Cancer targeting with biomolecules: a comparative study of photodynamic therapy efficacy using antibody or lectin conjugated phthalocyanine-PEG gold nanoparticles

The functionalisation of therapeutic nanoparticle constructs with cancer-specific biomolecules can enable selective tumour accumulation and targeted treatment.

Octa-alkyl zinc phthalocyanines: potential photosensitizers for use in the photodynamic therapy of cancer

The synthesis, characterization and electronic spectra of a series of nine 1,4,8,11,15,18,22,25-octa-alkyl zinc phthalocyanines (ZnPc), potential photosensitizers for the photodynamic therapy of cancer, are described. The substituents on the phthalocyanine (Pc) macrocycle "red-shift" the absorbance maximum, in cyclohexane, of all nine members of this series to a value of 703 +/- 2 nm, with a corrected fluorescence emission maximum for the octadecyl derivative of 715 nm. The solubilities and degree of aggregation of six examples in cyclohexane have been measured. The highest homologue, the octadecyl derivative, remains essentially unaggregated to a concentration of 1.5 x 10(-4) mol dm-3. the photostability of this Pc has been examined and the compound shown to be sensitive to photooxidation processes which lead to its decomposition to 3,6-bis-decylphthalimide. Known singlet oxygen quenchers inhibit the photodecomposition. In a comparative study, the octadecyl ZnPc underwent a more rapid photodecomposition than the corresponding metal-free derivative.

Targeted photodynamic therapy of breast cancer cells using lactose-phthalocyanine functionalized gold nanoparticles

Gold nanoparticles (AuNPs), which have been widely used for the delivery of photosensitizers for photodynamic therapy (PDT) of cancer, can be dispersed in aqueous solutions improving the delivery of the hydrophobic photosensitizer into the body. Furthermore, the large surface of AuNPs can be functionalized with a variety of ligands, including proteins, nucleic acids and carbohydrates, that allow selective targeting to cancer tissue. In this study, gold nanoparticles were functionalized with a mixed monolayer of a zinc phthalocyanine and a lactose derivative. For the first time, a carbohydrate was used with a dual purpose, as the stabilizing agent of the gold nanoparticles in aqueous solutions and as the targeting agent for breast cancer cells. The functionalization of the phthalocyanine-AuNPs with lactose led to the production of water-dispersible nanoparticles that are able to generate singlet oxygen and effect cell death upon irradiation. The targeting ability of lactose of the lactose-phthalocyanine functionalized AuNPs was studied in vitro towards the galectin-1 receptor on the surface of breast cancer cells. The targeting studies showed the exciting potential of lactose as a specific targeting agent for galactose-binding receptors overexpressed on breast cancer cells.

Zinc octa-n-alkyl phthalocyanines in photodynamic therapy: photophysical properties, accumulation and apoptosis in cell cultures, studies in erythrocytes and topical application to Balb/c mice skin

Two octa-substituted phthalocyanines, namely 1,4,8,11,15,18,22,25-octakis(decyl)phthalocyaninato zinc(II) (ZnODPc) and 1,4,8,11,15,18,22,25-octakis(pentyl)phthalocyaninato zinc(II) (ZnOPPc), were investigated for their use in photodynamic therapy (PDT) after topical application. Both substances exhibited favourable properties as photosensitisers in vitro: absorption maxima around 700 nm with absorption coefficients of about 190000 (M(-1) cm(-1)), a singlet oxygen quantum yield of 0.47 +/- 0.02 (ZnODPc), and good accumulation in keratinocytes and fibroblasts. Cell death after phthalocyanine-photosensitisation appeared to occur mainly via apoptosis. The in vivo experiments demonstrated a good accumulation of the phthalocyanines after topical application in a tetrahydrofuran-azone formulation onto the dorsal skin of Balb/c mice: [(4.6-4.7) +/- 1.0]% of deposited dye could be recovered after 3 h from deposition. ZnODPc showed significantly better skin-photosensitising properties than ZnOPPc and is therefore a potential candidate for the treatment of psoriasis.

