Laurent David

Claude Bernard Lyon 1 University · Polytech Lyon/ Material and Surface Engineering dpt

Loosely bound iron, due to its contribution to oxidative stress and inflammation, has become an important therapeutic target for many diseases. A water-soluble chitosan-based polymer exhibiting both antioxidant and chelating properties due to the dual functionalization with DOTAGA and DFO has been developed to extract this iron therefore preventing...

ESRF Highlights 2022, (2023) p. 135-137. https://www.esrf.fr/Apache_files/Highlights/2022/index.html#/page/136 A new strategy was developed for grafting multi-block (segmented) copolymers. Their composition and the number and molecular weight of their CO2-philic grafts were precisely controlled by an advanced design. The grafting induced a specifi...

Heavy metals present a threat to human health, even at minimal concentrations within the body. One source of exposure is due to the consumption of low-level contaminated foodstuff and water. Lead and cadmium have been shown to be absorbed by and accumulate within organs like the kidneys and liver, and they have also been associated to many diseases...

The aim of the present study was to evaluate the effect of activin A on the activation of in vitro folliculogenesis of human ovarian tissues from transgender men with or without our new compartmented chitosan hydrogel microbioreactor (“three-dimensional (3D)-structure”) enabling a three-dimensional tissue culture. Five fresh ovarian human tissues w...

Background and Objectives: To test the long-term ability of human ovarian cortex cells to develop in unconventional culture conditions. Materials and Methods. Ovarian cortex cells from fetuses aged 23 to 39 weeks gestation were cultured for 90 days in hollow chitosan hydrogel micro-bioreactors and concurrently in traditional wells. Various cell-typ...

The 3D printing of a multifunctional hydrogel biomaterial with bioactivity for tissue engineering, good mechanical properties and a biodegradability mediated by free and encapsulated cellulase was proposed. Bioinks of cellulase-laden and cellulose nanofiber filled chitosan viscous suspensions were used to 3D print enzymatic biodegradable and biocom...

In situ coupled mechanical/electrical/WAXS/SAXS investigations on EPDM-based composite materials filled with carbon black (CB) have been performed under uniaxial tensile stretching. The time-resolved correlation between the electrical conductivity and the microstructural state of the composite reveals the mechanisms governing the structure/properti...

In-situ coupled mechanical/electrical investigations on TPU-based nanocomposite materials filled with carbon black have been carried-out under continuous and cyclic mechanical loading, with simultaneous measurements of stress, strain and electrical conductivity as function of the strain rate and amplitude. The impact of mechanical deformation and t...

Linear poly(ether-urea-imide)s (PUIs) are attractive multi-block segmented copolymers well-known for high selectivity for CO2 separations. Their CO2 permeability generally increases but their selectivity decreases with their polyether soft content limited to 70 wt% to preserve their mechanical properties. In this work, the grafting of a PUI copolym...

Natural polymers, as extracted from biomass, may exhibit large macromolecular polydispersity. We investigated the impact of low molar mass chitosan (LMW, DPw~115) on the properties of chitosan fibers obtained by wet spinning of chitosan solutions with bimodal distributions of molar masses. The fiber crystallinity index (CrI) was assessed by synchro...

An emerging target to overcome cancer resistance to treatments is copper, which is upregulated in a wide variety of tumors and may be associated with cancer progression and metastases. The aim of this study was to develop a multimodal ultrasmall nanoparticle, CuPRiX, based on the clinical AGuIX nanoparticle made of the polysiloxane matrix on which...

In the present work, elegant modification of halloysite (Hal) by citric acid (CA) was realized. The corresponding novel bio-composite (Hal-CA) was then used as drug carrier. To validate this concept, ketoprofen (KET), a known non-steroidal anti-inflammatory agent, was chosen as drug model. KET has low solubility and a short biological half-life, wh...

We have previously shown that implantation of a fragmented chitosan hydrogel suspension (chitosan‐FPHS) into a traumatic spinal cord lesion in adult rats led to significant axon regrowth and functional recovery, which was associated to a modulation of inflammation. Using an in vitro culture system, we show here that polarization of bone marrow‐deri...

In-situ coupled mechanical/electrical investigations on EPDM-based composite materials prepared using CB fillers of different (low and high) structure and at different concentrations have been carried-out by cyclic and continuous loading, with simultaneous measurements of stress, strain and electrical conductivity. By investigations in dependence o...

In this article, we report the conception and the use of dialysis-based medical device for the extraction of metals. The medical device is obtained by addition in the dialysate of a functionalized chitosan that can chelate endogenous metals like iron or copper. This water-soluble functionalized chitosan is obtained after controlled reacetylation an...

