## 2 Metallic Nanoparticles in Conjugation with Chlorin Derivatives
### Gold Nanoparticles
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Type of NPs**} & \multirow{2}{*}{**Size of NPs**} & \multirow{2}{*}{**Preparation**} & \multirow{2}{*}{**Wavelength**} & \multirow{2}{*}{**Light**} & \multirow{2}{*}{**Cell Type**} & \multirow{2}{*}{**Cell Viability**} & \multirow{2}{*}{**Ref.**} \\  & & & **Method** & & **[nm]** & & **Power** & \\ \hline FeOOH & 197.5 \(\pm\) 8.2 nm & hydrothermal & & & & & \\  & & method & & & & & \\ \hline \multirow{4}{*}{Magnetic nanogenrades} & \multirow{4}{*}{60 nm} & thermal & & & & & \\  & & decomposition of & & & & & \\  & & an iron\(-\)oleate & & & & & \\  & & complex in the & & & & & \\  & & presence of & & & & & \\  & & & oely alcohol & & & & \\ \hline \multirow{4}{*}{Fe\({}_{3}\)O\({}_{4}\)} & \multirow{4}{*}{15 nm (bare Fe\({}_{3}\)O\({}_{4}\))} & thermal & & & & & \\  & & decomposition of & & & & & \\  & & an iron\(-\)oleate & & & & & \\  & & complex in the & & & & & \\  & & presence of ethanol & & & & & \\  & & and 1-octadecene & & & & & \\ \hline \multirow{4}{*}{\(\gamma\)-Fe\({}_{2}\)O\({}_{3}\)} & \multirow{4}{*}{11 \(\pm\) 2 nm} & chemical reduction & constant white & & & & \\  & & light (no & & & & \\  & & of FeCl\({}_{3}\) by NaBH\({}_{4}\) & specific & & & & \\  & in alkaline media & wavelength) & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: _Cont._provided total tumor remission, whereas PDT and PTT separately led only to a partial response [29]. [PERSON] et al. performed a synergistic photothermal and photodynamic cancer therapy using gold nanoflowers conjugated by glutathione moieties with Ce6 and finally coated with polydopamine obtained via the self-polymerization of dopamine [30]. In the in vitro and in vivo studies performed based on female BALB/c mice with HeLa cells, using combined 660 and 808 nm laser irradiation, excellent phototoxicity and synergistic effects of the obtained multifunctional material in killing cancer cells were observed. The activity enhancement was also noted for PDT/PTT bacteria inactivation. [PERSON] et al. obtained gold nanoparticles conjugated with a tin complex of chlorin e6 via a glutathione linker (Figure 5) [31]. The authors excited nanoparticles with white light and achieved ca. 2 logs of growth reduction for _Staphylococcus aureus_ at the concentration of 28.8 nM, whereas the PS only provided the same result at the concentration of 50 \(\upmu\)M [31]. [PERSON] et al. also noted the enhanced activity of nanogold particles linked with Ce6 in comparison to that of separately used ingredients [32]. These authors covalently linked thiourea to the carboxy group of Ce6. The obtained chlorin derivative was connected to the 18 nm gold nanoparticles through the sulfur atoms of the thiourea moieties. The obtained nanoparticles were tested against the human breast carcinoma cell line MDA-MB468 and revealed high biocompatibility without irradiation, as almost 100% of cancer cells survived incubation with nanoparticles. However, irradiating nanoparticles with light at 660 nm reduced viable cells to 0%, whereas when Ce6 alone was used, the loss of cancer cell viability was less significant [32]. Worth mentioning is the fact that when unmodified Ce6 was used to graft gold nanoparticles, almost no difference was found, which indicates that in this case, the modification with urea does not play a role in in vitro activity. The authors emphasized that the differences might appear more evident for the materials tested in vivo. Gold nanoparticles were also studied in theranostics, where the photodynamic activity of conjugates was used in both PDD and PDT. Such multimodal theranostic nanoparticles were designed by [PERSON] et al. [33]. They utilized a gold nanorod dimer with attached Ce6 for photothermal and photodynamic therapy, as well as for upconversion of luminescence, magnetic resonance, photoacoustic, and computed tomography imaging modalities. Figure 5: Chemical structure of the conjugate consisting of tin chlorins (black), glutathione linkers (blue), and gold nanoparticles (yellow) [31].