Fig. 5: Two representative biological applications based on a 3DBCPM as a platform.

a Study of protein–membrane interaction by incorporating EP4 proteins that were conjugated with a green fluorescent protein (GFP) and stabilized with amphipathic poly-γ-glutamic acid (APG): (i) injection of EP4; (ii) Insertion and adsorption of EP4 to 3DBCPM; (iii) Release of APG from 3DBCPM and desorption of adsorbed EP4 by repeated washing; and (iv) Successful incorporation of EP4 to 3DBCPM. b Cross-sectional confocal fluorescence microscopy images (top) and fluorescence intensities (bottom) of 3DBCPMs without (left) and with (right) EP4 incorporation. c Confirmation of the protein reconstitution on the 3DBCPM by distinguishing groups of fluorescence intensities of the 3DBCPM membranes incorporated without and with EP4. Data are presented as means ± standard deviation (n = 10 independent samples). d Fabrication and working principles of 3DBCPM-based artificial intestinal organs: (i) introduction of 1 mol% of 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[succinimidyl(polyethylene glycol)] (DSPE-PEG-NHS) onto the 3DBCPM; (ii) coupling of NHS with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC); (iii) conjugation of beta-galactosidase (β-Ga); and (iv) enzymatic reaction where fluorescein di-β-d-galactopyranoside (FDG) is hydrolyzed into galactose by β-Ga, releasing GFP molecules that cause an increase in fluorescence. e Comparison of time-dependent enzymatic kinetics of the proposed spherical and cilia-like 3DBCPMs and a planar block copolymer structure by monitoring the normalized fluorescence intensities after the enzymatic reaction. f Estimated enzymatic reaction rate constants and surface-area-normalized rate constants of three different block copolymer structures: planar, spherical, and cilia.