Dynamic Covalent Interactions Research Articles

Synthesis of Adhesive Polyrotaxanes Through Sequential Self-Assembly via Supramolecular Interactions and Dynamic Covalent Interactions.

Self-assembly is an effective approach to construct complicated structures. Polyrotaxanes (PRs) as one of the typical polymer types with complex structure, own interlocked structures and dynamic components, in which it results in unique characteristics and functions. Currently, the synthesis of which involves covalent reactions to hinder the development of polyrotaxanes. Herein, we employed supramolecular interactions as well as dynamic covalent bonds to synthesize PRs by sequential self-assembly. First, we prepared M1 possessing two diamine structures and M2 of a bisammonium salt with two dibenzylammonium (DBA) units modified by two stoppers at its ends, then M1 and M2 self-assembled into supramolecular polymers stemming from hydrogen bonding of [N+-H ⋅ ⋅ ⋅ O] under high concentrations. After adding 2,6-pyridinedicarboxaldehyde (M3), the imine bond formation enabled the generation of macrocycles, transforming supramolecular polymers into PRs. Besides, the solution of polyrotaxanes was applied as the adhesive for diverse hard and soft materials. This strategy provides an important approach for synthesizing PRs, accelerating the advances of mechanically interlocked polymers.

Bridging papermaking and hydrogel production: Nanoparticle-loaded cellulosic hollow fibers with pitted walls as skeleton materials for multifunctional electromagnetic hydrogels

Electromagnetic hydrogels have attracted significant attention due to their vast potential in soft robotics, biomedical engineering, and energy harvesting. To facilitate future commercialization via large-scale industrial processes, we present a facile concept that utilizes the specialized knowledge of papermaking to fabricate hydrogels with multifunctional electromagnetic properties. The principles of papermaking wet end chemistry, which involves the handling of interactions among cellulosic fibers, fines, polymeric additives, and other components in aqueous systems, serves as a key foundation for this concept. Notably, based on these principles, the versatile use of chemical additives in combination with cellulosic materials enables the tailored design of various products. Our methodology exploits the unique hierarchically pitted and hollow tube-like structures of papermaking grade cellulosic fibers with discernible pits, enabling the incorporation of magnetite nanoparticles through lumen loading. By combining microscale softwood-derived cellulosic fibers with additives, we achieve dynamic covalent interactions that transform the cellulosic fiber slurry into an impressive hydrogel. The cellulosic fibers act as a skeleton, providing structural support within the hydrogel framework and facilitating the dispersion of nanoparticles. In accordance with our concept, the typical hydrogel exhibits combined attributes, including electrical conductivity, self-healing properties, pH responsiveness, and dynamic rheologic behavior. Our approach not only yields hydrogels with interesting properties but also aligns with the forefront of advanced cellulosic material applications. These materials hold the promise in remote strain sensing devices, electromagnetic navigation systems, contactless toys, and flexible electronic devices. The concept and findings of the current work may shed light on materials innovation based on traditional pulp and paper processes. Furthermore, the facile processes involved in hydrogel formation can serve as valuable tools for chemistry and materials education, providing easy demonstrations of principles for university students at different levels.

Insulin-Dendrimer Nanocomplex for Multi-Day Glucose-Responsive Insulin Therapy in Ossabaw Miniature Swine with Type 1 Diabetes

