Xylem-inspired anisotropic porous silk microneedles enable efficient interstitial fluid sampling for local biomarker and proteomic profiling of skin diseases.

A single patch collects >10 μL interstitial fluid within 5 min, supports transport of macromolecules of at least 150 kDa, and achieves recovery efficiencies above 95%, yielding >180 μg total protein from mouse skin.

In psoriasis-like mice, anisotropic porous silk microneedle-collected interstitial fluid enables ELISA quantification of inflammatory biomarkers with sensitivity higher than serum and comparable to skin biopsy.