Formulating Zwitterionic, Responsive Polymers for Designing Smart Soils

In-vitro investigation on the biological activities of squalene derived from the soil fungus Talaromyces pinophilus

The consistent increase in multidrug resistance among pathogens and increased cancer incidence are serious public health concerns and threaten humans by killing countless lives. In the present study, Talaromyces pinophilus CJ15 was characterized and evaluated for its antibacterial, candidicidal and cytotoxic activities. The selected isolate Talaromyces pinophilus CJ15 with 18S rRNA gene sequence of 1021 base pairs exhibited antifungal activity on plant pathogens via dual culture. The GC-MS profiling of crude extract illustrated the existence of many bioactive macromolecules which include squalene belonging to the terpenoids family. The biological macromolecules in the bioactive fraction of CJ15 exhibited increasing antibacterial activity with an increase in concentration such that the highest activity was recorded against Shigella flexneri with 15, 18, 20, and 24 mm inhibition zones at 25, 50, 75 and 100 μl concentrations, respectively. The squalene, having a molecular weight of 410.718 g/mol, displayed candidicidal activity with a right-side shifted log phase in the growth curve of all the treated Candida species, indicating delayed exponential growth. In cytotoxic activity, the extracted squalene exhibited an IC50 concentration of 26.22 μg/ml against JURKAT cells and induced apoptosis-induced cell death. This study's outcomes encourage the researchers to explore further the development of new and improved bioactive macromolecules that could help to prevent infections and human blood cancer.

The sources, leaching, remediation, and environmental concerns associated with groundwater salinity

Water resources management and sustainable development depend on the quality of groundwater as a major source of fresh water. As a result of rising water demand in emerging nations and overexploitation, groundwater quality has declined globally in many aquifers. One of the most significant elements that lower the quality of the groundwater is salinization. This review is to provide an overview of various materials that are used in the design and development of innovative chitosan-based nanocomposite polymeric membranes for desalination. Biodegradable, non-toxic, affordable, and easily available, with film-forming ability and poly-functionality, chitosan is an ideal material for a sustainable future. Membrane preparation for desalination using chitosan helps to provide antibacterial and antioxidant activities, great chelating capabilities, and strong adsorption capacity. In this research, we discuss a variety of concepts concerning the different sources of elevated salinity and available desalination methods. A comprehensive framework was also developed to understand the leaching and percolation of salt in groundwater, an essential component of managing risks and ensuring safety. Additionally, we explain the various remediation strategies for reducing groundwater's salt concentration and explore the best method for desalination specifically focused on chitosan.

Editorial for Special Issue: Advances in Smart and Tough Hydrogels

Smart hydrogels possess both intelligent and responsive properties, which are designed to exhibit specific responses to external stimuli such as changes in temperature, pH, or the presence of specific ions/counterions, making them "smart" or "responsive" materials [...].

Tough, adhesive biomimetic hyaluronic acid methacryloyl hydrogels for effective wound healing

The development of cost-effective, biocompatible soft wound dressings is highly desirable; however, conventional dressings are only designed for flat wounds, which creates difficulty with promising healing efficiency in complex practical conditions. Herein, we developed a tough, adhesive biomimetic hyaluronic acid methacryloyl hydrogels composed of chemically crosslinked hyaluronic acid methacryloyl (HAMA) network and poly(N-hydroxyethyl acrylamide) (PHEAA) network rich in multiple hydrogen bonding. Due to the multiple chemical crosslinking sites (acrylamide groups) of HAMA; the bulk HEMA/PHEAA hydrogels presented significant enhancements in mechanical properties (∼0.45 MPa) than common hyaluronic acid hydrogels (<0.1 MPa). The abundant hydrogen bonding also endowed the resultant hydrogels with extremely high adhesiveness on many nonporous substrates, including glass and biological tissues (e.g., heart, liver, lung, kidney, stomach, and muscle), with a considerable interfacial toughness of ∼1432 J m-2. Accordingly, since both natural hyaluronic acid derivative polymers and hydrophilic PHEAA networks are highly biocompatible, the hydrogel matrix possesses good blood compatibility (<5% of hemolysis ratio) and satisfies the general dressing requirements (>99% of cell viability). Based on these physicochemical features, we have demonstrated that this adhesive hydrogel, administered in the form of a designed patch, could be applied to wound tissue healing by promoting epithelialization, angiogenesis, and collagen deposition. We believe that our proposed biomimetic hydrogel design holds great potential for wound repair and our developed HAMA/PHEAA hydrogels are extremely promising for the next-generation tissue healings in emergency situations.