Background: Therapy for type 1 diabetes resulting from immunogenic destruction of the insulin-producing pancreatic beta cells has been a challenge for over 100 years. Delivering exogenous insulin to maintain euglycemia is a delicate balance between plasma glucose transport to insulin-responsive tissues, glucose absorption in the gut, and the pharmacodynamics of insulin. The synthesis of short- and long-acting insulins and use of insulin pumps have made great strides in the standard of diabetes care. Despite advances, hypoglycemia is a major limitation. There is no approved therapy that offers glucose-responsive insulin function. Toward this end we engineered a nanoscale complex combining both electrostatic and dynamic-covalent interactions between a synthetic dendrimer carrier and an insulin analogue modified with a high-affnity glucose-binding motif. Hypothesis: This insulin nanocomplex will yield an injectable insulin depot providing both glucose-sensitive and long-lasting insulin availability in a translation preclinical model. Methods: Ossabaw minature swine (41-59 kg; N=6) were made diabetic with alloxan, which was confirmed by stable hyperglycemia (228±43 mg/dL). Oral glucose tolerance tests (OGTT) were conducted at the diabetic baseline and each of the following 6 days after one subcutaneous injection of the insulin nanocomplex. Results: The basline OGTT elicted blood glucose of 350-450 mg/dL for 90 min of the 150 min OGTT, while serum insulin remained at ~5 μU/mL, nearly the detection limit. In contrast, 3 h after injection of insulin nanocomplex (~0.8-0.9 mg/kg) blood glucose decreased to 71±12 mg/dL. Subsequent OGTTs on days 1-6 increased blood glucose from normoglycemia to ~200 mg/dL and serum insulin increased to ~60-220 μU/mL, followed by return to nearly normolgycemia hours after the OGTT. Hypoglycemia was avoided in all pigs. Conclusions: The subcutaneous nanocomplex of a modified insulin and a synthetic dendrimer carrier produced a glucose-responsive insulin depot for week-long glycemic control following a single routine injection. These findings offer great promise for overcoming the hypoglycemia risk of intensive glucose control. Future studies should include additional physiological challenges of exercise and nutritional states. Support: Juvenile Diabetes Research Foundation 5-CDA-2020-947-A-N, Helmsley Charitable Trust 2019PG-T1D016 and 2102-04994, American Diabetes Association Pathway 1-19-ACE-31, National Science Foundation BMAT1944875, European Union-Next Generation EU LX22NPO5104, Czech Academy of Sciences RVO 6138963. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

An organic/inorganic hybrid soft material for supramolecular adhesion.

Thioctic acid (TA) has been widely used to construct soft materials via supramolecular copolymerization with organic chemicals. In this study, TA and the inorganic compound MoS2 are used to fabricate poly[TA-MoS2] via dynamic covalent and supramolecular interactions. Poly[TA-MoS2] exhibits good and long-lasting adhesion performance on various artificial surfaces, with an adhesion strength up to 3.72 MPa (15 days). Further, it exhibits tough adhesion effects in an aqueous environment. Moreover, poly[TA-MoS2] displays good thermal processing behavior, thus enabling its molding through 3D printing.

A pseudo-Double-Network Hydrogel Built upon Layered Double Hydroxides with Self-Strengthening Properties.

While great achievements have been made in the development of mechanically robust nanocomposite hydrogels, incorporating multiple interactions on the bases of two demensional inorganic cross-linkers to construct self-strengthening hydrogels has rarely been investigated. To this end, we propose here a new method for the coupling the dynamic covalent bonds and non-covalent interactions within a pseudo double-network system. The pseudo first network, formed through the Schiff Base reation between Tris-modified layered double hydroxides (Tris-LDHs) and oxidized dextran (ODex), is linked to the second network built upon non-covalent interactions between Tris-LDHs and poly(acrylamide-co-2-acrylamido-2-methyl-propanesulfonate) (p-(AM-co-AMPS). The swelling and mechanical properties of the resulting hydrogels have been investigated as a function of the ODex and AMPS contents. The as-prepared hydrogel can swell to 420 times of its original size and retain more than 99.9 wt.% of water. Mechanical tests show that the hydrogel can bear 90 % of compression and is able to be stretched to near 30 times of its original length. Cyclic tensile tests reveal that the hydrogels are capable of self-strengthening after mechanical training. The unique energy dissipation mechanism based on the dynamic covalent and non-covalent interactions is considered to be responsible for the outstanding swelling and mechanical performances.

Solute Stabilization Effects of Nanoparticles Containing Boronic Acids in the Absence of Binding Pairs.

