## 3 Results
### Silica Nanoflakes Characterization
The volume of pores reached the value of 0.1501 cm\({}^{3}\)/g (according the Barrett, Joyner and Halenda method--BJH method), while their diameters (Figure S4B) were estimated in the range between 1.95 and 6 nm, with the peak in the range from 1.95 to 3 nm, for mSiO\({}_{2}\) after GO. For the flakes after removal of LDH Mg/Al, the pore volume was calculated to be 0.052 cm\({}^{3}\)/g (followed by the BJH method), and their diameters were in the range of 2.2 and 4.85 nm (Figure S4B). The contribution of pores with a larger diameter causes the specific surface area of the flakes after GO to be lower. In addition, the thickness and size of flakes for porous structures is crucial. The specific surface area is closely related to these dimensions, and despite the smaller diameter and pore volume, the overall surface area would be higher if the flakes are larger and thicker. The synthesis procedure of mesoporous silica, as well as pore volume and diameter distributions, is consistent with literature data, where CTAB was used as surfactant for synthesis MCM-41 type nanostructures [30; 31]. Figure 2: Atomic force microscopic images (**A**,**D**), flakes size distributions (**B**,**E**), and height profiles (**C**,**F**) of selected mSiO\({}_{2}\) after GO (upper panel) and mSiO\({}_{2}\) after LDH Mg/Al (lower panel). To confirm the functionalization of silica flakes with folic acid, spectra from Fourier-transform infrared spectroscopy (FTIR) were recorded (Figure 3). The spectra of all samples show bands characteristic for silica. The band at 460 cm\({}^{-1}\) and 585 cm\({}^{-1}\) corresponded to the out of plane of Si-O bonds. The strong peaks that appeared at around 1089, 960, and 812 cm\({}^{-1}\) are due to the stretching vibration of Si-O-Si, Si-OH, and Si-O, which are specific peaks of the silica nanoparticles, and the broad band around 3400 cm\({}^{-1}\) can be attributed to the O-H groups [32]. The band around 1640 cm\({}^{-1}\) belongs to adsorbed water. In both samples after functionalization, characteristic peaks for folic acid appeared. The peak at \(\approx\)665 cm\({}^{-1}\) or \(\approx\)730 cm\({}^{-1}\) can be attributed to amine bonds (NH\({}_{2}\)) [33]. The presence of a weak band around 2880-2920 cm\({}^{-1}\) is attributed to (C-H) of CH\({}_{2}\) groups of FA. The band at \(\approx\)1510 cm\({}^{-1}\) belongs to the aromatic rings vibration (C=C) of FA. The intensity of the peak at 1704 cm\({}^{-1}\) increased, which is probably due to the formation of amide bonds between the FA and nanoflakes [34]. Most of the vibrational bands from folic acid in Raman spectrum (Figure 4) are in the range from 600 to 1700 cm\({}^{-1}\). The peak at \(\approx\)1610 cm\({}^{-1}\) can be related to the stretching vibration of N-H. The band \(\approx\)1570 cm\({}^{-1}\) derives from C=N. The bands at 1359 cm\({}^{-1}\) and 1302 can be described as a rocking vibration of CH. The peaks at 1198 cm\({}^{-1}\) and 682 cm\({}^{-1}\) can be related to C=C [35; 36; 37]. These most characteristic bands of folic acid are detected in the samples after folic acid functionalization, confirming the effective attachment of folic acid to the silica flakes formed both on LDH Mg/Al and on GO templates. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Sample**} & **SBET** & **VTOTAL** & **Pore Size** & **Flake Size** & **Flake** \\  & **(m\({}^{2}\)/g)** & **(cm\({}^{3}\)/g)** & **(nm)** & **(nm)** & **Thickness** \\ \hline mSiO\({}_{2}\) after GO & 738 & 0.1501 & 1.95–6 & 40–220 & \\  & & & (1.95–3) & (80–100) & \\ mSiO\({}_{2}\) after & & 2.2–4.85 & 200–1000 & \\ LDH Mg/Al & 839 & 0.052 & (2.2–3.4) & (400–500) & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Brunauer, Emmett, and Teller (BET) surface area, pore size, and volume of silica flakes. Figure 3: FTIR spectra of silica flakes functionalized with folic acid: mSiO\({}_{2}\) after GO_FA (**A**) and mSiO\({}_{2}\) after LDH Mg/Al_FA (**B**).