Stéphanie Degoutin

Multilayered textile coating based on a β-cyclodextrin polyelectrolyte for the controlled release of drugs

The aim of this work was to develop the formation of multilayered coating incorporating a cyclodextrin polyelectrolyte onto a non-woven polyethylene terephthalate (PET) textile support in order to obtain reservoir and sustained release properties towards bioactive molecules. We optimized the multilayer assembly immobilization onto the PET surface according to the layer-by-layer (LbL) deposition process. After a pre-treatment of the textile support aiming to offer a sufficient ionic character to the surface, it was alternatively immersed into two polyelectrolytes aqueous solutions consisting of chitosan (CHT) as polycation on the one hand, and a β-cyclodextrin polymer (polyCTR-βCD) as polyanion on the other hand. In a second approach, a TBBA/polyCTR-βCD complex (4-tert-butylbenzoic acid, TBBA) was used in order to load the system with a drug model whose kinetics of release was assessed. Gravimetry, microscopy, OWLS, colorimetric titration, infrared and zetametry were used as characterization techniques. An effective deposition on the textile surface due to ionic interactions with alternation of up to 10 layers of each of both polyelectrolytes was clearly evidenced. However, we observed that layer formation occurred to a lesser extent when TBBA/polyCTR-βCD complex was applied instead of polyCTR-βCD alone. The release study showed that drug reservoir properties and release kinetics could be controlled by the number of layers in the system and that TBBA release was faster than the multilayered coating degradation.

Porous silicon-cyclodextrin based polymer composites for drug delivery applications

One of the main applications of porous silicon (PSi) in biomedicine is drug release, either as a single material or as a part of a composite. PSi composites are attractive candidates for drug delivery systems because they can display new chemical and physical characteristics, which are not exhibited by the individual constituents alone. Since cyclodextrin-based polymers have been proven efficient materials for drug delivery, in this work β-cyclodextrin-citric acid in-situ polymerization was used to functionalize two kinds of PSi (nanoporous and macroporous). The synthesized composites were characterized by microscopy techniques (SEM and AFM), physicochemical methods (ATR-FTIR, XPS, water contact angle, TGA and TBO titration) and a preliminary biological assay was performed. Both systems were tested as drug delivery platforms with two different model drugs, namely, ciprofloxacin (an antibiotic) and prednisolone (an anti-inflammatory), in two different media: pure water and PBS solution. Results show that both kinds of PSi/β-cyclodextrin-citric acid polymer composites, nano- and macro-, provide enhanced release control for drug delivery applications than non-functionalized PSi samples.

Anticoagulant and antimicrobial finishing of non-woven polypropylene textiles

The aim of this work is to prepare non-woven polypropylene (PP) textile functionalized with bioactive molecules in order to improve its anticoagulation and antibacterial properties. This paper describes the optimization of the grafting process of acrylic acid (AA) on low-pressure cold-plasma pre-activated PP, the characterization of the modified substrates and the effect of these modifications on the in vitro biological response towards cells. Then, the immobilization of gentamicin (aminoglycoside antibiotic) and heparin (anticoagulation agent) has been carried out on the grafted samples by either ionic interactions or covalent linkages. Their bioactivity has been investigated and related to the nature of their interactions with the substrate. For gentamicin-immobilized AA-grafted samples, an inhibition radius and a reduction of 99% of the adhesion of Escherichia coli have been observed when gentamicin was linked by ionic interactions, allowing the release of the antibiotic. By contrast, for heparin-immobilized AA-grafted PP samples, a strong increase of the anticoagulant effect up to 35 min has been highlighted when heparin was covalently bonded on the substrate, by contact with the blood drop.

Organically Modified Silica with Pyrazole-3-carbaldehyde as a New Sorbent for Solid-Liquid Extraction of Heavy Metals

A new chelating matrix, SiNP, has been prepared by immobilizing 1.5-dimethyl-1H-pyrazole-3-carbaldehyde on silica gel modified with 3-aminopropyl-trimethoxysilane. This new chelating material was well characterized by elemental analysis, FT-IR spectroscopy, cross polarization magic angle spinning solid state 13C-NMR, nitrogen adsorption-desorption isotherm, BET surface area, BJH pore size, and scanning electron microscopy (SEM). The new product exhibits good chemical and thermal stability as determined by thermogravimetry curves (TGA). The new prepared material was used as an adsorbent for the solid-phase extraction (SPE) of Pb(II), Cd(II), Cu(II) and Zn(II) from aqueous solutions using a batch method, prior to their determination by flame atomic adsorption spectrometry. The adsorption capacity was investigated using kinetics and pH effects. Common coexisting ions did not interfere with separation and determination.

