Control of Protein Affinity of Bioactive Nanocellulose and Passivation Using Engineered Block and Random Copolymers.

We passivated TEMPO-oxidized cellulose nanofibrils (TOCNF) toward human immunoglobulin G (hIgG) by modification with block and random copolymers of poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) and poly(oligo(ethylene glycol) methyl ether methacrylate) (POEGMA). The block copolymers reversibly adsorbed on TOCNF and were highly effective in preventing nonspecific interactions with hIgG, especially if short PDMAEMA blocks were used. In such cases, total protein rejection was achieved.

Cerebrospinal Fluids Leaks of the Cranial Vault Management with Compression Cap: Case Series.

Cerebrospinal fluid leaks of the cranial vault, constitute one of the most common complications after neurosurgical procedures. In this paper we introduce to you an observational study, in which a series of patients with this complication where managed by using elastic compression hat during 18 hours per day, for two weeks to four months. Every one of them presented complete resolution of the leak, without any recurrence until actual controls.

Interactions between Cellulolytic Enzymes with Native, Autohydrolysis, and Technical Lignins and the Effect of a Polysorbate Amphiphile in Reducing Nonproductive Binding.

Understanding enzyme-substrate interactions is critical in designing strategies for bioconversion of lignocellulosic biomass. In this study we monitored molecular events, in situ and in real time, including the adsorption and desorption of cellulolytic enzymes on lignins and cellulose, by using quartz crystal microgravimetry and surface plasmon resonance. The effect of a nonionic surface active molecule was also elucidated.

Effect of Molecular Architecture of PDMAEMA-POEGMA Random and Block Copolymers on Their Adsorption on Regenerated and Anionic Nanocelluloses and Evidence of Interfacial Water Expulsion.

Block copolymers of poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) and poly(oligo(ethylene glycol) methyl ether methacrylate) (POEGMA) with varying block sizes were synthesized by consecutive reversible addition-fragmentation chain transfer (RAFT) polymerization and then exposed to cellulose substrates with different anionic charge density. The extent and dynamics of quaternized PDMAEMA-b-POEGMA adsorption on regenerated cellulose, cellulose nanofibrils (CNF), and (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO)-oxidized cellulose nanofibrils (TOCNF) was determined by using electromechanical and optical techniques, namely, quartz crystal microbalance (QCM-D) and surface plasmon resonance (SPR), respectively. PDMAEMA-b-POEGMA equilibrium adsorption increased with the anionic charge of cellulose, an indication of electrostatic interactions.

Affinity interactions of human immunoglobulin G with short peptides: role of ligand spacer on binding, kinetics, and mass transfer.

The interaction affinity between human IgG and a short peptide ligand (hexameric HWRGWV) was investigated by following the shifts in frequency and energy dissipation in a quartz crystal microbalance (QCM). HWRGWV was immobilized by means of poly(ethylene glycol) tethered on QCM sensors coated with silicon oxide, which enhanced the accessibility of the peptide to hIgG and also passivated the surface. Ellipsometry and ToF-SIMS were employed for surface characterization.

Bio-based Wrinkled Surfaces Harnessed from Biological Design Principles of Wood and Peroxidase Activity.

A new and simple approach for surface wrinkling inspired by polymer assemblies in wood fibers is introduced. A hard skin is synthesized on a linear polysaccharide support that resembles the structural units of the cell wall. This skin, a wood mimetic layer, is produced through immersion in a solution containing phenolic precursor and subsequent surface reaction by horseradish peroxidase.

Role of textile substrate hydrophobicity on the adsorption of hydrosoluble nonionic block copolymers.

The adsorption of polyalkylene glycols and co-polymers of ethylene oxide and propylene oxide on substrates relevant to textiles with varying surface energies (cellulose, polypropylene, nylon and polyester) was studied by using quartz crystal microgravimetry. Langmuirian-type isotherms were observed for the adsorption profiles of nonionic block polymers of different architectures. The affinity with the surfaces is discussed based on experimental observations, which highlights the role of hydrophobic effects.

In-situ glyoxalization during biosynthesis of bacterial cellulose.

A novel method to synthesize highly crosslinked bacterial cellulose (BC) is reported. The glyoxalization is started in-situ, in the culture medium during biosynthesis of cellulose by Gluconacetobacter medellensis bacteria. Strong crosslinked networks were formed in the contact areas between extruded cellulose ribbons by reaction with the glyoxal precursors.

Effect of charge balance and dosage of polyelectrolyte complexes on the shear resistance of mineral floc strength and reversibility.

We evaluated the effect of polyelectrolyte complexes (PEC) with varying balance of charges on the flocculation of precipitated calcium carbonate (PCC) particles. PECs composed of polyacrylamides carrying opposite charges (A-PAM and C-PAM) were investigated in terms of PCC floc shear resistance and re-flocculation effects. Light transmission was used in real time to monitor the dynamics of flocculation under shear fields.

