Supramolecular Biocomposite Hydrogels Formed by Cellulose and Host-Guest Polymers Assisted by Calcium Ion Complexes

Zn/Al layered double hydroxide and carboxymethyl cellulose composite beads as support for the catalytic gold nanoparticles and their applications in the reduction of nitroarenes

Until now, many efficient catalysts have been reported that are used for the reduction of nitroarenes. However, a catalyst reusability is a challenge that is often faced in practical environment. In this report, we designed a hydrogel composite (CMC-LDH), which act as support and making it possible to address this challenge. In this research work, zinc/aluminum based layered double hydroxides (Zn/Al LDH) have been assembled with carboxymethyl cellulose (CMC) to prepare CMC/LDH hydrogel beads. The CMC/LDH hydrogel beads were prepared by the ionotropic gelation method. For CMC/LDH/Au preparation, the already prepared CMC/LDH beads were kept in gold ion (Au3+) solution, and their subsequent reduction with sodium borohydride (NaBH4). For the characterization of the prepared samples different instrumental techniques, such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy, and scanning electron microscopy (SEM) were adopted. For the catalytic evaluation of CMC/LDH/Au, it was utilized as a catalyst in 4-NP and 4-NA reduction reactions. The continuity of the reaction was monitored by a UV-visible spectrophotometer. Rate constant (kapp) of 0.48474 min-1 and 0.7486 min-1 were obtained for 4-NP and 4-NA reduction, respectively. The hydrogel beads were recycled and reused for up to five successive cycles without significantly changing their catalytic efficiency.

Open Linear Polymer Host-Guest Interactions Sensed by Luminescent Silver Nanodots

The selectivity of the linear polymer chain toward its binding moieties has been considered negligible; thus, a clear demonstration showing the best-fit binding of a linear polymer to its guest counterpart is still unknown. Luminescent poly(acrylic acid) (PAA)-stabilized silver nanodots (PAA-AgNDs) have been applied as a turn-on sensor to monitor the interaction between the PAA chain and its binding cations. The binding of cations ions to the PAA chain may cross-link the linear PAA chain via coordination with carboxylate, which increases the rigidity of the polymer chain, retards the nonradiative decay of PAA-AgNDs, and consequently enhances the emission of silver nanodots while inducing a blue-shift of its emission spectrum. For the first time, we have demonstrated that a linear polymer chain can act as an open host to selectively bind to its best-matching cations. Specifically, among Group 2 cations (Mg2+, Ca2+, Sr2+, Ba2+), calcium ions show the strongest bonding to the PAA polymer chain. Our research suggests that, with extra rigidity, the polymer improves its chemical stability as calcium ions cross-linked the linear polymer. Meanwhile, it has also been demonstrated that luminescent silver nanodots can be excellent probes for the detection of polymer activities with straightforward and simple visualization methods.

Chitosan and hyaluronic-based hydrogels could promote the infected wound healing

The most important function of skin is to prevent biological dehydration and protect internal structures from the environment. When a wound becomes infected, the bacteria cause a sustained inflammatory response at the infected site, further delaying the healing process. Therefore, the search for better antibacterial strategies has become a topic of great concern. Therefore, the development of multifunctional hydrogels with antibacterial properties, ROS removal, and hemostasis is urgently required for promoting wound healing process. Chitosan is the only cationic natural polysaccharide with good biocompatibility, antibacterial and hemostatic ability. It is a candidate material to prepare hydrogel wound dressing. Hyaluronic acid (HA) is a natural biological macromolecule that belongs to a group of heteropolysaccharides known as non-sulfated glycosaminoglycans. It is a major component of the skin extracellular matrix (ECM) and is involved in inflammation, angiogenesis, and tissue regeneration. Here, the hydrogel was designed with the natural macromolecular of the gallic acid-grafted quaternized chitosan (GA-QCS) and oxidized hyaluronic acid (OHA) via Schiff base and/or Michael addition reaction. It was found that the GA-QCS/OHA hydrogel exhibited multifunctional capabilities with injectable, hemostasis, degradation, and release of medicines. In addiation, GA-QCS/OHA hydrogels exhibited remarkable antioxidant and migration promoting effects in vitro. And the mupirocin-loaded GA-QCS/OHA hydrogels had inhibitory effects on E. coli (Gram-negative bacterium) and S. aureus (Gram-positive bacterium) in vitro. A full-thickness skin of S. aureus infection mouse wound model was used to test the bioactive effect of the hydrogels and the accelerated wound healing was obtained due to the inhibiting the proinflammatory factor TNF-α and upregulating the vascularization factor CD31. This study proposed an effective strategy based on antioxidant, antibacterial, self-healing multifunctional hydrogel for wound healing under various infectious complications. This natural macromolecular hydrogel could act as an effective reactive oxygen species scavenger to promote the wound healing in the future.

