What kinds of siRNA transfection methods we can pick beside lipofectomine? What are the corresponding mechanisms? Why suspension cells are always hard to be transfected?

Here are some websites to help with your questions:

Question 1 (better siRNA transfection methods)
http://www.invitrogen.com/site/us/en/home/Products-and-Services/Applications/RNAi-Epigenetics-and-Gene-Regulation/RNAi/Delivering-RNAi-to-cells-transfection-and-viral-delivery.reg.us.html

http://cell-transfection.blogspot.com/

http://www.molecularstation.com/sirna/sirna-protocols/sirna-transfection/

Question 2 (mechanism):

http://www.biocompare.com/featurearticle.asp?articleid=797

Question 3 (how to handle transfection of cells in suspension)

http://www.protocol-online.org/biology-forums/posts/5139.html

Good luck and come back with other questions, tell your friends!

Omai