Growing of Artificial Lignin on Cellulose Ferulate Thin Films.

Thin films of cellulose ferulate were designed to study the formation of dehydrogenation polymers (DHPs) on anchor groups of the surface. Trimethylsilyl (TMS) cellulose ferulate with degree of substitution values of 0.35 (ferulate) and 2.53 (TMS) was synthesized by sophisticated polysaccharide chemistry applying the Mitsunobu reaction. The biopolymer derivative was spin-coated into thin films to yield ferulate moieties on a smooth cellulose surface. Dehydrogenative polymerization of coniferyl alcohol was performed in a Quartz crystal microbalance with a dissipation monitoring device in the presence of H2O2 and adsorbed horseradish peroxidase. The amount of DHP formed on the surface was found to be independent of the base layer thickness from 14 to 75 nm. Pyrolysis-GC-MS measurements of the DHP revealed ß-O-4 and ß-5 linkages. Mimicking lignification of plant cell walls on highly defined model films enables reproducible investigations of structure-property relationships.

Designing Hydrophobically Modified Polysaccharide Derivatives for Highly Efficient Enzyme Immobilization.

In this contribution, a hydrophobically modified polysaccharide derivative is synthesized in an eco-friendly solvent water by conjugation of benzylamine with the backbone of the biopolymer. Owing to the presence of aromatic moieties, the resulting water-soluble polysaccharide derivative self-assembles spontaneously and selectively from solution on the surface of nanometric thin films and sheets of polystyrene (PS). The synthetic polymer modified in this way bears a biocompatible nanolayer suitable for the immobilization of horseradish peroxidase (HRP), a heme-containing metalloenzyme often employed in biocatalysis and biosensors. Besides the detailed characterization of the polysaccharide derivative, a quartz crystal microbalance with dissipation (QCM-D) and atomic force microscopy (AFM) are used to investigate the binding efficiency and interaction of HRP with the tailored polysaccharide interfaces. Subsequent enzyme activity tests reveal details of the interaction of HRP with the solid support. The novel polysaccharide derivative and its use as a material for the selective modification of PS lead to a beneficial, hydrophilic environment for HRP, resulting in high enzymatic activities and a stable immobilization of the enzyme for biocatalytic and analytic purposes.

A promising cellulose-based polyzwitterion with pH-sensitive charges.

A novel polyzwitterion possessing weak ionic groups could be efficiently synthesized from cellulose phenyl carbonate. Polyanion, polycation, and polyzwitterion are accessible by orthogonal removal of protecting groups. The molecular structure was proofed by FTIR- and NMR spectroscopy. Characteristic properties of the cellulose derivatives, e.g., acid dissociation constants, isoelectric point and complexation, were investigated by potentiometric titration (pH), nephelometry, rheology and dynamic light-scattering. The formation of pH-responsive interpolyelectrolyte complexes applying polydiallyldimethylammonium chloride was preliminary studied.

Biomimetic Dehydrogenation of Non-Conventional Lignin Monomers on Cellulose Ferulate Interfaces.

Cellulose ferulate, synthesized by Mitsunobu reaction, is shaped into thin films and also used as an aqueous dispersion to perform artificial lignin polymerization on anchor groups. This biomimetic approach is carried out in a Quartz crystal microbalance with a dissipation monitoring (QCM-D) device to enable online monitoring of the dehydrogenation, applying H2O2 and adsorbed horseradish peroxidase (HRP). The systematic use of phenylpropanoids with different oxidation states, i.e., ferulic acid, coniferyl aldehyde, coniferyl alcohol, and eugenol allowed to conclude structure-property relationships. Both the deposited material, as well as the surface roughness increased with the hydrophobicity of the monomers. Beyond surface characterizations, py-GC-MS, HSQC NMR spectroscopy and Size exclusion chromatography (SEC) measurements revealed the linkage types ß-ß, ß-5, 5-5, and ß-O-4, as well as the oligomeric character of the dehydrogenation products. All samples possessed an antibacterial activity against B. subtilis and can be used in the field of antimicrobial biomaterials.

Chemical Structure-Antioxidant Activity Relationship of Water-Based Enzymatic Polymerized Rutin and Its Wound Healing Potential.

The flavonoid rutin (RU) is a known antioxidant substance of plant origin. Its potential application in pharmaceutical and cosmetic fields is, however, limited, due to its low water solubility. This limitation can be overcome by polymerization of the phenolic RU into polyrutin (PR). In this work, an enzymatic polymerization of RU was performed in water, without the addition of organic solvents. Further, the chemical structure of PR was investigated using 1H NMR, and FTIR spectroscopy. Size-exclusion chromatography (SEC) was used to determine the molecular weight of PR, while its acid/base character was studied by potentiometric charge titrations. Additionally, this work investigated the antioxidant and free radical scavenging potential of PR with respect to its chemical structure, based on its ability to (i) scavenge non biological stable free radicals (ABTS), (ii) scavenge biologically important oxidants, such as O2•, NO•, and OH•, and (iii) chelate Fe2+. The influence of PR on fibroblast and HaCaT cell viability was evaluated to confirm the applicability of water soluble PR for wound healing application.

Functional dextran amino acid ester particles derived from N-protected S-trityl-L-cysteine.

This work describes the derivatization of dextran using N-(tert-butyloxycarbonyl)-S-(trityl)-L-cysteine in the presence of N,N'-carbonyldiimidazole (CDI) as a coupling agent. Homogeneous reactions in dimethyl sulfoxide allowed for an efficient coupling of the amino acid derivative to the polymer backbone. Derivatization was confirmed by infrared and 13C NMR spectroscopy, size exclusion chromatography and elemental analysis. The presence of hydrophobic protecting groups resulted in a product that can be shaped into water-insoluble particles stable in an aqueous environment and non-toxic for lung epithelial cells. It is suggested that materials composed of ester bonds between amino acids and polysaccharides are useful for targeted drug delivery, bio-imaging or surface functionalization.

