Substrate stress relaxation regulates neural stem cell fate commitment.

Adult neural stem cells (NSCs) reside in the dentate gyrus of the hippocampus, and their capacity to generate neurons and glia plays a role in learning and memory. In addition, neurodegenerative diseases are known to be caused by a loss of neurons and glial cells, resulting in a need to better understand stem cell fate commitment processes. We previously showed that NSC fate commitment toward a neuronal or glial lineage is strongly influenced by extracellular matrix stiffness, a property of elastic materials. However, tissues in vivo are not purely elastic and have varying degrees of viscous character. Relatively little is known about how the viscoelastic properties of the substrate impact NSC fate commitment. Here, we introduce a polyacrylamide-based cell culture platform that incorporates mismatched DNA oligonucleotide-based cross-links as well as covalent cross-links. This platform allows for tunable viscous stress relaxation properties via variation in the number of mismatched base pairs. We find that NSCs exhibit increased astrocytic differentiation as the degree of stress relaxation is increased. Furthermore, culturing NSCs on increasingly stress-relaxing substrates impacts cytoskeletal dynamics by decreasing intracellular actin flow rates and stimulating cyclic activation of the mechanosensitive protein RhoA. Additionally, inhibition of motor-clutch model components such as myosin II and focal adhesion kinase partially or completely reverts cells to lineage distributions observed on elastic substrates. Collectively, our results introduce a unique system for controlling matrix stress relaxation properties and offer insight into how NSCs integrate viscoelastic cues to direct fate commitment.

Dry double-sided tape for adhesion of wet tissues and devices.

Two dry surfaces can instantly adhere upon contact with each other through intermolecular forces such as hydrogen bonds, electrostatic interactions and van der Waals interactions1,2. However, such instant adhesion is challenging when wet surfaces such as body tissues are involved, because water separates the molecules of the two surfaces, preventing interactions3,4. Although tissue adhesives have potential advantages over suturing or stapling5,6, existing liquid or hydrogel tissue adhesives suffer from several limitations: weak bonding, low biological compatibility, poor mechanical match with tissues, and slow adhesion formation5-13. Here we propose an alternative tissue adhesive in the form of a dry double-sided tape (DST) made from a combination of a biopolymer (gelatin or chitosan) and crosslinked poly(acrylic acid) grafted with N-hydrosuccinimide ester. The adhesion mechanism of this DST relies on the removal of interfacial water from the tissue surface, resulting in fast temporary crosslinking to the surface. Subsequent covalent crosslinking with amine groups on the tissue surface further improves the adhesion stability and strength of the DST. In vitro mouse, in vivo rat and ex vivo porcine models show that the DST can achieve strong adhesion between diverse wet dynamic tissues and engineering solids within five seconds. The DST may be useful as a tissue adhesive and sealant, and in adhering wearable and implantable devices to wet tissues.

Self-Adhesive, Stretchable, and Thermosensitive Iontronic Hydrogels for Highly Sensitive Neuromorphic Sensing-Synaptic Systems.

Artificial sensory afferent nerves that emulate receptor nanochannel perception and synaptic ionic information processing in chemical environments are highly desirable for bioelectronics. However, challenges persist in achieving life-like nanoscale conformal contact, agile multimodal sensing response, and synaptic feedback with ions. Here, a precisely tuned phase transition poly(N-isopropylacrylamide) (PNIPAM) hydrogel is introduced through the water molecule reservoir strategy. The resulting hydrogel with strongly cross-linked networks exhibits excellent mechanical performance (∼2000% elongation) and robust adhesive strength. Importantly, the hydrogel's enhanced ionic conductance and heterogeneous structure of the temperature-sensitive component enable highly sensitive strain information perception (GFmax = 7.94, response time ∼ 87 ms), temperature information perception (TCRmax = -1.974%/°C, response time ∼ 270 ms), and low energy consumption synaptic plasticity (42.2 fJ/spike). As a demonstration, a neuromorphic sensing-synaptic system is constructed integrating iontronic strain/temperature sensors with fiber synapses for real-time information sensing, discrimination, and feedback. This work holds enormous potential in bioinspired robotics and bioelectronics.

Smart Free-Standing Bilayer Polyacrylamide/DNA Hybrid Hydrogel Film-Based Sensing System Using Changes in Bending Angles as a Visual Signal Readout.

