Functionalisation and behaviours of polysaccharides conjugated with phenolic compounds by oxidoreductase catalysis: A review.

Polysaccharides have been extensively studied in recent decades. Their conjugation with phenolic compounds of natural origin has demonstrated high added value, not only enhancing certain inherent properties but also introducing new ones. Recently, a sustainable approach utilizing oxidoreductase enzymes (Oxredases) (laccases (Lac), tyrosinases (Tyr) and peroxidases (Per)) has been employed, and interesting progress has been made.

Injectable polyoxazoline grafted hyaluronic acid thermoresponsive hydrogels for biomedical applications.

Injectable thermosensitive hydrogels based on hyaluronic acid (HA) grafted with lower critical solution temperature (LCST) polyoxazoline (copolymers of poly(isopropyl--butyl oxazoline)) or P(iPrOx--BuOx) have been elaborated with tunable solution/gel temperature transitions and gel state elastic modulus. A suitable HA--P(iPrOx--BuOx-67/33)-0.10 sample with an iPrOx/BuOx ratio of 67/33, a polymerization degree (DP) of 25, a substitution degree (DS) of 10%, and displaying thermally induced gelling character with elastic (') and viscous ('') moduli crossover points at 25 °C and a ' at 37 °C around 80 Pa has been chosen for medical application.

Exopolysaccharide from marine microalgae belonging to the genus: fragile gel behavior and suspension stability.

With the aim to find new polysaccharides of rheological interest with innovated properties, rhamnofucans produced as exopolysaccharides (EPS) in a photobioreactor (PBR) and an airlift bioreactor (ABR) by the marine microalgae Glossomastix sp. RCC3707 and RCC3688 were fully studied. Chemical characterizations have been conducted (UHPLC - MS HR).

Lyophilization for Formulation Optimization of Drug-Loaded Thermoresponsive Polyelectrolyte Complex Nanogels from Functionalized Hyaluronic Acid.

The lyophilization of nanogels is practical not only for their long-term conservation but also for adjusting their concentration and dispersant type during reconstitution for different applications. However, lyophilization strategies must be adapted to each kind of nanoformulation in order to minimize aggregation after reconstitution. In this work, the effects of formulation aspects (i.

Thermoresponsive nanogels based on polyelectrolyte complexes between polycations and functionalized hyaluronic acid.

A novel kind of thermoresponsive polyelectrolyte complex-based nanogels (PEC-NGs) was elaborated by mixing hyaluronic acid (HA) functionalized with Jeffamine® M-2005 (M2005, a thermoresponsive amine-terminated polyether) and diethylaminoethyl dextran (DEAE-D) or poly-l-lysine (PLL) in water. The presence of M2005 grafts led to PEC-NGs with larger particle size, lower net surface charge and thermoresponsiveness, namely shrinkage with increasing hydrophobicity at higher temperature. Both M2005 grafts and replacing DEAE-D with PLL as polycation allowed PEC-NGs to have higher stability against salinity and better encapsulation of curcumin, most probably through intraparticle hydrophobic interactions, whereas interparticle hydrophobic interactions may facilitate particle aggregation over time.

Biosourced Polymeric Emulsifiers for Miniemulsion Copolymerization of Myrcene and Styrene: Toward Biobased Waterborne Latex as Pickering Emulsion Stabilizer.

Biobased waterborne latexes were synthesized by miniemulsion radical copolymerization of a biosourced β-myrcene (My) terpenic monomer and styrene (S). Biobased amphiphilic copolymers were designed to act as stabilizers of the initial monomer droplets and the polymer colloids dispersed in the water phase. Two types of hydrophilic polymer backbones were hydrophobically modified by terpene molecules to synthesize two series of amphiphilic copolymers with various degrees of substitution.

Hyaluronic Acid Functionalization with Jeffamine M2005: A Comparison of the Thermo-Responsiveness Properties of the Hydrogel Obtained through Two Different Synthesis Routes.

Hyaluronic acid (HA) of different molar masses (respectively 38,000, 140,000 and 1,200,000 g.mol) have been functionalized with a commercial poly(etheramine), Jeffamine M2005, in order to devise physical thermo-responsive hydrogels. Two routes have been studied, involving the use of either water for the first one or of N,N'-Dimethylformamide (DMF), a polar aprotic solvent, for the second one.

