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In this work, using supramolecular polyurethanes theories, two polycaprolactone-based polyurethanes with 2-ureido-4-[1H]-pyrimidinone (UPy) motifs capable of forming quadruple hydrogen bonds were synthetized and characterized, focusing our attention on their capability to show thermally activated shape-memory response. In particular, 1H NMR analyses confirmed the chemical structure of the supramolecular polyurethanes, while DSC showed their totally amorphous morphology. DMTA in tensile mode was used to study their thermally activated shape-memory properties. In our case, the UPy units are the switching domains while the network formed by the segregated hard segments is the permanent domain obtained materials with excellent shape-memory response at both 100 and 85 °C. These materials are promising for multi-responsive materials where bio-based and potentially recyclable polymers with excellent shape-memory properties are needed. [ABSTRACT FROM AUTHOR]

Over the last couple of decades, stimuli-responsive supramolecular gels comprising synthetic short peptides as building blocks have been explored for various biological and material applications. Though a wide range of stimuli has been tested depending on the structure of the peptides, light as a stimulus has attracted extensive attention due to its non-invasive, non-contaminant, and remotely controllable nature, precise spatial and temporal resolution, and wavelength tunability. The integration of molecular photo-switch and low-molecular-weight synthetic peptides may thus provide access to supramolecular self-assembled systems, notably supramolecular gels, which may be used to create dynamic, light-responsive "smart" materials with a variety of structures and functions. This short review summarizes the recent advancement in the area of light-sensitive peptide gelation. At first, a glimpse of commonly used molecular photo-switches is given, followed by a detailed description of their incorporation into peptide sequences to design light-responsive peptide gels and the mechanism of their action. Finally, the challenges and future perspectives for developing next-generation photo-responsive gels and materials are outlined. [ABSTRACT FROM AUTHOR]

Traditional open surgery complications are typically due to trauma caused by accessing the procedural site rather than the procedure itself. Minimally invasive surgery allows for fewer complications as microdevices operate through small incisions or natural orifices. However, current minimally invasive tools typically have restricted maneuverability, accessibility, and positional control of microdevices. Thermomagnetic-responsive microgrippers are microscopic multi-fingered devices that respond to temperature changes due to the presence of thermal-responsive polymers. Polymeric devices, made of poly(N-isopropylacrylamide-co-acrylic acid) (pNIPAM-AAc) and polypropylene fumarate (PPF), self-fold due to swelling and contracting of the hydrogel layer. In comparison, soft metallic devices feature a pre-stressed metal bilayer and polymer hinges that soften with increased temperature. Both types of microdevices can self-actuate when exposed to the elevated temperature of a cancerous tumor region, allowing for direct targeting for biopsies. Microgrippers can also be doped to become magnetically responsive, allowing for direction without tethers and the retrieval of microdevices containing excised tissue. The smaller size of stimuli-responsive microgrippers allows for their movement through hard-to-reach areas within the body and the successful extraction of intact cells, RNA and DNA. This review discusses the mechanisms of thermal- and magnetic-responsive microdevices and recent advances in microgripper technology to improve minimally invasive surgical techniques. [ABSTRACT FROM AUTHOR]

In this study, fabrication of smart polymer and cotton fabrics with temperature- and pH-responsive as well as antibacterial activity was aimed. For this aim, random poly(N-isopropylacrylamide-comethacrylamide) P(NIPAM-co-MAM) copolymers containing different ratio of NIPAM/MAM monomers were synthesized through free radical addition polymerization method via 2,2'-azobis (2 methylpropionamide) dihydrochloride as an initiator. Analysis results showed that the copolymers were synthesized successfully and their LCST values were in the range of 33°C to 41°C. A selected sample of the synthesized copolymers was applied to the cotton fabric via double-bath impregnation method and thermo-responsive wetting property of the fabric was examined via wetting time and water uptake tests, contact angle measurement. The test results indicated that hydrophilic character of the fabric changed to the hydrophobic character reversibly depending on change in temperature. Besides, the fabric exhibited pH-responsive water absorption ability. The fabric could manage water vapor permeability via changing its pore size as well as hydrophilic character depending on temperature. Besides, it was concluded that the fabric had strong antibacterial activity against S.aureus bacteria. [ABSTRACT FROM AUTHOR]

Stimuli-responsive fibers are highly desirable for their potential applications in areas such as anti-counterfeiting, optical memory systems, colorimetric sensing, and bioimaging sensors. An iridescent luminescent fibers that can achieve multi-color with long afterglow and photochromic properties is always required in color-on-demand applications. Here, a set of distinct three-primary colors luminescent fibers based on red-green-blue (RGB) system. Y2O2S:Eu3+, Mg2+, Ti4+ (red), SrAl2O4:Eu2+, Dy3+ (green), Sr2MgSi2O7: Eu2+, Dy3+ (blue) are successfully synthesized. Spiropyran and as-prepared luminescent materials are introduced into PAN fibers by a one-step extrusion wet-spinning process to achieve distinct three-primary colors luminescent photochromic fiber. These as-prepared fibers emit bright lights under excitation of ultraviolet with long afterglow. These fibers exhibit outstanding tensile properties which allow knitting or weaving them into demonstrated functional designs for aesthetic designs and encryption/decryption protocols. Comparing with previous studied stimuli-responsive fibers, our research focus on distinct three-primary colors luminescent photochromic fibers present enormous potential in 3D printing, information encryption, and next generation smart fibers.

Donor-acceptor Stenhouse adducts (DASAs) are a photo-switch class that undergoes triene cyclisation in response to visible light. Herein, electrochemical oxidation is demonstrated as an effective alternative stimulus for the triene cyclisation commonly associated with photo-switching.