Stimuli-responsive DNA hydrogels have shown great potential in sensing applications due to their attractive properties such as programmable target responsiveness, excellent biocompatibility, and biodegradability. In contrast to the extensively developed DNA hydrogel sensing systems based on the stimuli-responsive hydrogel-to-solution phase transition of the hydrogel matrix, the quantitative sensing application of DNA hydrogels exhibiting smart shape deformations has rarely been explored. Moreover, bulk DNA hydrogel-based sensing systems also suffer from high material cost and slow response. Herein, free-standing bilayer polyacrylamide/DNA hybrid hydrogel films with programmable responsive properties directed by the sequence of functional DNA units have been constructed. Compared with bulk DNA hydrogels, these DNA hydrogel films with a thickness at the micrometer scale not only greatly reduce the consumption of DNA materials but also facilitate the mass transfer of biomacromolecular substances within the hydrogel network, thus favoring their sensing applications. Therefore, a target-responsive smart DNA hydrogel film-based sensor system is further demonstrated based on the large amplitude macroscopic shape deformation of the film as a visual signal readout. As a proof of concept, Pb2+ or UO22+ ion-responsive DNA units were introduced into the active layer of the bilayer hydrogel films. In the presence of Pb2+ or UO22+ ions, the occurrence of a cleavage reaction within the DNA units leads to the release of DNA segments from the hydrogel film, inducing a dramatic shape deformation of the film, and thus sensing of Pb2+ or UO22+ ions with high specificity is achieved based on measuring the bending angle changes of these smart free-standing films. These smart DNA hydrogel film sensors with target-programmable responsiveness, simple operation, and ease of storage may hold promise for future rapid on-site testing applications.

Optical Fiber Surface Plasmon Resonance Sensor for Glyceryl Tributyrate Detection Based on the PAA/CS Composite Hydrogel Embedding Protease Method.

Glycerol tributyrate as a low-density lipoprotein plays a crucial role in drug development and food safety. In this work, a novel high-stability fiber optic sensor for glyceryl tributyrate based on the poly(acrylic acid) (PAA) and chitosan (CS) composite hydrogel embedding method is first proposed. Compared with traditional functionalization, the lipase in a polymer network structure used in this article can not only avoid chemical reactions that cause damage to the enzyme structure but also avoid the instability of ionic bonds and physical adsorption. Therefore, the PAA/CS hydrogel method proposed in this article can effectively retain enzyme structure. First, the impact of different layers (one to five layers) of PAA/CS on pH sensing performance was explored, and it was determined that layers 1-3 could be used for subsequent sensing experiments. Within the linear detection range of 0.5-10 mM, the detection sensitivities of the one to three layers of the biosensor are divided into 0.65, 0.95, and 1.51 nm/mM, respectively, with the three layers having the best effect. When the number of coating layers is three, the detection limit of the sensor is 0.47 mM, meeting the millimole level detection standard for anticancer requirement. Furthermore, the stability and selectivity of the sensor (in the presence of hemoglobin, urea, cholesterol, acetylcholine, and glucose) were analyzed. The three-layer sensor is used for sample detection. At concentrations of 1-10 mM, the absolute value of the recovery percentage (%) is 82-99%, which can accurately detect samples. The sensor proposed in this paper has the advantages of low sample consumption, high sensitivity, simple structure, and label-free measurement. The enzyme-embedding method provides a new route for rapid and reliable glyceryl tributyrate detection, which has potential applications in food safety as well as the development of anticancer drugs.

A Stable and Sensitive Engineering Bacterial Sensor via Physical Biocontainment and Two-Stage Signal Amplification.

Although engineering bacterial sensors have outstanding advantages in reflecting the actual bioavailability and continuous monitoring of pollutants, the potential escape risk of engineering microorganisms and lower detection sensitivity have always been one of the biggest challenges limiting their wider application. In this study, a core-shell hydrogel bead with functionalized silica as the core and alginate-polyacrylamide as the shell have been developed not only to realize zero escape of engineered bacteria but also to maintain cell activity in harsh environments, such as extremely acidic/alkaline pH, high salt concentration, and strong pressure. Particularly, after combining the selective preconcentration toward pollutants by functionalized core and the positive feedback signal amplification of engineering bacteria, biosensors have realized two-stage signal amplification, significantly improving the detection sensitivity and reducing the detection limit. In addition, this strategy was actually applied to the detection of As(III) and As(V) coexisting in environmental samples, and the detection sensitivity was increased by 3.23 and 4.39 times compared to sensors without signal amplification strategy, respectively, and the detection limits were as low as 0.39 and 0.86 ppb, respectively.