Boronic acids are widely used in materials science because of their ability to reversibly bind with diol and catechol moieties through dynamic covalent interactions in a pH- and oxidative-dependent manner. Considerably fewer studies focus on property modulation of boronic acid-based materials in the absence of a biding pair. Herein, we discuss the effects of the boronic acid-containing polymer block length on solute release kinetics from nanoparticles in a stimuli-responsive manner for on-demand delivery. In this study, ABC-type linear amphiphiles of poly(d,l-lactide) and poly(2-methacryloyloxyethyl phosphorylcholine) containing a middle block functionalized with 3-aminophenylboronic acid were synthesized by a combination of ring-opening and controlled free radical polymerizations. Nile red-loaded nanoparticles were self-assembled using a multi-inlet vortex mixer in a well-controlled manner. Release was evaluated at pH above and below the pKa of the boronic acid and in the presence of hydrogen peroxide. Our results show that release kinetics from nanoparticles incorporating a boronic acid-functionalized interlayer were slower than those without it, and the rate could be modulated according to pH and oxidative conditions. These effects can be attributed to several factors, including the hydrophobicity of the boronic acid block as well as hydrogen bonding interactions existing between locally confined boronic acids. While boronic acids are generally utilized as boronic/boronate esters, their stabilizing effects in the absence of appropriate binding pairs are relevant and should be considered in the design of boronic acid-based technologies.

Orthogonal Supramolecular Assemblies Using Side-Chain Functionalized Helical Poly(isocyanide)s.

Mimicking the structure of proteins using synthetic polymers requires building blocks with structural similarity and the use of various noncovalent and dynamic covalent interactions. We report the synthesis of helical poly(isocyanide)s bearing diaminopyridine and pyridine side-chains and the multistep functionalization of the polymers' side-chains using hydrogen bonding and metal coordination. The orthogonality of the hydrogen bonding and metal coordination was proved by varying the sequence of the multistep assembly. The two side-chain functionalizations are reversible through the use of competitive solvents and/or competing ligands. Throughout the assembly and disassembly, the helical conformation of the polymer backbone is sustained as proved by circular dichroism spectroscopy. These results open the possibility to incorporate helical domains into complex polymer architectures and create a helical scaffold for smart materials.

Molecular Barrels as Potential Hosts: From Synthesis to Applications

Self-assembled discrete molecular architectures that show selective molecular recognition within their internal cavities are highly desirable. Such hosts often show guest recognition through several noncovalent interactions. This emulates the activity of naturally occurring enzymes and proteins. Research in the formation of 3D cages of different shapes and sizes has progressed rapidly since the development of coordination-driven self-assembly and dynamic covalent chemistry. Such molecular cages find applications in catalysis, stabilization of metastable molecules, purification of isomeric mixtures via selective encapsulation, and even in biomedical applications. Most of these applications stem from the ability of the host cages to bind guests strongly in a selective fashion, providing a suitable environment for the guests to perform their functions. Molecular cages having closed architectures with small windows either show poor encapsulation or inhibit easy guest release while those with wide open structures fail to form stable host-guest complexes. In this context, molecular barrels obtained by dynamic metal-ligand/covalent bond formation techniques possess optimized architectures. With a hollow-walled cavity and two large openings, molecular barrels satisfy the structural requirements for many applications. In this perspective, we will discuss in detail the synthetic strategies for obtaining barrels or barrel-like architectures employing dynamic coordination and covalent interactions, their structure-based classification, and their applications in catalysis, storing transient molecules, separation of chemicals, and photoinduced antibacterial activity. We aim to highlight the structural advantages of molecular barrels over other architectures for efficiently carrying out several functions and for the development of new applications.

