Phase-Change Materials for Controlled Release and Related Applications

Application of fatty acid-based eutectic mixture as a phase change material in microencapsulation of drugs: preparation, characterization and release behavior

Recently, microencapsulation has developed in various industries with its versatile applications. Its profound impact is particularly notable in the chemical, food, and pharmaceutical sectors. Among its research areas, the microencapsulation of drugs using phase change materials (PCMs) stands out as a groundbreaking advancement in drug delivery systems. This innovative approach involves encasing drugs within a PCM shell, significantly enhancing their stability and delivery regulation. The focus of our study is the microencapsulation of certain drugs with poor water solubility namely, cyclosporine, baclofen, and biotin within a bio-based PCM. It has identified PCMs with phase transition temperatures near human body temperature ( 310 K) as ideal candidates for this purpose. A eutectic mixture of stearic-lauric acid in a 1:3 mole ratio was selected for its optimal phase change properties to create microcapsules with core-shell morphology in spherical form. Our comprehensive characterization of the microcapsules, validated by FT-IR and SEM techniques, confirms their proper formation. All studied drugs microencapsulated with the PCM exhibited an excellent thermal stability at working temperature from thermal stability analysis based on TGA results. Furthermore, differential scanning calorimetry (DSC) tests conducted on the microencapsulated drugs obtained the melting point of all three microencapsulated drugs near the melting point of PCM. Also, the release behavior of drugs from drug delivery method was investigated in PBS (pH 7.4) and two temperatures (310.15 and 318.15) K. Drug release occurred sustainably, such that 50% and about 60% of the total of each drug was released from the microcapsules at mentioned temperatures respectively during 24 h.

Structured Liquid-in-Liquid Emulsion Stabilized by Surface-Engineered Liquid Metal Droplets as "Mutant" Pickering Emulsifiers

Liquid metals (LMs), i.e., metals and alloys that exist in a liquid state at room temperature, have recently attracted considerable attention owing to their electronic and rheological properties useful in various cutting-edge technologies. In this study, eutectic Ga-In (EGaIn), one of the most studied LMs, in its microdroplet form was engineered to produce a novel droplet-type surfactant that can stabilize a liquid-in-liquid emulsion with unique functionality and processability. Dual-engineered LM droplets with a robust SiO2 encapsulation shell and adsorbed amphiphilic cetyltrimethylammonium bromide (CTAB) exhibited high chemical stability against water-mediated oxidation while possessing excellent oil-water interfacial activity. These engineered droplet-type surfactants densely adsorb at microscale water-oil interfaces and prevent coalescence of the dispersed oil droplets in the liquid continuous phase, thereby producing long-term stable oil-in-water (O/W) emulsions─these droplet-type surfactants were named as "mutant" Pickering emulsifiers, indicating particle emulsifiers (different from molecular surfactants) that are similar to conventional Pickering emulsifiers, but consisting of the liquid core instead of the solid. The resulting emulsions exhibited enhanced yield stresses with viscoelastic properties, even at a minimal LM load, and showed remarkable sedimentation stability, indicating significant implications in terms of processability in versatile applications. The "structured" nature of such emulsions combined with the excellent photothermal conversion ability of LM droplets adsorbed at O/W interfaces resulted in the extremely localized photothermal heating effect. Furthermore, photothermally responsive phase-change oil droplets were produced using engineered LM droplets, which can be used for the on-demand release of valuable oil-soluble cargo as a potential application. We expect that engineered LM droplets as novel droplet-type emulsifiers of immiscible liquids in colloidal multidisperse systems will provide unique opportunities for various applications.

The extraction of inorganic phase-change materials from sugar industry wastes with the purpose of solid waste management

This study focused on the feasibility of identifying and recycling inorganic phase-change materials (PCMs) from sugar industry wastes in two cities of Qazvin and Hamadan in Iran. In this study, dry sugar beet pomace, sugar beet pomace, sugar beet molasses, leaves and plant residues of sugar beet and sugarcane bagasse were investigated. The inorganic materials were identified by X-ray Diffraction (XRD), thermal characteristics were determined by differential scanning calorimetry (DSC), and morphological characteristics were determined by scanning electron microscopy (SEM). Additionally, physical and thermal properties of molasses and bagasse samples were analyzed to determine their suitability as inorganic PCMs. The results of this study demonstrated that molasses and bagasse have the potential to be used as mineral PCMs in thermal energy storage applications. The results of this study demonstrated that in the wet sugar beet pomace the highest and lowest concentrations of inorganic PCMs were silicon dioxide (SiO2) and sodium chloride (NaCl), respectively. Moreover, the highest calcium fluoride (CaF₂) composition was reported in dry sugar beet pomace. In the samples of leaves and residues of sugar beet and sugarcane bagasse, the highest concentration of was NaCl. The detection and recycling of mineral PCMs from sugar industry wastes offer a sustainable solution for waste management and provide a renewable source of thermal energy storage materials.Implications: This study demonstrated the potential for the extraction of inorganic phase-change materials from sugar industry wastes as a means of solid waste management. By repurposing these materials, we can reduce the environmental impact of sugar production and contribute to sustainable practices in the industry.

Thermoresponsive Phase Change Oleogel Microcapsules for Coencapsulation of Hydrophilic and Hydrophobic Actives

To address the concurrent needs of the personal care industry for simultaneous protection of active ingredients and enhancement of product functionality, this study employs a microfluidic technique to fabricate EstoGel M-based oleogel microcapsules capable of coencapsulating both hydrophilic and hydrophobic actives. The oleogels exhibit gel-like characteristics with a melting point of approximately 70 °C, ensuring high encapsulation efficiency for hydrophilic and hydrophobic actives within aqueous environments. The oleogel microspheres encapsulating hydrophobic actives are prepared using microfluidic technology with robust elasticity, which can be ruptured by a force of less than 15 mN, contributing to a favorable tactile sensation upon application. The structural integrity of these microspheres is preserved within a temperature range up to 70 °C, indicating their thermodynamic stability. In addition, oleogel microcapsules are prepared using microfluidic technology, and their effectiveness in coencapsulating hydrophilic and hydrophobic active ingredients is successfully demonstrated, along with excellent skin feel and temperature stability. The exceptional tactile properties of EstoGel M-based oleogel microcapsules offer a promising strategy for creating innovative personal care products that integrate high encapsulation efficiency with multifunctional attributes.

Stearic Acid as Polymerization Medium, Dopant and Hydrophobizer: Chemical Oxidative Polymerization of Pyrrole

In recent years, fatty acids have garnered significant attention as a natural phase-change material and a hydrophobizer due to their biocompatibility and biodegradability. In this study, the utilization of fatty acid is proposed as a polymerization medium for the first time. As a specific reaction, chemical oxidative polymerizations of pyrrole is conducted using ferric chloride as an oxidant in a stearic acid medium. The polymerizations resulted in the production of micrometer-sized polypyrrole (PPy) grains, which are aggregates of atypical primary particles with submicrometer size. The PPy grains are doped with stearic acid, suggesting that the stearic acid functioned as a dopant and a hydrophobizing agent as well as a polymerization medium. The dried PPy grains can adsorb at the air-water interface and function as a liquid marble stabilizer with light-to-heat photothermal properties. The liquid marble can move on a planar air-water interface by Marangoni flow induced by NIR laser light irradiation.

