ABSTRACT
BACKGROUND: The general sluggish clearance kinetics of functional inorganic nanoparticles tend to raise potential biosafety concerns for in vivo applications. Renal clearance is a possible elimination pathway for functional inorganic nanoparticles delivered through intravenous injection, but largely depending on the surface physical chemical properties of a given particle apart from its size and shape. RESULTS: In this study, three small-molecule ligands that bear a diphosphonate (DP) group, but different terminal groups on the other side, i.e., anionic, cationic, and zwitterionic groups, were synthesized and used to modify ultrasmall Fe3O4 nanoparticles for evaluating the surface structure-dependent renal clearance behaviors. Systematic studies suggested that the variation of the surface ligands did not significantly increase the hydrodynamic diameter of ultrasmall Fe3O4 nanoparticles, nor influence their magnetic resonance imaging (MRI) contrast enhancement effects. Among the three particle samples, Fe3O4 nanoparticle coated with zwitterionic ligands, i.e., Fe3O4@DMSA, exhibited optimal renal clearance efficiency and reduced reticuloendothelial uptake. Therefore, this sample was further labeled with 99mTc through the DP moieties to achieve a renal-clearable MRI/single-photon emission computed tomography (SPECT) dual-modality imaging nanoprobe. The resulting nanoprobe showed satisfactory imaging capacities in a 4T1 xenograft tumor mouse model. Furthermore, the biocompatibility of Fe3O4@DMSA was evaluated both in vitro and in vivo through safety assessment experiments. CONCLUSIONS: We believe that the current investigations offer a simple and effective strategy for constructing renal-clearable nanoparticles for precise disease diagnosis.
Subject(s)
Kidney , Magnetic Resonance Imaging , Tomography, Emission-Computed, Single-Photon , Animals , Magnetic Resonance Imaging/methods , Mice , Tomography, Emission-Computed, Single-Photon/methods , Ligands , Kidney/diagnostic imaging , Kidney/metabolism , Cell Line, Tumor , Contrast Media/chemistry , Female , Mice, Inbred BALB C , Humans , Tissue Distribution , Neoplasms/diagnostic imaging , Magnetite Nanoparticles/chemistry , Nanoparticles/chemistryABSTRACT
Nanomaterials are increasingly being employed for biomedical applications, necessitating a comprehensive understanding of their degradation behavior and potential toxicity in the biological environment. This study utilizes a continuous flow system to simulate the biologically relevant degradation conditions and investigate the effects of pH, protein, redox species, and chelation ligand on the degradation of iron oxide nanoparticles. The morphology, aggregation state, and relaxivity of iron oxide nanoparticles after degradation are systematically characterized. The results reveal that the iron oxide nanoparticles degrade at a significantly higher rate under the acidic environment. Moreover, incubation with bovine serum albumin enhances the stability and decreases the dissolution rate of iron oxide nanoparticles. In contrast, glutathione accelerates the degradation of iron oxide nanoparticles, while the presence of sodium citrate leads to the fastest degradation. This study reveals that iron oxide nanoparticles undergo degradation through various mechanisms in different biological microenvironments. Furthermore, the dissolution and aggregation of iron oxide nanoparticles during degradation significantly impact their relaxivity, which has implications for their efficacy as magnetic resonance imaging contrast agents in vivo. The results provide valuable insights for assessing biosafety and bridge the gap between fundamental research and clinical applications of iron oxide nanoparticles.