Sustainable and Tough MXene Hydrogel Based on Interlocked Structure for Multifunctional Sensing

Traditional hydrogel sensors containing MXenes as a conductive substrate will inevitably face the problem of excessive stacking of MXene nanosheets, which limits electron transport, thus reducing conductivity and sensitivity. Moreover, existing MXene hydrogels generally exhibit poor mechanical properties and fragility. In addition, it is necessary to prepare degradable electronic skins for reducing environmental pollution and recycling energy materials─MXene. How to find a balance between mechanical properties and degradation properties is a challenge. In this work, we overcome this challenge by combining a dynamic covalent strategy and establishing a self-modified interlocked structure. A biodegradable physically cross-linked hydrogel (OMDDH─ordered MXene dynamic degradable hydrogel) is constructed, and a highly interconnected three-dimensional (3D) MXene@CS-Pba network is prepared, thus endowing the sensor with excellent conductivity (24 × 10–4 S cm–1). For excellent mechanical properties, dynamic covalent interactions, hydrogen-bonding interactions between the dual networks, and chain entanglement of poly(vinyl alcohol) (PVA) totally build interlocked structures, thus endowing the hydrogel with excellent mechanical strength (1000 kPa). In an acidic environment, the dynamic covalent bond is broken, and the chain entanglement of PVA is also disentangled due to the disruption of the electrostatic equilibrium, resulting in the release of MXene for recycling (recycling conductivity: 22 × 10–4 S cm–1). Undoubtedly, we exhibit a strategy to construct ordered and degradable MXene hydrogels possessing excellent conductivity, high mechanical strength, and degradation performance, which lays the sensors’ wide applications in smart devices.

Thermo‐responsive topological metamorphosis in covalent‐and‐supramolecular polymer architectures

AbstractTopological metamorphosis represents a powerful approach to modulate the properties of polymers. However, it still remains a major challenge to achieve the tunability of bulk mechanical properties via topological transformation in supramolecular polymer systems. Herein, we couple the covalent polymer and supramolecular polymer in a single system—referred to as covalent‐and‐supramolecular polymer (CSP)—to realize a thermo‐responsive macromolecular metamorphosis. The CSP is able to topologically switch from grafted polymer to cross‐linked network by taking advantage of synergistic dynamic covalent interactions and host–guest interactions. Benefiting from the topologically structural transformation, brittleness intrinsically evolves into toughness in our CSP architectures with minimum change of their molecular compositions from furan–maleimide to anthracene–maleimide linkers. Our work demonstrates that supramolecular polymers are a promising platform to design smart materials not only due to their inherent stimuli‐responsive properties but also because of their abilities in determining bulk mechanical properties of polymers with alterable topological structures.

A dynamic covalent polymeric antimicrobial for conquering drug-resistant bacterial infection.

Increasing bacterial drug resistance to antibiotics has posed a major threat to contemporary public health, which resulted in a large number of people suffering from serious infections and ending up dying without any effective therapies every year. Here, a dynamic covalent polymeric antimicrobial, based on phenylboronic acid (PBA)-installed micellar nanocarriers incorporating clinical vancomycin and curcumin, is developed to overcome drug-resistant bacterial infections. The formation of this antimicrobial is facilitated by reversible dynamic covalent interactions between PBA moieties in polymeric micelles and diols in vancomycin, which impart favorable stability in blood circulation and excellent acid-responsiveness in the infection microenvironment. Moreover, the structurally similar aromatic vancomycin and curcumin molecules can afford π-π stacking interaction to realize simultaneous delivery and release of payloads. In comparison with monotherapy, this dynamic covalent polymeric antimicrobial demonstrated more significant eradication of drug-resistant bacteria in vitro and in vivo due to the synergism of the two drugs. Furthermore, the achieved combination therapy shows satisfied biocompatibility without unwanted toxicity. Considering various antibiotics contain diol and aromatic structures, this simple and robust strategy can become a universal platform to combat the ever-threatening drug-resistant infectious diseases.

Metal Ion-Directed Functional Metal-Phenolic Materials.

Metal ions are ubiquitous in nature and play significant roles in assembling functional materials in fields spanning chemistry, biology, and materials science. Metal-phenolic materials are assembled from phenolic components in the presence of metal ions through the formation of metal-organic complexes. Alkali, alkali-earth, transition, and noble metal ions as well as metalloids interacting with phenolic building blocks have been widely exploited to generate diverse hybrid materials. Despite extensive studies on the synthesis of metal-phenolic materials, a comprehensive summary of how metal ions guide the assembly of phenolic compounds is lacking. A fundamental understanding of the roles of metal ions in metal-phenolic materials engineering will facilitate the assembly of materials with specific and functional properties. In this review, we focus on the diversity and function of metal ions in metal-phenolic material engineering and emerging applications. Specifically, we discuss the range of underlying interactions, including (i) cation-π, (ii) coordination, (iii) redox, and (iv) dynamic covalent interactions, and highlight the wide range of material properties resulting from these interactions. Applications (e.g., biological, catalytic, and environmental) and perspectives of metal-phenolic materials are also highlighted.