Near-infrared-responsive Prussian blue nanocages loaded with 5-fluorouracil for combined chemotherapy and photothermal therapy in tumor treatment

Nanodrug delivery systems (NDDS) have been proposed to improve the targeting and bioavailability of chemotherapy drugs. The approach of drug loading via physical adsorption is facile to operate; however, there exists a risk of premature leakage. Coupling the drug molecules with the carrier through chemical reactions can guarantee the stability of the drug delivery process, yet the preparation procedure is relatively intricate. In this research, a kind of Prussian blue nanocage (PB Cage) was fabricated, and the phase change material, 1-pentadecanol, was used as the gating material to solidify 5-fluorouracil (5-FU) inside the nanocage. Upon irradiation with near-infrared (NIR) light, the temperature of the PB Cage can rise rapidly. When the temperature exceeds 43 °C, 1-pentadecanol undergoes a solid-liquid phase transition and subsequently releases 5-FU to inhibit DNA synthesis. Meanwhile, the photothermal therapy (PTT) mediated by the PB Cage is also capable of ablating tumor cells. The NDDS constructed based on PB has achieved the precise release of 5-FU triggered by NIR light, which may avoid side effects on normal tissues. Moreover, the combination of chemotherapy and photothermal therapy can efficaciously suppress the proliferation of tumor cells.

Advanced Anti-Icing Strategies and Technologies by Macrostructured Photothermal Storage Superhydrophobic Surfaces

Water is the source of life and civilization, but water icing causes catastrophic damage to human life and diverse industrial processes. Currently, superhydrophobic surfaces (inspired by the lotus effect) aided anti-icing attracts intensive attention due to their energy-free property. Here, recent advances in anti-icing by design and functionalization of superhydrophobic surfaces are reviewed. The mechanisms and advantages of conventional, macrostructured, and photothermal superhydrophobic surfaces are introduced in turn. Conventional superhydrophobic surfaces, as well as macrostructured ones, easily lose the icephobic property under extreme conditions, while photothermal superhydrophobic surfaces strongly rely on solar illumination. To address the above issues, a potentially smart strategy is found by developing macrostructured photothermal storage superhydrophobic (MPSS) surfaces, which integrate the functions of macrostructured superhydrophobic materials, photothermal materials, and phase change materials (PCMs), and are expected to achieve all-day anti-icing in various fields. Finally, the latest achievements in developing MPSS surfaces, showcasing their immense potential, are highlighted. Besides, the perspectives on the future development of MPSS surfaces are provided and the problems that need to be solved in their practical applications are proposed.

Ultrasensitive Ratiometric Fluorescent Nanothermometer with Reverse Signal Changes for Intracellular Temperature Mapping

Sensing temperature at the subcellular level is pivotal for gaining essential thermal insights into diverse biological processes. However, achieving sensitive and accurate sensing of the intracellular temperature remains a challenge. Herein, we develop a ratiometric organic fluorescent nanothermometer with reverse signal changes for the ultrasensitive mapping of intracellular temperature. The nanothermometer is fabricated from a binary mixture of saturated fatty acids with a noneutectic composition, a red-emissive aggregation-caused quenching luminogen, and a green-emissive aggregation-induced emission luminogen using a modified nanoprecipitation method. Different from the eutectic mixture with a single phase-transition point, the noneutectic mixture possesses two solid-liquid phase transitions, which not only allows for reversible regulation of the aggregation states of the encapsulated luminogens but also effectively broadens the temperature sensing range (25-48 °C) across the physiological temperature range. Remarkably, the nanothermometer exhibits reverse and sensitive signal changes, demonstrating maximum relative thermal sensitivities of up to 63.66% °C-1 in aqueous systems and 44.01% °C-1 in the intracellular environment, respectively. Taking advantage of these outstanding thermometric performances, the nanothermometer is further employed to intracellularly monitor minute temperature variations upon chemical stimulation. This study provides a powerful tool for the exploration of dynamic cellular thermal activities, holding great promise in unveiling intricate physiological processes.

Design of Thermosensitive Niosomes by Eutectic Mixture of Natural Fatty Acids

In the current study, a smart release system responsive to temperature was developed to improve the efficiency of tetracycline (TC) in antibacterial therapy. The nanovesicles designed consist of a non-ionic surfactant, SPAN60, cholesterol and a phase change material (PCM) as a thermoresponsive gating material. Niosomes were prepared using an increasing amount of PCM and characterized in terms of size, zeta potential, colloidal stability and thermoresponsive properties. The vesicles that developed were homogenous in size, had good biocompatibility and stability for up to 3 months and demonstrated thermoresponsive behavior. A low drug leakage was observed at 37 °C, while a rapid release occurred at 42 °C, due to the faster diffusion rate of the drug trough the melted PCM. This controllable drug release capacity allows us to avoid premature drug release, minimizing unwanted and toxic effects and ensuring a long retention time in the nanodevice so that it reaches the infected sites. In addition, TC-loaded niosomes were screened to investigate their antibacterial activity against various Gram-positive and Gram-negative bacteria by minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays. An interesting temperature-dependent antibacterial activity was observed against some bacterial strains: the niosomes activity against S. epidermis, for example, was improved by the temperature increase, as suggested by a reduction in MIC values from 112.81 to 14.10 μM observed at 37 and 42 °C, respectively. Taken together, the thermoresponsive platform developed allows us to use lower antibiotic amounts while ensuring therapeutic efficacy and, so, will advance the development of a novel antibacterial agent in clinical practice.

Grapefruit-Inspired Polymeric Capsule with Hierarchical Microstructure: Advanced Nanomaterial Carrier Platform for Energy Storage, Drug Delivery, Catalysis, and Environmental Applications

Efficient support materials are crucial for maximizing the efficacy of nanomaterials in various applications such as energy storage, drug delivery, catalysis, and environmental remediation. However, traditional supports often hinder nanomaterial performance due to their high weight ratio and limited manageability, leading to issues like tube blocking and secondary pollution. To address this, a novel grapefruit-inspired polymeric capsule (GPC) as a promising carrier platform is introduced. The millimeter-scale GPC features a hydrophilic shell and an internal hierarchical microstructure with 80% void volume, providing ample space for encapsulating diverse nanomaterials including metals, polymers, metal-organic frameworks, and silica. Through liquid-phase bottom-up methods, it is successfully loaded Fe2O3, SiO2, polyacrylic acid, and Prussian blue nanomaterials onto the GPC, achieving high mass ratio (1776, 488, 898, and 634 wt.%, respectively). The GPC shell prevents nanomaterial leakage and the influx of suspended solids, while its internal framework enhances structural stability and mass transfer rates. With long-term storage stability, high carrying capacity, and versatile applicability, the GPC significantly enhances the field applicability of nanomaterials.

Body temperature responsive capsules templated from Pickering emulsion for thermally triggered release of β-carotene

In recent years, functional foods with lipophilic nutraceutical ingredients are gaining more and more attention because of its potential healthy and commercial value, and developing of various bioderived food-grade particles for use in fabrication of Pickering emulsion has attracted great attentions. Herein, the bio-originated sodium caseinate-lysozyme (Cas-Lyz) complex particles were firstly designed to be used as a novel interfacial emulsifier for Pickering emulsions. Pickering emulsions of various food oils were all successfully stabilized by the Cas-Lyz particles without addition of any synthetic surfactants, while the fluorescence microscopy and SEM characterizations clearly evidenced Cas-Lyz particles were attached on the surface of emulsion droplets. Additionally, the Cas-Lyz particles stabilized emulsion can also be used to encapsulate the β-carotene-loaded soybean oil, suggestion a potential method to carry lipophilic bioactive ingredients in an aqueous formulation for food, cosmetic and medical industry. At last, we present a Pickering emulsion strategy that utilizes biocompatible, edible and body temperature-responsive lard oil as the core material in microcapsules, which can achieve hermetic sealing and physiological temperature-triggered release of model nutraceutical ingredient (β-carotene).