Subject(s)
Contrast Media , Ferric Compounds , Ferric Compounds/chemistry , Contrast Media/chemistry , Sodium Citrate , Magnetic Iron Oxide NanoparticlesABSTRACT
Soft electronic circuits are crucial for wearable electronics, biomedical technologies, and soft robotics, requiring soft conductive materials with high conductivity, high strain limit, and stable electrical performance under deformation. Liquid metals (LMs) have become attractive candidates with high conductivity and fluidic compliance, while effective manufacturing methods are demanded. Digital light processing (DLP)-based projection lithography is a high-resolution and high-throughput printing technique for primarily polymers and some metals. If LMs can be printed with DLP as well, the entire soft devices can be fabricated by one printer in a streamlined and highly efficient process. Herein, fast and facile DLP-based LM printing is achieved. Simply with 5-10 s of patterned ultraviolet (UV)-light exposure, a highly conductive and stretchable pattern can be printed using a photo-crosslinkable LM particle ink. The printed eutectic gallium indium traces feature high resolution (≈20 µm), conductivity (3 × 106 S m-1 ), stretchability (≈2500%), and excellent stability (consistent performance at different deformation). Various patterns are printed in diverse material systems for broad applications including stretchable displays, epidermal strain sensors, heaters, humidity sensors, conformal electrodes for electrography, and multi-layer actuators. The facile and scalable process, excellent performance, and diverse applications ensure its broad impact on soft electronic manufacturing.
ABSTRACT
The high mortality of breast cancer is closely related to lymph node (LN) metastasis. Sentinel LNs (SLNs) are the first station where tumor cells metastasize through the lymphatic system. As such, achieving precise diagnosis of the early metastatic status of SLNs during surgery is of paramount importance for precision therapy of breast cancer. While invasive SLNs biopsy is the gold standard for evaluating the status of SLNs, its use is often time-consuming and may increase the risk of operation. It is still challenging to develop a means for rapid SLN metastasis diagnosis. Herein, NaGdF4:5%Nd@NaLuF4 rare earth nanoparticles (Gd:Nd-RENPs) with near-infrared-II (NIR-II) fluorescence and magnetic resonance imaging (MRI) properties were fabricated. With the nanoprobe, metastatic SLNs and lymph vessels (LVs) rapidly brighten and can be observed by the NIR-II imaging system, which is totally different from normal LNs and LVs. The remarkable contrast observed via NIR-II imaging serves to swiftly delineate metastatic SLNs from normal ones, subsequently guiding precise surgical resection of metastatic LNs in just 10 minutes. Furthermore, the consistency between the results obtained via MRI and NIR-II imaging further validates the dependability of this nanoprobe as a diagnostic tool for metastatic SLNs. Additionally, the Gd:Nd-RENPs exhibited good biocompatibility in vitro and in vivo. In this study, we demonstrated the advantages and prospects of NIR-II imaging for intraoperative early SLN metastasis assessment and shed light on the potential of the dual-modal Gd:Nd-RENPs as a nanoprobe.
ABSTRACT
The easy recurrence and high metastasis of fatal tumors require the development of a combination therapy, which is able to overcome the drawbacks of monomodal strategies such as surgery, photodynamic therapy (PDT), and radiotherapy (RT). Taking the complementary advantages of PDT and RT, we present herein the integration of lanthanide-doped upconversion nanoparticles (UCNPs) with chlorin e6 (Ce6)-imbedded RBC membrane vesicles as a near-infrared-induced PDT agent for achieving synchronous depth PDT and RT with reduced radiation exposure. In such a nanoagent, gadolinium-doped UCNPs with strong X-ray attenuation ability act not only as a light transductor to activate the loaded photosensitizer Ce6 to allow PDT but also as a radiosensitizer to enhance RT. PDT with enhanced low-dose RT can achieve synergistic inhibition of tumor growth by producing reactive oxygen species to destroy local tumor cells and inducing strong T-cell-dependent immunogenic cell death to arrest systemic cancer metastasis. This combination of PDT and RT might be a potential appealing strategy for tumor eradication.