Construction of thorough cross-linked networks in soybean meal adhesive system by biomimetic boronic acid-anchored cellulose nanofibril for multifunctionality of high-performance, mildew resistance, anti-bacterial, and flame resistance

The soybean meal (SM) adhesive has become the most promising bio-adhesive in wood industry. However, the insufficient mechanical properties and poor water resistance limits their practical applications. Current researches mostly focus on the cross-linking modification of soy protein isolate (SPI) components in SM, whereas ignoring the adverse effects of soy polysaccharide (SPS) components on the SM adhesive system. Herein, inspired of the borate chemistry in the higher plant cell walls, the thorough and strong cross-linked networks were constructed in SM adhesive system by the boronic acid-anchored cellulose nanofibril (BCNF) and tannic acid (TA). The combination of entanglement and interpenetration of polymer backbone molecular chains, dynamic covalent interactions and hydrogen bonds can promote the formation of tough and stable cross-linked network structure in SM adhesive system, and endowed the SM adhesive with excellent wet adhesion strength and water-resistant property. The wet shear strength of resultant SM adhesive increased to 0.92 MPa, which was 3 times of the pristine SM adhesive. Additionally, the resultant SM adhesive exhibited excellent mildew resistance, antibacterial activity, and flame retardance. This biomimetic strategy can achieve the construction of the thorough and strong cross-linked networks in SM adhesive, which provides a novel and versatile route to high-performance and multifunitional bio-adhesive.

Dopamine Assisted Self-Cleaning, Antifouling, and Antibacterial Coating via Dynamic Covalent Interactions.

The rapid accumulation of dead bacteria or protein on a bactericidal surface can reduce the effectiveness of the modified surface and alter its biocidal activity by shielding the surface biocide functional groups, promoting microbial attachment and subsequent biofilm formation. Thus, the alteration of biocidal activity due to biofilm formation can cause serious trouble including severe infection or implant or medical device failure leading to death. Therefore, developing a smart self-cleaning surface is of great interest. Ideally, such a surface can not only kill the attached microbials but also release the dead cells and foulants from the surface under a particular incitement on demand. In this project, a sugar-responsive self-cleaning coating has been developed by forming covalent boronic ester bonds between catechol groups from polydopamine and a benzoxaborole pendant from zwitterionic and cationic polymers. To incorporate antifouling properties and enhance the biocompatibility of the coating, bioinspired zwitterionic compound 2-methacryloyloxyethyl phosphorylcholine (MPC) was chosen and benzoxaborole pendant containing zwitterionic polymer poly(MPC-st-MAABO) (MAABO: 5-methacrylamido-1,2-benzoxaborole) was synthesized. Additionally to impart antibacterial properties to the surface, a quaternary ammonium containing cationic polymer poly(2-(methacryloyloxy)ethyl trimethylammonium (META)-st-MAABO)) was synthesized. These synthesized polymers were covalently grafted to a polydopamine (PDA) coated surface by forming a strong cyclic boronic ester complex with a catechol group of the PDA layer endowing the surface with bacteria contact-killing properties and capturing specific protein. After the addition of cis-diol containing competitive molecules, i.e., saccharides/sugars, this boronic ester complex with a catechol group of PDA was replaced and the attached polymer layer was cleaved from the surface, resulting in the release of both absorbed protein and live/killed bacteria electrostatically attached to the polymer layer. This dynamic self-cleaning surface can be a promising material for biomedical applications avoiding the gathering of dead cells and debris that are typically encountered on a traditional biocidal surface.

