in general all commercial transfection reagents are cationic in charge which leads to aggregation of cells when used in suspesion culture (like CHO cells). This decreases transfection efficiency because not every single cell will be reached.
For plasmid transfection of my CHO cells I use a new kind of transfection reagent which is zero in charge and avoids aggregation. Its called Viromer YELLOW and was develeopd from Lipocalyx (www.lipocalyx.de). Viromers are syntehtic polymers and due to their zero charge and an active endosome escape mechanism I get higher transfection efficiency compared to standard reagents.
Plasmid transfection of CHO cells by using Viromer YELLOW was published too (see attached file).