Membrane-Free Lateral Flow Assay with the Active Control of Fluid Transport for Ultrasensitive Cardiac Biomarker Detection.

Membrane-based lateral flow immunoassays (LFAs) have been employed as early point-of-care (POC) testing tools in clinical settings. However, the varying membrane properties, uncontrollable sample transport in LFAs, visual readout, and required large sample volumes have been major limiting factors in realizing needed sensitivity and desirable precise quantification. Addressing these challenges, we designed a membrane-free system in which the desirable three-dimensional (3D) structure of the detection zone is imitated and used a small pump for fluid flow and fluorescence as readout, all the while maintaining a one-step assay protocol. A hydrogel-like protein-polyelectrolyte complex (PPC) within a polyelectrolyte multilayer (PEM) was developed as the test line by complexing polystreptavidin (pSA) with poly(diallyldimethylammonium chloride) (PDDA), which in turn was layered with poly(acrylic acid) (PAA) resulting in a superior 3D streptavidin-rich test line. Since the remainder of the microchannel remains material-free, good flow control is achieved, and with the total volume of 20 µL, 7.5-fold smaller sample volumes can be used in comparison to conventional LFAs. High sensitivity with desirable reproducibility and a 20 min total assay time were achieved for the detection of NT-proBNP in plasma with a dynamic range of 60-9000 pg·mL-1 and a limit of detection of 56 pg·mL-1 using probe antibody-modified fluorescence nanoparticles. While instrument-free visual detection is no longer possible, the developed lateral flow channel platform has the potential to dramatically expand the LFA applicability, as it overcomes the limitations of membrane-based immunoassays, ultimately improving the accuracy and reducing the sample volume so that finger-prick analyses can easily be done in a one-step assay for analytes present at very low concentrations.

Oral delivery of Sunitinib malate using carboxymethyl cellulose/poly(acrylic acid-itaconic acid)/Cloisite 30B nanocomposite hydrogel as a pH-responsive carrier.

This work aimed to fabricate a Cloisite 30B-incorporated carboxymethyl cellulose graft copolymer of acrylic acid and itaconic acid hydrogel (Hyd) via a free radical polymerization method for controlled release of Sunitinib malate anticancer drug. The synthesized samples were characterized by FTIR, XRD, TEM, and SEM-dot mapping analyses. The encapsulation efficiency of Hyd and Hyd/Cloisite 30B (6 wt%) was 81 and 93%, respectively, showing the effectiveness of Cloisite 30B in drug loading. An in vitro drug release study showed that drug release from all samples in a buffer solution with pH 7.4 was higher than in a buffer solution with pH 5.5. During 240 min, the cumulative drug release from Hyd/Cloisite 30B (94.97% at pH 7.4) is lower than Hyd (53.71% at pH 7.4). Also, drug-loaded Hyd/Cloisite 30B (6 wt%) demonstrated better antibacterial activity towards S. Aureus bacteria and E. Coli. High anticancer activity of Hyd/Cloisite 30B against MCF-7 human breast cancer cells was shown by the MTT assay, with a MCF-7 cell viability of 23.82 ± 1.23% after 72-hour incubation. Our results suggest that Hyd/Cloisite 30B could be used as a pH-controlled carrier to deliver anticancer Sunitinib malate.

Resorbable Microspheres versus Trisacryl Gelatin Microspheres for Uterine Artery Embolization: A Randomized Controlled Trial.