Unlocking Structural Diversity in Gold(III) Hydrides: Unexpected Interplay of cis/ trans-Influence on Stability, Insertion Chemistry, and NMR Chemical Shifts

The synthesis of new families of stable or at least spectroscopically observable gold(III) hydride complexes is reported, including anionic cis-hydrido chloride, hydrido aryl, and cis-dihydride complexes. Reactions between (C^C)AuCl(PR3) and LiHBEt3 afford the first examples of gold(III) phosphino hydrides (C^C)AuH(PR3) (R = Me, Ph, p-tolyl; C^C = 4,4'-di- tert-butylbiphenyl-2,2'-diyl). The X-ray structure of (C^C)AuH(PMe3) was determined. LiHBEt3 reacts with (C^C)AuCl(py) to give [(C^C)Au(H)Cl]-, whereas (C^C)AuH(PR3) undergoes phosphine displacement, generating the dihydride [(C^C)AuH2]-. Monohydrido complexes hydroaurate dimethylacetylene dicarboxylate to give Z-vinyls. (C^N^C)Au pincer complexes give the first examples of gold(III) bridging hydrides. Stability, reactivity and bonding characteristics of Au(III)-H complexes crucially depend on the interplay between cis and trans-influence. Remarkably, these new gold(III) hydrides extend the range of observed NMR hydride shifts from δ -8.5 to +7 ppm. Relativistic DFT calculations show that the origin of this wide chemical shift variability as a function of the ligands depends on the different ordering and energy gap between "shielding" Au(dπ)-based orbitals and "deshielding" σ(Au-H)-type MOs, which are mixed to some extent upon inclusion of spin-orbit (SO) coupling. The resulting 1H hydride shifts correlate linearly with the DFT optimized Au-H distances and Au-H bond covalency. The effect of cis ligands follows a nearly inverse ordering to that of trans ligands. This study appears to be the first systematic delineation of cis ligand influence on M-H NMR shifts and provides the experimental evidence for the dramatic change of the 1H hydride shifts, including the sign change, upon mutual cis and trans ligand alternation.

Delivery of a hydrophobic phthalocyanine photosensitizer using PEGylated gold nanoparticle conjugates for the in vivo photodynamic therapy of amelanotic melanoma

Gold nanoparticles functionalised with PEG and a phthalocyanine photosensitiser achieved 40% no tumour regrowth and complete survival followingin vivoPDT.

Electrochemical and spectroscopic detection of self-association of octa-alkyl phthalocyaninato cadmium compounds into dimeric species

The solution phase behaviour of non-peripherally substituted octa-hexyl cadmium phthalocyanine 3 and peripherally substituted octa-2-ethylhexyl cadmium phthalocyanine has been investigated in fresh solutions of CH(2)Cl(2), CHCl(3)-d(1) and THF/THF-d(8) using (1)H NMR spectrometry, UV-Vis spectroscopy, cyclic voltammetry, square wave voltammetry and linear sweep voltammetry. The compounds show an unexpected propensity to form dimeric species in CH(2)Cl(2) and CHCl(3)-d(1), and, in the case of , also to a lesser extent in THF/THF-d(8). This phenomenon is not observed for their metal-free analogues or . The electrochemical results provide particularly strong evidence for the dimeric structures. In particular both the first one-electron oxidation and one-electron reduction waves for 3 and 4, unlike those of and , are split. This is consistent with sequential oxidation/reduction of the two Pc ligands within a dimer. The dimeric species are likely to be the immediate precursors of the recently discovered bis-cadmium tris-phthalocyanine triple-decker sandwich complexes and formed from and over a period of time. The electrochemical data for compounds also show that (i) relative to the metal-free phthalocyanines, the cadmium phthalocyanines exhibit smaller formal reduction potentials for all but one of the observed electron transfer processes and (ii) the electron transfer processes associated with the peripherally substituted compounds, 2 and 4, are observed at more positive potentials than those for the corresponding non-peripherally substituted analogues 1 and 3.

