Acroseal

Solutions of 10% PEG and 10% PLLA in 1,4-dioxane (AcroSeal™, ACROS Organics) were combined at a ratio of 6:4 (v/v) with stirring at 85 °C to create a homogenous mixture.

DeepTip^TM probes (silicon nitride, nominal resonance frequency 67 kHz–17 kHz; k = 0.48–0.06 N/m) were produced and supplied by the company Bioactive Surfaces S.L. [38 ]. 3-Aminopropyltriethoxysilane, (purity 99%), and AcroSeal^® was obtained from Acros Organics (Thermo Scientific Chemicals, Beerse, Geel, Belgium). Fluorescein 5(6)-isothiocyanate, 30% hydrogen peroxide solution, 50% glutaraldehyde solution in water, Streptavidin from Streptomyces avidinii, albumin biotinamidocaproyl-labeled bovine lyophilized powder, and poly(ethylene glycol)-(N-hydroxysuccinimide 5-pentanoate)-ether 2-(biotinylamino)ethane (MW = 10,000 Da, which corresponds to an approximate length for the spacer of 50 nm) were provided by Sigma-Aldrich (María de Molina, Madrid, Spain). An amount of 32% w/w ammonia solution was obtained from Scharlau (Sentmenat, Barcelona, Spain). Sodium dodecyl sulfate (SDS) was provided by Fisher Scientific (María de Molina, Madrid, Spain).

1-Octadecene (ODE), technical grade, 90%, Sigma Aldrich; Oleic acid (OA), 97%, Acros Organics; Oleylamine (OAm), 80–90%, Acros Organics; Cesium carbonate (Cs₂CO₃), 99.99% (trace metal basis), Acros Organics; Lead(II)chloride (PbCl₂), 99.999% (trace metal basis), Sigma Aldrich; Lead(II)bromide (PbBr₂), ≥98%, Sigma Aldrich; Toluene, 99.8%, extra dry, AcroSeal, Acros; Tetrachloroethylene (TCE), ≥99%, Acros Organics; Kapton® polyimide membranes (125 μm thickness) were purchased from DuPont; Si/SiOx wafers (200 nm SiO_x thickness) were purchased from Siegert Wafer GmbH. All chemicals were used as purchased.

All chemicals and reagents were used without further purification, with the exception of tetrabutylammonium hexafluorophosphate which was recrystallised from hot ethanol. Chloroacetonitrile (98 %), sodium hydroxide (pellets, 98 %), N,N‐dimethylformamide (anhydrous, amine‐free, 99.9 %), isobutanol (99 %) and 2,2,2‐tiflouroethanol (99+%) were purchased from Alfa Aesar. Sulfur (refined, 99.5 %), acetonitrile (anhydrous, extra dry, Acroseal®, 99.9+%) and tetraethylammonium chloride hydrate (99 %) were purchased from Acros Organics. Isopropanol (reagent grade, 99.5 %), ethanol (HPLC grade, 99.8 %) and iron(III) chloride (anhydrous, 99 %) were purchased from Fisher Scientific. Tetrabutylammonium hexafluorophosphate (>98 %) was purchased from Tokyo Chemical Industry UK Ltd. Ferrocene (98 %) was purchased from Sigma Aldrich.

Acetonitrile, DMF, ethanol and dimethoxyethane were purchased as absolute solvents from Acros Organics, Fisher Scientific and Sigma Aldrich. Toluene (Sigma Aldrich, 99.7%) was dried in an aluminum oxide column under inert conditions and stored in Schlenk bottle over 4A molecule sieves under argon atmosphere. Tetrahydrofuran was dried at reflux temperature under argon atmosphere over sodium until benzophenone indicated dryness by a deep blue color. 1,2-Dichloroethane was purchased from ACROS Organics as extra dry solvent (99.8%, AcroSeal®) and directly used in the reactions. All applied starting materials were commercially available from Alfa Aesar and Sigma Aldrich and were used as received. Silica gel chromatography was performed with Acros Organics silica gel 60 (35–70 μM). ¹H and ¹³C NMR spectra were recorded on a Bruker AVANCE III 300 spectrometer (¹H: 300.36 MHz; ¹³C: 75.53 MHz) and chemical shifts are referenced to residual protonated solvent signals as internal standard. Electron impact (EI, 70 eV) HRMS spectra were recorded on Waters GCT Premier equipped with direct insertion (DI) and GC (HP GC7890A). Melting points were determined with the apparatus ‘Mel-Temp®’ from Electrothermal with an integrated microscopical support.