Subject(s)
Nanoparticles , Photochemotherapy , Porphyrins , Cell Line, Tumor , Biomimetics , Photosensitizing Agents/pharmacology , Photosensitizing Agents/therapeutic use , Combined Modality Therapy , Nanoparticles/therapeutic use , Porphyrins/pharmacology , Porphyrins/therapeutic useABSTRACT
Lesion areas are distinguished from normal tissues surrounding them by distinct physiological characteristics. These features serve as biological hallmarks with which targeted biomedical imaging of the lesion sites can be achieved. Although tremendous efforts have been devoted to providing smart imaging probes with the capability of visualizing the physiological hallmarks at the molecular level, the majority of them are merely able to derive anatomical information from the tissues of interest, and thus are not suitable for taking part in in vivo quantification of the biomarkers. Recent advances in chemical construction of advanced ratiometric nanoprobes (RNPs) have enabled a horizon for quantitatively monitoring the biological abnormalities in vivo. In contrast to the conventional probes whose dependency of output on single-signal profiles restricts them from taking part in quantitative practices, RNPs are designed to provide information in two channels, affording a self-calibration opportunity to exclude the analyte-independent factors from the outputs and address the issue. Most of the conventional RNPs have encountered several challenges regarding the reliability and sufficiency of the obtained data for high-performance imaging. In this Review, we have summarized the recent progresses in developing highly advanced RNPs with the capabilities of deriving maximized information from the lesion areas of interest as well as adapting themselves to the complex biological systems in order to minimize microenvironmental-induced falsified signals. To provide a better outlook on the current advanced RNPs, nanoprobes based on optical, photoacoustic, and magnetic resonance imaging modalities for visualizing a wide range of analytes such as pH, reactive species, and different derivations of amino acids have been included. Furthermore, the physicochemical properties of the RNPs, the major constituents of the nanosystems and the analyte recognition mechanisms have been introduced. Moreover, the alterations in the values of the ratiometric signal in response to the analyte of interest as well as the time at which the highest value is achieved, have been included for most of RNPs discussed in this Review. Finally, the challenges as well as future perspectives in the field are discussed.
Subject(s)
Amino Acids , Magnetic Resonance Imaging , Reproducibility of ResultsABSTRACT
As the soaring demand for energy storage continues to grow, batteries that can cope with extreme conditions are highly desired. Yet, existing battery materials are limited by weak mechanical properties and freeze-vulnerability, prohibiting safe energy storage in devices that are exposed to low temperature and unusual mechanical impacts. Herein, a fabrication method harnessing the synergistic effect of co-nonsolvency and "salting-out" that can produce poly(vinyl alcohol) hydrogel electrolytes with unique open-cell porous structures, composed of strongly aggregated polymer chains, and containing disrupted hydrogen bonds among free water molecules, is introduced. The hydrogel electrolyte simultaneously combines high strength (tensile strength 15.6 MPa), freeze-tolerance (< -77 °C), high mass transport (10× lower overpotential), and dendrite and parasitic reactions suppression for stable performance (30 000 cycles). The high generality of this method is further demonstrated with poly(N-isopropylacrylamide) and poly(N-tertbutylacrylamide-co-acrylamide) hydrogels. This work takes a further step toward flexible battery development for harsh environments.
ABSTRACT
Magnetic resonance imaging (MRI)/nuclear medicine imaging (NMI) dual-modality imaging based on radiolabeled nanoparticles has been increasingly exploited for accurate diagnosis of tumor and cardiovascular diseases by virtue of high spatial resolution and high sensitivity. However, significant challenges exist in pursuing truly clinical applications, including massive preparation and rapid radiolabeling of nanoparticles. Herein, we report a clinically translatable kit for the convenient construction of MRI/NMI nanoprobes relying on the flow-synthesis and anchoring group-mediated radiolabeling (LAGMERAL) of iron oxide nanoparticles. First, homogeneous iron oxide nanoparticles with excellent performance were successfully obtained on a large scale by flow synthesis, followed by the surface anchoring of diphosphonate-polyethylene glycol (DP-PEG) to simultaneously render the underlying nanoparticles biocompatible and competent in robust labeling of radioactive metal ions. Moreover, to enable convenient and safe usage in clinics, the DP-PEG modified nanoparticle solution was freeze-dried and sterilized to make a radiolabeling kit followed by careful evaluations of its in vitro and in vivo performance and applicability. The results showed that 99mTc labeled nanoprobes are effectively obtained with a labeling yield of over 95% in 30 minutes after simply injecting Na[99mTcO4] solution into the kit. In addition, the Fe3O4 nanoparticles sealed in the kit can well stand long-term storage even for 300 days without deteriorating the colloidal stability and radiolabeling yield. Upon intravenous injection of the as-prepared radiolabeled nanoprobes, high-resolution vascular images of mice were obtained by vascular SPECT imaging and magnetic resonance angiography, demonstrating the promising clinical translational value of our radiolabeling kit.
