About the cover

April 2012 Volume 11 No 4

siRNA delivery has so far been hampered by carriers that inefficiently encapsulate RNA, and by its degradation prior to cellular uptake. Now, self-assembled crystalline microsponges consisting solely of cleavable RNA strands — which are converted to siRNA only after cellular uptake — achieve, with three orders of magnitude lower concentration, the same degree of gene silencing as conventional siRNA nanocarriers.

Letter p316; News & Views p268

IMAGE: JONG BUM LEE

COVER DESIGN: DAVID SHAND