Su 8 developer

All devices used in this paper were designed and fabricated via standard soft lithography protocols^{72 (link)}. Briefly, microfluidic molding masters were created by (1) coating 4” test-grade silicon wafers (University Wafer, South Boston, MA) with a single layer of SU-8 2050 negative photoresist, (2) soft baking, (3) exposing this SU-8 layer to UV light passing through a printed transparency mask (designed in AutoCAD (Autodesk); printed at 50,000 dpi by Fineline Imaging), (4) postexposure baking, and (5) developing away uncured photoresist using SU-8 developer (Microchem Corp, Newton, MA) according to standard manufacturer instructions. These molding masters were then used to cast single-layer droplet generators composed of a 1:5 ratio of poly(dimethylsiloxane) crosslinker:base (PDMS, RTV 615, Momentive Performance Materials, Albany, NY), and these resultant devices were assembled as described in the Supplemental Methods. All holes were punched by a catheter punch (SYNEO, 0.025” ID × 0.035” OD, Part No: CR0350255N20R4) to fit the outer diameters of PEEK tubing (ZEUS, 0.010” ID × 0.020” OD) and steel blunt pins (New England Small Tube, Part No: NE-1310-02). All design files and detailed protocols for the molding master and device fabrication are available as Supplementary Files and in an associated OSF repository (https://osf.io/jvnpc/).

The 3D micro-rocket was printed based on the direct laser writing technique by the Photonic Professional GT system (Nanoscribe GmbH). With a spin-coated 50-μm-thick photoresist (SU-8 50, MicroChem Corp.) on transparent glass and utilization of the pre-bake and soft-bake processes, a 780-nm laser was focused in the photoresist, and the structure was printed with 0.4-μm slicing and 0.4-μm filling. After the microprinting and post-bake processes, the sample was developed in an SU-8 developer (MicroChem Corp.) and rinsed with isopropyl alcohol. After air drying, hundreds of micro-rockets were obtained from the substrate. To realize near-infrared light actuation, a 100-nm-thick gold layer was coated on the micro-rocket surface.

Fabrication of PDMS microfluidic devices followed standard rapid prototyping procedures as previously described (18 (link)). The patterns on a silicon wafer for microchannels (4 μm high and 100 μm wide) and nanoslit (450 nm high and 40 μm wide overlayed with 4 μm high and 80 μm wide microchannels were fabricated using soft lithography. The Cr mask was obtained from Amed Inc. (Seoul, Korea). SU-8 2005 photoresist (Microchem, Newton, MA, USA) was spin-coated onto the silicon wafer to make 4 μm high photoresist layer. After spin coating, the baked wafer was exposed under 350 nm irradiation. The patterned wafer was baked again and developed using a SU-8 developer (Microchem). The height was measured by a profilameter (Dektak XT, Bruker). The PDMS pre-polymer mixed with curing agent (10:1 weight ratio) was cast on the patterned wafer and cured at 65° C for 4 h or longer. Cured PDMS was peeled off from the patterned wafer and then PDMS devices were treated in an air plasma generator for 30 s with 100W (Femto Science Cute Basic, Korea) to make PDMS surface hydrophilic. PDMS devices were stored in water and air-dried before use.

Phorbol-12-myristate 13-acetate (PMA) was purchased from Cayman Chemical (Ann Arbor, MI, USA). Dulbecco’s phosphate-buffered saline (DPBS), RPMI-1640 culture medium, and fetal bovine serum (FBS) were purchased from Welgene, Inc. (Daegu, Republic of Korea). Dopamine hydrochloride, RGD, and dexamethasone (Dex) were purchased from Sigma-Aldrich (St. Louis, MO, USA). SU-8 3005 and SU-8 developer were purchased from MicroChem (Round Rock, TX, USA). PDMS prepolymer (Sylgard 184) and a curing agent were purchased from Dow Corning (Midland, MI, USA). Norland Optical Adhesive (NOA) 63 was purchased from Norland Products (Jamesburg, NJ, USA). Tris-HCl was purchased from Biosesang (Seongnam, Republic of Korea). Ethylenediaminetetraacetic acid (EDTA) was purchased from Amresco Inc. (Solon, OH, USA). Granulocyte-macrophage colony-stimulating factor (GM-CSF) and interferon (IFN)-γ were purchased from R&D Systems (Minneapolis, MN, USA). Pluronic F-127 solution and antibiotic–antimycotic solution were purchased from Invitrogen Corp. (Waltham, MA, USA). 1,25-dihydroxy vitamin D3 (VitD3) was purchased from Toronto Research Chemicals Inc. (Toronto, ON, Canada).

Two gold electrodes with gap size of about 50.0 μm were fabricated using UV-lithography process. SU8 photoresist was deposited onto Si wafer of dimensions (1.0 cm × 1.0 cm) after cleaning using standard RCA method. Spin coating was carried-out at a speed of 2000 rpm for 1 minute. In the next step, UV light was exposed through the designed mask via the lithography process. Post Exposure Bake (PEB) at 95°C was followed by the develop process using MicroChem’s SU-8 developer. Au deposition onto the sample was achieved using thermal evaporation with thickness of about 100 nm. The resulting thin film of Au was then annealed for 30 minutes at 200°C.