Subject(s)
Nanoparticles , Nuclear Medicine , Mice , Animals , Radionuclide Imaging , Tomography, Emission-Computed, Single-Photon/methods , Magnetic Resonance Imaging/methods , Polyethylene GlycolsABSTRACT
Hypoxia is a common biological condition in many malignant solid tumors that plays an imperative role in regulating tumor growth and impacting the treatment's therapeutic effect. Therefore, the hypoxia assessment is of great significance in predicting tumor development and evaluating its prognosis. Among the plenty of existing tumor diagnosis techniques, magnetic resonance imaging (MRI) offers certain distinctive features, such as being free of ionizing radiation and providing images with a high spatial resolution. In this study, we develop a fluorescent traceable and hypoxia-sensitive T1-weighted MRI probe (Fe3O4-Met-Cy5.5) via conjugating notable hypoxia-sensitive metronidazole moiety and Cy5.5 dye with ultrasmall iron oxide (Fe3O4) nanoparticles. The results of in vitro and in vivo experiments show that Fe3O4-Met-Cy5.5 has excellent performance in relaxivity, biocompatibility, and hypoxia specificity. More importantly, the obvious signal enhancement in hypoxic areas indicates that the probe has great feasibility for sensing tumor hypoxia via T1-weighted MRI. These promising results may unlock the potential of Fe3O4 nanoparticles as T1-weighted contrast agents for the development of clinical hypoxia probes.
Subject(s)
Magnetite Nanoparticles , Nanoparticles , Neoplasms , Humans , Contrast Media , Tumor Hypoxia , Metronidazole , Magnetic Resonance Imaging/methods , Neoplasms/diagnostic imaging , Neoplasms/pathology , Hypoxia/diagnostic imaging , Magnetic Iron Oxide NanoparticlesABSTRACT
Bioluminescence (BL) imaging has emerged to tackle the potential challenges of fluorescence (FL) imaging including the autofluorescence background, inhomogeneous illumination over a wide imaging field, and the light-induced overheating effect. Taking advantage of the bioluminescence resonance energy transfer (BRET) mechanism between a conventional luciferin compound and a suitable acceptor, the visible light of the former can be extended to photons with longer wavelengths emitting from the latter. Although BRET-based self-illuminating imaging probes have already been prepared, employing potentially cytotoxic elements as the acceptor with the emission wavelengths which hardly reach the first near-infrared (NIR-I) window, has limited their applications as safe and high performance in vivo imaging agents. Herein, we report a biocompatible, self-illuminating, and second near-infrared (NIR-II) emissive probe to address the cytotoxicity concerns as well as improve the penetration depth and spatiotemporal resolution of BL imaging. To this end, NanoLuc luciferase enzyme molecules were immobilized on the surface of silver sulfide quantum dots to oxidize its luciferin substrate and initiate a single-step BRET mechanism, resulting in NIR-II photons from the quantum dots. The resulting dual modality (BL/FL) probes were successfully applied to in vivo tumor imaging in mice, demonstrating that NIR-II BL signals could be easily detected from the tumor sites, giving rise to â¼2 times higher signal-to-noise ratios compared to those obtained under FL mode. The results indicated that nontoxic NIR-II emitting nanocrystals deserve more attention to be tailored to fill the growing demands of preparing appropriate agents for high quality BL imaging.
