Dongdong Ma

Effect of axial ligands on the photophysical properties of new silicon(IV) phthalocyanines

A series of axial di-substituted silicon(IV) phthalocyanines with electron-donating and electron-withdrawing properties were synthesized. The compounds were characterized by elemental analysis, 1H NMR, IR, and ESI-MS. The effect of axial ligands on the photophysical properties of silicon phthalocyanines was studied by UV/Vis, steady-state and time-resolved fluorescence spectroscopic analyses. Compared with silicon phthalocyanines with electron-donating properties, silicon phthalocyanines with electron-withdrawing properties could expand the π-conjugation in the dyes, resulting in a redshift of Q bands, lower fluorescence emission intensity and fluorescence quantum yields, but increasing fluorescence lifetimes. These results strongly suggest that the molecular design of phthalocyanines is essential for construction of photoactive materials.

Photophysical property of a polymeric nanoparticle loaded with an aryl benzyl ester silicon (IV) phthalocyanine

Because of their excellent near-infrared (NIR) optical properties, phthalocyanines (Pcs) have been regarded as promising therapy agents for fluorescence image-guided drug delivery and noninvasive treatment of tumors by photodynamic therapy (PDT). Nevertheless, phthalocyanines are substantially limited in clinical applications owing to their poor solubility, aggregation and insufficient selectivity for cancer cells. To address these issues, we have developed a novel dendrimer-based theranostic nanoparticle for tumor-targeted delivery of phthalocyanine. The preparation procedure involved the modification of the silicon (IV) phthalocyanine molecule with a dendritic axially substitution, which significantly enhances their photophysical property. In order to improve biocompatibility and tumor-targeted delivery, the hydrophobic dendritic phthalocyanine was encapsulated by diblock amphiphilic copolymer poly (ethylene glycol)-poly (Epsilon-caprolactone) (MPEG-PCL) to form a polymeric nanoparticle. The polymeric nanoparticle is spherical with a diameter at about 90 nm. The photophysical property of the polymeric nanoparticle was studied by UV/Vis and fluorescence spectroscopic methods. Compared with the free dendritic phthalocyanine, the Q band of the polymeric nanoparticle was red-shifted, and the fluorescence intensity decreased. Furthermore, the polymeric nanoparticle has a relatively high loading amount and encapsulation rate. Therefore, the polymeric nanoparticle would be a promising third-generation photosensitizer (PS) for PDT.

Polyion complex micelles incorporating poly (aryl benzyl ether) dendritic phthalocyanine: effective photosensitizers for enhanced photodynamic therapy

A novel series of zinc (II) phthalocyanines bearing four poly (aryl benzyl ether) dendritic substituents with carboxylic acid functionalities (Gn-DPcZn (Gn=n-generation dendrimer, n=1-2)) loaded polymeric micelles (Gn-DPcZn/m) were formed. The time-dependent intracellular uptake of Gn-DPcZn in RPE cells increased as they were incorporated into micelles, but inversely correlated with the generation. The photocytoxity of Gn-DPcZn was improved by incorporation into polymeric micelles and increased with the generation.

Photophysical properties of dendrimer phthalocyanine-functionalized single-walled carbon nanotubes

The photophysical properties of a novel series dendrimer phthalocyanine-SWNTs nanoconjugates in which the dendrimer phthalocyanine was tetra-[3,5-di-(4-carboxylic benzyloxy)benzyloxy] zinc(Ⅱ) phthalocyanine covalently linked with SWNTs using ethylenediamine or hexamethylenediamine as space linkers were investigated in detailed by the fluorescent spectra and time-resolved spectroscopy. The photoindued intramolecular electron was transferred from phthalocyanine (donor) to carbon nanotubes (acceptor). Novel functionalized constituents in this work are fundamentally important due to the synergy effects of carbon nanotubes and dendritic zinc phthalocyanine, which may find potential applications in the drug delivery, biological labels and many other related fields.

Triblock copolymers encapsulated poly (aryl benzyl ether) dendrimer zinc(II) phthalocyanine nanoparticles for enhancement in vitro photodynamic efficacy

A novel series of nanoparticles formed via an electrostatic interaction between the periphery of negatively charged 1-2 generation aryl benzyl ether dendrimer zinc (II) phthalocyanines and positively charged poly(L-lysin) segment of triblock copolymer, poly(L-lysin)-block-poly(ethylene glycol)-block-poly(L-lysin), was developed for the use as an effective photosensitizers in photodynamic therapy. The dynamic light scattering, atomic force microscopy showed that two nanoparticles has a relevant size of 80-150nm. The photophysical properties and singlet oxygen quantum yields of free dendrimer phthalocyanines and nanoparticles exhibited generation dependence. The intracellular uptake of dendrimer phthalocyanines in Hela cells was significantly elevated as they were incorporated into the micelles, but was inversely correlated with the generation of dendrimer phthalocyanines. The photocytotoxicity of dendrimer phthalocyanines incorporated into polymeric micelles was also increased. The presence of nanoparticles induced efficient cell death. Using a mitochondrial-sepcific dye rhodamine 123 (Rh123), our fluorescence microscopic result indicated that nanoparticles localized to the mitochondria.

The effect of metal ions on the photophysical and photochemical property of phenylthio bromo metal phthalocyanines

Phthalocyanines have attracted great attention because of their applications in material science including electro-optical devices, electrochromic display, and photodynamic therapy (PDT) of cancer. In addition, the Pcs exhibit great flexibility of chemical structure modification enabled by either peripheral substituents or metal ions co-ordination to central cavity of highly conjugated tetrapyrrolic macrocycles. However, because of the hydrophobic nature of the phthalocyanine ring, Pcs have strong tendency to aggregate in solution, which limited their applications. To overcome this problem, the introduction of dendritic wedge to peripheral positions of phthalocyanines can prevent the formation of aggregation to some extent. The preparation procedure involved the modification of the zinc (II) and magnesium (II) phthalocyanines with peripherally dendritic substitutions. The photophysical and photochemical properties of dendritic phthalocyanines were studied by UV/Vis and fluorescence spectroscopic methods. Compared with the magnesium (II) phthalocyanine, the intensity of Q band of zinc (II) phthalocyanine was increased but no obviously position changes was observed. Furthermore, the zinc (II) phthalocyanine exhibited relatively higher fluorescence intensity than the magnesium (II) phthalocyanine. The fluorescence quantum yield and lifetimes of magnesium (II) phthalocyanine was clearly longer than that of zinc (II) phthalocyanine. As the better photosensitizer, the zinc (II) phthalocyanine has higher singlet oxygen quantum yield owning superior performance. This results indicated that the singlet oxygen quantum yield would be effected by the nature of metal ions.

Photoinduced electron transfer between benzyloxy dendrimer phthalocyanine and benzoquinone

Photo-induced electron transfer (PET) is an important and fundamental process in natural photosynthesis. To mimic such interesting PET process, a suitable donor and acceptor couple were properly chosen. Dendrimer phthalocyanines and their derivatives have emerged as promising materials for artificial photosynthesis systems. In this paper, the electron transfer between the light harvest dendrimer phthalocyanine (donor) and the 1,4-benzoquinone (acceptor) was studied by UV/Vis and fluorescence spectroscopic methods. It was found that fluorescence of phthalocyanine was quenched by benzoquinone (BQ) via excited state electron transfer, from the phthalocyanine to the BQ upon excitation at 610 nm. The Stern–Volmer constant (KSV) of electron transfer was calculated. Our study suggests that this dendritic phthalocyanine is an effective new electron donor and transmission complex and could be used as a potential artificial photosynthesis system.