Microgels Based on Carboxymethylpullulan Grafted with Ferulic Acid Obtained by Enzymatic Crosslinking in Emulsion for Drug Delivery Systems.

Carboxymethylpullulan (CMP) grafted with ferulic acid (FA) is crosslinked with laccase by the reverse water-in-oil emulsion technique (with sunflower oil) to obtain microgels with size from 40 to 200 µm. It is demonstrated that laccase activity and dispersion time have an impact on microgels' size. Fluorescence spectroscopy of different probes (e.

Biomimetic hydrogel by enzymatic crosslinking of pullulan grafted with ferulic acid.

A novel eco-friendly two-step synthesis process of neutral pullulan (PUL)-ferulic acid (FA) conjugates was reported in this work. Ferulic acid was first transformed to activated ferulate-imidazolide using N,N'-carbonyldiimidazole (CDI), a green activated reagent. Issued product was then reacted with pullulan.

Antioxidant properties and bioactivity of Carboxymethylpullulan grafted with ferulic acid and of their hydrogels obtained by enzymatic reaction.

Antioxidant and cytocompatible chemically modified polysaccharides and their hydrogels were obtained by a biomimetic approach. For this purpose, carboxymethylpullulan grafted with ferulic acid (CMP-FA) was firstly synthesized with different substitution degrees (DS). Their hydrogels were secondly obtained by enzymatic cross-linking with laccase.

Carboxymethylpullulan Grafted with Aminoguaiacol: Synthesis, Characterization, and Assessment of Antibacterial and Antioxidant Properties.

Aminoguaiacol, the aminated derivative of guaiacol, a natural phenolic compound, was chemically grafted onto a polysaccharide (carboxymethylpullulan, CMP) in the presence of the activator agent 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide hydrochloride (EDCI). The grafted polysaccharides were characterized by FTIR and H NMR spectroscopy to confirm and quantify the grafting. All polysaccharide derivatives (grafting rates of aminoguaiacol between 16% and 58%) were soluble in water.

Rheological study of in-situ crosslinkable hydrogels based on hyaluronanic acid, collagen and sericin.

The elaboration of chemically crosslinked hydrogels based on collagen (C), hyaluronanic acid (HA) and sericin (S) with different polymer ratios was investigated by in-situ rheology. This reaction was performed via amide or ester bond reaction activated by carbodiimide, in pure water. Prior to molecule crosslinking, the rheological behaviour of the biopolymers (alone or in mixture) was characterized in a semi-dilute concentration regime.

Enzymatic cross-linking of carboxymethylpullulan grafted with ferulic acid.

Carboxymethylpullulan (CMP) has been modified in a two-step grafting reaction of ferulic acid (FA). Acid adipic dihydrazyde (ADH) was first reacted with FA activated with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC). Then the product of this first reaction was reacted with CMP (activated with EDC).

Thermo-controlled rheology of electro-assembled polyanionic polysaccharide (alginate) and polycationic thermo-sensitive polymers.

Several thermo-sensitive polyelectrolyte complexes were prepared by ionic self-association between an anionic polysaccharide (alginate) and a monocationic copolymer (polyether amine, Jeffamine®-M2005) with a 'Low Critical Solubility Temperature' (LCST). We show that electro-association must be established below the aggregation temperature of the free Jeffamine®, after which the organization of the system is controlled by the thermo-association of Jeffamine® that was previously electro-associated with the alginate. Evidence for this comes primarily from the rheology in the semi-dilute region.

Crosslinked hydrogels based on biological macromolecules with potential use in skin tissue engineering.

Zero-length crosslinked hydrogels have been synthesized by covalent linking of three natural polymers (collagen, hyaluronic acid and sericin), in the presence of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide. The hydrogels have been investigated by FT-IR spectroscopy, microcalorimetry, in vitro swelling, enzymatic degradation, and in vitro cell viability studies. The obtained crosslinked hydrogels showed a macroporous structure, high swelling degree and in vitro enzymatic resistance compared to uncrosslinked collagen.

Covalent immobilization of pullulanase on alginate and study of its hydrolysis of pullulan.

The immobilization of pullulanase from Klebsiella pneumoniae by grafting was investigated. Pullulanase was linked after activation of alginate via a covalent bond between the amine groups of the enzyme and the carboxylic acid groups of alginate. The immobilization yield was 60%.

