Disclosed herein is a novel method to fabricate magnetic silica nanomembranes using thin polymer cores based on silica deposition and self-wrinkling induced by thermal shrinkage. These micro- and nano-scale structures have vastly enlarged the specific area of silica, thus the magnetic silica nanomembranes can be used for solid phase extraction of nucleic acids. The magnetic silica nanomembranes are suitable for nucleic acid purification and isolation and demonstrated better performance than commercial particles in terms of nucleic acid recovery yield and integrity. In addition, the magnetic silica nanomembranes may have high nucleic acid capacity due to significantly enlarged specific surface area of silica. Methods of use and devices comprising the magnetic silica nanomembranes are also provided herein.