Putting Hybrid Nanomaterials to Work for Biomedical Applications

Hybrid nanomaterials have found use in many biomedical applications. This article provides a comprehensive review of the principles, techniques, and recent advancements in the design and fabrication of hybrid nanomaterials for biomedicine. We begin with an introduction to the general concept of material hybridization, followed by a discussion of how this approach leads to materials with additional functionality and enhanced performance. We then highlight hybrid nanomaterials in the forms of nanostructures, nanocomposites, metal-organic frameworks, and biohybrids, including their fabrication methods. We also showcase the use of hybrid nanomaterials to advance biomedical engineering in the context of nanomedicine, regenerative medicine, diagnostics, theranostics, and biomanufacturing. Finally, we offer perspectives on challenges and opportunities.

Multistage Porous Carbon Derived from Enzyme-Treated Waste Walnut Green Husk and Polyethylene Glycol for Phase Change Energy Storage

The thermal storage performance, cost, and stability of phase-change materials (PCMs) are critical factors influencing their application in the field of thermal energy storage. Porous carbon, with its excellent support, thermal conductivity, and energy storage properties, is considered one of the most promising support matrix materials. However, the simple and efficient synthesis of high-performance and highly active bio-based materials under mild conditions still faces challenges. In our work, a novel method for preparing new functional composite phase-change materials based on enzyme treatment technology and using waste walnut green husk biomass and polyethylene glycol as raw materials was developed. The enzymatic treatment method exposes the internal structure of the walnut green husk, followed by the adjustment of the calcination temperature to increase the adsorption sites of the biochar, thereby stabilizing polyethylene glycol (PEG). The porous properties of walnut green husk biochar effectively regulate the phase-change behavior of polyethylene glycol. In the biochar carbonized at 600 °C, the PEG loading reached 72.09%, and the absorption heat of the solid-solid phase-change material (SSPCM) reached 194.76 J g-1. This work not only enriches the application of biomass in heat storage but also demonstrates the broad prospects of SSPCMs in solar thermal utilization.

Recent advances and perspectives in solar photothermal conversion and storage systems: A review

Developing high-efficiency solar photothermal conversion and storage (SPCS) technology is significant in solving the imbalance between the supply and demand of solar energy utilization in time and space. Aiming at the current research status in the field of SPCS, this review thoroughly examines the phase change materials and substrates in SPCS systems. It elucidates the design principles and methods of SPCS integrated composites. Comparatively, it analyzes the parameters of various types of SPCS composites in terms of photothermal conversion, thermal conductivity, energy density, and cycling stability. Additionally, the review discusses the trade-offs between each parameter to achieve the most optimal effect of SPCS. By sorting out the current status of the application of SPCS technology in solar thermal/photovoltaic, aerospace, buildings, textile, and other industries, this analysis clarifies the requirements for various latent heat, phase change temperature, and other properties under different environmental conditions. Through a comprehensive discussion of SPCS technology, this paper accurately captures the development trend of efficiently and comprehensively utilizing solar energy by analyzing existing scientific problems. It identifies bottlenecks in SPCS technology and suggests future development directions that need focused attention. The insights gained from this analysis may provide a theoretical basis for designing strategies, enhancing performance, and promoting the application of SPCS.

Digital automation of transdermal drug delivery with high spatiotemporal resolution

Transdermal drug delivery is of vital importance for medical treatments. However, user adherence to long-term repetitive drug delivery poses a grand challenge. Furthermore, the dynamic and unpredictable disease progression demands a pharmaceutical treatment that can be actively controlled in real-time to ensure medical precision and personalization. Here, we report a spatiotemporal on-demand patch (SOP) that integrates drug-loaded microneedles with biocompatible metallic membranes to enable electrically triggered active control of drug release. Precise control of drug release to targeted locations (<1 mm2), rapid drug release response to electrical triggers (<30 s), and multi-modal operation involving both drug release and electrical stimulation highlight the novelty. Solution-based fabrication ensures high customizability and scalability to tailor the SOP for various pharmaceutical needs. The wireless-powered and digital-controlled SOP demonstrates great promise in achieving full automation of drug delivery, improving user adherence while ensuring medical precision. Based on these characteristics, we utilized SOPs in sleep studies. We revealed that programmed release of exogenous melatonin from SOPs improve sleep of mice, indicating potential values for basic research and clinical treatments.

Encapsulation of conjugated linoleic acid and ruminant trans fatty acids to study the prevention of metabolic syndrome-a review

Studies have reported the potential benefits of consuming conjugated linoleic acid (CLA) and ruminant trans fatty acids (R-TFAs) in reducing the risk factors of metabolic syndrome (MetS). In addition, encapsulation of CLA and R-TFAs may improve their oral delivery and further decrease the risk factors of MetS. The objectives of this review were (1) to discuss the advantages of encapsulation; (2) to compare the materials and techniques used for encapsulating CLA and R-TFAs; and (3) to review the effects of encapsulated vs non-encapsulated CLA and R-TFAs on MetS risk factors. Examination of papers citing micro- and nano-encapsulation methods used in food sciences, as well as the effects of encapsulated vs non-encapsulated CLA and R-TFAs, was conducted using the PubMed database. A total of 84 papers were examined; of these, 18 studies were selected that contained information on the effects of encapsulated CLA and R-TFAs. The 18 studies that described encapsulation of CLA or R-TFAs indicated that micro- or nano-encapsulation processes stabilized CLA and prevented oxidation. CLA was mainly encapsulated using carbohydrates or proteins. So far, oil-in-water emulsification followed by spray-drying were the frequently used techniques for encapsulation of CLA. Further, 4 studies investigated the effects of encapsulated CLA on MetS risk factors compared with non-encapsulated CLA. A limited number of studies investigated the encapsulation of R-TFAs. The effects of encapsulated CLA or R-TFAs on the risk factors for MetS remain understudied; thus, additional studies comparing the effects of encapsulated and non-encapsulated CLA or R-TFAs are needed.

Multiple H-Bonding Cross-Linked Supramolecular Solid-Solid Phase Change Materials for Thermal Energy Storage and Management

Solid-solid phase change materials (SSPCMs) are considered among the most promising candidates for thermal energy storage and management. However, the application of SSPCMs is consistently hindered by the canonical trade-off between high TES capacity and mechanical robustness. In addition, they suffer from poor recyclability due to chemical cross-linking. Herein, a straightforward but effective strategy for fabricating supramolecular SSPCMs with high latent heat and mechanical strength is proposed. The supramolecular polymer employs multiple H-bonding interactions as robust physical cross-links. This enables SSPCM with a high enthalpy of phase transition (142.5 J g-1 ), strong mechanical strength (36.9 MPa), and sound shape stability (maintaining shape integrity at 120 °C) even with a high content of phase change component (97 wt%). When SSPCM is utilized to regulate the operating temperature of lithium-ion batteries, it significantly diminishes the battery working temperature by 23 °C at a discharge rate of 3 C. The robust thermal management capability enabled through solid-solid phase change provides practical opportunities for applications in fast discharging and high-power batteries. Overall, this study presents a feasible strategy for designing linear SSPCMs with high latent heat and exceptional mechanical strength for thermal management.