Bilayer Hydrogels by Reactive-Induced Macrophase Separation

Bilayer hydrogels encoded with smart functions have emerged as promising soft materials for engineered biological tissues and human-machine interfaces, due to the versatility and flexibility in designing their mechanical and chemical properties. However, conventional fabrication strategies often require multiple complicated steps to create an anisotropic bilayer structure with poor interfaces, which significantly limit the scope of bilayer hydrogel applications. Here, we reported a general, one-pot, macrophase separation strategy to fabricate a family of bilayer hydrogels made of vinyl and styryl monomers with a seamless interface and a controllable layer separation efficiency (20-99%). The working principle of a macrophase separation strategy allows for the decoupling of the two gelation processes to form distinct vinyl- and styryl-enriched layers by manipulating competitive polymerization reactions between vinyl and styryl monomers. This work presents a straightforward approach and a diverse range of radical monomers, which can be utilized to create next-generation bilayer hydrogels, beyond a few available today.

Development of Zn biofertilizer microbeads encapsulating Enterobacter ludwigii-PS10 mediated alginate, starch, poultry waste and its efficacy in Solanum lycopersicum growth enhancement

In the present farming era, rhizobacteria as beneficial biofertilizers can decrease the negative effects of Zinc (Zn) agrochemicals. However, their commercial viability and utility are constrained by their instability under field conditions. Thus, to enhance their stability, microbial formulations are considered, which will not only offer an appropriate microenvironment, and protection but also ensure a high rate of rhizospheric-colonization. The goal of this study was to create a new formulation for the Zn-solubilizing bacteria E. ludwigii-PS10. The studied formulation was prepared using the extrusion technique, wherein a composite solution containing alginate, starch, zinc oxide, and poultry waste was uniformly mixed with the bacterial strain PS10 to develop low-cost, eco-friendly, and slow-release microbeads. The produced microbead was spherical, and characterized by SEM, FTIR, and XRD. Further, the microbeads were analyzed for their survival stability over 3 months of storage at room temperature and 4 °C. The effect of the microbead on the vegetative growth of tomato plants was investigated. Results showed that 94 % of the encapsulated microbial beads (EMB) matrix was able to encapsulate the bacterial strain PS10. The dried EMB demonstrated a moisture content of 2.87 % and was able to preserve E. ludwigii-PS10 survival at room temperature at the rate of 85.6 %. The application of the microbead to the tomato plants significantly increased plant biomass and Zn content. As a result, our findings support the use of this novel EMB prepared using an alginate/poultry waste/starch mixture to increase bacterial cell viability and plant growth.

Organohydrogel Actuators with Adjustable Stimulus Responsiveness for On-Demand Morphing

Hydrogel actuators showing shape morphing in response to external stimuli are of significant interest for their applications in soft robots, artificial muscles, etc. However, there is still a lack of hydrogel actuators with adjustable stimulus responsiveness for on-demand driving. In this study, an organohydrogel actuator was prepared by a two-step interpenetrating method, resulting in the coexistence of poly(N-isopropylacrylamide-co-4-(2-sulfoethyl)-1-(4-vinylbenzyl) pyridinium betaine) (p(NIPAM-SVBP)) hydrophilic networks and poly(lauryl methacrylate) (pLMA) hydrophobic networks with gradient distribution. In the initial state, the organohydrogel actuator can be driven globally under thermal stimulation. Owing to the unique alkali-chromic performance of SVBP, the organohydrogel actuator can be endowed with photothermal properties and actuate locally under the stimulus of NIR light. More importantly, the organohydrogel will return to the original colorless state after being treated with acid solution. Our work provides a new insight into designing and fabricating novel actuators with adjustable stimulus responsiveness for on-demand morphing.

Triple Stimuli-Responsive Flexible Shape Memory Foams with Super-Amphiphilicity

Highly porous multi-responsive shape memory foams have unique advantages in designing 3D materials with lightweight for varied applications. Herein, a facile and efficient approach to fabricating a thermo-, electro-, and photo-responsive shape memory composite foam is demonstrated. A specific multi-step carbonization protocol is adopted for transforming commercial melamine sponge (MS) to highly porous carbon foam (CF) with robust elastic resilience, efficient electrothermal/photothermal conversions, and super-amphiphilicity. It is a novel proposal for CF to take the dual role of the elastic supporting framework and 3D energy conversion/transmission network without any functional fillers. The composite foam cPCL@CF incorporates the CF skeleton with in situ crosslinked polycaprolactone (PCL) layers, which exhibits high conductivity (≈140 S m^-1 ) and excellent light absorption (≈97.7%) in the range of 250-2500 nm. By triggering the crystalline transition of PCL, the composite foam displays sensitive electro- and photo-induced shape memory effect (SME) with outstanding shape fixation ratio (R_f ) and recovery ratio (R_r ). Thanks to the super-amphiphilicity and high electrical conductivity, the cPCL@CF composite foam can give rapid and distinguishable electric signals upon tiny drips of salt solutions or lithium-ion battery (LIB) electrolytes, making it a new type of sensor for detecting electrolyte leakage.