Metal complexation-mediated stable and biocompatible nanoformulation of clinically approved near-infrared absorber for improved tumor targeting and photonic theranostics

Indocyanine green (ICG) is a clinically approved dye that has shown great promise as a phototheranostic material with fluorescent, photoacoustic and photothermal responses in the near-infrared region. However, it has certain limitations, such as poor photostability and non-specific binding to serum proteins, subjected to rapid clearance and decreased theranostic efficacy in vivo. This study reports stable and biocompatible nanoparticles of ICG (ICG-Fe NPs) where ICG is electrostatically complexed with an endogenously abundant metal ion (Fe3+) and subsequently nanoformulated with a clinically approved polymer surfactant, Pluronic F127. Under near-infrared laser irradiation, ICG-Fe NPs were found to be more effective for photothermal temperature elevation than free ICG molecules owing to the improved photostability. In addition, ICG-Fe NPs showed the markedly enhanced tumor targeting and visualization with photoacoustic/fluorescent signaling upon intravenous injection, attributed to the stable metal complexation that prevents ICG-Fe NPs from releasing free ICG before tumor targeting. Under dual-modal imaging guidance, ICG-Fe NPs could successfully potentiate photothermal therapy of cancer by applying near-infrared laser irradiation, holding potential as a promising nanomedicine composed of all biocompatible ingredients for clinically relevant phototheranostics.

A Polymer Inclusion Membrane for Sensing Metal Complexation in Natural Waters

Metal speciation studies are of great importance in assessing metal bioavailability in aquatic environments. Functionalized membranes are a simple tool to perform metal chemical speciation. In this study, we have prepared and tested a polymer inclusion membrane (PIM) made of the polymer cellulose triacetate (CTA), the extractant di-(2-ethylhexyl) phosphoric acid (D2EHPA), and the plasticizer 2-nitrophenyloctyl ether (NPOE) as a sensor for Zn and Cu complexation studies. This PIM, incorporated in a device with an 0.01 M HNO3 receiving solution, is shown to effectively transport free metal ions, and it is demonstrated that the presence of ligands that form stable complexes with divalent metallic ions, such as ethylenediaminetetraacetic acid (EDTA) and humic acid (HA), greatly influences the accumulation of the metals in the receiving phase due to the increasing metal fraction complexed in the feed phase. Moreover, the effect of major ions found in natural waters has been investigated, and it is found that the presence of calcium did not decrease the accumulation of either Zn or Cu. Finally, the PIM sensor has been used successfully to evaluate metal complexation in a river water affected by Zn pollution.

One-Dimensional Bis(dipyrrinato)zinc(II)-Linked Porphyrinatozinc(II) Polymer: Synthesis, Exfoliation Into Single Wires, and Photofunctionality

One-dimensional bis(dipyrrinato)zinc(II)-linked porphyrinatozinc(II) polymer, 2 were synthesized by facile metal complexation reaction between 5,15-bis(3,5-dioctyloxyphenyl)-10,20-bis(dipyrrinato)porphyrinatozinc(II),1 and zinc(II) acetate. The bulky substituents on the porphyrin units allows 2 to be exfoliated into single molecular wires with a 2.8 nm height and 1.4 Om length. 2 exhibited promising photofunctionality derived from electronic interaction between bis(dipyrrinato)zinc and porphyrinatozinc(II) moieties, which can be engaged in energy transfer system such as photonic molecular wires.

Metal complexation mechanisms of polyphenols associated to Alzheimer’s Disease

: Polyphenols are a class of compounds produced by plants, which share the ability to act as potent antioxidants. First investigations on polyphenols’ antioxidant activity are dated almost twenty years ago when their relationship and implication with the prevention and treatment of cancer was proposed for the first time. Later, in the early 2000s, the neuroprotective effects of several polyphenols were demonstrated. Nowadays, the benefits of a plethora of polyphenols have been studied, and their ameliorating effects in several disease conditions, like cancer, cardiac and neuronal diseases, are widely recognized. More than 1000 papers dealing with polyphenols and Alzheimer’s disease have been published so far, describing the antioxidant properties, the chelating metal features, and the anti-aggregating behavior of these compounds. This review aims to rationalize, from a chemical point of view, the metal complexation mechanisms of polyphenols related to two significant events of Alzheimer’s disease: oxidative stress and metal ion dyshomeostasis. To address this issue, we have herein discussed several aspects implicated in Alzheimer’s disease and polyphenols involved in treating the disease.