Advances in Biocarbon and Soft Material Assembly for Enthalpy Storage: Fundamentals, Mechanisms, and Multimodal Applications

High-value-added biomass materials like biocarbon are being actively pursued integrating them with soft materials in a broad range of advanced renewable energy technologies owing to their advantages, such as lightweight, relatively low-cost, diverse structural engineering applications, and high energy storage potential. Consequently, the hybrid integration of soft and biomass-derived materials shall store energy to mitigate intermittency issues, primarily through enthalpy storage during phase change. This paper introduces the recent advances in the development of natural biomaterial-derived carbon materials in soft material assembly and its applications in multidirectional renewable energy storage. Various emerging biocarbon materials (biochar, carbon fiber, graphene, nanoporous carbon nanosheets (2D), and carbon aerogel) with intrinsic structures and engineered designs for enhanced enthalpy storage and multimodal applications are discussed. The fundamental design approaches, working mechanisms, and feature applications, such as including thermal management and electromagnetic interference shielding, sensors, flexible electronics and transparent nanopaper, and environmental applications of biocarbon-based soft material composites are highlighted. Furthermore, the challenges and potential opportunities of biocarbon-based composites are identified, and prospects in biomaterial-based soft materials composites are presented.

A General Strategy for Developing Ultrasensitive "Transistor-Like" Thermochromic Fluorescent Materials for Multilevel Information Encryption

Thermochromic fluorescent materials (TFMs) exhibit great potential in information encryption applications but are limited by low thermosensitivity, poor color tunability, and a wide temperature-responsive range. Herein, a novel strategy for constructing highly sensitive TFMs with tunable emission (450-650 nm) toward multilevel information encryption is proposed, which employs polarity-sensitive fluorophores with donor-acceptor-donor (D-A-D) type structures as emitters and long-chain alkanes as thermosensitive loading matrixes. The structure-function relationships between the performance of TFMs and the structures of both fluorescent emitters and phase-change molecules are systematically studied. Benefiting from the above design, the obtained TFMs exhibit over 9500-fold fluorescence enhancement toward the temperature change, as well as ultrahigh relative temperature sensitivity up to 80% K-1 , which are first confirmed. Thanks to the superior transducing performance, the above-prepared TFMs can be further developed as information-storage platforms within a relatively narrow interval of temperature variation, including temperature-dominated multicolored information display and multilevel information encryption. This work will not only provide a novel perspective for designing superior TFMs for information encryption but also bring inspiration to the design and preparation of other response-switching-type fluorescent probes with ultrahigh conversion efficiency.

Advancements in Phase Change Materials in Asphalt Pavements for Mitigation of Urban Heat Island Effect: Bibliometric Analysis and Systematic Review

This research presents a dual-pronged bibliometric and systematic review of the integration of phase change materials (PCM) in asphalt pavements to counteract the urban heat island (UHI) effect. The bibliometric approach discerns the evolution of PCM-inclusion asphalt research, highlighting a marked rise in the number of publications between 2019 and 2022. Notably, Chang'an University in China has emerged as a leading contributor. The systematic review addresses key questions like optimal PCM types for UHI effect mitigation, strategies for PCM leakage prevention in asphalt, and effects on mechanical properties. The findings identify polyethylene glycols (PEGs), especially PEG2000 and PEG4000, as prevailing PCM due to their wide phase-change temperature range and significant enthalpy during phase transitions. While including PCM can modify asphalt's mechanical attributes, such mixtures typically stay within performance norms. This review emphasises the potential of PCM in urban heat management and the need for further research to achieve optimal thermal and mechanical balance.

Photothermal-responsive Prussian blue nanocages loaded with thrombin for tumor starvation therapy and photothermal therapy

The goal of inhibiting tumor growth can be achieved by cutting off the supply of nutrients in the blood vessels of a tumor site, but finding ways to effectively, accurately and safely deliver drugs that can induce vascular embolism remains a challenge. Phase change materials (PCM) can undergo solid-liquid transformation at the phase change temperature. This study reports on a near-infrared ray (NIR)-responsive nano-drug delivery platform based on Prussian blue (PB) nanoparticles. The PCM (lauric acid) can encapsulate thrombin (Thr) in the Prussian blue nanocage (PB Cage), and effectively avoid the pre-leakage of Thr during blood circulation. When the (Thr/PCM)@PB Cage is accumulated at the tumor site and irradiated with NIR, the thermal effect induced by the PB Cage causes the PCM to undergo a solid-liquid state transition, rapidly releasing the encapsulated Thr and inducing coagulation in the tumor blood vessels. Based on the safe delivery and precisely controlled release of Thr, the proliferation of tumor cells can be inhibited without damaging other tissues and organs. In addition, PB Cage-induced photothermal therapy can also ablate tumor cells. Thr-induced "starvation therapy" based on PB Cage loading provides a good reference for precise controlled-release drug delivery systems.

Fire Retardant Phase Change Materials-Recent Developments and Future Perspectives

The accumulation of thermal energy in the form of latent heat of phase transition using phase change materials (PCMs) is one of the most attractive and studied research areas with huge application potential in both passive and active technical systems. The largest and most important group of PCMs for low-temperature applications are organic PCMs, mainly paraffins, fatty acids, fatty alcohols, and polymers. One of the major disadvantages of organic PCMs is their flammability. In many applications such as building, battery thermal management, and protective insulations, the crucial task is to reduce the fire risk of flammable PCMs. In the last decade, numerous research works have been performed to reduce the flammability of organic PCMs, without losing their thermal performance. In this review, the main groups of flame retardants, PCMs flame retardation methods as well as examples of flame-retarded PCMs and their application areas were described.

Mild-Temperature Responsive Nanocatalyst for Controlled Drug Release and Enhanced Catalytic Therapy

Owing to the advantages of the in situ production of toxic agents through catalytic reactions, nanocatalytic therapy has arisen as a highly potential strategy for cancer therapeutics in recent years. However, the insufficient amount of endogenous hydrogen peroxide (H₂O₂) in the tumor microenvironment commonly limits their catalytic efficacy. Here, we employed carbon vesicle nanoparticles (CV NPs) with high near-infrared (NIR, 808 nm) photothermal conversion efficiency as carriers. Ultrafine platinum iron alloy nanoparticles (PtFe NPs) were grown in situ on the CV NPs, where the highly porous nature of the resultant CV@PtFe NPs was employed to encapsulate a drug, β-lapachone (La), and phase-change material (PCM). As a multifunctional nanocatalyst CV@PtFe/(La-PCM) NPs can exhibit a NIR-triggered photothermal effect and activate cellular heat shock response, which upregulates the downstream NQO1 via HSP70/NQO1 axis to facilitate bio-reduction of the concurrently melted and released La. Moreover, sufficient oxygen (O₂) is supplied by CV@PtFe/(La-PCM) NPs catalyzed at the tumor site to reinforce the La cyclic reaction with abundant H₂O₂ generation. This promotes the bimetallic PtFe-based nanocatalysis, which breaks H₂O₂ down into highly toxic hydroxyl radicals (•OH) for catalytic therapy. Our results show that this multifunctional nanocatalyst can be used as a versatile synergistic therapeutic agent with NIR-enhanced nanocatalytic tumor therapy by tumor-specific H₂O₂ amplification and mild-temperature photothermal therapy, which holds promising potential for targeted cancer treatment. STATEMENT OF SIGNIFICANCE: We present a multifunctional nanoplatform with mild-temperature responsive nanocatalyst for controlled drug release and enhanced catalytic therapy. This work aimed at not only reduce the damage to normal tissues caused by photothermal therapy, but also improves the efficiency of nanocatalytic therapy by stimulating endogenous H₂O₂ production through photothermal heat. In vitro and in vivo confirmed that CV@PtFe/(La-PCM) NPs exhibited powerful and overall antitumor effects. This formulation may provide an alternative strategy for the development of the mild- photothermal enhanced nanocatalytic therapy effect in solid tumor.

