The NO₂S₂-donor macrocycle (L¹) was synthesised from the ring closure reaction between Boc-N-protected 2,2′-iminobis(ethanethiol) (3) and 2,2′-(ethylenedioxy)bis(benzyl chloride) (4) followed by deprotection of the Boc-group. α,α′-Dibromo-p-xylene was employed as a dialkylating agent to bridge two L¹ to yield the corresponding N-linked product (L²). The X-ray structure of L² (as its HBr salt) is described. A range of Cd(II) and Hg(II) complexes of L¹ (6–9) and L² (10–12) were prepared and characterised. Reaction of HgX₂ (X = Br or I) with L¹ afforded [Hg(L¹)Br]₂[Hg₂Br₆]·2CH₂Cl₂6 and [Hg(L¹)I₂] 7, respectively. For 6, the Hg(II) ion in the complex cation has a distorted tetrahedral coordination environment composed of S₂N donor atoms from L¹ and a bromo ligand. In 7 the coordination geometry is highly distorted tetrahedral, with the macrocycle coordinating in an exodentate manner via one S and one N atom. The remaining two coordination sites are occupied by iodide ions. [Hg(L¹)(ClO₄)]ClO₄8 was isolated from the reaction of Hg(ClO₄)₂ and L¹. The X-ray structure reveals that all macrocyclic ring donors bind to the central mercury ion in this case, with the latter exhibiting a highly distorted octahedral coordination geometry. The O₂S₂-donors from the macrocyclic ring define the equatorial plane while the axial positions are occupied by the ring nitrogen as well as by an oxygen from a monodentate perchlorato ion. Reaction of Cd(NO₃)₂·4H₂O with L¹ afforded [Cd(L¹)(NO₃)₂]·0.5CH₂Cl₂9 in which L¹ acts as a tridentate ligand, binding exo-fashion via its S₂N donors. The remaining coordination positions are filled by two bidentate nitrate ions such that, overall, the cadmium is seven-coordinate. Reactions of HgX₂ (X = Br or I) with L² yielded the isostructural 2 : 1 (metal : ligand) complexes, [Hg₂(L²)Br₄] 10 and [Hg₂(L²)I₄] 11. Each mercury ion has a distorted tetrahedral environment made up of S and N donors from an exodentate L² and two coordinated halides. Contrasting with this, the reaction of L² with Cd(NO₃)₂·4H₂O yielded a 1-D coordination network, {[Cd₂(L²)(NO₃)₄]·2CH₂Cl₂}_n12 in which each ring of L² is exo-coordinated via two S atoms and one N atom to a cadmium ion which is also bound to one monodentate and one bidentate nitrate anion. The latter also has one of its oxygen atom attached to a neighboring cadmium via a nitroso (µ₂-O) bridge such that the overall coordination geometry about each cadmium is seven-coordinate. The [Cd(L²)_0.5(NO₃)₂] units are linked by an inversion to yield the polymeric arrangement.

Gold nanoparticles (GNPs) conjugates of water soluble ionic photosensitizer (PS), purpurin-18-N-methyl-D-glucamine (Pu-18-NMGA), were synthesized using various molar ratios between HAuCl4 and Pu-18-NMGA without adding any particular reducing agents and surfactants. The PS-GNPs conjugates showed long wavelength absorption of range 702762 nm, and their different shapes and diameters depend on the molar ratios used in the synthesis. In vitro anticancer efficacy of the PS-GNPs conjugates was investigated by MTT assay against A549 cells, resulting in higher photodynamic activity than that of the free Pu-18-NMGA. Among the PS-GNPs conjugates, the GNPs conjugate from the molar ratio of 1:2 (Au(III): Pu-18-NMGA) exhibits the highest photodynamic activity corresponding to bigger size (~60nm) of the GNPs conjugate which could efficiently transport the PS into the cells than that of smaller size of the GNPs conjugate.

Photodynamic therapy (PDT) with a suitable photosensitizer molecule is a promising anticancer treatment. We evaluated two chlorin molecules as potential photosensitizers, methyl pyropheophorbide a (MPPa) and N-methoxyl purpurinimide (NMPi), against A549 human lung adenocarcinoma cells in vitro as well as in A549 tumor-bearing mice in vivo. Cell viability, microscopy, and fluorescence-activated cell sorting (FACS) analyses were performed for the in vitro studies. MPPa and NMPi showed high phototoxicity in vitro, which was dependent on the concentration of the photosensitizers as well as the light irradiation time. In the animal study, tumor volume change, tumor surface alterations, and hematoxylin & eosin (H&E) and terminal deoxyribonucleotidyl transferse-mediated dUTP nick-end labelling (TUNEL) staining analyses were performed and compared between small (tumor volume of 50 mm³) size of initial tumors. MPPa and NMPi showed high anticancer efficacy against small-size tumors, indicating that early treatment with PDT is effective. Especially, repeated two times PDT with NMPi allowed almost complete eradication against small-size tumors. However, MPPa and NMPi were not effective against large-size tumors. In conclusion, the two chlorin derivatives, MPPa and NMPi, show good anticancer efficacy as promising photosensitizers for PDT in vitro and in vivo. Moreover, their activity in vivo was significantly dependent on the initial tumor size in mice, which confirms the importance of early cancer treatment.

Purpurin-18 (P18) is one of the essential photosensitizers used in photodynamic therapy (PDT), but its hydrophobicity causes easy coalescence and poor bioavailability. This study aimed to synthesize P18 and design P18-loaded solid lipid nanoparticles (SLNs) to improve its bioavailability. The characteristics of the synthesized P18 and SLNs were evaluated by particle characteristics and release studies. The effects of P18 were evaluated using the 1,3-diphenylisobenzofuran (DPBF) assay as a nonbiological assay and a phototoxicity assay against HeLa and A549 cell lines as a biological assay. The mean particle size and zeta potential of the SLNs were 164.70–762.53 nm and −16.77–25.54 mV, respectively. These results indicate that P18-loaded SLNs are suitable for an enhanced permeability and retention effect as a passive targeting anti-cancer strategy. The formulations exhibited a burst and sustained release based on their stability. The DPBF assay indicated that the PDT effect of P18 improved when it was entrapped in the SLNs. The photocytotoxicity assay indicated that P18-loaded SLNs possessed light cytotoxicity but no dark cytotoxicity. In addition, the PDT activity of the formulations was cell type- and size-dependent. These results suggest that the designed P18-loaded SLNs are a promising tool for anticancer treatment using PDT.