Molecularly imprinted polymers for the clean-up of a basic drug from environmental and biological samples

A molecularly imprinted polymer (MIP) was synthesized and evaluated to selectively extract an alpha-blocker, i.e. alfuzosin, from human plasma. The synthesis of the MIP was performed in dichloromethane with methacrylic acid as monomer and the target drug as template. A first series of experiments was carried out in dichloromethane to estimate the potential of the MIP in its specific recognition medium, i.e. dichloromethane, by developing a selective procedure and by measuring the capacity of the sorbent. An optimized procedure was developed for the selective extraction of alfuzosin with a recovery close to 100% in this medium and a specific capacity of 1.3 micromol g(-1) of MIP was measured. A study in aqueous media was also carried out by a comprehensive approach of the retention mechanism in order to build a selective procedure of extraction. The effects of the amount and of the charge of cations were studied and an optimal pH value was defined to limit matrix effects. Then, the alfuzosin MIP was then directly used to selectively extract the target drug from human plasma with an extraction recovery of 60%. Lastly, a soil was extracted by a pressurized solvent and the resulting extract was cleaned up on the MIP, showing the possibility to use this selective sorbent for the sample treatment of various complex matrices.     

Highly Charged Ruthenium(II) Polypyridyl Complexes as Lysosome‐Localized Photosensitizers for Two‐Photon Photodynamic Therapy

Photodynamic therapy (PDT) is a noninvasive medical technique that has received increasing attention over the last years and been applied for the treatment of certain types of cancer. However, the currently clinically used PDT agents have several limitations, such as low water solubility, poor photostability, and limited selectivity towards cancer cells, aside from having very low two‐photon cross‐sections around 800 nm, which limits their potential use in TP‐PDT. To tackle these drawbacks, three highly positively charged ruthenium(II) polypyridyl complexes were synthesized. These complexes selectively localize in the lysosomes, an ideal localization for PDT purposes. One of these complexes showed an impressive phototoxicity index upon irradiation at 800 nm in 3D HeLa multicellular tumor spheroids and thus holds great promise for applications in two‐photon photodynamic therapy.     

Photoinduced Electron Transfer in Clicked Ferrocene-BODIPY-Fullerene Conjugates

Ferrocene-BODIPY (Fc-BDP) conjugates in which one or two ferrocene entities are linked to the β-positions of the BODIPY core by an ethynyl bridge have been developed. These derivatives were easily and efficiently grafted onto a dual-clickable fullerene platform using CuAAC reactions, leading to a clickable Fc-BDP-C₆₀ triad and a clickable [Fc]₂-BDP-C₆₀ tetrad which can be used for further derivatization with complex structures. Due to the extended π-conjugation and the presence of an intramolecular charge transfer band from Fc to BDP, all these conjugates display a broad absorption in the visible region, which is bathochromically shifted when two Fc are appended to the BDP core. Ultrafast multistep electron transfers leading to charge stabilization were demonstrated in the Fc-BDP-C₆₀ triad and [Fc]₂-BDP-C₆₀ tetrad by femtosecond transient absorption studies.     

GAMMA AND PULSE RADIOLYSIS STUDIES OF THE REACTION BETWEEN SUPEROXIDE IONS AND OXYHEMOGLOBIN-METHEMOGLOBIN SYSTEM

Abstract— The radiolytic studies of oxyhemoglobin or methemoglobin in neutral aerated aqueous solutions with formate ions, lead to three conclusions:
The oxidation of oxyhemoglobin by O^-₂ is not important. The observed low oxidation yield is probably due to the slow reaction with hydrogen peroxide produced by O^-₂ disproportionation.
The reduction of methemoglobin in γ radiolysis reaches a plateau which could be explained by structural considerations.
The reduction of methemoglobin by O^-₂ ions, if it occurs, is relatively slow: k = 1.4 × 10³ M ^-1 s^-1. But a problem remains concerning the spectral characteristics of the product.     

An integrated procedure of selective injection, sample stacking and fractionation of phosphopeptides for MALDI MS analysis

Protein phosphorylation is one of the most important post-translational modifications (PTM), however, the detection of phosphorylation in proteins using mass spectrometry (MS) remains challenging. This is because many phosphorylated proteins are only present in low abundance, and the ionization of the phosphorylated components in MS is very inefficient compared to the non-phosphorylated counterparts. Recently, we have reported a selective injection technique that can separate phosphopeptides from non-phosphorylated peptides due to the differences in their isoelectric points (pI) [1]. Phosphorylated peptides from α-casein were clearly observed at low femtomole level using MALDI MS. In this work, further developments on selective injection of phosphopeptides are presented to enhance its capability in handling higher sample complexity. The approach is to integrate selective injection with a sample stacking technique used in capillary electrophoresis to enrich the sample concentration, followed by electrophoresis to fractionate the components in preparation for MALDI MS analysis. The effectiveness of the selective injection and stacking was evaluated quantitatively using a synthetic phosphopeptide as sample, with an enrichment factor of up to 600 being recorded. Next, a tryptic digest of α-casein was used to evaluate the separation and fractionation of peptides for MALDI MS analysis. The elution order of phosphopeptides essentially followed the order of decreasing number of phosphates on the peptides. Finally, to illustrate the applicability, the integrated procedure was applied to evaluate the phosphorylation of a highly phosphorylated protein, osteopontin. Up to 41 phosphopeptides were observed, which allowed us to examine the phosphorylation of all 29 possible sites previously reported [2]. A high level of heterogeneity in the phosphorylation of OPN was evident by the multiple-forms of variable phosphorylation detected for a large number of peptides.     

A note on the derivation of rigid-plastic models

This note is devoted to a rigorous derivation of rigid-plasticity as the limit of elasto-plasticity when the elasticity tends to infinity.