Silaniza on. The substrates were treated to improve the adhesion of the 3D printed microstructures to the glass slide surface. For this purpose, glass coverslips (22 × 22 mm, 170 µm thickness) were washed with isopropanol and acetone and dried under pressurized N2. Then, the surface was cleaned and ac vated for 1.5 min by plasma treatment using a piezobrush PZ2 handheld plasma cleaner (Relyon Plasma GmbH, TDK Group Company). The coverslips were then immersed in a 4 x 10 -3 M solu on of 3-(trimethoxysilyl)propyl acrylate in toluene overnight. Finally, a er washing twice in toluene and once in acetone, the silanized glass slides were used for prin ng. Two-photon laser 3D prin ng. 3D prin ng was performed on the commercially available setup Photonic Professional GT2 (Nanoscribe GmbH & Co. KG) in oil immersion configura on with a femtosecond laser (λ = 780 nm) focused through a 63x oil objec ve (NA = 1.4; WD = 190 µm; Zeiss).