[Preparation and characterization of tumor targeted CdTe quantum dots modified with functional polymer].

N-acetyl-L-cysteine (NAC) capped quantum dots (QDs) were synthesized by a hydrothermal method and coated with 2-amino-2-deoxy-D-glucose (DG), polyethylene glycol (PEG), and 9-D-arginine (9R). The optical properties, morphology and structure of 9R/DG-coated CdTe QDs were characterized by ultraviolet-visible spectrometry, fluorescence spectrum, Fourier transform infrared (FTIR), proton nuclear magnetic resonance (1H NMR), liquid chromatography-mass spectrometer (LC-MS), sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and transmission electron micrographs (TEM). Furthermore, the biocompatibility, tumor targeted ability and transmembrane action of 9R/DG-coated CdTe QDs were studied. Results indicated that 9R/DG-coated CdTe QDs was constructed successfully by ligand exchange. The 9R/DG-coated CdTe QDs with the size of 8-10 nm had good dispersity and the absorbance and fluorescence peaks of CdTe QDs after modification were red shifted from 480 nm to 510 nm and 627 nm to 659 nm, respectively. In addition, the CdTe QDs modified by PEG, DG and 9R displayed good biocompatibility, high targeted ability to the cancer cells with glucose transporter type 1 (GLUT1) receptor high expression and obvious transmembrane ability.

Quantification of the sixth DNA base 5-hydroxymethylcytosine in colorectal cancer tissue and C-26 cell line.

BACKGROUND: DNA methylation at the five position of cytosine is well recognized as an important epigenetic modification in human health and disease. Recent evidences demonstrated that 5-methylcytosine (5-mC) by the TET family of enzymes can be converted to 5-hydroxymethylcytosine (5-hmC). Here, we use an ultrasensitive and accurate isotope-based LC-MS/MS method to precisely determine the levels of 5-hmC and 5-mC in colorectal cancer and the C-26 colon adenocarcinoma cell line. RESULTS: Our data showed that 5-hmC content is significantly reduced (approximately sixfold) in colorectal cancer as compared with adjacent normal tissue. Similarly, the ratio of 5-hmC to 5-mC dropped from 0.054 ± 0.005 in normal tissues, to 0.011 ± 0.002 in cancer. CONCLUSION: The analysis of 5-hmC levels and the ratio of 5-hmC:5-mC during tumor progression might provide insight into the role of this modification in cellular immortalization and transformation.