Ionic liquids (ILs) play a crucial role in the design of novel materials. The ionic nature of ILs provides numerous advantages in drug delivery, acting as a green solvent or active ingredient to enhance the solubility, permeability, and binding efficiency of drugs. They could also function as a structuring agent in the development of nano/micro particles for drug delivery, including micelles, vesicles, gels, emulsion, and more. This review summarize the ILs and IL-based gel structures with their advanced drug delivery applications. The first part of review focuses on the role of ILs in drug formulation and the applications of ILs in drug delivery. The second part of review offers a comprehensive overview of recent drug delivery applications of IL-based gel. It aims to offer new perspectives and attract more attention to open up new avenues in the biomedical applications of ILs and IL-based gels. [Display omitted] • Discussion on the classification and properties of ionic liquids, along with their key roles in drug formulation. • Identification of the properties and applications of ionic liquids and ionogels in various delivery methods. • Exploration of the classification, preparation, processing methods, and biomedical characteristics of ionogel. • Highlighting the challenges associated with ionic liquids and ionogels in drug delivery. [ABSTRACT FROM AUTHOR]

α-cyanostilbene derivatives, known as AIE molecules, have the potential to serve as optical recorders and vapor sensor by altering the molecular aggregation and / or stacking models. Despite the significant scientific and technological importance of the correlation between molecular stacking modes and modulated optical properties, relevant research remains scarce. Herein, two thermodynamically stable crystalline phase (BCr and GCr) were found for a biphenyl-based cyanostilbenic compound, DSB-SQ , condensed from its solution. Uniquely, the BCr demonstrated reversible mechanochromism and irreversible thermalchromism, whereas GCr remained unaffected by exposure to light, heat, grinding, etc. The discoloration process was correlated with the variation of local dipole coupling modes during the phase transition, leading to a significant change in π-π overlap and delocalization of excited states. Finally, the BCr was doped with polyvinyl alcohol (PVA) to prepare a composite membrane with dynamic information storage and encryption function. [Display omitted] [ABSTRACT FROM AUTHOR]

Design and fabrication of freestanding chiro‐photonic crystal film with the ability to change color over the whole visible light spectrum is appealing for anticounterfeiting technology and smart labels. Utilizing a newly synthesized light‐responsive molecular motor functionalized with cholesterol (chol‐MM) on the rotor, novel light‐controlled photonic crystal is prepared by doping the novel chol‐MM into liquid crystals (LCs). Thanks to the liquid crystalline cholesterol substituent, the chol‐MM can be triggered by visible light (420 nm). At the same time, the miscibility of chol‐MM in LC matrix is significantly enhanced. Integrating the chol‐MM with thermochromic hydrogen‐bonded LC matrix, thermal and light dual‐responsive cholesteric LC (CLC) material is prepared, in which the nanoscale helical pitch is tunable by photo‐induced molecular motions of chol‐MM. More importantly, utilizing UV‐initiated polymerization of the visible light‐modulated CLC material, structural colored photonic crystal films with arbitrary colorful patterns are fabricated. Such freestanding helical nanostructured labels have potential in the application of encrypted communication and anticounterfeiting. [ABSTRACT FROM AUTHOR]

Protein therapeutics have become increasingly popular for the treatment of a variety of diseases owing to their specificity to targets of interest. However, challenges associated with them have limited their use for a range of ailments, including the limited options available for local controlled delivery. To address this challenge, degradable hydrogel microparticles, or microgels, loaded with model biocargoes were created with tunable release profiles or triggered burst release using chemistries responsive to endogenous or exogeneous stimuli, respectively. Specifically, microfluidic flow-focusing was utilized to form homogenous microgels with different spontaneous click chemistries that afforded degradation either in response to redox environments for sustained cargo release or light for on-demand cargo release. The resulting microgels were an appropriate size to remain localized within tissues upon injection and were easily passed through a needle relevant for injection, providing means for localized delivery. Release of a model biopolymer was observed over the course of several weeks for redox-responsive formulations or triggered for immediate release from the light-responsive formulation. Overall, we demonstrate the ability of microgels to be formulated with different materials chemistries to achieve various therapeutic release modalities, providing new tools for creation of more complex protein release profiles to improve therapeutic regimens. [ABSTRACT FROM AUTHOR]

The present study aimed to develop a stable interconnected matrix as a sustained release drug delivery material. Arabinoxylan (AX) was extracted from ispaghula husk and then crosslinked with different concentrations, i.e., 0.5, 1.0, and 1.5 g of CaCl2 per 0.25 g of AX. The crosslinking was confirmed through Fourier transform infrared spectroscopy. The swelling capacity of crosslinked AX (CL-AX) was evaluated against buffer solutions of pH 1.2, 6.8, 7.4, and water. The swelling capacity increased from pH 1.2 to pH 7.4 and followed the second order swelling kinetics. The swelling study also revealed that CL-AX with 1.0 g CaCl2 showed maximum swelling capacity. The swelling–deswelling (on–off switching) behavior of CL-AX was evaluated in water–ethanol, water–0.9% NaCl solution, and buffer solutions of pH 7.4–1.2 and showed responsive swelling–deswelling behavior. Scanning electron microscopy revealed a highly porous nature of CL-AX with a mesh of thin fibrous networking. Hemocompatibility studies of CL-AX revealed its non-thrombogenic and nonhemolytic attributes. The CL-AX matrix tablet prolonged the release of enalapril maleate for 24 h, and the drug release followed the zero order kinetics and super case-II transport mechanism. Therefore, CL-AX can be recognized as a stimuli responsive and hemocompatible biomaterial with sustained drug release potential. [ABSTRACT FROM AUTHOR]