Nanopolyhybrids: Materials, Engineering Designs, and Advances in Thermal Management

The fundamental requirements for thermal comfort along with the unbalanced growth in the energy demand and consumption worldwide have triggered the development and innovation of advanced materials for high thermal-management capabilities. However, continuous development remains a significant challenge in designing thermally robust materials for the efficient thermal management of industrial devices and manufacturing technologies. The notable achievements thus far in nanopolyhybrid design technologies include multiresponsive energy harvesting/conversion (e.g., light, magnetic, and electric), thermoregulation (including microclimate), energy saving in construction, as well as the miniaturization, integration, and intelligentization of electronic systems. These are achieved by integrating nanomaterials and polymers with desired engineering strategies. Herein, fundamental design approaches that consider diverse nanomaterials and the properties of nanopolyhybrids are introduced, and the emerging applications of hybrid composites such as personal and electronic thermal management and advanced medical applications are highlighted. Finally, current challenges and outlook for future trends and prospects are summarized to develop nanopolyhybrid materials.

Bioinspired Mild Photothermal Effect-Reinforced Multifunctional Fiber Scaffolds Promote Bone Regeneration

Bone fractures are often companied with poor bone healing and high rates of infection. Early recruitment of mesenchymal stem cells (MSCs) is critical for initiating efficient bone repair, and mild thermal stimulation can accelerate the recovery of chronic diseases. Here, a bioinspired, staged photothermal effect-reinforced multifunctional scaffold was fabricated for bone repair. Uniaxially aligned electrospun polycaprolactone nanofibers were doped with black phosphorus nanosheets (BP NSs) to endow the scaffold with excellent near-infrared (NIR) responsive capability. Apt19S was then decorated on the surface of the scaffold to selectively recruit MSCs toward the injured site. Afterward, microparticles of phase change materials loaded with antibacterial drugs were also deposited on the surface of the scaffold, which could undergo a solid-to-liquid phase transition above 39 °C, triggering the release of payload to eliminate bacteria and prevent infection. Under NIR irradiation, photothermal-mediated up-regulation of heat shock proteins and accelerated biodegradation of BP NSs could promote the osteogenic differentiation of MSCs and biomineralization. Overall, this strategy shows the ability of bacteria elimination, MSCs recruitment, and bone regeneration promotion with the assistance of photothermal effect in vitro and in vivo, which emphasizes the design of a bioinspired scaffold and its potential for a mild photothermal effect in bone tissue engineering.

Stretchable and Skin-Attachable Electronic Device for Remotely Controlled Wearable Cancer Therapy

Surgery represents a primary clinical treatment of solid tumors. The high risk of local relapse typically requires frequent hospital visits for postoperative adjuvant therapy. Here, device designs and system integration of a stretchable electronic device for wearable cancer treatment are presented. The soft electronic patch harnesses compliant materials to achieve conformal and stable attachment to the surgical wound. A composite nanotextile dressing is laminated to the electronic patch to allow the on-demand release of anticancer drugs under electro-thermal actuation. An additional flexible circuit and a compact battery complete an untethered wearable system to execute remote therapeutic commands from a smartphone. The successful implementation of combined chemothermotherapy to inhibit tumor recurrence demonstrates the promising potential of stretchable electronics for advanced wearable therapies without interfering with daily activities.

Recent applications of phase-change materials in tumor therapy and theranostics

Phase-change materials (PCMs) are a type of special material which can store and release a large amount of thermal energy without any significant temperature change. They are emerging in recent years as a promising functional material in tumor therapy and theranostics due to their accurate responses to the temperature variations, biocompatibility and low toxicity. In this review, we will introduce the main types of PCMs and their desirable physiochemical properties for biomedical applications, and highlight the recent progress of PCM's applications in the modulated release of antitumor drugs, with special attentions paid to various ways to initiate temperature-dependent phase change, the concomitant thermal therapy and its combination with or activation of other therapies, particularly unconventional therapies. We will also summarize PCM's recent applications in tumor theranostics, where both drugs and imaging probes are delivered by PCMs for controlled drug release and imaging-guided therapy. Finally, the future perspectives and potential limitations of harnessing PCMs in tumor therapy will be discussed.

Phase Change Thermal Storage Materials for Interdisciplinary Applications

Functional phase change materials (PCMs) capable of reversibly storing and releasing tremendous thermal energy during the isothermal phase change process have recently received tremendous attention in interdisciplinary applications. The smart integration of PCMs with functional supporting materials enables multiple cutting-edge interdisciplinary applications, including optical, electrical, magnetic, acoustic, medical, mechanical, and catalytic disciplines etc. Herein, we systematically discuss thermal storage mechanism, thermal transfer mechanism, and energy conversion mechanism, and summarize the state-of-the-art advances in interdisciplinary applications of PCMs. In particular, the applications of PCMs in acoustic, mechanical, and catalytic disciplines are still in their infancy. Simultaneously, in-depth insights into the correlations between microscopic structures and thermophysical properties of composite PCMs are revealed. Finally, current challenges and future prospects are also highlighted according to the up-to-date interdisciplinary applications of PCMs. This review aims to arouse broad research interest in the interdisciplinary community and provide constructive references for exploring next generation advanced multifunctional PCMs for interdisciplinary applications, thereby facilitating their major breakthroughs in both fundamental researches and commercial applications.

Molecular Regulation of Flexible Composite Solid-Solid Phase Change Materials with Controllable Isotropic Thermal Conductivity for Thermal Energy Storage

In recent years, graphene has been introduced into phase change materials (PCMs) to improve thermal conductivity to enhance the heat transfer efficiency in thermal energy storage. However, graphenes tend to aggregate in PCMs, leading to the low thermal conductivity efficient enhancement (TCEE), anisotropic thermal conductivity, and deterioration of mechanical performance of PCMs. In this work, we fabricated biomimetic thermally conductive solid-solid PCMs (SSPCMs) by facile blending of the graphene into well-designed polyurethane SSPCMs, in which the graphene established a controllable and highly efficient isotropic thermally conductive pathway based on the π-π stacking between the graphene and the polymer aromatic ring segment. The as-fabricated SSPCMs showed high TCEE (156.78%), excellent flexibility (328% elongation at break), high enthalpy value (>101 J/g), and solid-solid phase transition properties, under 2% loading of graphene. The proportion of in-plane to through-plane thermal conductivity can be adjusted by an elaborate design of the aromatic ring segment in polyurethane SSPCMs. We further demonstrated mechanical flexibility and photothermal property of the composites to reveal their potential in practical applications.

