Table 2.
Chemical characterization determined by XPS analysis and water contact angles on different SAM on gold.
| samples | O 1s (%) | C 1s (%) | S 2p (%) | Au 4f (%) | N 1s (%) | Thickness [nm] | Contact angle [°] |
|---|---|---|---|---|---|---|---|
| Au | 18.0 | 17.6 | 3.1 | 57.5 | 3.7 | — | <5 |
| SAM (PEGthiol) | 23.7 | 42.7 | 2.0 | 31.6 | — | 1.23 | 38.8 ± 2.8 |
| SAM (PEGthiol + BiotinPEGlipo) | 19.0 | 45.5 | 2.2 | 29.1 | 4.1 | 1.14 | 34.5 ± 1.9 |
| SAM (PEGlipo) | 17.5 | 42.2 | 2.3 | 35.6 | 2.5 | 0.66 | 35.1 ± 3.9 |
| SAM (PEGlipo + BiotinPEGlipo) | 18.1 | 42.1 | 2.3 | 34.3 | 3.2 | 0.65 | 37.5 ± 2.9 |
Mixed SAM are obtained with a PEGthiol or PEGlipo:BiotinPEGlipo with 8:2 molar ratio. XPS standard error does not exceed the 1–2% of the reported value.