Visceral mesh modified with cyclodextrin for the local sustained delivery of ropivacaine

The aim of the study was to develop a polyester visceral implant modified with a cyclodextrin polymer for the local and prolonged delivery of ropivacaine to reduce post operatory pain. Therefore, we applied a coating of an inguinal mesh with a crosslinked polymer of hydroxypropyl-β-cyclodextrin (HPβCD) whose specific host-guest complex forming properties were expected to improve the adsorption capacity of the implant toward anesthetic, and then to release it within a sustained period. The modification reaction of the textile with cyclodextrin was explored through the study of the influence of the pad/dry/cure process parameters and the resulting implant (PET-CD) was characterized by solid state NMR and SEM. Besides, the inclusion complex between ropivacaine and CD was studied by NMR and capillary electrophoresis in PBS medium. Finally, ropivacaine sorption test showed that a maximum of 30 mg/g of ropivacaine could be adsorbed on the functionalized samples. In dynamic batch tests in PBS at pH 7.4, the release could be observed up to 6h. The cytocompatibility of the PET-CD loaded with ropivacaine was also studied and reached 65% cell vitality after 6 days.

An inorganic–organic hybrid material made of a silica-immobilized Schiff base receptor and its preliminary use in heavy metal removal

A novel and excellent host for heavy metals was synthesized by chemical immobilization of a (E)-4-((pyridin-2-yl-methylene)amino)phenol Schiff base receptor onto silica particles. The new hybrid material (SPSB) was analyzed and evaluated by elemental analysis, FT-IR spectroscopy, solid-state 13C NMR, scanning electron microscopy, BET surface area and BJH analyses. The surface exhibits good thermal stability determined by thermogravimetry and good chemical stability examined in various acidic and buffer solutions (pH 1–7). The coordination ability of SPSB was found to be most efficient in the pH range 6.5–8 for Hg2+, Cd2+, Pb2+ and Zn2+. Alkali coexisting ions did not interfere with separation and determination. The adsorbent can be regenerated at ease without destruction. Heavy metal removal performance (99 mg g−1) was found to be higher compared to previous literature reports.

Poly‐cyclodextrin functionalized porous bioceramics for local chemotherapy and anticancer bone reconstruction

The progress in bone cancer surgery and multimodal treatment concept achieve only modest improvement in the overall survival, due to failure in clearing out residual cancer cells at the surgical margin and extreme side-effects of adjuvant postoperative treatments. Our study aims to propose a new method based on cyclodextrin polymer (polyCD) functionalized hydroxyapatite (HA) for achieving a high local drug concentration with a sustained release profile and a better control of residual malignant cells via local drug delivery and promotion of the reconstruction of bone defects. PolyCD, a versatile carrier for therapeutic molecules, can be incorporated into HA (bone regeneration scaffold) through thermal treatment. The parameters of polyCD treatment on the macroporous HA (porosity 65%) were characterized via thermogravimetric analysis. Good cytocompatibility of polyCD functionalized bioceramics was demonstrated on osteoblast cells by cell vitality assay. An antibiotic (gentamicin) and an anticancer agent (cisplatin) were respectively loaded on polyCD functionalized bioceramics for drug release test. The results show that polyCD functionalization leads to significantly improved drug loading quantity (30% more concerning gentamicin and twice more for cisplatin) and drug release duration (7 days longer concerning gentamicin and 3 days longer for cisplatin). Conclusively, this study offers a safe and reliable drug delivery system for bioceramic matrices, which can load anticancer agents (or/and antibiotics) to reduce local recurrence (or/and infection).

triclosan loaded electrospun nanofibers based on a cyclodextrin polymer and chitosan polyelectrolyte complex