Electrochemical and EPR studies of two substituted bis-cadmium tris-phthalocyanine complexes: elucidation of unexpectedly different free-radical character

The electronic and electron transfer behaviour of two examples of a recently discovered class of triple-decker sandwich complex based on three phthalocyanine ligands linked by two chelated cadmium ions has been investigated by EPR spectroscopy and cyclic voltammetry, square wave voltammetry and linear sweep voltammetry experiments. The two compounds, and , differ in the location of the eight alkyl groups attached to each of the phthalocyanine rings; at the non-peripheral sites in and the peripheral sites in . Quantitative comparison of the free radical character of and in solutions was undertaken by EPR spectroscopy and revealed that exists as a mixture of s = 0 and s = (1/2) species, whereas compound exists essentially as a spin (1/2) species alone. The electrochemical study of and was undertaken in both dichloromethane (CH(2)Cl(2)) and tetrahydrofuran (THF). The two compounds show comparable but subtly different redox behaviour which can only be attributed to the different locations of the substituents. Seventeen of the possible eighteen one-electron transfer processes could be identified for . The first oxidation wave for , both in THF and in CH(2)Cl(2) solutions, was encountered at ca. 160 mV lower potential than for implying that is much easier to initially oxidise than . This finding provides a rationale for the EPR results described above. In separate experiments, oxidation of and as solutions and spin-coated film formulations was achieved using iodine and was characterised by significant changes in the visible region absorption spectra of the compounds.

Gold(III) Alkyne Complexes: Bonding and Reaction Pathways

The synthesis and characterization of hitherto hypothetical AuIII π-alkyne complexes is reported. Bonding and stability depend strongly on the trans effect and steric factors. Bonding characteristics shed light on the reasons for the very different stabilities between the classical alkyne complexes of PtII and their drastically more reactive AuIII congeners. Lack of back-bonding facilitates alkyne slippage, which is energetically less costly for gold than for platinum and explains the propensity of gold to facilitate C-C bond formation. Cycloaddition followed by aryl migration and reductive deprotonation is presented as a new reaction sequence in gold chemistry.

First example of a di-cadmium tris-phthalocyanine triple-decker sandwich complex

An unprecedented M(II)2Pc3 (M = Cd) triple-decker sandwich complex has been synthesized and characterised by single crystal X-ray crystallography; cyclic voltammetry shows an unusually large range of redox states and EPR spectroscopy indicates that the material exists in at least two redox states, one having spin (1/2).

Towards optimisation of surface enhanced photodynamic therapy of breast cancer cells using gold nanoparticle–photosensitiser conjugates

Surface enhanced fluorescence of zinc pthalocyanine-functionalised gold nanoparticles leads to a remarkable enhancement in photodynamic efficiency and cell death.

Thermally Stable Gold(III) Alkene and Alkyne Complexes: Synthesis, Structures, and Assessment of the trans-Influence on Gold-Ligand Bond Enthalpies

The reaction of [C^C)Au(OEt₂ )₂ ]⁺ with 1,5-cyclooctadiene or norbornadiene affords the corresponding olefin complexes [(C^C)Au(COD)]SbF₆ and [(C^C)Au(NBD)]SbF₆ , which are thermally stable in solution and the solid state (C^C=4,4'-di-tert-butylbiphenyl-2,2'-diyl). The crystal structures of these complexes have been determined. By contrast, dienones such as dibenzylideneacetone are O- rather than C=C-bonded. The reactions of (C^C)Au(OAc^F )(L) (L=PMe₃ or CNxyl) with B(C₆ F₅ )₃ in the presence of bis(1-adamantyl)acetylene give the mixed-ligand alkyne complexes [(C^C)Au(AdC≡CAd)(L)]⁺ , the first complexes of their type in gold chemistry. In the presence of an excess of acetylene these compounds are thermally stable in solution and as solids. The bonding of n- and π-donor ligands to Au^III fragments and the effect of the trans influence exerted by N- and C-donors was explored with the aid of DFT calculations. Results show that the Au-L bond enthalpies trans to anionic C are 35-60 % of the enthalpies trans to N, with strong π-acceptors being particularly affected. In comparison with [Me₂ Au]⁺ , the [(C^C)Au]⁺ fragment is more polar and in bond enthalpy terms resembles Me₂ Pt.