Deciphering the Structure and Chemical Composition of Drug Nanocarriers: From Bulk Approaches to Individual Nanoparticle Characterization

Drug nanocarriers (NCs) with sizes usually below 200 nm are gaining increasing interest in the treatment of severe diseases such as cancer and infections. Characterization methods to investigate the morphology and physicochemical properties of multifunctional NCs are key in their optimization and in the study of their in vitro and in vivo fate. Whereas a variety of methods has been developed to characterize “bulk” NCs in suspension, the scope of this review is to describe the different approaches for the NC characterization on an individual basis, for which fewer techniques are available. The accent is put on methods devoid of labelling, which could lead to artefacts. For each characterization method, the principles and approaches to analyze the data are presented in an accessible manner. Aspects related to sample preparation to avoid artefacts are indicated, and emphasis is put on examples of applications. NC characterization on an individual basis allows gaining invaluable information in terms of quality control, on: i) NC localization and fate in biological samples; ii) NC morphology and crystallinity; iii) distribution of the NC components (drugs, shells), and iv) quantification of NCs’ chemical composition. The individual characterization approaches are expected to gain increasing interest in the near future.     

Detection of Frozen–Thawed Duck Fatty Liver by MALDI-TOF Mass Spectrometry: A Chemometrics Study

The marketing of poultry livers is only authorized as fresh, frozen, or deep-frozen. The higher consumer demand for these products for a short period of time may lead to the marketing of frozen–thawed poultry livers: this constitutes fraud. The aim of this study was to design a method for distinguishing frozen–thawed livers from fresh livers. For this, the spectral fingerprint of liver proteins was acquired using Matrix-Assisted Laser Dissociation Ionization-Time-Of-Flight mass spectrometry. The spectra were analyzed using the chemometrics approach. First, principal component analysis studied the expected variability of commercial conditions before and after freezing–thawing. Then, the discriminant power of spectral fingerprint of liver proteins was assessed using supervised model generation. The combined approach of mass spectrometry and chemometrics successfully described the evolution of protein profile during storage time, before and after freezing-thawing, and successfully discriminated the fresh and frozen–thawed livers. These results are promising in terms of fraud detection, providing an opportunity for implementation of a reference method for agencies to fight fraud.     

Neutron activation analysis by the monostandard method

The “absolute” quantitative processing of complex gamma-ray spectra has been made possible by the use of high resolution detectors and by irradiation with a well thermalized neutron flux. So, the simultaneous determination of many stable elements, either major or trace components is possible without destruction of the sample. The results of measurements on the irradiated samples show a threefold recurrence: (1) each element appears as often as it possesses activable isotopes, under the form of ray emitting nuclides, (2) each nuclide is determined as often as it presents ditinct emission lines, (3) all measurements are repeated in time. So under these conditions and with an original computer data processing, neutron activation analysis is a powerful analytical tool. The recurrence of the results gives access to the interpretation of the origin of various errors which consequently are better estimated. If applied to the study of ancients ceramics, this method should perhaps allow to evaluate the relationship between the geochemical imprint characteristic of the artifact and the original location, or even workshop.     

Raman identification of H2CO in aqueous solutions

Aqueous formaldehyde solutions of mole fraction from 0.05 to 0.20 were studied by Raman spectroscopy at temperatures up to 180 °C. The previously unreported Raman spectrum of formaldehyde under its non‐hydrated form H₂CO has been identified, in addition to the already known bands from methanediol CH₂(OH)₂ and poly(oxymethylene)glycols HO(CH₂O)_nH formed by hydration and subsequent polymerization of the formaldehyde molecules. The experimental spectrum of formaldehyde in solutions agrees perfectly with the theoretical calculations. Copyright © 2010 John Wiley & Sons, Ltd.     

Regular rapidly decreasing nonlinear generalized functions. Application to microlocal regularity

We present new types of regularity for nonlinear generalized functions, based on the notion of regular growth with respect to the regularizing parameter of the Colombeau simplified model. This generalizes the notion of G^∞-regularity introduced by M. Oberguggenberger. A key point is that these regularities can be characterized, for compactly supported generalized functions, by a property of their Fourier transform. This opens the door to microanalysis of singularities of generalized functions, with respect to these regularities. We present a complete study of this topic, including properties of the Fourier transform (exchange and regularity theorems) and relationship with classical theory, via suitable results of embeddings.     

Topology on Asymptotic Algebras of Generalized Functions and Applications

 Starting from a locally convex metrisable topological space and from any asymptotic scale, we construct a generalized extension of this space. To those extensions, we associate Hausdorff topologies. We introduce the notion of a temperate map, with respect to a given asymptotic scale, between two locally convex metrisable semi-normed spaces. We show that such mappings extend in a canonical way to mappings between the respective generalized extensions. We give an application to nonlinear Dirichlet boundary value problems with singular data in the framework of generalized extensions.     

Water-Soluble Fe(II) Complexes for Theranostic Application: Synthesis,Photoacoustic Imaging,and Photothermal Conversion

Significant effort focused on developing photoactivatable theranostics for localized image guided therapy of cancer by thermal ablation. In this context iron complexes were recently identified as photoactivatable theranostic agents with adequate biocompatibility and body clearance. Herein, a series of Fe^II complexes bearing polypyridine or N-heterocyclic carbenes is reported that rely on rational complex engineering to red-shift their MLCT based excited-state deactivation via a straightforward approach. The non-radiative decay of their MLCT upon irradiation is exploited for theranostic purposes by combining both tracking in photoacoustic imaging (PA) and photothermal therapy (PTT). The influence of structural modifications introduced herein on the solubility and stability of the complexes in biorelevant aqueous media is discussed. The relationship between complexes’ design, production of contrast in photoacoustic and photothermal efficiency are explored to develop tailored PA/PTT theranostic agents.     

Characterization of mechanically alloyed materials by Mössbauer spectrometry

High-energy ball-milling is a way of synthesizing metastable materials, of inducing phase transformations or chemical reactions or of changing the reactivity of solids. Some contributions of Mössbauer spectrometry to a better characterization and understanding of the synthesis process and of mechanically alloyed materials are briefly sketched.     

High-Energy Ball-Milling of Alloys and Compounds

Hyperfine Interactions - After outlining some characteristics of high-energy ball-milling, we discuss selected examples of phase transformation and of alloy synthesis which focus on deviations from...