Bacterial biofilm infections have been threatening the human's life and health globally for a long time because they typically cause chronic and persistent infections. Traditional antibiotic therapies can hardly eradicate biofilms in many cases, as biofilms always form a robust fortress for pathogens inside, inhibiting the penetration of drugs. To address the issues, many novel drug carriers emerged as promising strategies for biofilm treatment. Among them, stimuli-responsive nanocarriers have attracted much attentions for their intriguing physicochemical properties, such as tunable size, shape and surface chemistry, especially smart drug release characteristic. Based on the microenvironmental difference between biofilm infection sites and normal tissue, many stimuli, such as bacterial products accumulating in biofilms (enzymes, glutathione, etc.), lower pH and higher H2O2 levels, have been employed and proved in favor of "on-demand" drug release for biofilm elimination. Additionally, external stimuli including light, heat, microwave and magnetic fields are also able to control the drug releasing behavior artificially. In this review, we summarized recent advances in stimuli-responsive nanocarriers for combating biofilm infections, and mainly, focusing on the different stimuli that trigger the drug release. 摘要: 细菌生物膜常造成长期, 顽固的感染, 因此长久以来都严重威胁着全球人类的生命健康。 由于生物膜会为内部病原体建造其保护性屏障, 阻碍药物的渗透, 因此传统的抗生素疗法通常难以根除生物膜。 为了解决这一问题, 研究人员构建了许多新型的药物载体, 以作为颇具前景的生物膜治疗策略。 其中, 刺激响应型纳米载体具有有趣的物理-化学性质, 例如尺寸, 形状和表面化学可调节的性质, 特别是智能药物释放性质, 因此吸引了人们的广泛关注。 根据生物膜感染位置和正常组织之间的微环境差异, 人们利用多种刺激物, 比如生物膜内积累的细菌产物 (酶, 谷胱甘肽等), 低pH和高H2O2水平, 来设计药物的"按需释放"以清除生物膜。 此外, 包括光, 热, 微波和磁场在内的外源刺激, 也可以用于人工控制药物的释放行为。 本篇综述中, 我们总结了刺激响应型纳米载体在对抗细菌生物膜中的最新进展, 并着重于引发药物释放的多种刺激物。 [ABSTRACT FROM AUTHOR]

Recently, we presented a strategy for packaging peptides as side‐chains in high‐density brush polymers. For this globular protein‐like polymer (PLP) formulation, therapeutic peptides were shown to resist proteolytic degradation, enter cells efficiently and maintain biological function. In this paper, we establish the role charge plays in dictating the cellular uptake of these peptide formulations, finding that peptides with a net positive charge will enter cells when polymerized, while those formed from anionic or neutral peptides remain outside of cells. Given these findings, we explored whether cellular uptake could be selectively induced by a stimulus. In our design, a cationic peptide is appended to a sequence of charge‐neutralizing anionic amino acids through stimuli‐responsive cleavable linkers. As a proof‐of‐concept study, we tested this strategy with two different classes of stimuli, exogenous UV light and an enzyme (a matrix metalloproteinase) associated with the inflammatory response. The key finding is that these materials enter cells only when acted upon by the stimulus. This approach makes it possible to achieve delivery of the polymers, therapeutic peptides or an appended cargo into cells in response to an appropriate stimulus. [ABSTRACT FROM AUTHOR]

Conventional tumor-targeted drug delivery systems (DDSs) face challenges, such as unsatisfied systemic circulation, low targeting efficiency, poor tumoral penetration, and uncontrolled drug release. Recently, tumor cellular molecules-triggered DDSs have aroused great interests in addressing such dilemmas. With the introduction of several additional functionalities, the properties of these smart DDSs including size, surface charge and ligand exposure can response to different tumor microenvironments for a more efficient tumor targeting, and eventually achieve desired drug release for an optimized therapeutic efficiency. This review highlights the recent research progresses on smart tumor environment responsive drug delivery systems for targeted drug delivery. Dynamic targeting strategies and functional moieties sensitive to a variety of tumor cellular stimuli, including pH, glutathione, adenosine-triphosphate, reactive oxygen species, enzyme and inflammatory factors are summarized. Special emphasis of this review is placed on their responsive mechanisms, drug loading models, drawbacks and merits. Several typical multi-stimuli responsive DDSs are listed. And the main challenges and potential future development are discussed.

Synthetic cells, which mimic cellular function within a minimal compartment, are finding wide application, for instance in studying cellular communication and as delivery devices to living cells. However, to fully realise the potential of synthetic cells, control of their function is vital. An array of tools has already been developed to control the communication of synthetic cells to neighbouring synthetic cells or living cells. These tools use either chemical inputs, such as small molecules, or physical inputs, such as light. Here, we examine these current methods of controlling synthetic cell communication and consider alternative mechanisms for future use.

The design of novel drug delivery systems is exceptionally critical in disease treatments. Among the existing drug delivery systems, mesoporous silica nanoparticles (MSNs) have shown profuse promise owing to their structural stability, tunable morphologies/sizes, and ability to load different payload chemistry. Significantly, the presence of surface silanol groups enables functionalization with relevant drugs, imaging, and targeting agents, promoting their utility and popularity among researchers. Stimuli-responsive silanol conjugates have been developed as a novel, more effective way to conjugate, deliver, and release therapeutic drugs on demand and precisely to the selected location. Therefore, it is urgent to summarize the current understanding and the surface silanols' role in making MSN a versatile drug delivery platform. This review provides an analytical understanding of the surface silanols, chemistry, identification methods, and their property-performance correlation. The chemistry involved in converting surface silanols to a stimuli-responsive silica delivery system by endogenous/exogenous stimuli, including pH, redox potential, temperature, and hypoxia, is discussed in depth. Different chemistries for converting surface silanols to stimuli-responsive bonds are discussed in the context of drug delivery. The critical discussion is culminated by outlining the challenges in identifying silanols' role and overcoming the limitations in synthesizing stimuli-responsive mesoporous silica-based drug delivery systems., (© 2023 The Authors. Small published by Wiley‐VCH GmbH.)