Furfuryl- and Maleimido Polysaccharides: Synthetic Strategies Toward Functional Biomaterials.

In context with facile and efficient syntheses of functional polymeric materials, the combination of polysaccharides and functional moieties based on renewable resources is a sustainable and valuable approach. This review presents alternatives to prominent click reactions utilizing biopolymer derivatives with furfuryl and maleimide groups. On the one hand, the cross-linking by Diels-Alder reaction of these polymers enables the synthesis of novel materials in the fields of self-healing polymers, tissue engineering, and drug delivery. On the other hand, thiol-ene click reactions allow their conjugation to complex (bio)molecules. Different synthetic strategies are reviewed and the applicability of functional materials is evaluated.

Synthesis and film formation of furfuryl- and maleimido carbonic acid derivatives of dextran.

Carbonic acid derivatives of dextran possessing furfuryl- and maleimido moieties were synthesized and processed into thin films by spin coating. First, products with different degrees of substitution (DS) of up to 3.0 and substitution patterns were obtained and characterized by NMR- and FTIR spectroscopy, as well as elemental analysis. Thin films possessing maleimide groups were obtained by spin coating of maleimido dextran (furan-protected) and dextran furfuryl carbamate that was converted with bismaleimide. The removal of the protecting group (furan) on the thin film was monitored by QCM-D and compared with gravimetric analysis of the bulk material. Film morphology and wettability were determined by means of AFM and contact angle measurements.

Zwitterionic Cellulose Carbamate with Regioselective Substitution Pattern: A Coating Material Possessing Antimicrobial Activity.

A polyzwitterion is synthesized by regioselective functionalization of cellulose possessing a uniform charge distribution. The positively charged ammonium group is present at position 6, while the negative charge of carboxylate is located at positions 2 and 3 of the repeating unit. The molecular structure of the biopolymer derivative is proved by NMR spectroscopy. This cellulose-based zwitterion is applied to several support materials by spin-coating and characterized by means of atomic force microscope, contact angle measurements, ellipsometry, and X-ray photoelectron spectroscopy. The coatings possess antimicrobial activity depending on the support materials (glass, titanium, tissue culture poly(styrene)) as revealed by confocal laser scanning microscopy and live/dead staining.

Cellulose carbonates: a platform for promising biopolymer derivatives with multifunctional capabilities.

Cellulose carbonates as a platform compound open new possibilities for the design of advanced materials based on the most important renewable resource cellulose. In the present feature, the chemistry of cellulose carbonates is discussed considering own research results adequately. After a short overview about methods for activation of polysaccharides for a conversion with nucleophilic compounds in particular with amines, details about various methods for the synthesis of polysaccharide carbonates are discussed. The main issue of the feature is the synthesis and aminolysis of cellulose carbonates with low, intermediate, and high degree of substitution and the evaluation of this chemistry with respect to specific challenges. Functional cellulose carbamates, obtained from cellulose phenyl carbonate by aminolysis, show the potential use of this class of celluloses. Immunoassays and zwitterionic polymers are included as representative examples regarding properties and application of the new cellulose-based products.

Film formation of ω-aminoalkylcellulose carbamates--a quartz crystal microbalance (QCM) study.

The film formation of novel ω-aminoalkylcellulose carbamates on gold surface was studied by means of quartz crystal microbalance with dissipation monitoring (QCM-D) and atomic force microscopy (AFM). The influence of the pH value of the buffer solution, the concentration, the degree of polymerization, and the structure (spacer length) of the polymers on the coating was investigated. The layer formation was explained based on the pKa value and the degree of substitution of the ω-aminoalkylcellulose carbamates determined by potentiometric titration. This work provides novel supporting materials that might be applied in field of immobilization of biomolecules.

Synthesis of cellulose tricarbonates in 1-butyl-3-methylimidazolium chloride/pyridine.

Cellulose phenyl tricarbonates could be synthesized by a novel and fast procedure applying 1-butyl-3-methylimidazolium chloride/pyridine as reaction medium. Even cellulose phenyl carbonates with high degree of substitution are accessible at low molar ratio very efficiently. The reagent phenyl chloroformate is inert in the mixture, which is different from the solvent N,N-dimethylacetamide/LiCl that is usually applied. The products were characterized in detail by two-dimensional NMR- and FTIR-spectroscopy, elemental analysis, and size-exclusion chromatography. This class of cellulose derivatives is a very important intermediate for the design of structures based on cellulose by nucleophilc attack on the carbonyl group.

Rapid flow through immunoassay for CRP determination based on polyethylene filters modified with ω-aminocellulose carbamate.

A novel method for antibody immobilization is discussed and applied in a column based flow through immunoassay system (ABICAP). It is shown that porous polyethylene material can be modified with different ω-aminocellulose carbamates yielding an amino group containing biocompatible support for antibody immobilization. Anti-h CRP antibodies can be bound covalently to the surface via various homobifunctional cross-linkers. The antibody modified filters are validated for the CRP determination in a sandwich ABICAP system. In a 10 min test procedure based on colloidal dye particles, a limit of detection of 5 ng CRP mL(-1) and coefficients of variation of <9.1% are obtained.

Syntheses and detailed structure characterization of dextran carbonates.

Dextran alkyl carbonates were synthesized applying ethyl chloroformate, butyl chloroformate, butyl fluoroformate and 1H-imidazole-1-carboxylates. The influence of the reaction conditions on the reaction efficiency and the substitution pattern was studied in detail. The structure of the products obtained was clearly described by means of NMR- and IR-spectroscopy.