Trichloro octadecyl silane

Peptide GCRDVPMS↓MRGGDRCG (VPM) with a molecular mass of 1696.97 Da was purchased from Proteogenix, France. Collagenase Activity Colorimetric Assay Kit, collagenase from Clostridium histolyticum for general use Type I (Product number C0130, Lot SLBW6959, MW 125,000 Da), 4-arm poly(ethylene glycol) norbornene (MW 20,000 Da), tricine (N-[tris(hydroxymethyl)methyl]glycine, 99%), sodium chloride (99.5%), calcium chloride dihydrate (99%), phosphate-buffered saline (PBS) tablet, anhydrous toluene (99.8%), 3-(trimethoxysilyl)propyl methacrylate (98%) and trichloro(octadecyl)silane (90%) were purchased from Sigma. Concentrated sulfuric acid (95–98%), zinc chloride and hydrogen peroxide (30% H₂O₂ (w/w)) were purchased from Fluka (Bucharest, Rumania). Sodium hydroxide (1 M) was purchased from Fisher Chemicals, (Loughborough, UK). Microscopic glass slides (Menzel-glaser, 75 mm × 25 mm) from Thermo Scientific (Loughborough, UK) were used in sensor fabrication. Round glass cover slips (20 mm) were purchased from VWR (Lutterworth, UK). Polished, gold-coated QCM crystals (AT-cut, 10 MHz) were purchased from International Crystal Manufacturing Company, Inc. (Oklahoma City, OK, USA). All solutions were prepared with Milli-Q water (resistivity 18.2 MΩ·cm).

Hexamethylene diisocyanate
(HDI), polycaprolactone diol (PCL-OH, Mn ∼ 2000 g mol^–1), pyromellitic dianhydride (PMD), dibutyltin dilaurate (DBTDL),
ethanolamine, zirconium oxychloride octahydrate (ZrCl₂·8H₂O), 2-aminoterepthalic acid (ATPA), octanoic acid, sodium
hydroxide, acetic acid, trichloro(octadecyl)silane (OTS), dimethyl
formamide (DMF), chloroform, acetone, toluene, isopropanol, hexane,
and silicone oil (20, 100, 500, and 1000 cSt) were purchased from
Sigma-Aldrich. 1,5-Diisocyanatonaphthalene (NDI) was purchased from
Tokyo Chemical Industry UK Ltd. All the chemicals were used without
further purification. Commercial NeverWet coating components, used
as a control for comparison, were obtained from the Rust-Oleum.

The working MAPI stamp was fabricated using a UV-curable polymer (MINS 311RM resin, Changsung sheet, Korea) attached to chrome-coated glass with a rectangular-shaped transparent pattern (namely, a chrome shadow mask). The rectangular transparent area was 100 mm × 100 mm at the center of the chrome shadow mask having an area of 9 in × 9 in and a thickness of 3 mm. First, a surface molecular activator (GP083, GLASS PAINT, USA) was smoothly coated on the chrome-coated side for UV NIL. Then, the UV-curable resin was uniformly coated onto the chrome mask, and the micropatterns were imprinted using a transparent soft mold. An LED UV lamp with an irradiance of 110 mJ/cm² (LZL-FL-220220, LICHTZEN, Korea) was used to exposure the NIL process. After gently demolding the soft mold from the chrome mask, post-curing was performed using an LED UV lamp. Finally, oxygen plasma cleaning was performed for 5 min and trichloro(octadecyl)silane (Sigma-Aldrich, USA) was deposited to improve the release properties during the MAPI process. For demonstration purpose, two types of representative microstructured surfaces composed of interconnected hexagonal microcavities (wall width of 2 μm, height of 9 μm, and center-to-center distance of 70 μm) and MLA (diameter of 47 μm, sag height of 3.5 μm, and pitch of 50 μm) were used.