Phase-change composite filled natural nanotubes in hydrogel promote wound healing under photothermally triggered drug release

It is of great importance to treat a bacterial-infected wound by a smart dressing capable of delivering antibiotics in a smart manner without causing drug resistance. The construction of smart release nanocontainers responsive to near-infrared (NIR) laser irradiation in an on-demand and stepwise way is a promising strategy for avoiding the emergence of multidrug-resistant bacteria. Here, we develop a hydrogel composite made of alginate and nanotubes with an efficient NIR-triggered release of rifampicin and outstanding antibacterial ability. This composite hydrogel is prepared through co-encapsulating antibacterial drug (rifampicin), NIR-absorbing dye (indocyanine green), and phase-change materials (a eutectic mixture of fatty acids) into halloysite nanotubes, followed by incorporation into alginate hydrogels, allowing the in-situ gelation at room temperature and maintaining the integrity of drug-loaded nanotubes. Among them, the eutectic mixture with a melting point of 39 °C serves as the biocompatible phase-change material to facilitate the NIR-triggered drug release. The resultant phase-change material gated-nanotubes exhibit a prominent photothermal efficiency with multistep drug release under laser irradiation. In an in vitro assay, composite hydrogel provides good antibacterial potency against Staphylococcus aureus, one of the most prevalent microorganisms of dangerous gas gangrene. A bacterial-infected rat full-thickness wound model demonstrates that the NIR-responsive composite hydrogel inhibits the bacteria colonization and suppresses the inflammatory response caused by bacteria, promoting angiogenesis and collagen deposition to accelerate wound regeneration. The NIR-responsive composite hydrogel has a great potential as an antibacterial wound dressing functionalized with controlled multistep treatment of the infected sites.

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Phase change material-gated nanocontainer exhibits an efficient NIR-triggered release of drugs.

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Photothermal-responsive hydrogel shows efficient antibacterial properties through the NIR-responsive step-wise antibacterial drug release.

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In vivo, photothermal-responsive hydrogel inhibits bacterial proliferation and effectively suppress the inflammatory response caused by bacteria, thus accelerating bacteria-infected wound regeneration.

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Various types of drugs and biological effectors can be loaded in the nanotubes while the hydrogel matrix can also be regulated to achieve multiple healing functions.

Magneto-mechanical therapeutic effects and associated cell death pathways of magnetic nanocomposites with distinct geometries

Recent years have witnessed important developments in the emerging field of magneto-mechanical therapies. While such approaches have been demonstrated as a highly efficient route to augment, complement, or entirely replace other therapeutic strategies, important aspects are still poorly understood. Among these, the dependence between the cell death pathway and the geometry of magnetic nanocomposites enabling magneto-mechanical therapies under a low-frequency rotating magnetic field (RMF) is yet to be deciphered. To provide insights into this important problem, we evaluate the cell death pathway for two magnetic nanocomposites with highly distinct geometries: Zn_0.2Fe_2.8O₄-PLGA magnetic nanospheres (MNSs) and Zn_0.2Fe_2.8O₄-PLGA magnetic nanochains (MNCs). We show that under exposure to an RMF, the MNSs and the MNCs exhibit a corkscrewed circular propulsion mode and a steering propulsion mode, respectively. This distinct behavior, with important implications for the associated magneto-mechanical forces exerted by these nanomaterials on surrounding structures (e.g., the cellular membrane), depends on their specific geometries. Next, using numerical simulations and cell viability experiments, we demonstrate that the field strength of the RMF and the rotating speed of the MNSs or MNCs have strong implications for their magneto-mechanical therapeutic performance. Last, we reveal that the magneto-mechanical effects of MNSs are more prone to induce cell apoptosis, whereas those of the MNCs favor instead cell necrosis. Overall, this work enhances the current understanding of the dependences existing between the magneto-mechanical therapeutic effects of magnetic nanocomposites with different geometries and associated cell death pathways, paving the way for novel functionalization routes which could enable significantly enhanced cures and biomedical tools. STATEMENT OF SIGNIFICANCE.

Constructing a drug release model by central composite design to investigate the interaction between drugs and temperature-sensitive controlled release nanoparticles

To study the release behavior of a thermosensitive controlled release drug delivery system and construct a predictable mathematical model of drug release, poly(N-isopropylacrylamide-co-Allylamine) (P(NIPA-AL17)) and ploy(styrene sulfonate) (PSS) were functionalized on the surface of hollow mesoporous carbon nanoparticles (HMCNs) through layer-by-layer (LBL) assembly to construct a photothermal responsive controlled release system. A five-level four-factorial central composite design (CCD) was performed to investigate the relationship between four independent variables including drug loading (A), number of polymer layers (B), temperature (C) and vibration rate of the shaker (D), and three dependent response variables, including cumulative release over 1 h (Y₁), cumulative release over 24 h (Y₂) and the release rate constant k (Y₃). The CCD results indicate that A and C significantly affect Y₁ (P < 0.05). C significantly affects Y₂ (P < 0.05). A and B is found to affect Y₃ (P < 0.05) significantly. When C is below 39 °C, Y₁ and Y₂ decrease with the increase of A and B, and when C is above 39 °C, they increase with the increase of A and B; Y₃ decreases as A and B increase; and D shows the least or even no influence on Y₁, Y₂ and Y₃. The constructed predictable mathematical model will provide a scientific reference for the further development and application of photothermal responsive controlled-release preparations.

Photo- and Thermoresponsive Liquid Marbles Based on Fatty Acid as Phase Change Material Coated by Polypyrrole: From Design to Applications

Responsive liquid marbles (LMs), which can change their shape, stability, and motion by the application of stimuli, attract a growing interest due to their wide range of applications. Our approach to design photo- and thermoresponsive LMs is based on the use of micrometer-sized fatty acid (FA) particles as phase change material covered with polypyrrole (PPy) overlayers with photothermal property. The core-shell particles were synthesized by aqueous chemical oxidative seeded dispersion polymerization. First, we investigated the effect of the alkyl chain length of FA on the resulting FA/PPy core-shell particles by characterizing their size and its distribution, shape, morphology, chemical composition, and photothermal behavior. Then LMs were fabricated by rolling water droplets on the dried FA/PPy particle powder bed and their light and temperature dual stimuli-responsive nature was studied as a function of the FA alkyl chain length. For all FAs studied, LMs disrupted in a domino manner by light irradiation as the first trigger: the temperature of the FA/PPy particles on the LM surface increased by light irradiation, followed by phase change of FA core of the particles from solid to liquid, resulting in disruption of the LM and release of the encapsulated water. The disruption time was closely correlated to the melting point of FA linked to the alkyl chain length and light irradiation power, and it could be controlled and tuned easily between quasi instantaneous and approximately 10 s. Finally, we showed potential applications of the LMs as a carrier for controlled delivery and release of substances and a sensor.

Phase Change Materials for Renewable Energy Storage at Intermediate Temperatures

Thermal energy storage technologies utilizing phase change materials (PCMs) that melt in the intermediate temperature range, between 100 and 220 °C, have the potential to mitigate the intermittency issues of wind and solar energy. This technology can take thermal or electrical energy from renewable sources and store it in the form of heat. This is of particular utility when the end use of the energy is also as heat. For this purpose, the material should have a phase change between 100 and 220 °C with a high latent heat of fusion. Although a range of PCMs are known for this temperature range, many of these materials are not practically viable for stability and safety reasons, a perspective not often clear in the primary literature. This review examines the recent development of thermal energy storage materials for application with renewables, the different material classes, their physicochemical properties, and the chemical structural origins of their advantageous thermal properties. Perspectives on further research directions needed to reach the goal of large scale, highly efficient, inexpensive, and reliable intermediate temperature thermal energy storage technologies are also presented.