Background There are insufficient data comparing resorbable microspheres (RMs) with permanent trisacryl gelatin microspheres (TAGMs) for uterine artery embolization (UAE). Purpose To compare therapeutic efficacy and clinical outcomes in participants with symptomatic fibroids after UAE with RMs or TAGMs. Materials and Methods This randomized controlled trial included participants undergoing UAE for symptomatic fibroids at a single institution (from May 2021 to May 2023). Participants were randomized one-to-one to undergo UAE with either RMs or TAGMs. Numeric rating scale pain scores and cumulative fentanyl consumption were assessed for 24 hours after undergoing UAE. Anti-Mullerian hormone was measured to assess effects of UAE on ovarian function. MRI was performed before and 3 months after UAE to evaluate fibroid necrosis and uterine artery recanalization. Repeated variables such as pain were analyzed using Mann-Whitney U test with post hoc Bonferroni correction. Results Sixty female participants (mean age, 45.7 years ± 3.6 [SD]) completed the study, with 30 in each group. No evidence of a difference in pain scores was observed between groups (P > .99). Moreover, there was no evidence of a difference in the total fentanyl consumption at 24 hours after UAE between groups (median: RMs, 423 [IQR, 330-530] vs TAGMs, 562 [IQR, 437-780]; P = .15). Serum anti-Mullerian hormone 3 months after UAE showed no evidence of a difference between groups (RMs vs TAGMs, 0.71 ng/mL ± 0.73 vs 0.49 ng/mL ± 0.45, respectively; P = .09). No evidence of a difference in the rate of complete necrosis of the dominant fibroid was observed between groups (97% [29 of 30] for both groups; P > .99). The rate of uterine artery recanalization was higher in RM versus TAGM groups (70% [21 of 30] vs 17% [five of 30], respectively; P < .001). Conclusion UAE with RMs, compared with UAE with TAGMs, showed no evidence of a difference in terms of therapeutic effectiveness or postprocedural pain scores in participants with symptomatic fibroids. Clinical trial registration no. NCT05086770 © RSNA, 2024 See also the editorial by Spies in this issue.

Thermal-Responsive Gel-Based Overheat Limiter Enabled Intelligent Photothermal Therapy.

Uncontrolled and excessive photothermal heating in photothermal therapy (PTT) inevitably causes thermal damage to surrounding normal tissues, severely limiting the universality and safety of PTT. To address this issue, an intelligent cooling thermal-responsive (ICTR) gel containing poly(N-isopropylacrylamide-co-acrylamide) (P(NIPAM-AM))microgel is applied onto the skin to realize intelligent PTT, which can avoid excessive heating and accidental injury. The high near-infrared (NIR) light transmittance (> 95%) of the ICTR gel ensures effective light delivery at low temperatures, while the refractive index of the P(NIPAM-AM) microgel increases remarkably when the temperature exceeds a predetermined threshold, resulting in progressively enhanced light scattering and weakened photothermal conversion. In animal studies, the negative feedback regulation of ICTR gel on light transmittance and photothermal heating allows the photothermal temperature in the lesion site to be stabilized within the effective therapeutic range (45 °C) while ensuring that the skin surface temperature does not exceed 35 °C. Compared with the severe skin thermal damage found in the histological staining of mice skin receiving conventional PTT, the mice skin receiving the ICTR gel-enabled intelligent PTT remains in good condition. This study establishes an intelligent and universal paradigm for PTT thermal regulation, which is of great significance for achieving safe and effective PTT.

Designing Tough Hydrogel Shells for Glucose Sensing.

Conventional hydrogel microcapsules often suffer from inadequate mechanical stability, hindering their use. Here, water-cored double-network (DN) hydrogel shells are designed, formed by polyacrylamide and calcium alginate networks using triple-emulsion templates. These DN hydrogel shells offer robust mechanical stability, optical transparency, and a precisely-defined cut-off threshold. The feasibility of this platform is demonstrated through the development of a fluorometric glucose sensor. Glucose oxidase is enclosed within the water core, while a pH-responsive fluorescent dye is incorporated into the DN shells. Glucose diffuses into the core through the DN shells, where the glucose oxidase converts glucose into gluconic acid, leading to pH reduction and a subsequent decrease in fluorescence intensity of DN shells. Additionally, the pH-sensitive colorant dissolved in the medium enables visual pH assessment. Thus, glucose levels can be determined using both fluorometric and colorimetric methods. Notably, the DN shells exhibit exceptional stability, enduring intense mechanical stress and cycles of drying and rehydration without leakage. Moreover, the DN shells act as effective barriers, safeguarding glucose oxidase against proteolysis by large disruptive proteins, like pancreatin. This versatile DN shell platform extends beyond glucose oxidase encapsulation, serving as a foundation for various capsule sensors utilizing enzymes and heterogeneous catalysts.

