## 2 Metallic Nanoparticles in Conjugation with Chlorin Derivatives
### Gold Nanoparticles
Distribution half-life time and an elimination half-life time values were determined and were equal to 0.17 and 20.49 h, respectively. In the in vivo test, the significant inhibition of tumor growth after irradiation of the administrated nanoparticles at 633 nm was observed. The authors also checked the influence of presented gold nanoclusters on mice. They performed hematoxylin and eosin staining. This test indicated no changes within crucial organs, i.e., the liver, heart, kidney, and brain. Moreover, the biochemistry analyses of liver and kidney function were evaluated. All tested probes revealed no toxicity; thus, the studied nanoparticles seemed to constitute promising candidates for selective efficient cancer treatment [42]. The deep location of some tumor tissues and the low ability of light to penetrate biological tissues are the main obstacles in modern PDT. For this reason, new methods of ROS production have to be developed. One of them is sonodynamic therapy (SDT), where an alternative excitation source instead of light--ultrasound--has been implemented. As an external excitation source, ultrasound demonstrates some advantages of less invasiveness, deeper penetration, a wider range, and lower cost compared to PDT [43; 44]. Following this line of thinking, the pH-sensitive silica-coated gold nanoparticles encapsulated within a phospholipid carrier and conjugated with Ce6 were fabricated and used in SDT as a first example of a sonosensitizer based on gold NPs and chlorin. What is more, the obtained material was further conjugated with doxorubicin hydrochloride. The in vitro and in vivo studies against C26 and 3T3 cells and mice with orthotopic colorectal tumors revealed good cytotoxic effects when classic chemotherapy was combined with SDT [43]. Despite PDT-targeted anticancer approaches, numerous studies related to the photodynamic inactivation of bacteria have been performed. The potentiation effect of a PS doped onto nanometallic particles against bacteria was confirmed by [PERSON] et al. [45]. The authors attached an amphiphilic block copolymer--poly(NIPAAm-\(b\)-styrene)--to the gold nanoparticles. The hydrophobic part of the polymer was linked to the gold nanoparticles via a sulfur atom, whereas the hydrophilic part was oriented outside the particle. Consequently, the hydrophobic pockets inside the nanoparticles were formed, onto which hydrophobic Ce6 was loaded. Developed nanogold particles with Ce6 were stable over weeks. The block copolymer allowed for the dispersion of nanoparticles in the water environment. The biocompatibility of nanoparticles was evaluated. Therefore, nanoparticles were incubated with MCF-7 cells, and their viability was assessed as above 80%. Next, the authors evaluated the potential for the photoinactivation of methicillin-resistant _Staphylococcus aureus_. Irradiation with white light at a dose of 73 J/cm\({}^{2}\) of the bacterial cultures incubated previously with nanoparticles demonstrated ca. 6 log inactivation rate, higher than that with Ce6 only or gold nanoparticles bearing an amphiphilic block copolymer [45]. The data described in Section 2.2 are summarized in Table 2.  
\begin{table}
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