Subject(s)
Neoplasms , Quantum Dots , Animals , Mice , Quantum Dots/chemistry , Luciferases , Optical Imaging/methodsABSTRACT
Metal patterning via additive manufacturing has been phasing-in to broad applications in many medical, electronics, aerospace, and automotive industries. While previous efforts have produced various promising metal-patterning strategies, their complexity and high cost have limited their practical application in rapid production and prototyping. Herein, a one-step gold printing technique based on anion-assisted photochemical deposition (APD), which can directly print highly conductive gold patterns (1.08 × 107 S m-1 ) under ambient conditions without post-annealing treatment, is introduced. Uniquely, the APD uses specific ion effects with projection lithography to pattern Au nanoparticles and simultaneously sinter them into tunable porous gold structures. The significant influence of kosmotropic or chaotropic anions in the precursor ink on tuning the morphologies and conductivities of the printed patterns by employing a series of different ions, including Cl- ions, in the printing process is presented. Additionally, the resistance stabilities and the electrochemical properties of the APD-printed gold patterns are carefully investigated. The high conductivity and excellent conformability of the printed Au electrodes are demonstrated with reliable performance in electrophysiological signal delivery and acquisition for biomedical applications. This work exploits the potential of photochemical-deposition-based metal patterning in flexible electronic manufacturing.
ABSTRACT
Icing and frosting on transparent surfaces compromise visibility on various optical equipment and transparent infrastructures. It remains challenging to fabricate energy-saving coatings for harvesting solar energy while maintaining high transparency. Here, transparent, photothermic, and icephobic composite surfaces composed of photothermal nanomaterials and polyelectrolytes via layer-by-layer assembly are designed and constructed. The positively-charged polypyrrole nanoparticles and negatively-charged poly(acrylic acid) are assembled as exemplary materials via electrostatic attractions. The optically transparent photothermal coatings are successfully fabricated and exhibited photothermal capabilities and light-transmittance performance. Among the various coatings applied, the seven-bilayer coating can increase the temperature by 35 °C under 1.9-sun illumination, maintaining high transmittance (>60%) of visible light. With sunlight illumination at subzero temperatures (> -35 °C), the coatings show pronounced capabilities to inhibit freezing, melt accumulated frost, and decrease ice adhesion. Precisely, the icephobic surfaces remain free of frost at -35 °C as long as sunlight illumination is present; the accumulated frost melts rapidly within 300 s. The ice adhesion strength decreases to ≈0 kPa as the melted water acts as a lubricant. Furthermore, the negatively-charged graphene oxide and positively-charged poly(diallyldimethylammonium chloride) show their material diversity applicable in the coating fabrication.
ABSTRACT
Ice structures and their formation process are fundamentally important to cryobiology, geoscience, and physical chemistry. In this work, we synthesized gold nanoprobes by grafting water-soluble polyethylene glycol (PEG) onto spherical gold nanoparticles and analyzed the structure of ice formation in the vicinity of the resulting hybrid PEG-Au nanoparticles (AuPEGNPs). Temperature-dependent in situ small-angle X-ray scattering (SAXS) indicated that AuPEGNPs, like PEG, caused the formation of bulk spherulite ice. Unlike for PEG, we observed the formation of lamellar ice with a periodicty of 4.6 nm, which is thermodynamically less stable than the bulk form. The lamellar ice formed after AuPEGNP agglomeration during cooling at -19 °C, and it remained during subsequent heating from -20 to -11 °C and melted at around -10 °C, far below the melting temperature of bulk ice. We explain different effects of AuPEGNP and free PEG on ice formation by the topological differences. The highly concentrated PEG chains on the agglomerated Au cores lead to the formation of PEG-hydrates that assemble into lamellar ice with a periodicity of 4.6 nm.
