Mechanochemiluminescent hydrogels for real-time visualization of chemical bond scission

Quantitative and real-time characterization of mechanically induced bond scission events taken place in polymeric hydrogels is essential to uncover their fracture mechanics. Herein, a class of mechanochemiluminescent swelling hydrogels have been synthesized through a facile micellar copolymerization method using chemiluminescent bis(adamantyl)-1,2-dioxetane (Ad) as a crosslinker. This design and synthetic strategy ensure intense mechanochemiluminescence from Ad located in a hydrophobic network inside micelles. Moreover, the mechanochemiluminescent colors can be tailored from blue to red by mixing variant acceptors. Taking advantages of the transient nature of dioxetane chemiluminescence, the damage distribution and crack evolution of the hydrogels can be visualized and analyzed with high spatial and temporal resolution. The results demonstrate the strengths of the Ad mechanophore and micellar copolymerization method in the study of damage evolution and fracture mechanism of swelling hydrogels.

Dually Reactive Multilayer Coatings Enable Orthogonal Manipulation of Underwater Superoleophobicity and Oil Adhesion via Post-Functionalization

Fish scale-inspired underwater superoleophobic coatings with low oil adhesion can be achieved through the creation of hierarchical surface topography on water-compatible materials (including polymeric hydrogels, metal oxides, and electrostatic multilayers)....

Enzyme-Triggered Hydrogels for Pharmaceutical and Food Applications

Enzyme-mediated polymeric hydrogels are drawing considerable attention in pharmaceutical and food sectors owing to their superior biocompatibility and process controllability under physiological conditions. Enzymes play a significant role in polymeric hydrogel formation through different mechanisms. Oxidases (e.g., horseradish peroxidase and tyrosinase) have demonstrated to drive the crosslinking of gel precursors by oxidizing the phenolic or acrylic moieties to free radicals. Transferases and hydrolases catalyze elongation of biopolymer chains which gradually self-assemble into hydrogels. Still more certain enzymes also participate in hydrogel formation by releasing gelation factors. Enhancement of the desired properties of certain hydrogels through the interior and exterior post-modifications has also been demonstrated by certain enzymes. Hence, in this chapter, the authors explore the different mechanisms of enzyme-mediated hydrogels preparations and its fabrication towards pharmaceutical and food sectors along with the discussion of recent trends and further prospects.

Abnormal activity of functional groups during uranyl ions sorption by polymethacrylic acid-poly-4-vinylpyridine intergel system

Uranyl ions sorption by intergel system consisting of polymethacrylic acid hydrogel (hPMAA) and poly-4-vinylpyridine hydrogel (hP4VP) has been studied. First, reciprocal activation of PMAA and P4VP polymeric hydrogels in water environment was examined in order to predict intergel system sorption activity. Based on the obtained results, it was found that area of maximum hydrogel activation was within the ratios of 100 % hPMAA and 67 % hPMAA:33 % hP4VP. The maximum rate of uranyl ions extraction was also observed within these ratios. The highest uranyl ions sorption by intergel system occurred at 83 %hPMAA:17 % hP4VP ratio. Maximum uranyl ions extraction rate after 56 hours of hydrogels remote interaction was 82.5 %, when polymeric chain binding rate was 9.94 % and effective dynamic exchange capacity was 1.12 mmol/g. Significant increase of intergel system sorption activity within the ratios of 100 % hPMAA and 67 % hPMAA:33 % hP4VP in comparison with initial inactivated hydrogels 100 % hPMAA and 100 % hP4VP was confirmed by combined calculation data of extraction rates of inactivated PMAA and P4VP polymeric hydrogels. The obtained results illustrated changes of initial polymeric hydrogels’ electrochemical sorption properties in intergel system leading to functional groups obtaining higher reactive ability, which made it possible to use them for further development of highly efficient uranyl ions extraction sorption technology

Development of Poly-NIsopropylacrylamide Surfaces for the Selection of Swine Sperm

