It is worth noticing that selective crosslinking occurs only on substrates with λLSPR of the AuNPs matching the wavelength of the NIR fs laser beam λL. This was demonstrated by employing enlarged AuNPs (D ≈ 210 nm, Figure ) with the correspondingly redshifted LSPR that become detuned from λL (see Figure and compare with Figure ). This leads to a lower field amplitude enhancement factor |E/E0| (Figure ) and, therefore, to a weaker plasmonic enhancement effect for triggering the MPC. In this case, a continuous layer of hydrogel is formed around the particles as seen in Figure for conditions above the threshold while below it no polymer is attached over the entire surface.