Tunable electrospun scaffolds of polyacrylonitrile loaded with carbon nanotubes: from synthesis to biological applications.

Growing cells in a biomimetic environment is critical for tissue engineering as well as for studying the cell biology underlying disease mechanisms. To this aim a range of 3D matrices have been developed, from hydrogels to decellularized matrices. They need to mimic the extracellular matrix to ensure the optimal growth and function of cells. Electrospinning has gained in popularity due to its capacity to individually tune chemistry and mechanical properties and as such influence cell attachment, differentiation or maturation. Polyacrylonitrile (PAN) derived electrospun fibres scaffolds have shown exciting potential due to reports of mechanical tunability and biocompatibility. Building on previous work we fabricate here a range of PAN fibre scaffolds with different concentrations of carbon nanotubes. We characterize them in-depth in respect to their structure, surface chemistry and mechanical properties, using scanning electron microscopy, image processing, ultramicrotomic transmission electron microscopy, x-ray nanotomography, infrared spectroscopy, atomic force microscopy and nanoindentation. Together the data demonstrate this approach to enable finetuning the mechanical properties, while keeping the structure and chemistry unaltered and hence offering ideal properties for comparative studies of the cellular mechanobiology. Finally, we confirm the biocompatibility of the scaffolds using primary rat cardiomyocytes, vascular smooth muscle (A7r5) and myoblast (C2C12) cell lines.

Optical fiber sensing probe for detecting a carcinoembryonic antigen using a composite sensitive film of PAN nanofiber membrane and gold nanomembrane.

An optical fiber sensing probe using a composite sensitive film of polyacrylonitrile (PAN) nanofiber membrane and gold nanomembrane is presented for the detection of a carcinoembryonic antigen (CEA), a biomarker associated with colorectal cancer and other diseases. The probe is based on a tilted fiber Bragg grating (TFBG) with a surface plasmon resonance (SPR) gold nanomembrane and a functionalized polyacrylonitrile (PAN) PAN nanofiber coating that selectively binds to CEA molecules. The performance of the probe is evaluated by measuring the spectral shift of the TFBG resonances as a function of CEA concentration in buffer. The probe exhibits a sensitivity of 0.46 dB/(µg/ml), a low limit of detection of 505.4 ng/mL in buffer, and a good selectivity and reproducibility. The proposed probe offers a simple, cost-effective, and a novel method for CEA detection that can be potentially applied for clinical diagnosis and monitoring of CEA-related diseases.

In vitro effects of wound-dressings on key wound healing properties of dermal fibroblasts.

Healing of complex wounds requires dressings that must, at least, not hinder and should ideally promote the activity of key healing cells, in particular fibroblasts. This in vitro study assessed the effects of three wound-dressings (a pure Ca2+ alginate: Algostéril®, a Ca2+ alginate + carboxymethylcellulose: Biatain alginate® and a polyacrylate impregnated with lipido-colloid matrix: UrgoClean®) on dermal fibroblast activity. The results showed the pure calcium alginate to be non-cytotoxic, whereas the other wound-dressings showed moderate to strong cytotoxicity. The two alginates stimulated fibroblast migration and proliferation, whereas the polyacrylate altered migration and had no effect on proliferation. The pure Ca2+ alginate significantly increased the TGF-ß-induced fibroblast activation, which is essential to healing. This activation was confirmed by a significant increase in Vascular endothelial growth factor (VEGF) secretion and a higher collagen production. The other dressings reduced these fibroblast activities. The pure Ca2+ alginate was also able to counteract the inhibitory effect of NK cell supernatants on fibroblast migration. These in vitro results demonstrate that tested wound-dressings are not equivalent for fibroblast activation. Only Algostéril was found to promote all the fibroblast activities tested, which could contribute to its healing efficacy demonstrated in the clinic.

Effect of Polymer Architecture and Acidic Group Density on the Degree of Salt Formation in Amorphous Solid Dispersions.

