ABSTRACT
Increasing acidity is an effective method for bacterial inactivation by inhibiting the synthesis of intracellular proteins at low pH. Photo-driven proton release probe can be used for the measurement of proton in hydrophobic condition. To develop fluorescent proton donor, two boron dipyrromethene derivatives (BDP-S and BDP-S2) were characterized by spectroscopic methods. Irradiation of BDP-S by white LED light resulted in efficient generation of acidic species with changes of fluorescence emission. The linear relationship between the pH value and the fluorescence intensity of BDP-S was obtained, indicating that BDP-S is a fluorescent visual proton donor. Light-induced antibacterial results indicate that BDP-S can significantly inhibit the growth of E. coli. The results prove that BDP-S is a very promising photoacid sterilant.
Subject(s)
Anti-Bacterial Agents/pharmacology , Boron Compounds/pharmacology , Escherichia coli/drug effects , Fluorescent Dyes/pharmacology , Protons , Sulfonic Acids/pharmacology , Anti-Bacterial Agents/chemical synthesis , Anti-Bacterial Agents/chemistry , Boron Compounds/chemistry , Fluorescent Dyes/chemical synthesis , Fluorescent Dyes/chemistry , Hydrogen-Ion Concentration , Microbial Sensitivity Tests , Molecular Structure , Spectrometry, Fluorescence , Sulfonic Acids/chemistryABSTRACT
Hypoxia promotes not only the metastasis of tumors but also therapeutic resistance. Photosensitizer-mediated consumption of O2 during photodynamic therapy (PDT) reinforces tumor hypoxia. Herein, a light-dependent attenuator of a hypoxic environment is reported for accurate MRI and phototherapy of hypoxic cancer. First, a photoresponsive Mn(ii) nanoassembly was constructed, then it was assembled with bovine serum albumin (BSA) and modified with polyethylene glycol-folic acid (PEG-FA), forming cancer targeting Mn-DBA@BSA-FA nanoassemblies, which offer T1 signals and can catalyze the water oxidation reaction under irradiation of red light emitting diode (LED) light with the generation of O2 and heat. Moreover, they could selectively penetrate through and accumulate in the tumor tissues with clear T1 magnetic resonance imaging (MRI) signals, and have remarkably eliminated the tumors in vivo, while they are of low toxicity to the healthy organs. The release of the Mn(ii) complex from the nanoparticles in an acidic environment and the in vivo biodistribution results confirm the selective cancer targeting. Our work demonstrates the potential of nanoparticles as excellent theranostic agents for MR imaging combined with phototherapy triggered by near-infrared light.
ABSTRACT
The interactions of Salvianolic acis A (SAA) and Salvianolic acid B (SAB) with insulin were studied by using fluorescence spectroscopy, UV-vis spectroscopy and ATR-FTIR spectroscopy in simulating physiological condition (pH 7.40). The fluorescence quenching of insulin by SAA and SAB were static quenching process. The results of synchronous fluorescence and three-dimensional fluorescence spectra suggested no obvious conformation changes of insulin after SAA or SAB binding. But ATR-FTIR spectra showed that SAA and SAB could change the secondary structures of insulin, of which ß-turns decreased and random coil increased accompanied with α-belices and ß-sheets no clear change. The glucose might influenced the bioactivity of insulin in the SAA-insulin and SAB-insulin systems by changing the binding constants of SAA (or SAB) with insulin and exacerbating the changes of insulin conformation and relative contents of α-belices.