Figure 1.

Schematic of the process for the micropillar fabrication, PEM coating and DOX loading and release. (A) Macropore formation by electrochemical etching; (B) SiO₂ growth by thermal oxidation; (C) backside oxide removal; (D) backside silicon removal by TMAH etching and micropillar releasing; (E) polyelectrolyte pair PAH/PSS alternative deposition on the internal sidewalls of SiO₂ micropillars via the LbL method to construct a pH-responsive drug delivery system; (F) DOX loading in the swollen PEM film at pH 2.0; (G) DOX confinement due to the PEM layer contraction at pH 8.0; and (H) DOX release in different media at pH 7.4 and 5.2.