Water enabled self-healing polymeric coating with reduced graphene oxide-reinforcement for sensors

Intrinsic self-healing materials have received significant attention due to the characteristic recovery after damage properties through reversible dynamic covalent and non-covalent interactions. Furthermore, functional recovery with reliable mechanical properties are highly keen as protective coatings, specifically for devices and sensors vulnerable to abrasion in severe environments. Here, we present a functional hierarchical nanostructure capable of multiple micro-sized healings, with enhanced mechanical hardness due to the incorporation of graphene oxide (rGO) nanoplatelets. A self-healing multilayered nanocomposite formed by poly(ethylene imine) (PEI) and poly(acrylic acid) (PAA) was easily assembled by the layer-by-layer (LbL) technique. The addition of the rGO nanoplatelets in the LbL nanostructure resulted in a 13-fold increase in hardness (0.4 ± 0.1 GPa) when compared to the (PEI/PAA) architecture (0.03 ± 0.01 GPa). In addition, the nanocomposite presents an enhanced insulating electrical behavior (∼ 4.10−8 S/cm) despite the addition of the rGO nanoplatelets. Raman and Zeta Potential analysis indicated a possible wrapping of the rGOs by PEI, justifying the observed insulating electrical characteristics. The nanocomposite presents good hydrophobicity with a water contact angle of 136°, interesting to extend the lifetime and protect underlying layers from humidity, degradation, and encrustation. Therefore, we propose an attractive hydrophobic, electrically insulating, and mechanically resistant multifunctional coating for high-performance electronic interfaces from minor cuts and abrasions, dispensing maintainer intervention.

Dual Stimuli-Responsive Dynamic Covalent Peptide Tags: Toward Sequence-Controlled Release in Tumor-like Microenvironments.

Dynamic covalent chemistry (DCvC) has emerged as a versatile synthetic tool for devising stable, stimuli-responsive linkers or conjugates. The interplay of binding affinity, association and dissociation constants exhibits a strong influence on the selectivity of the reaction, the conversion rate, as well as the stability in aqueous solutions. Nevertheless, dynamic covalent interactions often exhibit fast binding and fast dissociation events or vice versa, affecting their conversion rates or stabilities. To overcome the limitation in linker design, we reported herein dual responsive dynamic covalent peptide tags combining a pH responsive boronate ester with fast association and dissociation rates, and a redox-active disulfide with slow formation and dissociation rate. Precoordination by boronic acid–catechol interaction improves self-sorting and selectivity in disulfide formation into heterodimers. The resulting bis-peptide conjugate exhibited improved complex stability in aqueous solution and acidic tumor-like extracellular microenvironment. Furthermore, the conjugate responds to pH changes within the physiological range as well as to redox conditions found inside cancer cells. Such tags hold great promise, through cooperative effects, for controlling the stability of bioconjugates under dilution in aqueous media, as well as designing intelligent pharmaceutics that react to distinct biological stimuli in cells.

Highly Strong, Stretchable, and Conductive Reduced Graphene Oxide Composite Hydrogel-Based Sensors for Motoring Strain and Pressure

Conductive hydrogels have shown great potential for fabricating flexible and wearable sensors, especially strain/pressure sensors to monitor human motion/health. In practice, the use of conductive hydrogel-based sensors is often limited because of hydrogels’ poor mechanical properties and low sensitivity. In the present article, a composite hydrogel comprising acrylamide, N-(3-aminopropyl) methyl acrylamide hydrochloride, and polydopamine-coated reduced graphene oxide is prepared. The dynamic covalent and noncovalent interactions that exist in the hydrogel matrix including C–N bonds, intra-/intermolecular hydrogen bonds and NH3+–π interaction, and π–π interactions rendered the hydrogels with superior fracture stress (496.4 ± 85.9 kPa) and ductility (1156.9 ± 110.1%). Also, prepared hydrogels have excellent cytocompatibility and show appropriate adhesion to the skin, showcasing their potential in fabricating wearable devices. On the basis of these facts, hydrogel-based strain/pressure sensors that cause a change in resistance when strain or pressure is applied are fabricated. The fabricated sensors show a high strain sensitivity in the strain range of 0–800% where, at a subtle strain (100%), the gauge factor reached 5.4. In addition, sensors are also responsive to pressure with a sensitivity of −0.74% kPa–1 in the range from 0 to 10 kPa. The fabricated strain/pressure sensors have the cyclic ability and self-healing property at room temperature. As a proof-of-concept, the sensors are shown to monitor movements of the elbow, knee, fingers, and wrists as well as sense the vocal cord vibration.

