The synthesis and investigation of photochemical, photophysical and biological properties of new lutetium, indium, and zinc phthalocyanines substituted with PEGME-2000 blocks

Zinc(II) (5), indium(III) (6), and lutetium(III) (7) phthalocyanines (Pcs) peripherally substituted with poly (ethylene glycol) (PEG) monomethyl ether 2000 (PEGME-2000) blocks were synthesized via Sonogashira coupling reaction with high yields and their photophysical, photochemical and photobiological properties were investigated. We elucidated the interactions of these compounds with calf thymus DNA and bovine serum albumin (BSA), and determined K_(DNA) and K_(BSA) binding constants at degrees of 10⁵ and 10⁶, respectively. Singlet oxygen quantum yields were found (Ф_∆ = 0.44, 0.54, and 0.68 for 5, 6, and 7, respectively). Thermodynamic parameters, as well as thermal denaturation profile of double-stranded CT-DNA were examined to determine the type of binding mode. According to our experimental data, we report that PEGME-2000 favors the formation of binary complex between DNA, and phthalocyanine complexes. Therein, thermodynamic data suggest that this binding mode is indeed spontaneous under reported conditions, and rather non-specific. Additionally, Pcs 5, 6, and 7 substituted with PEGME-2000 blocks showed antimicrobial activity against Gram-positive and Gram-negative bacteria, as well as fungi (yeast), and Pc 5 had the highest antimicrobial activity among them, as revealed by disc diffusion assay results. In short, our results suggest that these compounds could be used for photodynamic therapy, they have both antibacterial and antifungal activity, and the binding ability of new phthalocyanines 5, 6, and 7 with BSA paves the way for their utilization as drug vehicle in blood plasma.

Laser-responsive liposome for selective tumor targeting of nitazoxanide nanoparticles

Nitazoxanide [2-(Acetyloxy)-N-(5-nitro-2-thiazolyl)benzamide], usually referred as NTZ, is an antiparasites drug with a potential anti-cancer reactivity. However, the bioavailability of nitazoxanide is limited due to its poor water solubility. In this study, nitazoxanide could be successfully incorporated in a stable biocompatible liposome (NTZ-LP) using a modified thin film hydration technique. Further, a novel lipophilic phthalocyanine star polymer R₄PcZn was prepared as photosensitizer and in situ incorporated with NTZ in the liposome formulation affording a laser-responsive liposome (NTZ-ZnPc-LP). Both (NTZ-LP) and (NTZ-ZnPc-LP) showed high entrapment efficiency (EE) and high in vitro drug release rates. Transmission electron microscope (TEM) images and dynamic light scattering (DLS) measurements of (NTZ-LP) and (NTZ-ZnPc-LP) showed unilamellar vesicles of mean diameter 192.2 and 87.4nm, respectively. In addition, NTZ nanoparticles (NTZ NPs) were prepared via membrane extrusion method using DMF and water as solvents. All formulations were similarly prepared using radiolabeled nitazoxanide ¹²⁵I-NTZ. After induction of solid tumor in mices using Ehrlich Ascites Carcinoma, the prepared formulations were injected in the tail vein of the mices. Tumor sites of the animal injected with (¹²⁵I-NTZ-ZnPc-LP) were illuminated with a HeNe laser (λ=630nm). Afterwards, the biodistriburtion of ¹²⁵I-NTZ was tagged using γ counter. Results showed that the light-responsive formulation (¹²⁵I-NTZ-ZnPc-LP) affords a higher accumulation of ¹²⁵I NTZ in the tumor sites after illumination. This can be attributed to the rupture of liposome lipid bilayer as a result of the photosensitization process and the singlet oxygen species resulted thereof. Despite (NTZ NPs) formulation showed a rapid accumulation of NTZ in tumor, it showed unfavoured rapid blood clearance rate.

Polymerization of Ethylene Oxide, Propylene Oxide, and Other Alkylene Oxides: Synthesis, Novel Polymer Architectures, and Bioconjugation

The review summarizes current trends and developments in the polymerization of alkylene oxides in the last two decades since 1995, with a particular focus on the most important epoxide monomers ethylene oxide (EO), propylene oxide (PO), and butylene oxide (BO). Classical synthetic pathways, i.e., anionic polymerization, coordination polymerization, and cationic polymerization of epoxides (oxiranes), are briefly reviewed. The main focus of the review lies on more recent and in some cases metal-free methods for epoxide polymerization, i.e., the activated monomer strategy, the use of organocatalysts, such as N-heterocyclic carbenes (NHCs) and N-heterocyclic olefins (NHOs) as well as phosphazene bases. In addition, the commercially relevant double-metal cyanide (DMC) catalyst systems are discussed. Besides the synthetic progress, new types of multifunctional linear PEG (mf-PEG) and PPO structures accessible by copolymerization of EO or PO with functional epoxide comonomers are presented as well as complex branched, hyperbranched, and dendrimer like polyethers. Amphiphilic block copolymers based on PEO and PPO (Poloxamers and Pluronics) and advances in the area of PEGylation as the most important bioconjugation strategy are also summarized. With the ever growing toolbox for epoxide polymerization, a "polyether universe" may be envisaged that in its structural diversity parallels the immense variety of structural options available for polymers based on vinyl monomers with a purely carbon-based backbone.