Background: The aim of the present study was to evaluate the effect of Activin A on the activation of in vitro folliculogenesis of human ovarian tissues with or without our new three-dimensional structure (3D-structure). Methods: Five fresh ovarian human tissues were cultured in vitro in 4 groups with 100ng/mL Activin A or without Activine A and wi...

In this article, we report the conception and the use of dialysis based medical device for extraction of metals. The medical device is obtained by addition in the dialysate of a functionnalized chitosan that can chelate endogenous metals like iron or copper. The water soluble functionnalized chitosan is obtained after controlled reacetylation and a...

We prepared chitosan (CHI) hydrogels reinforced with highly charged cellulose nanofibrils (CNF) by the desalting method. To this end, the screening of electrostatic interactions between CHI polycation and CNF polyanion was performed by adding NaCl at 0.4 mol/L to the chitosan acetate solution and to the cellulose nanofibrils suspension. The polyele...

Soft tissues are commonly fiber-reinforced hydrogel composite structures, distinguishable from hard tissues by their low mineral and high water content. In this work, we proposed the development of 3D printed hydrogel constructs of the biopolymers chitosan (CHI) and cellulose nanofibers (CNFs), both without any chemical modification, which processi...

Extremely high mechanical performance spun bionanocomposite fibers of chitosan (CHI), and cellulose nanofibers (CNFs) were successfully achieved by gel spinning of CHI aqueous viscous formulations filled with CNFs. The microstructural characterization of the fibers by X-ray diffraction revealed the crystallization of the CHI polymer chains into anh...

In this work, nanocomposites that combine mucopenetrating and mucoadhesive properties in a single system are proposed as innovative strategy to increase drug residence time in the intestine following oral administration. To this aim, novel mucoadhesive chitosan (CH) sponges loaded with mucopenetrating nanoemulsions (NE) were developed via freeze-ca...

In the context of tissue engineering, chitosan hydrogels are attractive biomaterials because they represent a family of natural polymers exhibiting several suitable features (cytocompatibility, bioresorbability, wound healing, bacteriostatic and fungistatic properties, structural similarity with glycosaminoglycans), and tunable mechanical propertie...

This work explores the epicardial implantation of acellular chitosan hydrogels in two murine models of cardiomyopathy, focusing on their potential to restore the functional capacity of the heart. Different chitosan hydrogels were generated using polymers of four degrees of acetylation, ranging from 2.5% to 38%, because the degree of acetylation aff...

Current pulpotomy is limited in its ability to induce regeneration of the dental-pulp (DP) complex. Hydrogels are reported to be well-suited for tissue engineering and are unlikely to induce an inflammatory response that might damage the remaining tissue. The present study investigated the molecular and cellular actors in the early inflammatory/imm...

Chitosan–caseinate nanoparticles were synthesized by polyelectrolyte complex (PEC) formation. Caseinate is an anionic micellar nanocolloid in aqueous solutions, which association with the polycationic chitosan yielded polyelectrolyte complexes with caseinate cores surrounded by a chitosan corona. The pre-structuration of caseinate micelles facilita...

Fe3O4nanoparticles coated with chito-oligosaccharides (COS) were prepared in-situ by a simple co-precipitation method through a mixing of iron ions (Fe3+and Fe2+) and COS aqueous solutions followed by precipitation with ammonia. The impact of COS with different degree of polymerization (DP 10, 24 and 45) and degree of N-acetylation (DA) ∽ 24 and 50...

The use of dimethyl sulfoxide (Me2SO) as a cryoprotectant agent (CPA) is controversial. Indeed, this cryoprotectant agent (CPA) is cytotoxic and potentially mutagenic. Therefore, other cryoprotectants must be used to reduce the proportion of Me2SO in slow-freezing solutions. In this chapter, we propose to present the first evaluation of new non-pen...

Single-cell microfluidics is a powerful method to study bacteria and determine their susceptibility to antibiotic treatment. Glass treatment by adhesive molecules is a potential solution to immobilize bacterial cells and perform microscopy, but traditional cationic polymers such as polylysine deeply affect bacterial physiology. In this work, we che...

We have fabricated two types of crosslinked chitosan-based nanoparticles (NPs), namely (1) ionically crosslinked with tripolyphosphate (TPP), designated as IC-NPs and (2) dually co-crosslinked (ionically and covalently with TPP and genipin, respectively) termed CC-NPs. The two types of NPs were physichochemically characterized by means of DLS-NIBS,...

