Abstract: A single-use bag includes a collapsible a body having a first end and an opposing second end bounding a compartment. The collapsible body comprises at least one flexible sheet having an interior surface and an exterior surface; wherein the interior surface layer comprises low density polyethylene having a melt index from 0.9 to 2.0 g/10 min with a weight average molecular weight (Mw) greater than 200,000 Da, and an Mz greater than 1,500,000 Da. Optionally, the flexible sheet comprises an oriented film as an additional layer on the exterior surface. The single-use bag is useful in biological processing, including use in a disposable cell culture bioreactor.