Two methods for one-point anchoring of a linear polysaccharide on a gold surface.

Two strategies to achieve a one-point anchoring of a hydrolyzed pullulan (P9000) on a gold surface are compared. The first strategy consists of forming a self-assembled monolayer of a 6-amino-1-hexanethiol (AHT) and then achieving reductive amination on the surface between the aminated surface and the aldehyde of the polysaccharide reductive end sugar. The second consists of incorporating a thiol function at the extremity of the pullulan (via the same reductive amination), leading to P9000-AHT and then immobilizing it on gold by a spontaneous reaction between solid gold and thiol.

Rigidity-patterned polyelectrolyte films to control myoblast cell adhesion and spatial organization.

, cells are sensitive to the stiffness of their micro-environment and especially to the spatial organization of the stiffness. studies of this phenomenon can help to better understand the mechanisms of the cell response to spatial variations of the matrix stiffness. In this work, we design polelyelectrolyte multilayer films made of poly(L-lysine) and a photo-reactive hyaluronan derivative.

Organization of "Pullulan"-block-polyether copolymers at the aqueous solution/air interface.

Interfacial behavior of a thermosensitive homologous series of linear copolymers based on polyetheramine (commercially named Jeffamine® M2005) and on pullulan is investigated. The influence of the polysaccharide block length has been significantly highlighted on the copolymer structuring at the aqueous solution/air interface. Indeed, these systems induce a decrease in the surface tension depending on the pullulan length.

Influence of polyelectrolyte film stiffness on bacterial growth.

Photo-cross-linkable polyelectrolyte films, whose nanomechanical properties can be varied under UV light illumination, were prepared from poly(l-lysine) (PLL) and a hyaluronan derivative modified with photoreactive vinylbenzyl groups (HAVB). The adhesion and the growth of two model bacteria, namely Escherichia coli and Lactococcus lactis , were studied on non-cross-linked and cross-linked films to investigate how the film stiffness influences the bacterial behavior. While the Gram positive L.

Survival of cord blood haematopoietic stem cells in a hyaluronan hydrogel for ex vivo biomimicry.

Haematopoietic stem cells (HSCs) and haematopoietic progenitor cells (HPCs) grow in a specified niche in close association with the microenvironment, the so-called 'haematopoietic niche'. Scaffolds have been introduced to overcome the liquid culture limitations, mimicking the presence of the extracellular matrix (ECM). In the present study the hyaluronic acid scaffold, already developed in the laboratory, has been used for the first time to maintain long-term cultures of CD34⁺ haematopoietic cells obtained from human cord blood.

Rheological behavior and non-enzymatic degradation of a sulfated galactan from Halymenia durvillei (Halymeniales, Rhodophyta).

The rheological behavior of a sulfated galactan extracted from Halymenia durvillei, a red seaweed collected in the coastal waters of a small island of Madagascar (Nosy-be in Indian Ocean), was investigated in dilute and semi-dilute solutions. In dilute solution with NaCl at 0.3 M, the polysaccharide adopted a coil conformation whereas, at higher concentrations, the polymer had the behavior of shear-thinning fluid, typical of polymer with high molar mass or semi-rigid conformation.

Elastin-derived peptides: matrikines critical for glioblastoma cell aggressiveness in a 3-D system.

In the most common primary brain tumors, malignant glioma cells invade the extracellular matrix (ECM) and proliferate rapidly in the cerebral tissue, which is mainly composed of hyaluronan (HA) along with the elastin present in the basement membrane of blood vessels. To determine the role of ECM components in the invasive capacity of glioma cell lines, we developed a 3-D cell-culture system, based on a hydrogel in which HA can be coreticulated with kappa-elastin (HA-kappaE). Using this system, the invasiveness of cells from four glioma cell lines was dramatically increased by the presence of kappaE and a related, specific peptide (VGVAPG)(3).

Variation of polyelectrolyte film stiffness by photo-cross-linking: a new way to control cell adhesion.

We report on the preparation of polyelectrolyte films based on biopolymers whose nanomechanical properties can be tuned by photo-cross-linking. Cationic poly(L-lysine) was layer-by-layer assembled with anionic hyaluronan (HA) derivatives modified by photoreactive vinylbenzyl (VB) groups. The study of the multilayer buildup by quartz crystal microbalance with dissipation monitoring showed that the presence of VB groups does not influence significantly the multilayer growth.