We present chitosan hydrogel microfluidic devices with self-assembled complex microcapillary patterns, conveniently formed by a diffusion-reaction process. These patterns in chitosan hydrogels are formed by a single-step procedure involving diffusion of a gelation agent into the polymer solution inside a microfluidic channel. By changing the channe...

2 Hardystonite scaffolds produced by ceramization of 3-D printed preceramic filled polymer were impregnated with chitosan solutions, later neutralized into physical hydrogels. Hardystonite bioceramic and chitosan physical hydrogel were chosen for their interesting biological properties as potential bone substitutes. Five impregnation protocols, dif...

Objective: Regenerating a functional dental pulp in the pulpectomized root canal has been recently proposed as a novel therapeutic strategy in dentistry. To reach this goal, designing an appropriate scaffold able to prevent the growth of residual endodontic bacteria, while supporting dental pulp tissue neoformation, is needed. Our aim was to creat...

Single cell microfluidics is powerful to study bacteria and determine their susceptibility to antibiotics treatment. Glass treatment by adhesive molecules is a potential solution to immobilize bacterial cells and perform microscopy but traditional cationic polymers such as poly-lysine deeply affect bacterial physiology. In this work, we chemically...

Aims: The need for small caliber vessels to treat cardiovascular diseases has grown. However, synthetic polymers perform poorly in small-diameter applications. Chitosan hydrogels can provide a novel biological scaffold for vascular engineering. The goal of this study was to explore host cell and tissue behavior at the interface with chitosan-based...

The development of non-cellularized composites of chitosan (CHI) hydrogels, filled with cellulose nanofibers (CNFs) of the type nanofibrillated cellulose, was proposed for the repair and regeneration of the intervertebral disc (IVD) annulus fibrosus (AF) tissue. With the achievement of CNF-filled CHI hydrogels, biomaterial-based implants were desig...

This work emphazises the importance of the solubilizing conditions for the elaboration of chitosan hydrogel beads, which were produced using electromagnetic laminar jet breakup technology, resulting in dried porous beads by further freeze-drying. Paramaters such as the acid nature and concentration (acetic, formic, citric, lactic, maleic and malic,...

Porous collagen/chitosan scaffolds with different Collagen:Chitosan (Coll:Ch) ratios were prepared by freeze-drying followed by self-crosslinking via dehydrothermal treatment (DHT) and characterized as biomaterials for tissue engineering. Cy7 and Cy5.5 fluorochromes were covalently grafted to collagen and chitosan, respectively. Thus, it was possib...

Chitosans, a family of β-(1,4)-linked, partially N-acetylated polyglucosamines, are considered to be among the most versatile and most promising functional biopolymers. Chemical analysis and bioactivity studies revealed that the functionalities of chitosans strongly depend on the polymers’ degree of polymerization and fraction of acetylation. More...

Bone substitute fabrication is of interest to meet the worldwide incidence of bone disorders. Physical chitosan hydrogels with intertwined apatite particles were chosen to meet the bio-physical and mechanical properties required by a potential bone substitute. A set up for 3-D printing by robocasting was found adequate to fabricate scaffolds. Inks...

We report the fabrication and the use of a bioinspired synovial fluid acting as a lubricant fluid and anti-wear agent at soft and porous chitosan hydrogel tribopairs. This synthetic synovial fluid is composed of sodium hyaluronate (HA) and a bottle-brush polymer (BB) having a polycationic attachment group and polyzwitterionic pendant chains. 2.5 %w...

The morphology and mechanical properties of chitosan fibers obtained by spinning of hydroalcoholic (1,2propanediol/water) chitosan solutions of low DA and high molecular mass are reported. The impact of processing parameters on final fiber properties, such as fiber stretching at different steps of the spinning process, is investigated. A stretching...

Polymers exhibiting the bottlebrush (BB) architecture have excellent lubricating properties. However, in order to motivate their use in real life systems, they must also protect surfaces against frictional damage. In this article, we synthesized a library of polyzwiterrionic bottlebrush polymers of different architectures to explore the effect of i...

Membranes made from cellulose acetate grafted with imidazolium or ammonium ionic liquids (ILs) containing different anions were considered for ethyl tert-butyl ether biofuel purification by pervaporation. The new cellulosic materials were obtained after bromide (Br⁻) exchange by different anions (Tf2N⁻, BF4⁻, AcO⁻). IL structure-membrane property r...

In this manuscript, magnetite nanoparticles have been synthesized via an optimized method that consists in the thermal degradation of a polymer-metal complex prepared from an appropriated mix of polyvinyl alcohol and iron nitrate. Negatively charged (Zeta potential) nanoparticles, with a cubic spinel structure (Fd3¯ space group) and a narrow size d...

