## 2 Metallic Nanoparticles in Conjugation with Chlorin Derivatives
### Other Metallic Nanoparticles  
Other metallic nanoparticles were also used in conjugation with chlorins for biomedical purposes. [PERSON] et al. designed nanoparticles based on copper sulfide and Ce6 for photodynamic and photothermal therapy [50]. Copper sulfide nanoparticles provided high near-infrared (NIR) absorption and hyperthermic properties. Moreover, the authors noted that a high-amplitude photoacoustic signal allows for cancer cell visualization in photoacoustic tomography (PAT) imaging. Copper sulfide nanoparticles were conjugated with Ce6 using polyethyleneimine (PEI) linker (Figure 8). The obtained nanoparticles were stable in the physiological solution for three months. In the experiment with diphenylisobenzofuran (DPBF), the authors confirmed the formation of singlet oxygen under irradiation with light at 670 nm. The conjugation of Ce6 with Cu5 nanoparticles was profitable for many reasons. It allowed to increase the generation of singlet oxygen and stimulated the rise of the temperature up to 53 \({}^{\circ}\)C (after the exposure of 200 \(\upmu\)g/mL nanoparticles to the light at 808 nm with a power density of 2 W/cm\({}^{2}\) for 10 min). It is also worth noting that without irradiation, high biocompatibility of particles with cells was observed with a 92.5% survival rate. Simultaneously, the authors noted the synergistic cytotoxic activity effects related to the photothermal therapy after particle excitation with light at 808 nm and PDT when light excitation with light at 670 nm was applied. Combined photodynamic and photothermal therapy with 200 \(\upmu\)g/mL Cu5-Ce6 nanoparticles induced 84% death of MDA-MB-231 cells. However, separately performed therapies caused 55% and 41% death, respectively [50]. Figure 8: Chemical structure of the Cu5 nanoparticle (orange) surfaces, which were modified with polyethyleneimine (black) and Ce6 (green) [50]. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Type of NPs** & **Size of NPs** & **Preparation Method** & **Wavelength [nm]** & **Light Dose/Light Power** & **Cell Type** & **Cell Viability** & **Ref.** \\ \hline NaYF\({}_{4}\)Yb\({}_{2}\)Er/NaGdF\({}_{4}\) & 33 nm (diameter) \(\times\) 40 nm (length) & metal-oleate complex reduction with NaOH in methanol & 980 & N/A & U87 MG glioblastoma cells & approx. 55\% & [48] \\ \hline Fe\({}_{3}\)O\({}_{4}\)/MnO\({}_{2}\)-doped 40 nm & 0.31 nm for UCNPs & 0-100 nm black phosphorous & hydrothermal synthesis & 808 & 2 W/cm\({}^{2}\) & HeLa cells & 0\% & [49] \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Summary of the data presented in Section 2.3. [PERSON] et al. also used PEI in fabricated hollow Pd nanospheres linked with Ce6 for cancer treatment using PDT/PTT [51]. The obtained nano agent, after excitation at 808 nm, effectively converted light energy into heat with a conversion efficiency \(\eta\) equal to 70%. Moreover, it also produced singlet oxygen under 660 nm irradiation. The nanoagent in the in vitro experiment with HeLa cells in the dark phase revealed good biocompatibility up to the concentration of 100 \(\upmu\)g/mL. Simultaneous irradiation of nanospheres with light at wavelengths of 660 nm and 808 nm with the power of 0.5 and 2 W/cm\({}^{2}\), respectively, caused the death of 86% HeLa cells in the culture population. Irradiation of the nanoagent with light at 660 nm or 808 nm only gave a partial response [51]. The ternary quantum dots were proposed by [PERSON] et al., who obtained nanorods with the core based on Cu-In-S (CIS) to which HA-polyanionic glycosaminoglycan and a Ce6 PS were covalently attached [52]. The CIS core provided photothermal properties, whereas the HA-polyglycosaminoglycan was responsible for the solubility improvement of the particles in the water environment. Moreover, this component facilitated specific binding to the cluster determinant 44 (CD44) receptors overexpressed in many cancer cells. The obtained nanoparticles of 94 nm in diameter absorbed light in the range from 400 to 1400 nm.