Tunable, thiol-ene, interpenetrating network hydrogels of norbornene-modified carboxymethyl cellulose and cellulose nanofibrils.

Carboxymethyl cellulose modified with norbornene groups (NorCMC) and cellulose nanofibrils (CNFs) produced through mechanical refining without chemical pretreatment formed interpenetrating network hydrogels through a UV-light initiated thiol-ene reaction. The molar ratio of thiols in crosslinkers to norbornene groups off the NorCMC (T:N), total polymer weight percent in the hydrogel, and weight percent of CNFs of the total polymer content of the hydrogels were varied to control hydrogel properties. This method enabled orders of magnitude changes to behavior.

Impact of Aqueous Grafting of Polystyrene through Methacrylate-Modified Cellulose Nanofibrils on Emulsion Stabilization and Drying Behavior.

Cellulose nanofibrils (CNFs) are abundant materials limited in application by their hydrophilic nature and fibrillar collapse during drying. Herein, hydrophobic CNFs (PS-MetCNFs) were produced via the grafting of polystyrene through a methacrylate handle on modified CNFs. This modification prevented fibrillar collapse of the CNFs upon drying with as low as 3.

Optimizing lignocellulosic nanofibril dimensions and morphology by mechanical refining for enhanced adhesion.

Using lignocellulosic nanofibrils as adhesive binders in structural composites is a growing field of interest attributable to their renewability, recyclability, and strength. A fundamental understanding of their adhesion mechanisms is crucial to tailor performance and optimize production costs. These mechanisms were elucidated by studying the morphology dependent adhesion in a model system composed of cellulose nanofibrils (CNFs) at different degrees of refinement and porous paper substrates.

Thiol-norbornene reactions to improve natural rubber dispersion in cellulose nanofiber coatings.

Cellulose nanofibrils (CNF) coatings are excellent grease barriers for biodegradable packaging. However, barrier properties are moisture sensitive, so hydrophobic components such as latexes or polymers are needed to impart moisture resistance, but incompatibility leads to poor dispersion. In this work, CNF modified with norbornenes was reacted with natural rubber (NR) latex in water to improve dispersion, coating formation, and coating moisture resistance by creating hybrid particles.

The influence of versatile thiol-norbornene modifications to cellulose nanofibers on rheology and film properties.

Cellulose nanofibrils (CNF) can form impressive barrier layers but difficult rheological properties, brittleness, and sensitivity to moisture limit their use. To overcome these challenges, esterification reactions were performed in water without volatile organic solvents to create carbic-functionalized CNFs (cCNFs) that enabled versatile, thiol-norbornene secondary modifications. Chemical analysis determined that on average 5% anhydroglucose repeat units were functionalized with norbornene groups.

Fluorescent Dye Adsorption in Aqueous Suspension to Produce Tagged Cellulose Nanofibers for Visualization on Paper.

Cellulose nanofibers (CNFs) have great potential to be a layer in packaging materials because of their good barrier properties. When paper is coated with CNFs, they are difficult to distinguish from the base sheet. This issue creates challenges when trying to determine where CNFs migrate relative to the paper fibers during coating and drying.

Dose and Timing of N-Cadherin Mimetic Peptides Regulate MSC Chondrogenesis within Hydrogels.

The transmembrane glycoprotein N-cadherin (NCad) mediates cell-cell interactions found during mesenchymal condensation and chondrogenesis. Here, NCad-derived peptides (i.e.

Dry-Spun Neat Cellulose Nanofibril Filaments: Influence of Drying Temperature and Nanofibril Structure on Filament Properties.

Cellulose nanofibrils (CNF) were spun into filaments directly from suspension without the aid of solvents. The influence of starting material properties and drying temperature on the properties of filaments produced from three different CNF suspensions was studied. Refiner-produced CNF was ground using a microgrinder at grinding times of 50 and 100 minutes.

Synthesis and Spatiotemporal Modification of Biocompatible and Stimuli-Responsive Carboxymethyl Cellulose Hydrogels Using Thiol-Norbornene Chemistry.

Carboxymethyl cellulose (CMC) is functionalized with norbornene groups to undergo thiol-norbornene cross-linking reactions. Hydrogels synthesized from a single norbornene-modified carboxymethyl cellulose (NorCMC) via a light-initiated thiol-ene cross-linking reaction with a variety of dithiol cross-linkers yield hydrogels with a tunable compression modulus ranging from 1.7 to 103 kPa.

Spatiotemporal Modification of Stimuli-Responsive Hyaluronic Acid/Poly(-isopropylacrylamide) Hydrogels.

Current methods to spatiotemporally modify stimuli response in hydrogels are typically subtractive and lead to a decrease in response. To increase the breadth of hydrogel applications and biomedical systems, new formulations are needed that can introduce and increase stimuli response spatiotemporally in hydrogels. In this work, the light-induced thiol-norbornene click chemistry reaction was used to modify the stimuli response of robust hyaluronic acid hydrogels through an additive process in spatiotemporal fashion, overcoming this limitation.

Nanofibrous hydrogels with spatially patterned biochemical signals to control cell behavior.

The ability to spatially pattern biochemical signals into nanofibrous materials using thiol-ene reactions of thiolated molecules to presented norbornene groups is demonstrated. This approach is used to pattern three molecules independently within one scaffold, to pattern molecules through the depth of a scaffold, and to spatially control cell adhesion and morphology.

Nanometer-scale self-assembly of amphiphilic copolymers to control and prevent biofouling.

Bacterial infections occur on nearly 4% of all implanted medical devices, leading to a loss in patient quality of life, higher medical costs, and in some cases permanent disability. These infections typically form biofilms that limit the effectiveness of antibiotics and may require removal of the device. Since the infections are difficult to cure once established, methods to prevent the initial bacterial infection have been investigated.

Transdermal gelation of methacrylated macromers with near-infrared light and gold nanorods.

Injectable hydrogels provide locally controlled tissue bulking and a means to deliver drugs and cells to the body. The formation of hydrogels in vivo may involve the delivery of two solutions that spontaneously crosslink when mixed, with pH or temperature changes, or with light (e.g.

Synthesis and orthogonal photopatterning of hyaluronic acid hydrogels with thiol-norbornene chemistry.

The patterning of chemical and mechanical signals within hydrogels permits added complexity towards their use as cell microenvironments for biomedical applications. Specifically, photopatterning is emerging to introduce heterogeneity in hydrogel properties; however, currently employed systems are limited in the range of properties that can be obtained, as well as in decoupling mechanical properties from changes in chemical signals. Here, we present an orthogonal photopatterning system that utilizes thiol-norbornene chemistry and permits extensive hydrogel modification, including with multiple signals, due to the number of reactive handles accessible for secondary reaction.