This work investigates, mainly from modelling point of view, the process of chitosan fibers formation by coagulation from aqueous solution using sodium hydroxide solution as coagulant (wet spinning). The experimental data were obtained using a spinning laboratory plant. The modelling and simulation study of the chitosan hydrogel wet-spinning conduc...

We describe the fabrication of physical chitosan hydrogels exhibiting a layered structure. This bilayered structure, as shown by SEM and confocal microscopy, is composed of a thin dense superficial zone (SZ), covering a deeper zone (DZ) containing microchannels orientated perpendicularly to the SZ. We show that such structure favors diffusion of ma...

The mucus gel covers the wet epithelia that forms the inner lining of the body. It constitutes our first line of defense protecting the body from infections and other deleterious molecules. Failure of the mucus barrier can lead to the inflammation of the mucosa such as in inflammatory bowel diseases. Unfortunately, there are no effective strategies...

In this study, we investigated the kinetics of chitosan hydrogel formation from aqueous chitosan solutions with sodium hydroxide (NaOH) as the coagulant. Two sets of experiments were performed, one in a parallelepiped cell and the other with cylindrical chitosan solution extrudates. The coagulation occurred by the neutralization of the protonated a...

Aims: Vascular grafts made of synthetic polymers perform poorly in small-diameter applications (cardiac and peripheral bypass). Chitosan is a biocompatible natural polymer that can provide a novel biological scaffold for tissue engineering development. The goal of this study was to demonstrate the biocompatibility of a novel chitosan preparation i...

Vascular grafts made of synthetic polymers perform poorly in cardiac and peripheral bypass applications. In these applications, chitosan-based materials can be produced and shaped to provide a novel scaffold for vascular tissue engineering. The goal of this study was to evaluate in vitro the mechanical properties of a novel chitosan formulation to...

The preparation of chitosan-coated alginate fibers by a wet spin process is presented and the characterization of the antibacterial activities of these fibers is discussed. Preformed calcium alginate fibers were passed in chitosan acetate solutions. The coagulation method of the coating consisted in the immersion of fibers in a bath of calcium dihy...

We studied the microstructure of physical chitosan hydrogels formed by neutralization of chitosan aqueous solutions highlighting the structural gradients within thick gels (up to thicknesses of 16 mm). We explored a high polymer concentrations range (Cp ≥ 1.0 % w/w) with different molar mass of chitosan and different concentrations of the coagulati...

Polyethylene oxide (PEO)-containing multi-block copolymers are good candidates for CO2 membrane separations because of their strong affinity for CO2 but PEO crystallization and weak mechanical properties are two limitations to be overcome at high PEO content. In this work, PEO block incorporation within new linear multi-block copolymers avoided PEO...

In the present study, we monitored the conformation and chemical stability of a hydrophilic bottlebrush (BB) polymer in pure water and buffered saline solutions. We correlated these parameters to lubricating and wear protecting properties. Using the Surface Forces Apparatus (SFA), we show that the BB polymer partially adsorbs on mica surfaces and e...

Chitosan hydrogel and Adipose Derived Stem Cells (ADCS) have been reported as the optimal partnership for colorectal tissue engineering. In that field, the aim of the current experiment was to asses, the interest of seeding ADSC on chitosan hydrogel patches in an in vivo comparative study and on a tube intended replace a colonic segment in an in vi...

The controlled complex coacervation of oppositely charged hyaluronic acid (M = 800–1000 kg/mol) and chitosan (M = 160 kg/mol, degree of acetylation = 15%) led to hydrogels with controllable properties in terms of elasticity and strength. In this work, we performed desalting by dialysis of high ionic strength solutions of mixed polyelectrolytes and...

Recovery from traumatic spinal cord injury (SCI) usually fails due to a cascade of cellular and molecular events that compromise neural tissue reconstitution by giving rise to glial scarring and cavity formation. We designed a scaffold material for SCI treatment containing only chitosan and water as fragmented physical hydrogel suspension (Chitosan...

ABSTRACT Introduction: Recently, chitosan fibers are being used to fabricate or reinforce scaffolds or supports for tissue engineering, thus improving their biomechanical properties. Wet spinning of chitosan and protein in solution has not been assessed before and can be used to obtain bioinspired fibers of chitosan-albumin complex having suitable...

Formation of O/W surfactant-free microemulsions from water/oil/acetone ternary systems is exploited to construct precisely-defined shell-functionalized core-loaded nanocapsules with tunable diameters (ranging from 50 to 190 nm) in one step.