A Thermoregulatory Flexible Phase Change Nonwoven for All-Season High-Efficiency Wearable Thermal Management

Phase change materials have a key role for wearable thermal management, but suffer from poor water vapor permeability, low enthalpy value and weak shape stability caused by liquid phase leakage and intrinsic rigidity of solid-liquid phase change materials. Herein, we report for the first time a versatile strategy for designed assembly of high-enthalpy flexible phase change nonwovens (GB-PCN) by wet-spinning hybrid graphene-boron nitride (GB) fiber and subsequent impregnating paraffins (e.g., eicosane, octadecane). As a result, our GB-PCN exhibited an unprecedented enthalpy value of 206.0 J g-1, excellent thermal reliability and anti-leakage capacity, superb thermal cycling ability of 97.6% after 1000 cycles, and ultrahigh water vapor permeability (close to the cotton), outperforming the reported PCM films and fibers to date. Notably, the wearable thermal management systems based on GB-PCN for both clothing and face mask were demonstrated, which can maintain the human body at a comfortable temperature range for a significantly long time. Therefore, our results demonstrate huge potential of GB-PCN for human-wearable passive thermal management in real scenarios.

A biomimetic and bioactive scaffold with intelligently pulsatile teriparatide delivery for local and systemic osteoporosis regeneration

Osteoporosis is one of the most disabling consequences of aging, osteoporotic fractures and higher risk of the subsequent fractures leading to substantial disability and deaths, indicating both local fractures healing and the early anti-osteoporosis therapy are of great significance. Teriparatide is strong bone formation promoter effective in treating osteoporosis, while side effects limit clinical applications. Traditional drug delivery is lack of sensitive and short-term release, finding a new non-invasive and easily controllable drug delivery to not only repair the local fractures but also improve total bone mass has remained a great challenge. Thus, bioinspired by the natural bone components, we develop appropriate interactions between inorganic biological scaffolds and organic drug molecules, achieving both loaded with the teriparatide in the scaffold and capable of releasing on demand. Herein, biomimetic bone microstructure of mesoporous bioglass, a near-infrared ray triggered switch, thermosensitive liposomes based on a valve, and polydopamine coated as a heater is developed rationally for osteoporotic bone regeneration. Teriparatide is pulsatile released from intelligent delivery, not only rejuvenating osteoporotic bone defect, but also presenting strong systemic anti-osteoporosis therapy. This biomimetic bone carrying novel drug delivery platform is well worth expecting to be a new promising strategy and clinically commercialized to help patients survive from the osteoporotic fracture.

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A novel NIR-triggered three-in-one smart platform was proposed.

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Highly NIR-sensitive in vivo controlled release and self-regulating pulsatile release can be achieved.

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Local precise pulsatile release accelerates osteoporotic bone healing.

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This study focused on the osteoporotic bone regeneration of both skull and femur at the same time.

Advances in stimuli-responsive systems for pesticides delivery: Recent efforts and future outlook

Effective pest management for enhanced crop output is one of the primary goals of establishing sustainable agricultural practices in the world. Pesticides are critical in preventing biological disasters, ensuring crop productivity, and fostering sustainable agricultural production growth. Studies showed that crops are unable to properly utilize pesticides because of several limiting factors, such as leaching and bioconversion, thereby damaging ecosystems and human health. In recent years, stimuli-responsive systems for pesticides delivery (SRSP) by nanotechnology demonstrated excellent promise in enhancing the effectiveness and safety of pesticides. SRSP are being developed with the goal of delivering precise amounts of active substances in response to biological needs and environmental factors. An in-depth analysis of carrier materials, design fundamentals, and classification of SRSP were provided. The adhesion of SRSP to crop tissue, absorption, translocation in and within plants, mobility in the soil, and toxicity were also discussed. The problems and shortcomings that need be resolved to accelerate the actual deployment of SRSP were highlighted in this review.

A Smart Photothermal Nanosystem with an Intrinsic Temperature-Control Mechanism for Thermostatic Treatment of Bacterial Infections

Photothermal therapy (PTT) has attracted extensive attention in disease treatments. However, conventional photothermal systems do not possess a temperature-control mechanism, which poses a serious risk to healthy tissues and/or organs due to inevitable thermal damage. Herein, a smart photothermal nanosystem with an intrinsic temperature-control mechanism for thermostatic treatment of bacterial infections is reported. The smart photothermal nanosystem is constructed by loading a thermochromic material into a hollow-structured silica nanocarrier, in which the thermochromic material is composed of naturally occurring phase-change materials (PCMs), a proton-responsive spirolactone, and a proton source. The resulting nanosystem shows strong near-infrared (NIR) absorption and efficient photothermal conversion in solid PCMs but becomes NIR-transparent when PCMs are melted upon NIR irradiation. Such an attractive feature can precisely regulate the photothermal equilibrium temperature to the melting point of PCMs, regardless of the variation in external experimental parameters. In contrast to conventional PTT with severe thermal damage, the reported smart photothermal nanosystem provides an internal protection mechanism on healthy tissues and/or organs, which remarkably accelerates the recovery of bacteria-infected wounds. The smart photothermal nanosystem is a versatile PTT platform, holding great promise in the safe and efficient treatment of bacterial infections and multimodality synergistic therapy.

Flask-like Janus Colloidal Motors with Explicit Direction and Tunable Speed

Nanoparticles with an anisotropic morphology and composition are flourishing in various scientific fields. Their morphology has a great impact on their functions, but the precise regulation of their growth and final morphology is still challenging. Here, flask-like Janus particles (FJPs) with different compositions segmented on the inner and outer surfaces were fabricated via a sol-gel process using different silane precursors. The neck length of the flask-like particles can be controllably regulated by employing different silane precursors. The Pt catalyst was selectively loaded in their cavities, and as-formed FJPs@Pt are employed as colloidal motors. Due to the adjustable neck length, the Janus colloidal motors have explicit directionality and tunable speeds (max diffusion coefficient is 18.2 μm² s^-1).

Photo/Thermo Dual Stimulus-Responsive Liquid Marbles Stabilized with Polypyrrole-Coated Stearic Acid Particles

In this study, we report on the fabrication of photo/thermo dual stimulus-responsive liquid marbles (LMs) that can be disrupted by light irradiation and/or heating. To stabilize the LMs, we synthesized micrometer-sized stearic acid (SA) particles coated with overlayers of polypyrrole (PPy) by aqueous chemical oxidative seeded dispersion polymerization. The SA/PPy core-shell particles could adsorb at the air-water interface to stabilize LMs by rolling water droplets on the particle powder bed. The presence of SA, known as a phase-change material, which undergoes a transition from solid to liquid by heating, and PPy, which can transduce light to heat, gives rise to the photo and thermo dual stimulus-responsive characters of the LMs. The disruption of the LMs could be induced in a cascade manner: light irradiation on the LM induced a temperature increase, followed by melting of the SA component on the LM surface, leading to its disruption and release of the inner water. The disruption time is linked to the PPy loading and light irradiation power, and it can be tuned from quasi-instantaneous to a few tens of seconds. The melting of SA due to a light-induced phase change from the solid to liquid state is a new mechanism to trigger the disruption of LMs. We finally demonstrated two applications of the LMs as a light-responsive microreactor and a sensor.

