We used confocal imaging to measure the thermodynamic partitioning coefficient of IgG* into the PA gels.16 (link) After silanization of the μ-Slide chambered coverslips, gels were fabricated using wafer molds with 40 μm feature heights within these containers and incubated in TBS-T for 24 h. Gels were then exposed to 1:20 dilution of IgG* solution (from 2 mg/mL stock solution from manufacturer, spun down to remove aggregates) in 2% BSA/TBS-T for >2 h to equilibrium. Confocal imaging experiments were conducted on an inverted Zeiss LSM 710 AxioObserver at the CRL Molecular Imaging Center. Images were acquired at room temperature using a 40× water immersion objective (LD C-Apochromat 40×/1.1 NA W Corr M27, Zeiss) with the correction collar manually assessed to optimal calibration at 0.150 mm. IgG* within the chambered coverslips was imaged using a HeNe633 laser at 17% power, using the MBS488/561/633 beam splitter and the Zen 2010 software (Zeiss). We collected fluorescence image stacks (field of view: 212.55 μm × 212.55 μm; cubic voxels: 0.71 μm × 0.71 μm × 0.70 μm) and analyzed using an in-house Fiji (1.52i, NIH) script.