Water-resistant, transparent hybrid nanopaper by physical cross-linking with chitosan.

One of the major, but often overlooked, challenges toward high end applications of nanocelluloses is to maintain their high mechanical properties under hydrated or even fully wet conditions. As such, permanent covalent cross-linking or surface hydrophobization are viable approaches, however, the former may hamper processability and the latter may have adverse effect on interfibrillar bonding and resulting material strength. Here we show a concept based on physical cross-linking of cellulose nanofibers (CNF, also denoted as microfibrillated cellulose, MFC, and, nanofibrillated cellulose, NFC) with chitosan for the aqueous preparation of films showing high mechanical strength in the wet state.

Lignin supracolloids synthesized from (W/O) microemulsions: use in the interfacial stabilization of Pickering systems and organic carriers for silver metal.

Taking advantage of the aromatic and cross-linking tendency of lignin macromolecules extracted from plants, we present a novel method for their assembly into supracolloidal structures. Specifically, spherical particles with controllable size (∼90 nm to 1 μm) were obtained from water-in-oil (W/O) microemulsions formulated with a mixture of nonionic surfactants and a colloidal dispersion of a low molecular weight alkali lignin. After spontaneous emulsification, the internal lignin-rich phase was cross-linked to produce the solid particles that could be easily separated by removal of the organic, continuous phase.

Cellulose nanofibrils for one-step stabilization of multiple emulsions (W/O/W) based on soybean oil.

Cellulose nanofibrils (CNF) were incorporated in water-in-oil (W/O) microemulsions and emulsions, as well as water-in-oil-in-water (W/O/W) multiple emulsions using soybean oil. The addition of CNF to the aqueous phase expanded the composition range to obtain W/O/W emulsions. CNF also increased the viscosity of the continuous phase and reduced the drop size both of which increased the stability and effective viscosity of the emulsions.

Single-molecule resolution of protein dynamics on polymeric membrane surfaces: the roles of spatial and population heterogeneity.

Although polymeric membranes are widely used in the purification of protein pharmaceuticals, interactions between biomolecules and membrane surfaces can lead to reduced membrane performance and damage to the product. In this study, single-molecule fluorescence microscopy provided direct observation of bovine serum albumin (BSA) and human monoclonal antibody (IgG) dynamics at the interface between aqueous buffer and polymeric membrane materials including regenerated cellulose and unmodified poly(ether sulfone) (PES) blended with either polyvinylpyrrolidone (PVP), polyvinyl acetate-co-polyvinylpyrrolidone (PVAc-PVP), or polyethylene glycol methacrylate (PEGM) before casting. These polymer surfaces were compared with model surfaces composed of hydrophilic bare fused silica and hydrophobic trimethylsilane-coated fused silica.

Microemulsion systems for fiber deconstruction into cellulose nanofibrils.

A new method to produce cellulose nanofibrils (CNF) is proposed to reduce the energy demand during deconstruction of precursor fibers suspended in aqueous media. Microemulsions were formulated with aqueous solutions of urea or ethylenediamine and applied to disrupt interfibril hydrogen bonding. Compared to typical fibrillation of lignin-containing and lignin-free fibers, pretreatment with microemulsion systems allowed energy savings during microfluidization of 55 and 32%, respectively.

Acid-generated soy protein hydrolysates and their interfacial behavior on model surfaces.

The present work attempts to provide data to warrant the consideration of soy proteins (SP) as potentially useful biomolecules for practical chemical and surface applications. Despite their sundry properties, SP use has been limited by their high molecular weight. In response to this limitation, we analyze acid hydrolysates of soy proteins (0.

Microbeads and hollow microcapsules obtained by self-assembly of pickering magneto-responsive cellulose nanocrystals.

Cellulose microbeads can be used as immobilization supports. We report on the design and preparation of magneto-responsive cellulose microbeads and microcapsules by self-assembled shells of cellulose nanocrystals (CNC) carrying magnetic CoFe2O4 nanoparticles, that is, a mixture of isotropic and anisotropic nanomaterials. The magnetic CNCs formed a structured layer, a mesh, consisting of CNCs and magnetic particles bound together on the surface of distinct droplets of hexadecane and styrene dispersed in water.

A facile and green method to hydrophobize films of cellulose nanofibrils and silica by laccase-mediated coupling of nonpolar colloidal particles.

Hydrophobic particles based on dodecyl 3,4,5-trihydroxybenzoate (LG) were coupled onto the surface of cellulose nanofibrils (CNFs) and silica by treatment with a multicomponent colloidal system (MCS) derived from the laccase-mediated reaction of LG in the presence of a sulfonated lignin (SL). Surface modification upon treatment with MCS was monitored in situ and in real time by quartz crystal microgravimetry. The colloidal stability of MCS and its components in water was followed by measuring space- and time-resolved light transmission and back scattering.

