Aminopropyltrimethoxysilane

Aminopropyl trimethoxysilane (catalog no.: 440140), acetic acid (catalog no.: 695092), succinic anhydride (catalog no.: 239690), dimethyl sulfoxide (DMSO; catalog no.: 276855), anhydrous ethanol (catalog no.: 676829), and ethanolamine (catalog no.: E6133) were purchased from Sigma–Aldrich. Pierce premium grade N-hydroxysulfosuccinimide (sulfo-NHS; catalog no.: PG82071) and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC; catalog no.: 22980) were purchased from Thermo Fisher Scientific.

The inert silicon master was cleaned with water, acetone and isopropanol and dried with a stream of nitrogen and is used as tamplate for the PDMS-stamp.
The PDMS-stamp was prepared by using a mixture of Sylgard 184 silicone elastomer and curing agent (10:1; v/v). Then the mixture was degassed in a desiccator and casted on the inert silicon master using the micromolding process, cured for 2 h at 120°C and finally was peeled off from the silicon master (see Figure 3).
The as-prepared PDMS-stamps were oxidized in oxygen plasma for around 10 min. Thereafter the oxidized PDMS-stamps were silanized with aminopropyltrimethoxysilane (Sigma Aldrich) in a desiccator using the vapor method; for that the PDMS-stamps were placed in a desiccator containing two drops of amino-silane agent and vacuum was kept for 2 h. After the amino-silanization of the PDMS-stamps they were immersed in Au NPs solutions for around 1 h (see Figure 4). Thereafter the stamps containing the Au NPs on their surfaces were washed with water and dried under a stream of nitrogen gas.

Tetraethoxysilane (TEOS, 99%), tetramethoxysilane (TMOS, 98%), aminopropyltrimethoxysilane (APTMS, 97%), phenyltrimethoxysilane (PhTES, 98%), dodecyl dimethylamine N-oxide (DDAO 30% solution in water), were purchased from Sigma-Aldrich (Germany). Cyclohexane (99%) was obtained from ECOS-1 (Russia). Absolute ethanol (C₂H₅OH, 98%) was used in sol-gel synthesis. Deionized (DI) water with specific resistivity higher than 18.2 MΩcm from a three-stage Milli-Q Plus 185 purification system was used. The 4,4-difluoro-8-antryl-1,3,5,7-tetramethyl-2,6-diethyl-4-boron-3a,4a-diaza-s-indacene (BODIPY-1), 4,4-difluoro-8-(3,5 dimetyl)phenyl-1,3,5,7-tetramethyl-2-formyl-4-boron-3a,4a-diaza-s-indacene (BODIPY-2) (Figure 3) were used in the experiments for their immobilization onto silica-based materials. The synthesis of these fluorescent dyes, their characterization and photophysical properties of BODIPY-1 can be found in our previously published works [55 (link)], data on BODIPY-2 are presented in [56 (link)].