Surface modification of silica substrate was done by following the method suggested by Thomas et al. thomas2022combined Particles of size 14.7 ± 1.9 nm (labelled G 1 ), 34.8 ± 4.6 nm (G 2 ), 63.2 ± 7.7 nm (G 3 ), and 107.4 ± 6.9 nm (G 4 ) were used for this study. These NPs were dip-coated on the silane-modified silica substrates overnight.