The reproductive efficiency of pig farms is directly correlated with the fertility of the boars. The aim of this work was to develop polymeric materials that can be used as a platform to select a subpopulation of sperm with better cell physiological parameters. Polymeric hydrogels composed of Poly-N-isopropylacrylamide with different positive charges given by copolymerization with (3-acrylamidopropyl) trimethylammonium chloride (APTA, 5-10-15%), were synthesized. Subsequently, the interaction between the sperm cells and the polymeric surfaces was analyzed in TALP medium. Release of the spermatozoa from the polymeric surfaces was induced by changing to Ca2+ free media. Sperm motility, cell viability, plasma membrane and acrosome integrity were evaluated. The results indicated that a higher percentage of swine sperm attached to PNIPAM co-15% APTA hydrogels (62.86±3.33%). Ninety seven percent (97.19±1.45 %) of the sperm released from the PNIPAM co-15%APTA surfaces were viable (p<0.05 vs unbound population and raw semen), with acceptable motility (58.89±1.28%) and with intact plasma and acrosomal membranes (69±1.2% and 98.5±0.65% respectively). These results indicate that hydrogels can be used to select boar sperm with high viability and mobility for use in assisted reproductive techniques.

State-of-the-Art Irradiation Technology for Polymeric Hydrogel Fabrication and Application in Drug Release System

Chronic and debilitating diseases can be marginally cured by anti-inflammatory, antiseptic, and antibiotic drugs, there is still need for more efficacious delivery approaches. Biodegradable and biocompatible polymeric hydrogels are essential requirements for drug release systems due to sustained or targeted drug delivery. Irradiation crosslinking of polymers is considered a safe route for the fabrication of hydrogels because crosslinking takes place without addition of unnecessary toxic reagents such as initiators or crosslinkers. This technology is a useful way to induce sterilization and crosslinking in a single step. Several natural and synthetic polymers in different combinations are crosslinked through high energy ionizing radiation such as electron beam and gamma ray irradiation. Polymeric hydrogels prepared using these techniques exhibit good gel fraction, swelling ratio, and mechanical properties. In addition, hydrogels possess drug loading and release characteristics, antimicrobial characteristics, and in-vivo/in-vitro cytocompatibility. The advantage of biodegradable and biocompatible drug release systems is the controlled release of drugs without deleterious effects on targeted sites. This mini review about irradiation crosslinked hydrogels will provide sufficient guidelines for new researchers to proceed further in this field.

Expanding the Biocatalytic Scope of Enzyme-Loaded Polymeric Hydrogels

In recent years, polymeric hydrogels have appeared promising matrices for enzyme immobilization to design, signify and expand bio-catalysis engineering. Therefore, the development and deployment of polymeric supports in the form of hydrogels and other robust geometries are continuously growing to green the twenty-first-century bio-catalysis. Furthermore, adequately fabricated polymeric hydrogel materials offer numerous advantages that shield pristine enzymes from denaturation under harsh reaction environments. For instance, cross-linking modulation of hydrogels, distinct rheological behavior, tunable surface entities along with elasticity and mesh size, larger surface-volume area, and hydrogels’ mechanical cushioning attributes are of supreme interest makes them the ideal candidate for enzyme immobilization. Furthermore, suitable coordination of polymeric hydrogels with requisite enzyme fraction enables pronounced loading, elevated biocatalytic activity, and exceptional stability. Additionally, the unique catalytic harmony of enzyme-loaded polymeric hydrogels offers numerous applications, such as hydrogels as immobilization matrix, bio-catalysis, sensing, detection and monitoring, tissue engineering, wound healing, and drug delivery applications. In this review, we spotlight the applied perspective of enzyme-loaded polymeric hydrogels with recent and relevant examples. The work also signifies the combined use of multienzyme systems and the future directions that should be attempted in this field.

Self-Healing Hydrogels: Preparation, Mechanism and Advancement in Biomedical Applications

Polymeric hydrogels are widely explored materials for biomedical applications. However, they have inherent limitations like poor resistance to stimuli and low mechanical strength. This drawback of hydrogels gave rise to ‘’smart self-healing hydrogels’’ which autonomously repair themselves when ruptured or traumatized. It is superior in terms of durability and stability due to its capacity to reform its shape, injectability, and stretchability thereby regaining back the original mechanical property. This review focuses on various self-healing mechanisms (covalent and non-covalent interactions) of these hydrogels, methods used to evaluate their self-healing properties, and their applications in wound healing, drug delivery, cell encapsulation, and tissue engineering systems. Furthermore, composite materials are used to enhance the hydrogel’s mechanical properties. Hence, findings of research with various composite materials are briefly discussed in order to emphasize the healing capacity of such hydrogels. Additionally, various methods to evaluate the self-healing properties of hydrogels and their recent advancements towards 3D bioprinting are also reviewed. The review is concluded by proposing several pertinent challenges encountered at present as well as some prominent future perspectives.