A Novel Fluorescent and Colorimetric Method for the Determination of Formaldehyde Based on Albumin Nanoparticles-Polyethyleneimine-Ag+ Ion Nanohybrids.

As a carcinogenic substance, high dose of formaldehyde exposure may lead to poisoning and even death. Long-term exposure to low doses of formaldehyde can harm human skin, respiratory organs and immune system. Therefore, it is vital to detect formaldehyde content in real time. In this paper, a simple method for the determination of formaldehyde based on fluorometry and colorimetry was established in the range of 0-1.92 mg·mL-1. A fluorescence protein nanoparticles (BSA NPs) was prepared utlizing bovine serum albumin (BSA) as the raw material. Based on the silver mirror reaction, silver nanoparticles can be generated from the reaction between BSA NPs combined with polyethylenimide (PEI) and silver ion (Ag+) ions complex (BSA NPs-PEI-Ag) and formaldehyde. The fluorescent detection principle for formaldehyde was based on the fluorescence queching of BSA NPs-PEI-Ag system at 514 nm upon the reduction of Ag+ ions by formaldehyde. The colorimetric detection principle for formaldehyde was based on the enhancement of absorption band of BSA NPs-PEI-Ag system at 460 nm and color changes along with the generation of silver nanoparticles after the addition of formaldehyde. The proposed method was succesfully used for formaldehyde detection in real water sample with the recovery range of 106-110%.

PTOP and TRF1 help enhance the radio resistance in breast cancer cell.

PURPOSE: The telomere binding proteins play an important role in telomere function, which contribute greatly to the radio resistant in human cancers. This research is designed to investigate the relationship among the telomere length, telomerase activity and changes of telomere binding protein PTOP and TRF1 in radio resistant breast cancer cell lines. METHODS: Irradiate MDA-MB-435 s breast cancer cell with total dose of 60 Gy delivered in 2 Gy/fraction and 6 Gy/fraction respectively, then measuring their telomere length by Southern blot analysis,telomerase activity by Telomerase PCR Elisa and detecting the expression of PTOP and TRF1 in both gene and protein levels. To further investigate the function of PTOP, using lentivirus technic to silence the PTOP gene and the detected the new silenced cells by southern blot and telomerase activity. RESULTS: 2 radio resistant breast cancer cell lines were successfully established. The MDA-MB-435 s R60/6 was (approximate 8.1-8.6 kbp) about 2-2.4 folds to the patent cell (3.6-4.2 kbp), the MDA-MB-435 s R60/2 cell (approximate 5.3-6.3 kbp) was about 1.3-1.75 fold to the parent cell line. The telomerase activity was more enhanced in radio resistant cell lines than the parent cell. The expression of PTOP and TRF1 were significant increased in radio resistant cell lines than the patent cell in both gene and protein level. Otherwise, after using lentivirus technic to silence the PTOP gene, we found the radio resistant cell lines were significant decrease their radio resistances and telomerase activities. CONCLUSION: The telomere binding protein PTOP and TRF1 were increased expressed in radio resistant breast cancer cell, PTOP was observed instinct positive correlated with telomere lengthen and telomerase activity enhancement.