Water‐Soluble (Poly)acylhydrazones: Syntheses and Applications

International audienceAcylhydrazone-based (macro)molecules display an increasingly broad spectrum of applications, from small therapeutic molecules and metal-ions probes to self-healing films and biorelevant dynamic polymers. The acylhydrazone function is indeed of prime interest since its unique design combines hydrogen bonds, pH-dependent reversibility, ability to undergo molecular exchanges, and a possible polyvalency. However, a key parameter of its use in aqueous media is the associated water-solubility of the resulting (macro)molecule. This property can indeed become a limitation for applications requiring high concentrations or no organic cosolvent. This review firstly focuses on describing the acylhydrazone function, its properties, and its relevancy in dynamic combinatorial chemistry (DCC). Then it details the synthesis strategies (molecular design, cosolvent, reaction conditions) reported in literature to ensure a sufficient solubilization of both single-bond and multiple-bond acylhydrazone (macro)molecules, together with their various applications

Chitosan Hydrogels Incorporating Colloids For Sustained Drug Delivery

International audienceIn today's biomedical research, a huge effort is being made towards the development of efficient drug delivery systems, achieving sustainable and controlled delivery of drugs. Chitosan (CS) hydrogels are high water content materials with very relevant biological properties to that purpose. Their use for a local and delayed delivery has already been demonstrated for a wide variety of therapeutic agents. One relatively recent strategy to improve these CS-based systems consists in the insertion of colloids, embedding drugs, within their three-dimensional matrix. This provides a second barrier to the diffusion of drugs through the system, and allows to better control their release. The main objective of this review is to report the many existing complex systems composed of CS hydrogels embedding different types of colloids used as drug delivery devices to delay the release of drugs. The various biomedical applications of such final systems are also detailed in this review

Impact of HILIC Amino-Based Column Equilibration Conditions on the Analysis of Chitooligosaccharides

International audienceObtaining well-defined Chitooligosaccharides (COS) structures is very important as their physicochemical and biological properties depends strongly on their degree of polymerization (DP) and degree of N-acetylation (DA). Hydrophilic Interaction Liquid Chromatography (HILIC), that is commonly used for COS analyses, suffers from several drawbacks, related to their complex structure, leading to broadening/splitting of the chromatogram signals. We investigated, herein, on the role of the equilibration step of an amino-based HILIC column on the separation of COS DP ≤ 5. We demonstrated that COS could be separated according to their DP after equilibrating the column by a NaHCO3 buffer solution (100 mM, pH = 10) and mild elution chromatographic parameters (neutral mobile phase, r.t.); or according to their DA after equilibrating the column by an NH4Ac buffer solution (50 mM, pH = 4.5). Also, the nature of the counterion of the column stationary phase was found to affect both retention times and signal profiles of analyzed COS

Les polymères dans la santé : approches diagnostiques, thérapeutiques et théranostiques

International audienceDans cet article, nous présentons un panorama de l'utilisation des polymères dans la santé particulièrement dans les domaines du diagnostic, de la thérapie et du théranostic. Nous explicitons comment le polymère y joue des rôles variés, aussi bien de support, d'enveloppe protectrice, de vecteur ou de marqueur. Souvent, il ne suffit pas que le polymère soit biocompatible, voire dans certains cas biodégradable; le polymère doit aussi permettre d'améliorer les performances de l'application en termes d'efficacité et/ou de sensibilité, de spécificité, de reproductibilité, de robustesse. En fin d'article, nous présentons les principaux défis à relever dans ces différents domaines à l'avenir. Mots-clés : nanomédecine-diagnostic in vitro-imagerie in vivo-théranostic-vectorisationnanoparticules-polymères hydrosolubles-dendrimère

A green method for polybutylene succinate recycling: Depolymerization catalyzed by lipase B from Candida antarctica during reactive extrusion

International audienceThis study aims to investigate a "green" recycling route for polybutylene succinate (PBS) based on reactive extrusion in the presence of an enzyme catalyzing the hydrolysis of this aliphatic polyester: lipase B from Candida antarctica. This enzyme was chosen due to its thermal stability, since reactive extrusion was performed at 120 degrees C (i.e. above PBS melting temperature). PBS hydrolysis was measured after extrusion at 120 degrees C either in a single or a twin screw extruder, in the presence of 0-10 wt% C. antarctica lipase for 5 or 30 min. In a twin screw extruder, the residual activity of the enzyme was still 38% or 24%, after 5-30 min extrusion at 120 degrees C, respectively. For instance, the weight average molecular weight (M-w) of PBS decreased from 82,000 to 4500 g mol(-1) after extrusion for 5 min in the presence of 1% wt of lipase. The highest yield of free succinic acid release (44%) was obtained following a 30 min extrusion in the presence of 10 wt% of C. antarctica lipase. The drastic decrease in weight average molecular weight of PBS after enzymatic hydrolysis caused an only 10 degrees C decrease in the melting temperature

