Three-dimensional (3D) in vitro scaffolds that
mimic the irregular fibrous structures of in vivo extracellular
matrix (ECM) are critical for many important biological ap-
plications. However, structural properties modulation of fi-
brous 3D scaffolds remains a challenge. Here, we report the
first highly modulable 3D fibrous scaffolds self-assembled by
high-aspect-ratio (HAR) microfibers. The scaffolds structural
properties can be easily tailored to incorporate various physi-
cal cues, including geometry, stiffness, heterogeneity and
nanotopography. Moreover, the fibrous scaffolds are readily
and accurately patterned on desired locations of the substrate.
Cell culture exhibits that our scaffolds can elicit strong

• Fabrication of highly modulable fibrous 3D extracellular microenvironments