Objective: To design and evaluate a matrix metalloproteinase 9 (MMP-9)-responsive hydrogel for vital pulp therapy., Methods: A peptide linker with optimized sensitivity toward MMP-9 was crosslinked with 4-arm poly (ethylene glycol)-norbornene (PEG-NB) by thiol-norbornene photo-polymerization. This resulted in the formation of a hydrogel network in which the peptide IDR-1002 was incorporated. Hydrogel characterization and gelation kinetics were examined with Fourier-transform infrared spectroscopy, scanning electron microscopy, rheological testing, and swelling evaluation. Hydrogel degradation was examined through multiple exposure to pre-activated MMP-9, to simulate flare-ups of dental pulp inflammation. The IDR-1002 released from degraded hydrogels was measured with high-performance liquid chromatography. Effect of IDR-1002 released from hydrogels on one-week-old multispecies oral biofilms was evaluated using confocal laser scanning microscopy., Results: MMP-9-responsive, injectable, and photo-crosslinkable hydrogels were successfully synthesized. When hydrogel degradation and release of IDR-1002 were examined with exposure to pre-activated MMP-9, IDR-1002 release was significantly correlated with elevated levels of MMP-9 (p < 0.05). The effectiveness of IDR-1002 in killing bacteria in multispecies oral biofilms was significantly enhanced when the hydrogels were immersed in 10 nM or 20 nM pre-activated MMP-9, compared to immersion in phosphate-buffered saline (p < 0.05)., Conclusions: The MMP-9-responsive hydrogel is a promising candidate for on-demand delivery of bioactive agent in vital pulp therapy., Clinical Significance: MMP-9 is one of the most important diagnostic and prognostic biomarkers for pulpitis. An MMP-9-responsive hydrogel has potential to be used as an in-situ on-demand release system for the diagnosis and treatment of dental pulp inflammation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Published by Elsevier Ltd.)

Peptide-based drug delivery systems have many advantages when compared to synthetic systems in that they have better biocompatibility, biochemical and biophysical properties, lack of toxicity, controlled molecular weight via solid phase synthesis and purification. Lysosomes, solid lipid nanoparticles, dendrimers, polymeric micelles can be applied by intravenous administration, however they are of artificial nature and thus may induce side effects and possess lack of ability to penetrate the blood-brain barrier. An analysis of nontoxic drug delivery systems and an establishment of prospective trends in the development of drug delivery systems was needed. This review paper summarizes data, mainly from the past 5 years, devoted to the use of peptide-based carriers for delivery of various toxic drugs, mostly anticancer or drugs with limiting bioavailability. Peptide-based drug delivery platforms are utilized as peptide–drug conjugates, injectable biodegradable particles and depots for delivering small molecule pharmaceutical substances (500 Da) and therapeutic proteins. Controlled drug delivery systems that can effectively deliver anticancer and peptide-based drugs leading to accelerated recovery without significant side effects are discussed. Moreover, cell penetrating peptides and their molecular mechanisms as targeting peptides, as well as stimuli responsive (enzyme-responsive and pH-responsive) peptides and peptide-based self-assembly scaffolds are also reviewed. [ABSTRACT FROM AUTHOR]

Peptide-based hydrogels have captivated remarkable attention in recent times and serve as an excellent platform for biomedical applications owing to the impressive amalgamation of unique properties such as biocompatibility, biodegradability, easily tunable hydrophilicity/hydrophobicity, modular incorporation of stimuli sensitivity and other functionalities, adjustable mechanical stiffness/rigidity and close mimicry to biological molecules. Putting all these on the same plate offers smart soft materials that can be used for tissue engineering, drug delivery, 3D bioprinting, wound healing to name a few. A plethora of work has been accomplished and a significant progress has been realized using these peptide-based platforms. However, designing hydrogelators with the desired functionalities and their self-assembled nanostructures is still highly serendipitous in nature and thus a roadmap providing guidelines toward designing and preparing these soft-materials and applying them for a desired goal is a pressing need of the hour. This review aims to provide a concise outline for that purpose and the design principles of peptide-based hydrogels along with their potential for biomedical applications are discussed with the help of selected recent reports.

Donor-acceptor Stenhouse adducts (DASAs) are a photo-switch class that undergoes triene cyclisation in response to visible light. Herein, electrochemical oxidation is demonstrated as an effective alternative stimulus for the triene cyclisation commonly associated with photo-switching. [ABSTRACT FROM AUTHOR]

Microbial growth and fluctuations in environmental conditions have been shown to cause microbial contamination and deterioration of food. Thus, it is paramount to develop reliable strategies to effectively prevent the sale and consumption of contaminated or spoiled food. Responsive packaging systems are designed to react to specific stimuli in the food or environment, such as microorganisms or temperature, then implement an informational or corrective response. Informative responsive packaging is aimed at continuously monitoring the changes in food or environmental conditions and conveys this information to the users in real time. Meanwhile, packaging systems with the capacity to control contamination or deterioration are also of great interest. Encouragingly, corrective responsive packaging attempting to mitigate the adverse effects of condition fluctuations on food has been investigated. This packaging exerts its effects through the triggered release of active agents by environmental stimuli. In this review, informative and corrective responsive packaging is conceptualized clearly and concisely. The mechanism and characteristics of each type of packaging are discussed in depth. This review also summarized the latest research progress of responsive packaging and objectively appraised their advantages. Evidently, the mechanism through which packaging systems respond to microbial contamination and associated environmental factors was also highlighted. Moreover, risk concerns, related legislation, and consumer perspective in the application of responsive packaging are discussed as well. Broadly, this comprehensive review covering the latest information on responsive packaging aims to provide a timely reference for scientific research and offer guidance for presenting their applications in food industry. [ABSTRACT FROM AUTHOR]