Liposome-loaded chitosan physical hydrogel: Toward a promising delayed-release biosystem

International audienceThis work deals with the elaboration of an original biosystem in view of its application as drug delayed-release device in biomedical area. This innovative "hybrid" system is composed of phosphatidylcholine liposomes entrapped within a chitosan physical hydrogel (only constituted of polymer and water). To this end, pre-formed liposomes were suspended into chitosan solutions, and the polymer gelation process was subsequently carried out following particular experimental conditions. This liposome incorporation did absolutely not prevent the gel formation as shown by rheological properties of the resulting tridimensional matrix. The presence of liposomes within the hydrogel was confirmed by fluorescence and cryo-scanning electron microscopies. Then, the expected concept of delayed-release of this "hybrid" system was proved using a model water soluble molecule (carboxyfluorescein, CF) encapsulated in liposomes, themselves incorporated into the chitosan hydrogel. The CF release was assayed after repeated and intensive washings of hydrogels, and was found to be higher in the CF-in-hydrogel systems in comparison with the CF-in-liposomes-in-hydrogel ones, demonstrating a CF delayed-release thanks to lipid vesicles

Taking Advantage of Oxidation to Characterize Thiol-Containing Polymer Chains by MALDI-TOF Mass Spectrometry

International audienceMALDI-TOF mass spectrometry analyses revealed the oxidation of thiol-containing polymer chain-ends during sample preparation using THF as solvent. In these conditions, the extent of oxidation was hardly reproducible, and led to various types of oxidized compounds. Preparing the samples at the last minute using commercial THF stabilized with an antioxidant led to more reproducible results, with the least oxidation. However, it is demonstrated herein that thiol oxidation can be advantageously taken into profit to further ascertain the presence of the thiol at the polymer chain-end. To force thiol oxidation we used THF without any antioxidant stabilizer, thus more prone to form peroxides. Thiol-containing polymer chains can thereby be indirectly evidenced by the formation of oxidation products such as chain−chain disulfide bonds and sulfonic acid chains-ends. More importantly, in these oxidizing conditions and in the negative mode, sulfonic acid-terminated polymer chains can be more sensitively detected than thiol ones (the low pK a of sulfonic acids facilitating their anionization in MALDI source). In conclusion, performing MALDI-TOF mass spectrometry analyses in oxidizing conditions, as complement to regular analyses, was found to be very useful for the chain-end identification of different thiol-containing polymer chains

Solution viscosity - molar mass relationships for poly(butylene succinate) and discussion on molar mass analysis

International audiencePoly(butylene succinate) (PBS) is currently developing due to its biodegradability and the similarity of its mechanical properties to those of polyolefins. Relationships between the number average molar mass,(M) over bar (n), and solution viscosity such as [eta] and eta(red) were derived for this aliphatic polyester. (M) over bar (n) values were determined by end-group analysis and size exclusion chromatography (SEC). Mark-Houwink-Sakurada (MHS) parameters were proposed in two solvents and for the different molar masses and viscosity measurement methods. As an example, the MHS equations were respectively, [eta] = 6.4 10(-4).M-n (0.67) in chloroform and [eta] = 7.1.10(-4).(M) over bar (-0.69)(n) in 50/ 50 wt% 1,2-dichlorobenzene/ phenol at 25 degrees C for molar masses measured by SEC in hexafluoro isopropanol (HFIP) with poly(methyl methacrylate) (PMMA) standards. Empirical relationships were also suggested to derive (M) over bar (n)directly from reduced viscosity, eta(red), which is much easier to determine than intrinsic viscosity. With these data, the number average molar mass of PBS can be conveniently estimated from a single viscosity measurement. In addition, it was shown that PBS contains 1-2 wt% of cyclic oligomers produced during esterification and that molar masses determined by taking this fraction into account or not were significantly different, especially for long chains

Innovative particle standards and long-lived imaging for 2D and 3D dSTORM.

International audienceDirect stochastic optical reconstruction microscopy (dSTORM), developed in the last decade, has revolutionised optical microscopy by enabling scientists to visualise objects beyond the resolution provided by conventional microscopy (200 nm). We developed an innovative method based on blinking particle standards and conditions for long-lived imaging over several weeks. Stable localisation precisions within the 10 nm-range were achieved for single virions and in cellulo 2D imaging of centrosomes, as well as their reliable reconstruction in 3D dSTORM