benzaldehyde (NIB) based on a nitronaphthalimide skeleton that could respond to nitroreductase (NTR) overexpressed in hypoxic tumors is designed and its application in imaging tumor hypoxia is demonstrated. The docking studies revealed favourable interactions of NIB with the binding pocket of NTR-Escherichia coli. NIB, which is synthesized through a simple and single step imidation of 4−nitro−1,8−naphthalic anhydride displayed excellent reducible capacity under hypoxic conditions as evidenced from cyclic voltammetry investigations. The fluorescence measurements confirmed the formation of identical products (NIB-red) during chemical as well as NTR−aided enzymatic reduction in the presence of NADH. The potential fluorescence imaging of hypoxia based on NTR-mediated reduction of NIB is confirmed using in-vitro cell culture experiments using human breast cancer (MCF−7) cells, which displayed a significant change in the fluorescence colour and intensity at low NIB concentration within a short incubation period in hypoxic conditions. Graphical abstract

Design, Synthesis and Antimicrobial Evaluation of Novel Benzimidazole-incorporated Naphthalimide Derivatives As Salmonella typhimurium DNA Intercalators, and Combination Researches

Objective: A series of novel benzimidazole-incorporated naphthalimide derivatives were designed and prepared to overcome the increasing antibiotic resistance. Method: The target novel benzimidazole-incorporated naphthalimide derivatives were synthesized from commercial 4-bromo-1,8-naphthalic anhydride and o-phenylene diamine by aminolysis, N-alkylation, and so on. The antimicrobial activity of the synthesized compounds was evaluated in vitro by a two-fold serial dilution technique. The interaction of compound 10g with Salmonella typhimurium DNA was studied using UV-vis spectroscopic methods. Results: Compound 10g bearing a 2,4-dichlorobenzyl moiety exhibited the best antimicrobial activities in this series relatively, especially it gave the comparable action against Salmonella typhimurium compared to the reference drug Norfloxacin (MIC = 4 mg/mL). Further research showed that compound 10g could effectively intercalate into the Salmonella typhimurium DNA to form the 10g–DNA complex, which might correlate with the inhibitory activity. Molecular docking results demonstrated that naphthalimide compound 10g could interact with base-pairs of DNA hexamer duplex by p–p stacking. Additionally, the combinations of the solid active combination with clinical drugs gave better antimicrobial efficiency with less dosage and broader antimicrobial spectrum than the separated use alone. Notably, these combined systems were more sensitive to Fluconazole-insensitive M. ruber. Conclusion: This work opened up a good starting point to optimize the structures of benzimidazole-incorporated naphthalimide derivatives as potent antimicrobial agents.

Cellulose based fluorescent macromolecular sensors and their ability in 2, 4, 6-trinitrophenol detection

This article deals with three cellulose-based fluorescent macromolecular sensors by introducing 1,8-naphthimide fluorophore to cellulose. Firstly, through the etherification reaction of cellulose with BrCH2CH2NH2, -NH2 group bearing cellulose CS 1 was obtained. And then -NH2 group reacts with 4-bromo-1,8-naphthalic anhydride to synthesize a naphthalimide cellulose derivative (CS 2). Finally, recognition group was introduced by substituting Br atoms, and three cellulose fluorescent probes (CS 3, CS 4, CS 5) were obtained eventually. Structure and fluorescence properties of the macromolecular sensors were characterized and confirmed. Fluorescence detection measurements show that these probes can be used as selective and sensitive fluorescent sensors to 2,4,6-trinitrophenol (TNP). The detection limits are 0.52µM, 0.76µM and 0.81µM, respectively, indicating good detection performance. This work provides a new method for the selective detection of TNP and also a method to enlarge the application scope of cellulose.

Microwave-Assisted Synthesis and Fluorescent Properties of 4-Phenyl-1,8-naphthalimide

4-Phenyl-1,8-naphthalimide was synthesized by imidation of commercially available 4-bromo-1,8-naphthalic anhydride, followed by Suzuki coupling with phenyl boronic acid, both under microwave heating. The microwave-assisted reactions were found to be faster and more efficient than reactions carried out by heating in oil-baths. While this compound was quite fluorescent in solvents such as chloroform, methanol and ethanol, it is virtually non-fluorescent in DMSO; however, upon the addition of water to DMSO solutions of this dye, fluorescence was restored, suggesting a tendency for aggregation-induced emission. The fluorescent properties of 4-phenyl-1,8-naphthalimide were found to be influenced by salt concentrations, likely as a result of hydrophobic effects. While this dye does not show binding to DNA, presence of bovine serum albumin leads to effective fluorescence quenching.