Applications of phase change materials in smart drug delivery for cancer treatment

Phase change materials (PCMs) are materials that are stimulated by the external enthalpy change (temperature) to realize solid-liquid and liquid-solid phase transformation. Due to temperature sensitivity, friendly modification, and low toxicity, PCMs have been widely used in smart drug delivery. More often than not, the drug was encapsulated in a solid PCMs matrix, a thermally responsive material. After the trigger implementation, PCMs change into a solid-liquid phase, and the loading drug is released accordingly. Therefore, PCMs can achieve precise release control with different temperature adjustments, which is especially important for small molecular drugs with severe side effects. The combination of drug therapy and hyperthermia through PCMs can achieve more accurate and effective treatment of tumor target areas. This study briefly summarizes the latest developments on PCMs as smart gate-keepers for anti-tumor applications in light of PCMs becoming a research hot spot in the nanomedicine sector in recent years.

Phase-change materials-based platforms for biomedicine

Recently, phase-change materials (PCMs) have gathered enormous attention in diverse fields of medicine, particularly in bioimaging, therapeutic delivery, and tissue engineering. Due to the excellent physicochemical characteristics and morphological characteristics of PCMs, several developments have been demonstrated in the construction of diverse PCMs-based architectures toward providing new burgeoning opportunities in developing innovative technologies and improving the therapeutic benefits of the existing formulations. However, the fabrication of PCM-based materials into colloidally stable particles remains challenging due to their natural hydrophobicity and high crystallinity. This review systematically emphasizes various PCMs-based platforms, such as traditional PCMs (liposomes) and their nanoarchitectured composites, including PCMs as core, shell, and gatekeeper, highlighting the pros and cons of these architectures for delivering bioactives, imaging anatomical features, and engineering tissues. Finally, we summarize the article with an exciting outlook, discussing the current challenges and future prospects for PCM-based platforms as biomaterials.

Iron-Based Hollow Nanoplatforms for Cancer Imaging and Theranostics

Over the past decade, iron (Fe)-based hollow nanoplatforms (Fe-HNPs) have attracted increasing attention for cancer theranostics, due to their high safety and superior diagnostic/therapeutic features. Specifically, Fe-involved components can serve as magnetic resonance imaging (MRI) contrast agents (CAs) and Fenton-like/photothermal/magnetic hyperthermia (MTH) therapy agents, while the cavities are able to load various small molecules (e.g., fluorescent dyes, chemotherapeutic drugs, photosensitizers, etc.) to allow multifunctional all-in-one theranostics. In this review, the recent advances of Fe-HNPs for cancer imaging and treatment are summarized. Firstly, the use of Fe-HNPs in single T1-weighted MRI and T2-weighted MRI, T1-/T2-weighted dual-modal MRI as well as other dual-modal imaging modalities are presented. Secondly, diverse Fe-HNPs, including hollow iron oxide (IO) nanoparticles (NPs), hollow matrix-supported IO NPs, hollow Fe-complex NPs and hollow Prussian blue (PB) NPs are described for MRI-guided therapies. Lastly, the potential clinical obstacles and implications for future research of these hollow Fe-based nanotheranostics are discussed.

Filler dimensionality effect on the performance of paraffin-based phase change materials

HYPOTHESIS

Phase change materials have the potential for use in high-density thermal energy storage. However, their low thermal conductivity and the need for shape stabilization restrict their performances and implementation in various fields. The inclusion of thermally conductive nanomaterial as a single or hybrid filling is expected to form 3D network that enhances the thermal performances of phase change materials. The encapsulation of the colloidal composites in a polymer matrix stabilizes the phase change material.

EXPERIMENTS

A paraffin matrix was loaded with carbon-based fillers of various dimensionalities, namely, 1D-carbon nanotubes, 2D-graphene nanoplatelets, and 3D-graphite flakes. The thermal conductivity of the colloidal composite was measured by transient plane source and the latent heat capacity by differential scanning calorimetry techniques. Modeling the thermal conductivity by the effective medium approach predicts the experimental results.

FINDINGS

The thermal conductivity of the phase change material loaded with fillers is enhanced from 0.2 to 11 W (m K)^-1 (×55) compared with a filler-free paraffin matrix. We attribute this enhancement to the synergetic effect of the hybrid fillers (8 vol% graphite flakes and 12 vol% graphene nanoplatelets) and consequent compression (25 bar) of the colloidal composite. Moreover, the obtained phase change material is completely stable during charging and discharging cycles.

Temperature-Sensitive Anti-Inflammatory Organohydrogels Containing Janus Particle Stabilized Phase-Change Microinclusions

A fabrication strategy for multifunctional organohydrogels is proposed, which combines phase-change microinclusions within a double-network (DN) hydrogel under the stabilization of Janus particles. Janus particles possess reactivity and colloidal stability for more robust organohydrogels, while the interstice among Janus particles enhances the mass transfer between the phase interfaces. Moreover, DN hydrogels are achieved through dynamic cross-linking networks, endowing organohydrogels with injectability and self-healing performance. Phase-change microinclusions are beneficial to the organohydrogels with temperature-responsive mechanical property and temperature-programed shape-memory performance. Organohydrogels can be employed for temperature therapy through the melting-crystallization process of phase-change microinclusions. Simultaneously, the payloads within microinclusions can be released for antibacteria upon melting the encapsulated wax. The organohydrogels can be served as an ideal dressing with temperature-responsive mechanical property, temperature therapy effectiveness, and temperature-triggered antibacterial ability.

Stimuli-Responsive Gold Nanocages for Cancer Diagnosis and Treatment

With advances in nanotechnology, various new drug delivery systems (DDSs) have emerged and played a key role in the diagnosis and treatment of cancers. Over the last two decades, gold nanocages (AuNCs) have been attracting considerable attention because of their outstanding properties. This review summarizes current advancements in endogenous, exogenous, and dual/multi-stimuli responsive AuNCs in drug delivery. This review focuses on the properties, clinical translation potential, and limitations of stimuli-responsive AuNCs for cancer diagnosis and treatment.

An Opto- and Thermal-Rewrite PCM/CNF-IR 780 Energy Storage Nanopaper with Mechanical Regulated Performance

In spite of efforts to fabricate self-assembled energy storage nanopaper with potential applications in displays, greenhouses, and sensors, few studies have investigated their multiple stimuli-sensitivities. Here, an opto- and thermal-rewrite phase change material/cellulose nanofibril (PCM/CNF) energy storage nanopaper with mechanical regulated performance is facilely fabricated, through 5 min sonication of PCMs and CNFs in an aqueous system. The combination of PCM and CNF not only guarantees the recyclability of PCM without leakage, but also offers nanopaper adaptive properties by leveraging the mobility and optical variation accompanying solid-to-liquid transition of PCM. Besides, trace near-infrared (NIR) dye (IR 780) in it imparts a PCM-embedded nanopaper photothermal effect to modulate the local transparency via time- and position-controlled laser exposure, leading to a reusable opto-writing nanopaper. Furthermore, since the synergistic effect of stick-and-slip function attributes from PCMs and pore structures are produced by calcium ions, the PCM/CNF energy storage nanopaper exhibits excellent mechanically regulated performance from rigid to flexible, which greatly enriches their application in energy-efficient smart buildings and displays.