[Display omitted] • DMSN with highly loaded hydrophobic drug was used as the drug delivery vehicle. • DMSN featured with small particle size, high pore volume and large pore size. • A vacuum rotary evaporation-mediated casting method was applied for drug loading. • A GSH-responsive PMAsh shell and Tf were functionalized for tumor-targeting therapy. The efficacy of hydrophobic chemotherapy drugs in cancer treatment is often hampered by their poor solubility in the physiological environment, which causes their low delivery efficiency in the body. This manuscript develops an intelligent nanocarrier (~100 nm) drug delivery system that can highly load a water-insoluble drug, and possesses desirable tumor-targeting properties for cancer therapy. In this system, highly porous silica nanoparticles (pore volume ~ 1.4 cm3 g−1) with a dendritic pore structure (denoted as DMSN) are applied as a matrix for drug loading. A facile, vacuum rotary evaporation-mediated casting method is applied to quantitatively load a high content of a hydrophobic drug (i.e., paclitaxel) in the DMSN matrix. A thiol-modified poly(methacrylic acid) (denoted as PMAsh) shell is then assembled and crosslinked via disulfide bonds on the particle surface to improve the dispersibility of the particles in an aqueous environment. After functionalization of the PMAsh shell with the targeting ligand transferrin (Tf), the nanocarriers exhibit accumulation ability on tumor cells, both in vitro and in vivo. Combining the fascinating properties of high drug-loading, excellent colloidal stability, low cytotoxicity, targeting ability and glutathione-responsive PMAsh shell deconstruction properties, the nanocarriers described here hold great promise for the efficient delivery of hydrophobic drugs and tumor treatment. [ABSTRACT FROM AUTHOR]

Systemic treatments for rheumatoid arthritis are associated with many side effects. This study aimed to minimize the side effects associated with the systemic administration of leflunomide (LEF) by formulating LEF-loaded emulsomes (EMLs) for intra-articular administration. Additionally, EMLs were loaded with supramagnetic nanoparticles (SPIONs) to enhance joint localization, where a magnet was placed on the joint area after intra-articular administration. Full in vitro characterization, including colloidal characteristics, entrapment efficiency, and in vitro release were conducted besides the in vivo evaluation in rats with adjuvant-induced arthritis. In vivo study included joint diameter measurement, X-ray radiographic analysis, RT-PCR analysis, Western blotting, ELISA for inflammatory markers, and histopathological examination of dissected joints. The particle size and entrapment efficiency of the selected LEF SPION EMLs were 198.2 nm and 83.7%, respectively. The EMLs exhibited sustained release for 24 h. Moreover, in vivo evaluation revealed LEF SPION EMLs to be superior to the LEF suspension, likely due to the increase in LEF solubility by nanoencapsulation that improved the pharmacological effects and the use of SPION that ensured the localization of EMLs in the intra-articular cavity upon administration.

Cancer seriously threatens human health. Surgery, radiotherapy and chemotherapy are the three pillars of traditional cancer treatment, with targeted therapy and immunotherapy emerging over recent decades. Standard drug regimens are mostly executed via intravenous injection (IV), especially for chemotherapy agents. However, these treatments pose severe risks, including off-target toxic side effects, low drug accumulation and penetration at the tumor site, repeated administration, etc., leading to inadequate treatment and failure to meet patients’ needs. Arising from these challenges, a local regional anticancer strategy has been proposed to enhance therapeutic efficacy and concomitantly reduce systemic toxicity. With the advances in biomaterials and our understanding of the tumor microenvironment, in situ stimulus-responsive hydrogels, also called smart hydrogels, have been extensively investigated for local anticancer therapy due to their injectability, compatibility and responsiveness to various stimuli (pH, enzyme, heat, light, magnetic fields, electric fields etc.). Herein, we focus on the latest progress regarding various stimuli that cause phase transition and drug release from smart hydrogels in local regional anticancer therapy. Additionally, the challenges and future trends of the reviewed in situ smart hydrogels for local drug delivery are summarized and proposed.

Over the last couple of decades, stimuli-responsive supramolecular gels comprising synthetic short peptides as building blocks have been explored for various biological and material applications. Though a wide range of stimuli has been tested depending on the structure of the peptides, light as a stimulus has attracted extensive attention due to its non-invasive, non-contaminant, and remotely controllable nature, precise spatial and temporal resolution, and wavelength tunability. The integration of molecular photo-switch and low-molecular-weight synthetic peptides may thus provide access to supramolecular self-assembled systems, notably supramolecular gels, which may be used to create dynamic, light-responsive “smart” materials with a variety of structures and functions. This short review summarizes the recent advancement in the area of light-sensitive peptide gelation. At first, a glimpse of commonly used molecular photo-switches is given, followed by a detailed description of their incorporation into peptide sequences to design light-responsive peptide gels and the mechanism of their action. Finally, the challenges and future perspectives for developing next-generation photo-responsive gels and materials are outlined.

Traditional open surgery complications are typically due to trauma caused by accessing the procedural site rather than the procedure itself. Minimally invasive surgery allows for fewer complications as microdevices operate through small incisions or natural orifices. However, current minimally invasive tools typically have restricted maneuverability, accessibility, and positional control of microdevices. Thermomagnetic-responsive microgrippers are microscopic multi-fingered devices that respond to temperature changes due to the presence of thermal-responsive polymers. Polymeric devices, made of poly(N-isopropylacrylamide-co-acrylic acid) (pNIPAM-AAc) and polypropylene fumarate (PPF), self-fold due to swelling and contracting of the hydrogel layer. In comparison, soft metallic devices feature a pre-stressed metal bilayer and polymer hinges that soften with increased temperature. Both types of microdevices can self-actuate when exposed to the elevated temperature of a cancerous tumor region, allowing for direct targeting for biopsies. Microgrippers can also be doped to become magnetically responsive, allowing for direction without tethers and the retrieval of microdevices containing excised tissue. The smaller size of stimuli-responsive microgrippers allows for their movement through hard-to-reach areas within the body and the successful extraction of intact cells, RNA and DNA. This review discusses the mechanisms of thermal- and magnetic-responsive microdevices and recent advances in microgripper technology to improve minimally invasive surgical techniques.

