A highly sensitive,dual-signal assay based on rhodamine B covered silver nanoparticles for carbamate pesticides

A highly sensitive sensor for determination of carbamate pesticides based rhodamine B（RB） modified silver nanoparticle（RB-AgNPs） was developed.Compared with the classical method,it combined colorimetric with fluorescence for detecting carbamate pesticides in complex solutions.Carbamate pesticides can inhibit the activity of acetylcholinesterase（AChE）,thus preventing the generation of thiocholine.On the other hand,thioncholine can transform the yellow RB-AgNPs solutions gray color and unquenches the fluorescence of RB simultaneously.Once the activity of AChE was inhibited by the pesticide,the color of the RB-AgNPs solution remains yellow and the fluorescence of RB molecules remains quenched.Under optimized experimental conditions,carbaryl was detected in a concentration range from 0.1 ng/L to 8.0ng/L with a detection limit of 0.023 ng/L（it was detected by fluorescence spectra）.This simple method is suitable for determination of carbamate pesticides in complex samples,such as tomato,apple and river water.

Enhancement of gemcitabine against pancreatic cancer by loading in mesoporous silica vesicles

Gemcitabine（Gem） is currently the first-line chemotherapeutic drug in management of pancreatic cancer, however the therapeutic efficacy of Gem is limited due to its short half-life and poor cell membrane permeability. Here we designed mesoporous silica vesicles（MSVs） with large pore sizes as a novel drug delivery system. The MSVs were synthesized using cetyltrimethyl ammonium bromide（CTAB） as a structure-directing agent, tetraethoxysilane（TEOS） as silica source in n-hexane/water biliquid system. By virtue of the large pore size and large pore volume of the MSVs, Gem was loaded into the mesoporous of MSVs via ＂nanocasting＂ method. In vitro drug release experiments of gemcitabineloaded MSVs showed an accelerating release of gemcitabine in acidic condition. These fluorescently labeled MSVs could be effectively internalized by both a human（BxPC-3） and a mouse pancreatic cancer cell lines（Pan02）. Additionally, some MSVs could even reach the nuclei of the pancreatic cancer cells. Cell viability assays demonstrated that gemcitabine-loaded MSVs exhibited enhanced anticancer activity in inhibiting the proliferation of Bx PC-3 and Pan02 cells compared with free Gem, while the MSVs alone showed no significant cytotoxicity. Our results indicate that our synthesized MSVs might represent a promising novel drug delivery platform for the treatment of pancreatic cancer.