Radially cross-aligned nanofiber membrane

A fiber membrane, comprising electrospun fiberizeable material in at least three adjacent layers of nanofibers, each layer comprising a plurality of aligned nanofibers oriented at oblique angles relative to nanofibers in adjacent layers, said plurality of aligned nanofibers in each layer extending from a first membrane edge to a second membrane edge, wherein a plurality of aligned nanofibers in each layer cross a plurality of aligned nanofibers in adjacent layers at a plurality of distinct points of intersection, forming a crossing at each distinct point of intersection consisting of three crossing nanofibers extending directionally as six radials from each of said distinct points of intersection, wherein relative cross-alignment angles between said six radials at each distinct point of intersection are in the range of 50 to 70 degrees, and wherein said relative cross-alignment angles of said aligned nanofibers and spacing between said aligned nanofibers each have a specific average numerical value in said membrane, and wherein said aligned nanofibers in each said layer comprise at least one of solid, hollow, or core-shell fiber, and wherein said nanofibers further comprise a polymeric material and a chromogenic agent responsive to enzymatic activity, and wherein said polymeric nanofibers further comprise an absorbable and biodegradable polymer that can be is-enzymatically or nonenzymatically decomposed, yields no toxic decomposition product, and has ability of releasing a drug.