This work focuses on the relevance of antibacterial nanofibers based on a polyelectrolyte complex formed between positively charged chitosan (CHT) and an anionic hydroxypropyl betacyclodextrin (CD)-citric acid polymer (PCD) complexing triclosan (TCL). The study of PCD/TCL inclusion complex and its release in dynamic conditions, a cytocompatibility study, and finally the antibacterial activity assessment were studied. The fibers were obtained by electrospinning a solution containing chitosan mixed with PCD/TCL inclusion complex. CHT/TCL and CHT-CD/TCL were also prepared as control samples. The TCL loaded nanofibers were analyzed by Scanning Electron Microscopy (SEM), Fourier Transformed Infrared spectroscopy (FTIR) and X-Ray Diffraction (XRD). Nanofibers stability and swelling behavior in aqueous medium were pH and CHT:PCD weight ratio dependent. Such results confirmed that CHT and PCD interacted through ionic interactions, forming a polyelectrolyte complex. A high PCD content in addition to a thermal post treatment at 90°C were necessary to reach a nanofibers stability during 15days in soft acidic conditions, at pH=5.5. In dynamic conditions (USP IV system), a prolonged release of TCL with a reduced burst effect was observed on CHT-PCD polyelectrolyte complex based fibers compared to CHT-CD nanofibers. These results were confirmed by a microbiology study showing prolonged antibacterial activity of the nanofibers against Escherichia coli and Staphylococcus aureus. Such results could be explained by the fact that the stability of the polyelectrolyte CHT-PCD complex in the nanofibers matrix prevented the diffusion of the PCD/triclosan inclusion complex in the supernatant, on the contrary of the similar system including cyclodextrin in its monomeric form.

Fabrication and covalent modification of highly chelated hybrid material based on silica-bipyridine framework for efficient adsorption of heavy metals: isotherms, kinetics and thermodynamics studies

Adsorbent materials are essential in clean-up processes. Research of efficient materials is a well-established technology. In this work, a novel and excellent host for heavy metals was synthesized by covalent immobilization of bipyridine tripodal receptor onto silica particles. The new engineered surface was well analyzed and evaluated by BET, BJH, EA, FT-IR, SEM, TGA and solid-state 13C NMR. The adsorption properties were investigated using Pb(II), Cd(II), Zn(II) and Cu(II) metals by varying all relevant parameters such as pH, contact time, concentration, thermodynamic parameters, kinetics, Langmuir and Freundlich isotherms, etc. The hybrid material has been found to exhibit high distribution coefficients for heavy metals. Adsorption kinetics follows a pseudo-second-order model, as a rapid process as evidenced by equilibrium achieved within 20 min. The resulting adsorption isotherms of the material were better represented by the Langmuir model than the Freundlich model. The thermodynamic parameters (ΔH°, ΔS° and ΔG°) revealed that the adsorption was endothermic and spontaneous. In addition, the proposed material demonstrates a high degree of reusability over a number of cycles, thus enhancing its potential for application in heavy metals recycling. All metal ions were determined by atomic absorption measurements.

New Amine-Modified Silicas: Synthesis, Characterization and Its Use in the Cu(II)-Removal from Aqueous Solutions

Porous silica has been chemically modified with conjugated phenylamine and phenyldiamine moieties using the homogeneous route. This synthetic route involved the reaction of carbaldehyde derivatives with 3-aminopropyltrimethoxysilane prior to immobilization on the support. The resulting materials have been characterized by elemental analysis, FT-IR, 13 C NMR of the solid state, nitrogen adsorption-desorption isotherm, BET surface area, B.J.H. Pore sizes, thermogravimetry analyser (TGA) curves, X-ray diffraction (XRD) and scanning electron microscope (SEM). The new chelating surfaces exhibit good chemical and thermal stability. The solids were employed as Cu(II) adsorbents from aqueous solutions at room temperature. The effects of pH and adsorption kinetics have been studied using the batch technique. Flame atomic absorption spectrometry was used to determine the Cu(II) concentration in the filtrate after the adsorption process. The results indicate that under the optimum conditions, the maximum adsorption value for Cu(II) was 24.5 mg Cu(II) g −1 modified silica, whereas the adsorption capacity of the unmodified silica was only 1 mg Cu(II) g −1 silica. On the basis of these results, it can be concluded that it is possible to modify chemically silica with amine derivatives and to use the resulting modified porous silica as an effective adsorbent for Cu(II) in aqueous media.