Peptide-Based Supramolecular Systems Chemistry.

Peptide-based supramolecular systems chemistry seeks to mimic the ability of life forms to use conserved sets of building blocks and chemical reactions to achieve a bewildering array of functions. Building on the design principles for short peptide-based nanomaterials with properties, such as self-assembly, recognition, catalysis, and actuation, are increasingly available. Peptide-based supramolecular systems chemistry is starting to address the far greater challenge of systems-level design to access complex functions that emerge when multiple reactions and interactions are coordinated and integrated. We discuss key features relevant to systems-level design, including regulating supramolecular order and disorder, development of active and adaptive systems by considering kinetic and thermodynamic design aspects and combinatorial dynamic covalent and noncovalent interactions. Finally, we discuss how structural and dynamic design concepts, including preorganization and induced fit, are critical to the ability to develop adaptive materials with adaptive and tunable photonic, electronic, and catalytic properties. Finally, we highlight examples where multiple features are combined, resulting in chemical systems and materials that display adaptive properties that cannot be achieved without this level of integration.

Biohydrogel Based on Dynamic Covalent Bonds for Wound Healing Applications

In this work, a biohydrogel based on alginate and dynamic covalent B-O bonds, and derived composites, has been evaluated for wound healing applications. In particular, a phenylboronic acid–alginate (PBA-Alg) complex was synthesized by coupling 3-aminophenylboronic acid onto alginate, and used to prepare varied concentrations of hydrogels and silicate-based nanocomposites in PBS. The resulting hydrogels were characterized in terms of interfacial tension, moisture uptake and loss, interaction with fresh acid-soluble collagen, self-healing ability, effects on blood clotting and wound healing. The interfacial tension between the hydrogels and biorelevant fluids was low and moisture loss of 55–60% was evident without uptake from the environment. The components of the hydrogels and their mixtures with collagen were found to be compatible. These hydrogels showed efficient self-healing and thixotropic behavior, and the animals in the treatment groups displayed blood clotting times between 9.1 min and 10.7 min. In contrast, the composites showed much longer or shorter clotting times depending on the silicate content. A significant improvement in wound healing was observed in 3% w/v PBA-Alg formulations. Overall, the PBA-Alg hydrogels exhibit self-healing dynamic covalent interactions and may be useful in dressings for incision wounds.

Bioinspired hyperbranched protein adhesive based on boronic acid-functionalized cellulose nanofibril and water-soluble polyester

The development of high-performance and sustainable bio-adhesive materials has attracted significant research attention in recent years. However, producing high-performance biopolymer materials with desirable mechanical and antibacterial properties remains a challenge. Herein, a mussel-mimetic strategy is reported to fabricate a soy protein (SP)-based composite film via aqueous co-assembly of 3-aminophenylboronic acid-functionalized cellulose nanofibril (AB@CNF) and hyperbranched polyester (HPE). The water-soluble HPE with numerous hydroxyl end groups was synthesized by using a facile and green method. Through enhanced dynamic covalent interactions and intermolecular sacrificial hydrogen bonds, the incorporated AB@CNF hybrids with conjugated cis-diols strongly interact and entangle with biopolymer chains in the hyperbranched network. As a result of multiple synergistic cross-linking, the toughness and strength of the SP/HPE/AB@CNF film increase by 574% and 346% to 10.05 MJ/m3 and 14.23 MPa, respectively. Additionally, the film offers excellent antibacterial activity, flame retardance, and thermal stability. This sustainable approach should open new avenues for the design and development of biomimetic plant-derived functional materials in biomass adhesive and active packaging.