Progress of cationic gene delivery reagents for non-viral vector.

Gene delivery systems play a vital role in gene therapy and recombinant protein production. The advantages of using gene delivery reagents for non-viral vector include the capacity to accommodate a large packaging load and their low or absent immunogenicity. Furthermore, they are easy to produce at a large scale and preserve. Gene delivery reagents for non-viral vector are commonly used for transfecting a variety of cells and tissues. It is mainly composed of liposomes and non-liposome cationic polymers. According to the different head structures used, the non-viral cationic transfection reagents include a quaternary ammonium salt, amine, amino acid or polypeptide, guanidine salt, and a heterocyclic ring. This article summarizes these approaches and developments of types and components of transfection reagents and optimization of gene delivery. The optimization of mammalian cell transient recombinant protein expression system and cationic reagents for clinical or clinical trials are also discussed.

Effects of different 2A peptides on transgene expression mediated by tricistronic vectors in transfected CHO cells.

Multicistronic vectors can increase transgene expression and decrease the imbalance of gene expression in the Chinese hamster ovary (CHO) cell expression system. Small, self-cleaving 2A peptides have a high cleavage efficiency and are essential for constructing high-expression multicistronic vectors. In this study, we investigated the effects of two different 2A peptides on transgene expression in CHO cells via their mediating action on tricistronic vectors. The enhanced green fluorescent protein (eGFP) and red fluorescent protein (RFP) genes were linked by the porcine teschovirus-1 (P2A) and Thosea asigna virus (T2A) peptides in a multicistronic vector. We transfected CHO cells with these vectors and screened for the presence of blasticidin-resistant colonies. Flow cytometry and real-time quantitative PCR (qPCR) were used to detect the expression levels of eGFP and RFP and the copy numbers of stably transfected cells. The results showed that P2A could enhance eGFP and RFP expression by 1.48- and 1.47-fold, respectively, compared to T2A. The expression levels of the genes were not proportional to their copy numbers. In conclusion, we found that P2A can effectively drive transgene expression in CHO cells and a potent 2A peptide can be used for recombinant protein production in the CHO cell system.

[Research on several times of abruptly changes in the ultrafast transient reflectivity in Co films].

In the present paper, cobalt films, chromium and cobalt double layer films, and silver and cobalt double layer films were deposited by magnetron sputtering technique. The transient reflectivity response in cobalt thin films and their double layer films was studied by using femtosecond laser pump-probe transient reflection experimental technology. The result shows that, under the condition of the cobalt films of the same thickness, when the pump power increases, the heating time of the electrons in cobalt thin films is independent of the pump power, and is 0. 134 4 ps. And for the cobalt films of different thickness, the electron thermalization time is directly related to the film thickness. In addition, when the laser pulse power is high enough, two or three transient reflectivity decline signals on glass substrate films are found which is different with previous researches, when the cobalt films were thin, there are three times of transient reflectivity abruptly decline signals, and when the cobalt films were thick, there are two times of transient reflectivity abruptly decline signals, so the thickness of the cobalt films determines the times of the changes of the ultrafast dynamics in cobalt films.