## 2 Metallic Nanoparticles in Conjugation with Chlorin Derivatives
### In summary:  
* Gold nanoparticle@chlorin conjugates were studied regarding the PRET phenomenon and photothermal and photodynamic effects to assess their prospective biomedical applications.
* For Ce6, the laser irradiation wavelengths used for PDT purposes were in the range of 633-671 nm due to the different structures of obtained conjugates.
* Most conjugates between Ce6 and nanogold were based on covalent bonding via various molecules, such as glutathione, thiourea, oligonucleotide, and 3-mercaptopropionic acid.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Type of NPs** & **Size of NPs** & **Preparation Method** & **Wavelength** & **Light** & **Cell Type** & **Cell Viability** & **Ref.** \\ \hline Gold nanorods & & & & & 0.2 W/cm\({}^{2}\) for & & & \\ dimers/upconverted & -40 nm & gold seed-mediated growth method & 808 and 980 & 808 nm and 2 mW/cm\({}^{2}\) & HeLa cells & 0\% & [33] \\ \hline EGF- & & & conventional sodium citrate reduction of gold NPs & 660 & 25 mW/cm\({}^{2}\) & human breast carcinoma cells & 14\% & [34] \\ \hline Human serum & & & gold chloride & & (25 )/cm\({}^{2}\) & MDA-MB-468 & & \\ \hline corona & 46.5 \(\pm\) 12 nm by protein-coated gold nanorods & 19.0 \(\pm\) 07 nm & chemical reduction of HAuCl\({}_{4}\) by NaBH\({}_{4}\) & 665 & 250 mW/cm\({}^{2}\) & carcinoma (OSCC) cells & 4.8\% & [35] \\ \hline Gold & 67.93 \(\pm\) 8.5 nm & & chemical reduction of HAuCl\({}_{4}\) by ascorbic acid in bovine serum & 671 & 2 W/cm\({}^{2}\) & human breast carcinoma cells & approx. 5\% & [36] \\ \hline PEGylated gold nanoparticles & 119.2 nm & & sacrificial galvanic replacement of cobalt nanoparticles based on chlorouratic acid & 670 and 808 & 2 W/cm\({}^{2}\) for 808 nm & HeLa cells & approx. 25\% & [37,38] \\ \hline Gold & 12 \(\pm\) 1 nm & & aqueous reduction of HAuCl\({}_{4}\) with citrate using the Turkevich-Frens method & 650 & 1 J/cm\({}^{2}\) & SH-SYSY human neuroblastoma cells & 0\% at Ce6 conc. 0.64 uM & [39] \\ \hline CeO\({}_{2}\)-coated gold nanorods & 55 nm & & chemical reduction of HAuCl\({}_{4}\) by NaBH\({}_{4}\) in presence of CTAB, AgNO\({}_{3}\), and NH\({}_{2}\)OH \(\times\) HCl & & & \\ \hline  & & aqueous reduction of aqueous reduction of Bimetallic gold-platinum NPs & 19 \(\pm\) 8 nm & HAuCl\({}_{4}\) with trisodium citrate using the Turkevich-Enustun method & 660 & 102 J/cm\({}^{2}\) & melanoma cell line B16F10-Nex2 & 14\% & [41] \\ \hline  & & & modified & & & \\ \hline Folic acid functionalized gold nanoclusters & 6.1 \(\pm\) 1.2 nm & & TBAB-reduction method (aqueous reduction of HAuCl\({}_{4}\) with tetrabutylammonium borohydride) & & & \\ \hline Silica-coated gold nanoparticles & 61.21 nm & & chemical reduction of HAuCl\({}_{4}\) by sodium citrate in presence of CTAB & Not applicable—sonodynamic therapy & orthotopic colorectal tumor C26 and 3T3 cells & [44] \\ \hline Poly(NIPAAm-b-styrene/gold nanoparticles copolymer & -40 nm & aqueous reduction of HAuCl\({}_{4}\) with trisodium citrate & white light trisodium citrate & 408 mW/cm\({}^{2}\) (73 J/cm\({}^{2}\)) & _Staphylococcus aureus_ & 7 log reduction & [45] \\ \hline \hline \end{tabular}
\end{table}
Table 2: _Cont._* Gold nanoparticles were mainly synthesized via the chemical reduction of HAuCl\({}_{4}\) by sodium citrate (the Turkevich method) or NaBH\({}_{4}\).
* Depending on the synthetic procedure, various types of gold nanoparticles, including nanorods, nanocups, and nanoflowers, were obtained.
* Polymer coating of the gold nanoparticles allowed for the formation of inclusion complexes with Ce6.