Recent work has shown that an amorphous drug-polymer salt can be highly stable against crystallization under hot and humid storage conditions (e.g., 40 °C/75% RH) and provide fast release and that these advantages depend on the degree of salt formation. Here, we investigate the salt formation between the basic drug lumefantrine (LMF) and several acidic polymers: poly(acrylic acid) (PAA), hypromellose phthalate (HPMCP), hypromellose acetate succinate (HPMCAS), cellulose acetate phthalate (CAP), Eudragit L100, and Eudragit L100-55. Salt formation was performed by "slurry synthesis" where dry components were mixed at room temperature in the presence of a small quantity of an organic solvent, which was subsequently removed. This method achieved more complete salt formation than the conventional methods of hot-melt extrusion and rotary evaporation. The acidic group density of a polymer was determined by nonaqueous titration in the same solvent used for slurry synthesis; the degree of LMF protonation was determined by X-ray photoelectron spectroscopy. The polymers studied show very different abilities to protonate LMF when compared at a common drug loading, following the order PAA > (HPMCP ∼ CAP ∼ L100 ∼ L100-55) > HPMCAS, but the difference largely disappears when the degree of protonation is plotted against the concentration of the available acidic groups for reaction. This indicates that the extent of salt formation is mainly controlled by the acidic group density and is less sensitive to the polymer architecture. Our results are relevant for selecting the optimal polymer to control the degree of ionization in amorphous solid dispersions.

Bioinspired Lubricity from Surface Gel Layers.

Surface gel layers on commercially available contact lenses have been shown to reduce frictional shear stresses and mitigate damage during sliding contact with fragile epithelial cell layers in vitro. Spencer and co-workers recently demonstrated that surface gel layers could arise from oxygen-inhibited free-radical polymerization. In this study, polyacrylamide hydrogel shell probes (7.5 wt % acrylamide, 0.3 wt % N,N'-methylenebisacrylamide) were polymerized in three hemispherical molds listed in order of decreasing surface energy and increasing oxygen permeability: borosilicate glass, polyether ether ketone (PEEK), and polytetrafluoroethylene (PTFE). Hydrogel probes polymerized in PEEK and PTFE molds exhibited 100× lower elastic moduli at the surface (EPEEK* = 80 ± 31 and EPTFE* = 106 ± 26 Pa, respectively) than those polymerized in glass molds (Eglass* = 31,560 ± 1,570 Pa), in agreement with previous investigations by Spencer and co-workers. Biotribological experiments revealed that hydrogel probes with surface gel layers reduced frictional shear stresses against cells (τPEEK = 35 ± 15 and τPTFE = 22 ± 16 Pa) more than those without (τglass = 68 ± 15 Pa) and offered greater protection against cell damage when sliding against human telomerase-immortalized corneal epithelial (hTCEpi) cell monolayers. Our work demonstrates that the "mold effect" resulting in oxygen-inhibition polymerization creates hydrogels with surface gel layers that reduce shear stresses in sliding contact with cell monolayers, similar to the protection offered by gradient mucin gel networks across epithelial cell layers.

Synergistic Dual Antibacterial Activity of Magnetite Hydrogels Doped with Silver.

In this work, we utilized poly-N-isopropylacrylamide (NIPAM), magnetic nanoparticles (MNPs), and silver nitrate to prepare magnetic hydrogel microparticles doped with silver, which exhibited a dual antimicrobial effect. The antibacterial effect of these composites was mediated by the antimicrobial activity of silver and the magnetic hyperthermic induction, which we believe increased biofilm disruption and silver release into the surrounding bacterial biofilms. The prepared particles were characterized by using several analytical techniques. The particles exhibited a porous morphology impregnated evenly with silver nanoparticles, as observed by scanning electron microscopy (SEM). Furthermore, we examined the antibacterial activity of our microparticles against Escherichia coli by determining the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Our findings revealed that the composites demonstrated significant antibacterial activity of up to 81% under magnetic hyperthermia as compared to 45% when samples were heated to the same temperature in a water bath at constant silver concentration. This demonstrates the distinctive inhibitory features of MNPs in enhancing bacterial killing when a magnetic field is applied. The findings of this study lay the groundwork for further exploration of microparticle-based antimicrobial therapies, which can contribute to the development of more advanced wound healing devices and better sterilization methods for medical devices.

Bioinspired Photoelectronic Synergy Coating with Antifogging and Antibacterial Properties.