ABSTRACT
Quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) has become a popular technique to assess gene expression. Suitable reference genes are normally identified first to ensure accurate normalization. The aim of the present study was to select the most stable genes in embryonic developmental stages, the early development of immune organs, and cells infected with Chinese rice-field eel rhabdovirus (CrERV) of the rice-field eel (Monopterus albus). Four reference genes, including those encoding 18S ribosomal RNA (18SrRNA), beta actin (ß-actin), elongation factor 1 alpha (EF1É), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were assessed using geNorm, NormFinder, BestKeeper, and RefFinder software. Analyses indicated the stability ranking was 18SrRNA > ß-actin > GAPDH > EF1α in the embryonic stage, with 18SrRNA as the most stable reference gene. For immunity-related organs at different developmental stages, the order in the thymus was ß-actin > GAPDH > EF1α > 18SrRNA, with ß-actin as the most stable gene. In both spleen and kidney tissues, the rank order was EF1É > GAPDH > ß-actin > 18SrRNA, with EF1α as the most stable gene. Furthermore, in rice-field eel kidney (CrE-K) cells infected with CrERV, the ranking was EF1É > ß-actin > GAPDH > 18SrRNA, with EF1α as the most stable gene. The results for cells infected with CrERV were verified by testing signaling pathway genes catenin beta 1 (CTNNB1) and NOTCH1 based on the above four genes after virus infection in CrE-K cells. This study laid the foundation for choosing suitable reference genes for immunity-related gene expression analysis in rice-field eel.
Subject(s)
Rhabdoviridae Infections/veterinary , Smegmamorpha , Actins/genetics , Animals , Gene Expression Profiling , Glyceraldehyde-3-Phosphate Dehydrogenases/genetics , RNA, Ribosomal, 18S/genetics , Real-Time Polymerase Chain Reaction/veterinary , Reference Standards , Reverse Transcriptase Polymerase Chain Reaction/veterinary , Rhabdoviridae , Smegmamorpha/genetics , Smegmamorpha/immunology , Smegmamorpha/virologyABSTRACT
Hydrogels have gained tremendous attention due to their versatility in soft electronics, actuators, biomedical sensors, etc. Due to the high water content, hydrogels are usually soft, weak, and freeze below 0°C, which brings severe limitations to applications such as soft robotics and flexible electronics in harsh environments. Most existing anti-freezing gels suffer from poor mechanical properties and urgently need further improvements. Here, we took inspirations from tendon and coniferous trees and provided an effective method to strengthen polyvinyl alcohol (PVA) hydrogel while making it freeze resistant. The salting-out effect was utilized to create a hierarchically structured polymer network, which induced superior mechanical properties (Young's modulus: 10.1 MPa, tensile strength: 13.5 MPa, and toughness: 127.9 MJ/m3). Meanwhile, the cononsolvency effect was employed to preserve the structure and suppress the freezing point to -60°C. Moreover, we have demonstrated the broad applicability of our material by fabricating PVA hydrogel-based hydraulic actuators and ionic conductors.
ABSTRACT
Understanding the effects of soluble impurities or suspended particles on ice growth is of significant importance from Earth science to materials engineering. Ions are common impurities with ice in a wide range of fields, but their effects on ice growth remain largely elusive. Here, we studied the ion-specific effects on single ice crystal growth in various electrolyte and polyelectrolyte solutions and found F- and NH4+ show remarkable abilities of inducing single ice crystals to form hexagonal shapes and reducing the growth rates of ice crystals. Molecular dynamics simulations reveal the accumulation of F- around the ice/solution interface that plays a key role in the shapes and growth rates of single ice crystals. The understanding of ion-specific effects on ice growth opens up more possibilities for improving related fields, e.g., freeze desalination and cryopreservation.
ABSTRACT
Inspired by the biological self-recovery mechanism of superhydrophobicity, a new class of waxgel material with sustainable hierarchical surface micro-structures has been reported. After being damaged or removed, the waxgel material can self-reconstruct its surface layer both chemically and structurally, as well as successfully recovers its superhydrophobicity. In addition, it shows non-fluorinated composition, durability to severe mechanical challenges, and self-recoverable surface structures without external input of any kind such as; heat, UV, plasma etc., which distinguishes waxgel from any previous self-healing superhydrophobic systems. This strategy will open a new path for improving the long-term functionality of different interfacial materials.