The present study aimed to develop a stable interconnected matrix as a sustained release drug delivery material. Arabinoxylan (AX) was extracted from ispaghula husk and then crosslinked with different concentrations, i.e., 0.5, 1.0, and 1.5 g of CaCl2 per 0.25 g of AX. The crosslinking was confirmed through Fourier transform infrared spectroscopy. The swelling capacity of crosslinked AX (CL-AX) was evaluated against buffer solutions of pH 1.2, 6.8, 7.4, and water. The swelling capacity increased from pH 1.2 to pH 7.4 and followed the second order swelling kinetics. The swelling study also revealed that CL-AX with 1.0 g CaCl2 showed maximum swelling capacity. The swelling–deswelling (on–off switching) behavior of CL-AX was evaluated in water–ethanol, water–0.9% NaCl solution, and buffer solutions of pH 7.4–1.2 and showed responsive swelling–deswelling behavior. Scanning electron microscopy revealed a highly porous nature of CL-AX with a mesh of thin fibrous networking. Hemocompatibility studies of CL-AX revealed its non-thrombogenic and nonhemolytic attributes. The CL-AX matrix tablet prolonged the release of enalapril maleate for 24 h, and the drug release followed the zero order kinetics and super case-II transport mechanism. Therefore, CL-AX can be recognized as a stimuli responsive and hemocompatible biomaterial with sustained drug release potential.

Chemotherapy using single drug is not successful now a days due to the emergence of multidrug-resistant cancer cells. In the present work, Methotrexate (MTX) and Mitomycin C (MMC) loaded hydrogel sensitive to both reduction and pH are prepared and well characterized using various instrumentation techniques like FTIR, XRD, SEM and TEM. The drug loading and encapsulation efficiencies (DEE and DLE) of MTX are found to be 90.5 and 54.3% respectively and for MMC the value is 95.1 and 62.7% respectively. Invitro cytotoxicity and Apoptosis studies confirm the increased anticancer activity and selectivity of the novel carrier. [ABSTRACT FROM AUTHOR]

The aim of this study was to develop smart materials with stimuli-responsive properties for the long-term protection of steel. The idea was to obtain a tailored and controlled release of protective agents in response to the environment stimuli. First, the protective efficacy of three inhibitors containing a carboxylic moiety, such as p-aminobenzoic (pAB), succinic (SA), and caffeic (CA) acids, was investigated in alkaline chloride solutions. The results revealed that pAB is the most effective protective agent, significantly better than SA and CA. It is surprising that the steel surface in the pAB solution remains unchanged even after 5 months of corrosion treatment, whereas the formation of degradation products in the SA and CA solutions was observed after only 6 days. Based on these findings, pAB was selected and used for the functionalization of silica nanoparticles and layered double hydroxides (LDHs) that can act as delivery vehicles and as an inhibitor reservoir. Specifically, pAB was chemisorbed on silica amino groups via an amide bond, and this makes possible a gradual inhibitor release induced by an alkaline environment. The intercalation of pAB in its anionic form into the LDHs structure is responsible for a completely different behavior since the release is induced by chloride ions and occurs by an anionic exchange reaction. Thus, these materials play a dual role by acting as an inhibitor reservoir and by capturing chlorides. These findings reveal that it is possible to create a reservoir of corrosion inhibitors gradually released on demand based on the chemical environment. The stimuli-responsive properties and the complementary protective action of inhibitor-loaded silica and LDHs make them attractive for the long-term protection of steel and open the way for innovative solutions in the preservation of concrete cultural heritage.

Acid stimulus responsive stealthy nanoparticles were prepared by utilizing three types of copolymers, i.e. acid cleavable polycaprolactone-polyethyleneimine-polyethylene glycol (PCL-PEI-PEG), acid charge reversal polycaprolactone-polyethyleneimine (PCL-PEI), and ligand containing polycaprolactone-polyethyleneimine-folate (PCL-PEI-Fol). FTIR, NMR, and UV-visible spectroscopy confirmed the formation of these copolymers. Acid cleavable property of PCL-PEI-PEG copolymer was examined by FTIR. The formation of nanoparticles was determined by DLS and SEM. Aggregation, structural destabilization, and charge reversibility of nanoparticles at low pH were evaluated by DLS, SEM, and Zeta analyzer, respectively. MTT assay was used to evaluate anticancer effect of nanoparticles. Overall, nanoparticles exhibited improved cytotoxic activity against MCF-7 cancer cells. [ABSTRACT FROM AUTHOR]

Developing safe and efficient delivery systems for therapeutic biomacromolecules is a long‐standing challenge. Herein, we report a newly developed combinatorial library of cholesteryl‐based disulfide bond‐containing biodegradable cationic lipidoid nanoparticles. We have identified a subset of this library which is effective for protein and mRNA delivery in vitro and in vivo. These lipidoids showed comparable transfection efficacies but much lower cytotoxicities compared to the Lpf2k in vitro. In vivo studies in adult mice demonstrated the successful delivery of genome engineering protein and mRNA molecules in the skeletal muscle (via intramuscular injection), lung and spleen (via intravenous injection), and brain (via lateral ventricle infusion). [ABSTRACT FROM AUTHOR]

Synthetic materials that mimic the ability of natural occurring features to self‐actuate in response to different stimuli have wide applications in soft robotics, microdevices, drug delivery, regenerative medicine, and sensing. Here, unexpected and counter‐intuitive findings are presented in which a strongly polyelectrolytic hydrogel repels from strong polar solvents upon partial exposure (e.g., partial hydration by water). This repulsion drives the actuation and self‐folding of the gel, which results in rapid formation of different three‐dimensional shapes by simply placing the corresponding two‐dimensional films on water. A detailed investigation into the role of hydrogel chemistry, pH, and morphology on hydration‐triggered actuation behavior of the gels and their nanocomposites is described. Finally, a computational model is developed in order to further elucidate mechanisms of actuation. Modeling partial hydration as a repulsive driving force, it tracks the evolution of the shape of the thin film that results from restoring elastic forces. Taken together, the results indicate that an interplay between elastic and Coulombic repulsive forces leads to seemingly unexpected behavior of actuation of strongly polyelectrolytic gels away from polar solvents, leading to a novel and simple fabrication strategy for diverse 3D devices. [ABSTRACT FROM AUTHOR]