Optically transparent glass with antifogging and antibacterial properties is in high demand for endoscopes, goggles, and medical display equipment. However, many of the previously reported coatings have limitations in terms of long-term antifogging and efficient antibacterial properties, environmental friendliness, and versatility. In this study, inspired by catfish and sphagnum moss, a novel photoelectronic synergy antifogging and antibacterial coating was prepared by cross-linking polyethylenimine-modified titanium dioxide (PEI-TiO2), polyvinylpyrrolidone (PVP), and poly(acrylic acid) (PAA). The as-prepared coating could remain fog-free under hot steam for more than 40 min. The experimental results indicate that the long-term antifogging properties are due to the water absorption and spreading characteristics. Moreover, the organic-inorganic hybrid of PEI and TiO2 was first applied to enhance the antibacterial performance. The Staphylococcus aureus and the Escherichia coli growth inhibition rates of the as-prepared coating reached 97 and 96% respectively. A photoelectronic synergy antifogging and antibacterial mechanism based on the positive electrical and photocatalytic properties of PEI-TiO2 was proposed. This investigation provides insight into designing multifunctional bioinspired surface materials to realize antifogging and antibacterial that can be applied to medicine and daily lives.

Ecofriendly Controlled-Release Insecticide Carrier: pH-/Temperature-Responsive Rosin-Derived Hydrogels for Avermectin Delivery against Mythimna separata (Walker).

The exploration of environmentally friendly, less toxic, sustained-release insecticide is increasing with the growing demand for food to meet the requirements of the expanding population. As a sustained-release carrier, the unique, environmentally friendly intelligent responsive hydrogel system is an important factor in improving the efficiency of insecticide utilization and accurate release. In this study, we developed a facile approach for incorporating the natural compound rosin (dehydroabietic acid, DA) and zinc ions (Zn2+) into a poly(N-isopropylacrylamide) (PNIPAM) hydrogel network to construct a controlled-release hydrogel carrier (DA-PNIPAM-Zn2+). Then, the model insecticide avermectin (AVM) was encapsulated in the carrier at a drug loading rate of 36.32% to form AVM@DA-PNIPAM-Zn2+. Surprisingly, the smart controlled carrier exhibited environmental responsiveness, strongly enhanced mechanical properties, self-healing ability, hydrophobicity, and photostability to ensure a balance between environmental friendliness and the precision of the drug release. The release experiments showed that the carboxyl and amide groups in the polymer chains alter the intermolecular forces within the hydrogel meshes and ingredient diffusion by changing temperatures (25 and 40 °C) and pH values (5.8, 7.4, and 8.5), leading to different release behaviors. The insecticidal activity of the AVM@DA-PNIPAM-Zn2+ against oriental armyworms was good, with an effective minimum toxicity toward aquatic animals. Therefore, AVM@DA-PNIPAM-Zn2+ is an effective drug delivery system against oriental armyworms. We anticipate that this ecofriendly, sustainable, smart-response carrier may broaden the utilization rosin and its possible applications in the agricultural sector.

Molecularly Engineered Supramolecular Thermoresponsive Hydrogels with Tunable Mechanical and Dynamic Properties.

Synthetic supramolecular polymers and hydrogels in water are emerging as promising biomaterials due to their modularity and intrinsic dynamics. Here, we introduce temperature sensitivity into the nonfunctionalized benzene-1,3,5-tricarboxamide (BTA-EG4) supramolecular system by incorporating a poly(N-isopropylacrylamide)-functionalized (BTA-PNIPAM) moiety, enabling 3D cell encapsulation applications. The viscous and structural properties in the solution state as well as the mechanical and dynamic features in the gel state of BTA-PNIPAM/BTA-EG4 mixtures were investigated and modulated. In the dilute state (c ∼µM), BTA-PNIPAM acted as a chain capper below the cloud point temperature (Tcp = 24 °C) but served as a cross-linker above Tcp. At higher concentrations (c ∼mM), weak or stiff hydrogels were obtained, depending on the BTA-PNIPAM/BTA-EG4 ratio. The mixture with the highest BTA-PNIPAM ratio was ∼100 times stiffer and ∼10 times less dynamic than BTA-EG4 hydrogel. Facile cell encapsulation in 3D was realized by leveraging the temperature-sensitive sol-gel transition, opening opportunities for utilizing this hydrogel as an extracellular matrix mimic.