ABSTRACT
All-solid-state supercapacitors are seeing emerging applications in flexible and stretchable electronics. Supercapacitors with high capacitance, high power density, simple form factor, and good mechanical robustness are highly desired, which demands electrode materials with high surface area, high mass loading, good conductivity, larger thickness, low tortuosity, and high toughness. However, it has been challenging to simultaneously realize them in a single material. By compositing a superficial layer of tough hydrogel on conductive and low tortuous foams, a thick capacitor electrode with large capacitance (5.25 F cm-2 ), high power density (41.28 mW cm-2 ), and good mechanical robustness (ε = 140%, Γ = 1000 J m-2 ) is achieved. The tough hydrogel serves as both a load-bearing layer to maintain structural integrity during deformation and a permeable binder to allow interaction between the conductive electrode and electrolyte. It is shown that the tough hydrogel reinforcement is beneficial for both electrical and mechanical stability. With a simple design and facile fabrication, this strategy is generalizable for various conductive materials.
ABSTRACT
The inhibition of condensation freezing under extreme conditions (i.e., ultra-low temperature and high humidity) remains a daunting challenge in the field of anti-icing. As water vapor easily condensates or desublimates and melted water refreezes instantly, these cause significant performance decrease of most anti-icing surfaces at such extreme conditions. Herein, inspired by wheat leaves, an effective condensate self-removing solar anti-icing/frosting surface (CR-SAS) is fabricated using ultrafast pulsed laser deposition technology, which exhibits synergistic effects of enhanced condensate self-removal and efficient solar anti-icing. The superblack CR-SAS displays superior anti-reflection and photothermal conversion performance, benefiting from the light trapping effect in the micro/nano hierarchical structures and the thermoplasmonic effect of the iron oxide nanoparticles. Meanwhile, the CR-SAS displays superhydrophobicity to condensed water, which can be instantly shed off from the surface before freezing through self-propelled droplet jumping, thus leading to a continuously refreshed dry area available for sunlight absorption and photothermal conversion. Under one-sun illumination, the CR-SAS can be maintained ice free even under an ambient environment of -50 °C ultra-low temperature and extremely high humidity (ice supersaturation degree of â¼260). The excellent environmental versatility, mechanical durability, and material adaptability make CR-SAS a promising anti-icing candidate for broad practical applications even in harsh environments.
ABSTRACT
Crosslinked polymers and gels are important in soft robotics, solar vapor generation, energy storage, drug delivery, catalysis, and biosensing. However, their attractive mass transport and volume-changing abilities are diffusion-limited, requiring miniaturization to avoid slow response. Typical approaches to improving diffusion in hydrogels sacrifice mechanical properties by increasing porosity or limit the total volumetric flux by directionally confining the pores. Despite tremendous efforts, simultaneous enhancement of diffusion and mechanical properties remains a long-standing challenge hindering broader practical applications of hydrogels. In this work, cononsolvency photopolymerization is developed as a universal approach to overcome this swelling-mechanical property trade-off. The as-synthesized poly(N-isopropylacrylamide) hydrogel, as an exemplary system, presents a unique open porous network with continuous microchannels, leading to record-high volumetric (de)swelling speeds, almost an order of magnitude higher than reported previously. This swelling enhancement comes with a simultaneous improvement in Young's modulus and toughness over conventional hydrogels fabricated in pure solvents. The resulting fast mass transport enables in-air operation of the hydrogel via rapid water replenishment and ultrafast actuation. The method is compatible with 3D printing. The generalizability is demonstrated by extending the technique to poly(N-tertbutylacrylamide-co-polyacrylamide) and polyacrylamide hydrogels, non-temperature-responsive polymer systems, validating the present hypothesis that cononsolvency is a generic phenomenon driven by competitive adsorption.