Novel thermal- and pH-responsive hollow nanocapsules (HNCaps) were fabricated through the grafting of a thiol-end capped PNIPAAm-b-PAA by thiol-ene "click" reaction onto PMMA HNCaps. The lowest critical solution temperature (LCST) of the fabricated HNCaps was obtained as 38–40°C. The fabricated nanosystem was loaded with doxorubicin hydrochloride (Dox), and its drug loading and encapsulation efficiencies were obtained as 62 and 53%, respectively. The in vitro stimuli-responsive drug release behavior of the fabricated nanomedicine was investigated extensively. The anticancer activity of the drug-loaded HNCaps was evaluated using MTT assay against MCF7 cells. The results exhibited excellent potential of nanosystem as a drug delivery system (DDS) for cancer chemotherapy. Novel thermal- and pH-responsive poly(methyl metacrylate)-grafted-[poly(N-isopropylacrylamide-block-acrylic acid)] hollow nanocapsules were fabricated as "smart" anticancer drug delivery system (DDS). [ABSTRACT FROM AUTHOR]

Proteinosome, characterized by an inner aqueous cavity wrapped by membrane with embedded protein, is one of the most attractive structures, has huge potential applications on drug delivery, tissue engineering, catalysis, synthetic biology, artificial cells, engineering of the biomachines, biosensors, and biodevices, etc. Here, inspired by polyphenol chemistry, a facile and universal method is presented to fabricate the diverse proteinosomes, with independence on the amino acid sequence, isoelectric points, molecular weight (Mw), wettability, and functional domains of applied proteins. Besides, the materials employed here are green and cost‐effective, and the method developed here is efficient and easily operated without any expensive equipments. The proteinosomes and the mechanism of generating proteinosomes are well characterized and analyzed by various techniques. The permeability of generated proteinosomes is underlined, which not only shows dependence on the applied proteins but also the Mw of diffused molecules. In addition, the permeability can be reversibly switched on/off in 100% by environmental pH. Capitalizing the facility and university of this method, it is believed it paves the way of the proteinosomes to multiple potential applications, such as drug delivery, micro‐/nanoreactors, tissue engineering, catalysis, biosensor, etc. [ABSTRACT FROM AUTHOR]

Chemodynamic therapy (CDT) takes the advantages of Fenton‐type reactions triggered by endogenous chemical energy to generate highly cytotoxic hydroxyl radicals. As a novel modality for cancer treatment, CDT shows minimal invasiveness and high tumor specificity by responding to the acidic and the highly concentrated hydrogen peroxide microenvironment of tumor. The CDT approach for spatiotemporal controllable reactive oxygen species generation exhibits preferable therapeutic performance and satisfying biosafety. In this review article, we summarized the recent advances of stimuli‐activatable nanomedicines for CDT. We also overviewed the strategies for augmenting CDT performance, including increasing the catalytic efficacy through rational design of the nanomaterials, modulating the reaction condition, inputting external energy field, and regulating the tumor microenvironment. Furthermore, we discussed the potential and challenges of stimuli‐activatable nanomedicine for clinical translation and future development of CDT. This article is categorized under:Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic DiseaseNanotechnology Approaches to Biology > Nanoscale Systems in BiologyDiagnostic Tools > In Vivo Nanodiagnostics and Imaging [ABSTRACT FROM AUTHOR]

Bioinspired actuators with stimuli-responsive and deformable properties are being pursued in fields such as artificial tissues, medical devices and diagnostics, and intelligent biosensors. These applications require that actuator systems have biocompatibility, controlled deformability, biodegradability, mechanical durability, and stable reversibility. Herein, we report a bionic actuator system consisting of stimuli-responsive genetically engineered silk-elastin-like protein (SELP) hydrogels and wood-derived cellulose nanofibers (CNFs), which respond to temperature and ionic strength underwater by eco-friendly methods. Programmed site-selective actuation can be predicted and folded into three-dimensional (3D) origami-like shapes. The reversible deformation performance of the SELP/CNF actuators was quantified, and complex spatial transformations of multilayer actuators were demonstrated, including a biomimetic flower design with selective petal movements. Such actuators consisting entirely of biocompatible and biodegradable materials will offer an option toward constructing stimuli-responsive systems for in vivo biomedicine soft robotics and bionic research. [ABSTRACT FROM AUTHOR]

Lung cancer is one of the major causes of cancer-related deaths worldwide. Stimuli-responsive polymers and nanoparticles, which respond to exogenous or endogenous stimuli in the tumor microenvironment, have been widely investigated for spatiotemporal chemotherapeutic drug release applications for cancer chemotherapy. We developed glutathione (GSH)-responsive polyurethane nanoparticles (GPUs) using a GSH-cleavable disulfide bond containing polyurethane that responds to elevated levels of GSH within lung cancer cells. The polyurethane nanoparticles were fabricated using a single emulsion and mixed organic solvent method. Cisplatin-loaded GSH-sensitive nanoparticles (CGPU) displayed a GSH-dose dependent release of cisplatin. In addition, a significant reduction in in vitro survival fraction of A549 lung cancer cells was observed compared to free cisplatin of equivalent concentration (survival fraction of ~0.5 and ~0.7, respectively). The in vivo biodistribution studies showed localization of fluorescently labeled GPUs (~7% of total injected dose per gram tissue) in the lung tumor regions after mouse-tail IV injections in xenograft A549 lung tumor models. The animals exposed to CGPUs also exhibited the inhibition of lung tumor growth compared to animals administered with saline (tumor growth rate of 1.5 vs. 13 in saline) and free cisplatin (tumor growth rate of 5.9) in mouse xenograft A549 lung tumor models within 14 days. These nanoparticles have potential to be used for on-demand drug release for an enhanced chemotherapy to effectively treat lung cancer. Unlabelled Image • Glutathione is abundantly available in lung cancer microenvironment. • Biodegradable polyurethane nanoparticles were fabricated via a single emulsion with a mixed organic solvent. • GSH-sensitive degradable polyurethane nanoparticles (GPUs) released encapsulated cisplatin in response to elevated glutathione levels. • Cisplatin loaded GPUs significantly reduced tumor growth in a subcutaneous A549 lung tumor mouse model compared to the free cisplatin. [ABSTRACT FROM AUTHOR]

