A Zn(II)-Metal-Organic Framework Based on 4-(4-Carboxy phenoxy) Phthalate Acid as Luminescent Sensor for Detection of Acetone and Tetracycline.

As hazardous environmental pollutants, residual tetracycline (TC) and acetone are harmful to the ecosystem. Therefore, it is necessary to detect the presence of these pollutants in the environment. In this work, using Zn (II) salt, 4-(4-carboxy phenoxy) phthalic acid (H3L), and 3,5-bis(1-imidazolyl) pyridine (BMP), a new metal-organic framework (Zn-MOF) known as [Zn3(BMP)2L2(H2O)4]·2H2O was synthesized using a one-pot hydrothermal method. The Zn-MOF has a three-dimensional framework based on the [Zn1N2O2] and [Zn2N2O4] nodes linked by a tridentate bridge BMP ligand and an L ligand with the µ1:η1η0/µ1:η1η0/µ0:η0η0 coordination mode. There were two kinds of left- and right-handed helix chains, Zn1-BMP and Zn1-BMP-Zn1-L. The complex was stable in aqueous solutions with pH values of 4-10. The Zn-MOF exhibited a strong emission band centered at 385 nm owing to the π*→π electron transition of the ligand. It showed high luminescence in some common organic solvents as well as in the aqueous solutions of pH 4-10. Interestingly, TC and acetone effectively quenched the luminescence of the Zn-MOF in aqueous solution and enabled the Zn-MOF to be used as a sensor to detect TC and acetone. The detection limits of TC and acetone were observed to be 3.34 µM and 0.1597%, respectively. Even in acidic (pH = 4) and alkaline (pH = 10) conditions, the Zn-MOF showed a stable luminescence sensing capability to detect TC. Luminescence sensing of the Zn-MOF for TC in urine and aquaculture wastewater systems was not affected by the interfering agent. Furthermore, the mechanism of sensing TC was investigated in this study. Fluorescence resonance energy transfer and photoinduced electron transfer were found to be the possible quenching mechanisms via UV-Vis absorption spectra/the excitation spectra measurements and DFT calculations.

Synthesis of temperature/pH dual-sensitive supramolecular micelles from ß-cyclodextrin-poly(N-isopropylacrylamide) star polymer for drug delivery.

In this paper, temperature and pH dual-sensitive supramolecular micelles were constructed from star polymer ß-cyclodextrin-poly(N-isopropylacrylamide) (ß-CD-PNIPAM) and benzimidazole terminated poly(ε-caprolactone) (BM-PCL). The supramolecular micelles were formed based on the reversible host-guest recognition between ß-CD and BM. The size of supramolecular micelles was about 50-100 nm and the LCST was about 30.5 ℃. The drug loading efficiency of supramolecular micelles for DOX was high due to the hydrophobic micelles core of PCL and hydrophobic cavity of ß-CD. The release of drugs from supramolecular micelles was suppressed at neutral solution and room temperature but accelerated at acidic solution and 37 ℃. The drug loaded supramolecular micelles exhibited higher anti-cancer activity than free drugs. These temperature and pH dual-sensitive supramolecular micelles might possess potential applications for anticancer drug delivery.

Dual pH-sensitive supramolecular micelles from star-shaped PDMAEMA based on ß-cyclodextrin for drug release.

Star-shaped poly(2-(dimethylamino)ethyl methacrylate) based on ß-cyclodextrin (ß-CD-(PDMAEMA)7) was synthesized by means of atomic transfer radical polymerization (ATRP). Dual pH-sensitive supramolecular micelles were formed from ß-CD-(PDMAEMA)7 and benzimidazole modified poly(ε-caprolactone) (BM-PCL) through the host-guest interactions between ß-CD and benzimidazole. The supramolecular micelles have regular spherical structure with hydrophobic ß-CD/BM-PCL as the core and pH-sensitive PDMAEMA as the shell. The hydrophobic PCL as well as the hydrophobic cavity of ß-CD can efficiently encapsulate doxorubicin (DOX) with the drug-loading content and entrapment efficiency up to 40% and 86%. The drug release from micelles accelerated when the pH decreased from 7.0 to 2.0 and the temperature increased from 25 °C to 45 °C. MTT assay showed that drug loaded supramolecular micelles exhibited excellent anti-cancer activity than free DOX. These supramolecular micelles have promising potential applications as intelligent nanocarriers in drug delivery system.