Effects of residual lignin and heteropolysaccharides on the bioconversion of softwood lignocellulose nanofibrils obtained by SO2-ethanol-water fractionation.

The amount of residual lignin and hemicelluloses in softwood fibers was systematically varied by SO2-ethanol-water fractionation for integrated biorefinery with nanomaterial and biofuel production. On the basis of their low energy demand in mechanical processing, the fibers were deconstructed to lignocellulose nanofibrils (LCNF) and used as substrate for bioconversion. The effect of LCNF composition on saccharification via multicomponent enzymes was investigated at different loadings.

Dynamic and equilibrium performance of sensors based on short peptide ligands for affinity adsorption of human IgG using surface plasmon resonance.

This paper characterizes the potential of novel hexameric peptide ligands for on-line IgG detection in bioprocesses. Surface Plasmon Resonance (SPR) was used to study the binding of human IgG to the hexameric peptide ligand HWRGWV, which was covalently grafted to alkanethiol self-assembled monolayers (SAM) on gold surfaces. Peptide coupling on SAMs was verified, followed by covalent grafting of peptides with a removable Fmoc or acetylated N-termini via their C-termini to produce active peptide SPR sensors that were tested for IgG binding.

Molecular dynamics simulations of the adhesion of a thin annealed film of oleic acid onto crystalline cellulose.

Molecular dynamics simulations were used to characterize the wetting behavior of crystalline cellulose planes in contact with a thin oily film of oleic acid. Cellulose crystal planes with higher molecular protrusions and increased surface area produced stronger adhesion if compared to other crystal planes due to enhanced wetting and hydrogen bonding. The detailed characteristics of crystal plane features and the contribution of directional hydrogen bonding was investigated.

Adsorption of polyalkyl glycol ethers and triblock nonionic polymers on PET.

Surface modification enables fiber lubrication and processing but little is known about the extent and dynamics of adsorption of typical adsorbates applied for such purposes, which often includes water-soluble block nonionic amphiphilic polymers. In this work we used quartz crystal microgravimetry (QCM) to investigate the adsorption on poly(ethylene terephthalate) (PET) of polyalkyl glycol ethers and triblock molecules of ethylene oxide and propylene oxide. The adsorption from aqueous solution of the block nonionic amphiphilic polymers strongly correlated with the self-association driven by the chain length of the respective hydrophobic blocks.

Modification of cellulose nanofibrils with luminescent carbon dots.

Films and hydrogels consisting of cellulose nanofibrils (CNF) were modified by covalent EDC/NHS coupling of luminescent, water-dispersible carbon dots (CDs). Quartz crystal microgravimetry with dissipation monitoring (QCM-D) and surface plasmon resonance (SPR) were used to investigate the attachment of CDs on carboxymethylated CNF (CM-CNF). As the first reported use of CD in nanocellulose products, we provide proof-of-concept for the synthesis of transparent and fluorescent nanopaper and for its tunable luminescence as confirmed by confocal microscopy imaging.

Cellulose nanocrystal-mediated synthesis of silver nanoparticles: role of sulfate groups in nucleation phenomena.

Developing sustainable chemical methods to synthesize silver nanoparticles has drawn significant research interest. Due to their unique and well-defined physical-chemical properties, cellulose nanocrystals (CNCs) have become one of the most promising renewable nanomaterials. Here we use CNC to mediate silver nanoparticle synthesis and elucidate the effect of CNC surface chemistry (as defined by sulfate groups) in nanoparticle formation and nucleation in the presence of borohydride reduction.

Antimicrobial wound dressing nanofiber mats from multicomponent (chitosan/silver-NPs/polyvinyl alcohol) systems.

Novel hybrid nanomaterials have been developed for antimicrobial applications. Here we introduce a green route to produce antibacterial nanofiber mats loaded with silver nanoparticles (Ag-NPs, 25 nm diameter) enveloped in chitosan after reduction with glucose. The nanofiber mats were obtained from colloidal dispersions of chitosan-based Ag-NPs blended with polyvinyl alcohol.

A method for the heterogeneous modification of nanofibrillar cellulose in aqueous media.

Cellulosic substrates were modified by using sequential adsorption of functionalized carboxymethyl cellulose (CMC) and "click" chemistry in aqueous media. First, the effect of degree of substitution (DS), and level of functionalization as well as ionic strength of the medium were systematically investigated in situ by using quartz crystal microbalance with dissipation (QCM-D) in terms of the extent of adsorption of propargyl and azido functionalized CMC. It was found that the functionalization of CMC did not prevent its adsorption on cellulose.