Preparation, optical properties and cell staining of water soluble amine-terminated PAMAM G2.0-Au nanocomposites

The solution chemical and optical characteristics of formation of amine-terminated polyamidoamine dendrimer G2.0（NH2-PAMAM G2.0）-Au nanocomposites in the aqueous solution of NH2-PAMAM G2.0 at various mole ratios of Au（Ⅲ） to NH2-PAMAM G2.0 were studied by both UV-visible spectrometry and fluorospectrometry. The NH2-PAMAM G2.0-Au nanocomposites, with a type of structure in which one Au nanoparticle is surrounded by several NH2-PAMAM G2.0 dendrimers, emit strong bluish violet fluorescence, and are uniform, water soluble and biocompatible as well as very stable in frozen conditions. The size of gold nanoparticles in the nanocomposites is about 2.5 nm and decreases with the increase of NH2-PAMAM G2.0 concentration. The NH2-PAMAM G2.0 plays an important role in acting as host or micro-reactor for Au（Ⅲ） before Au（Ⅲ） reduction and acting as dispersant and stabilizer for gold nanoparticles after Au（Ⅲ） reduction. Preliminary experiments of cells staining to human embryonic lung fibroblast cell lines show that the NH2-PAMAM G2.0-Au nanocomposites can be used as optical imaging markers for bioanalyses and medical diagnoses.

Detection of Mycoplasma Contamination in Animal Cell Cultures

[ Objective ] To develop a rapid efficient method for detecting mycoplasma contamination in cell cultures. [ Method] A pair of primers was designed according to two highly conserved nucleotide sequences of the 16S RNA from six kinds of mycoplasma that commonly contaminated cells. Then the mycoplasma contamination of 25 cell samples was defected by PCR and DNA fluorescence staining. EResultl When these cell samples were detected by DNA fluorescence staining, the positive rate and probable positive rate were respectively 24% and 16%. And when they were detected by PCR, the positive rate was 36%. [ Condusion] The PCR method is more sensitive and specific than the DNA fluorescence staining, and combining these two methods is the optimal way to detect mycoplasma contamination in cell cultures.

A novel method for the synthesis of carbon dots assisted by free radicals

Carbon dots(CDs)have gradually become a widely favored type of fluorescent nanomaterials with unlimited and promising applications.This work reports a means of breaking the shackle of method to develop new red and white CDs by introducing free radicals.The resulting white emissive CDs in this strategy are employed to demonstrate electroluminescent white-light-emitting diodes(WLEDs)and achieve a record-high external quantum efficiency(0.95%)of one-step-produced white CDs(WCD)-LEDs,which dramatically simplifies the whole fabrication processes of WLEDs.With additional passivation treatment,the red CDs(RCD2)with excellent properties such as N and S co-doping,bright(quantum yield=49%)and stable photoluminescence(PL),large positive zeta potential(+20.5 mV),and two-photon fluorescence are obtained.Such RCD2 are used for rapid staining(5 min)of yeast cells.The two CDs synthesized via this method have outstanding performance in different aspects,which provides new promise of CDs for further functionalization and applications.