Polydopamine-doped supramolecular chiral hydrogels for postoperative tumor recurrence inhibition and simultaneously enhanced wound repair

Cancer recurrence remains a major challenge after primary tumor excision, and the inflammation of tumor-caused wounds can hinder wound healing and potentially promote tumor growth. Herein, a chiral L-phenylalanine-based (LPFEG) supramolecular hydrogel system encapsulated with polydopamine nanoparticles (PDA-NPs) has been developed in order to prevent tumor relapse after surgery and promote wound repair. PDA-NPs allow for near-infrared (NIR) light-triggered photothermal therapy, especially, it can scavenge free radicals in the surgical wound. LPFEG can mimic native extracellular matrix (ECM) structure to create a chiral microenvironment that enhances fibroblast adhesion, proliferation, and new tissue regeneration. With anticancer drug doxorubicin (DOX) loaded into the composite hydrogel, the antitumor effect is significantly enhanced by the integration of chemo-photothermal therapy both in vitro and in vivo. The PDA-based chiral supramolecular composite hydrogel as an effective postoperative adjuvant possesses promising applicable prospects in inhibiting tumor recurrence and accelerating wound healing after operation. STATEMENT OF SIGNIFICANCE: After primary tumor excision, cancer recurrence remains a severe concern, and the inflammation induced by tumor-related wounds can delay wound healing. Herein, we designed a chiral L-phenylalanine-based (LPFEG) supramolecular hydrogel platform that was co-assembled with polydopamine nanoparticles (PDA-NPs). Among them, PDA-NPs can offer photothermal therapy and scavenge free radicals in surgical wounds. LPFEG can create a chiral microenvironment that promotes fibroblast adhesion, proliferation, and new tissue regeneration. Furthermore, with anticancer drug doxorubicin (DOX) loaded into the composite hydrogel, the antitumor effect is considerably boosted. Therefore, the PDA-based chiral supramolecular hydrogel shows high application potential as a postoperative adjuvant in preventing tumor relapse as well as accelerating wound healing after surgery.

Self-healing polysaccharide-based injectable hydrogels with antibacterial activity for wound healing

Because the wound is difficult to heal, repeated bacterial infection will lead to complex clinical problems. Therefore, it is necessary to find an effective method to strengthen the healing process and resist bacterial infection. Hydrogels have many advantages, such as injectability and self-healing under physiological conditions, so they have been widely studied in recent years. Hydrogels can keep the wound moist and promote the wound healing. In addition, the growth of bacteria can be obviously inhibited by hydrogels themself or by doping some antibacterial active substances. Based on this, herein, this review highlighted the preparation and properties of different polysaccharide-based injectable hydrogels, and discuss their biological applications in antibacterial therapy for wound healing in recent years.

Size-Controlled Preparation of Gold Nanoparticles Deposited on Surface-Fibrillated Cellulose Obtained by Citric Acid Modification

Cellulose-based functional materials have gained immense interest due to their low density, hydrophilicity, chirality, and degradability. So far, a facile and scalable preparation of fibrillated cellulose by treating the hydroxy groups of cellulose with citric acid (F-CAC) has been developed and applied as a reinforcing filler for polypropylene composite. Herein, a size-selective preparation of Au nanoparticles (NPs) stabilized by F-CAC is described. By modifying the conditions of transdeposition method, established in our group previously, a transfer of Au NPs from poly(N-vinyl-2-pyrrolidone) (PVP) to F-CAC proceeded up to 96% transfer efficiency with retaining its cluster sizes in EtOH. Meanwhile, the deposition efficiency drastically decreased in the case of nonmodified cellulose, showing the significance of citric acid modification. A shift of binding energy at Au 4f core level X-ray photoelectron spectroscopy from 82.0 to 83.3 eV indicated that the NPs were stabilized on an F-CAC surface rather than by PVP matrix. The reproducible particle size growth was observed when 2-propanol was used as a solvent instead of EtOH, expanding the range of the available particle size with simple manipulation. The thus-obtained Au:F-CAC nanocatalysts exhibited a catalytic activity toward an aerobic oxidation of 1-indonol in toluene to yield 1-indanone quantitatively and were recyclable at least six times, illustrating high tolerance against organic solvents.