Self‐assembly of 3D structures presents an attractive and scalable route to realize reconfigurable and functionally capable mesoscale devices without human intervention. A common approach for achieving this is to utilize stimuli‐responsive folding of hinged structures, which requires the integration of different materials and/or geometric arrangements along the hinges. It is demonstrated that the inclusion of Kirigami cuts in planar, hingeless bilayer thin sheets can be used to produce complex 3D shapes in an on‐demand manner. Nonlinear finite element models are developed to elucidate the mechanics of shape morphing in bilayer thin sheets and verify the predictions through swelling experiments of planar, millimeter‐scaled PDMS (polydimethylsiloxane) bilayers in organic solvents. Building upon the mechanistic understandings, The transformation of Kirigami‐cut simple bilayers into 3D shapes such as letters from the Roman alphabet (to make "ADVANCED FUNCTIONAL MATERIALS") and open/closed polyhedral architectures is experimentally demonstrated. A possible application of the bilayers as tether‐less optical metamaterials with dynamically tunable light transmission and reflection behaviors is also shown. As the proposed mechanistic design principles could be applied to a variety of materials, this research broadly contributes toward the development of smart, tetherless, and reconfigurable multifunctional systems. [ABSTRACT FROM AUTHOR]

This review presents an overview of the versatile shape memory polyurethane/graphene nanocomposites. Shape memory polyurethanes can recover their original shape from an intermediate shape when triggered by an external stimulus, such as heat, electrical voltage, light, pH change, or water absorption. Shape memory polymers have a successful history in commercial use. The applications for shape memory polymers are highly varied across numerous industries ranging from aircraft structure to biomedical implants. Three different groups of stimuli-responsive shape memory polyurethane/graphene nanocomposites, thermoresponsive, resistive heating actuated, and photon absorption actuated, will be discussed in this review. The applications of shape memory polyurethane/graphene nanocomposite as actuators are also discussed. This article will be pioneering in widespread impression on the state-of-the-art knowledge in shape memory polyurethane/graphene nanocomposites. It does not intend to be an extensive summary, but instead is a guide for scientists looking to apply these uniquely functional materials for advance high-performance applications. Future research may reveal shape memory applications for polyurethane/graphene nanocomposites in electronics, aerospace, and biomedical industries. [ABSTRACT FROM AUTHOR]

The narrowly dispersed functional silica/poly(di(metacryloylooxy-1-ethoxy) methane-co-acryl amide) (SiO2/P(DMOEM-co-AAm)) core-shell microspheres were synthesized by distillation precipitation polymerization of DMOEM as a degradable crosslinker and AAm as a functional monomer with the presence of 3-(methacryloxy)propyltrimethoxysilane (MPS) modified silica microspheres as seeds. Indole-3-acetic acid (IAA) can be efficiently loaded into the microspheres with a loading capacity of 37.5% via hydrogen-bonding interaction between the carboxylic acid group of IAA and the amide groups on the surface of SiO2/P(DMOEM-co-AAm). The loaded IAA can be triggered released by pH due to the presence of pH-responsive crosslinker (DMOEM). [ABSTRACT FROM AUTHOR]

A recent approach in the treatment of diseased cells/tissues is the use of smart, stimuli-responsive nanomaterials. Well-known examples include photosensitizer agents that after light irradiation at a specific wavelength generate singlet oxygen species (strongly cytotoxic) or self-assembled supramolecular structures, which blow up cancer cells by releasing their payload upon an external stimulus, thus making cancer cells swell and burst (so-called "nanobombs"). In this work we synthesized and characterized a polymeric star-like pentaporphyrin system (5P) that, depending on the photoexcitation wavelength selected, can act either as a photosensitizer or as a nanobomb. The 5P compound was characterized by using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, nuclear magnetic resonance, UV–vis, and fluorescence spectroscopy techniques. The hydrodynamic size of the 5P compound in physiological buffer solution, as determined by dynamic light spectroscopy, pointed to the formation of aggregates. The toxicity and the blow-up capability of 5P were tested on human neuroblastoma (SH-SY5Y cell line). Results demonstrated that the 5P system can work as a light-triggered nanobomb for targeted cell death. In fact, while the cell's treatment with the compound in the darkness did not induce cell toxicity, the 5P irradiation with laser light at wavelengths of 458 or 405 nm resulted in the generation of singlet oxygen species or a true explosion in a cellular environment, respectively. [ABSTRACT FROM AUTHOR]

Self‐assembly of asymmetric block copolymers (BCPs) around active pore edges has emerged as an important strategy to produce smart membranes with tunable pathways for solute transport. However, thus far, it is still challenging to manipulate pore shape and functionality for directional transformation under external stimuli. Here, a versatile strategy by mesoscale simulations to design stimuli‐responsive pores with various edge decorations in hybrid membranes is reported. Dopant BCPs are used as decorators to stabilize pore edges and extend their function in reconfiguring pores in response to repeated membrane stretching/shrinking caused by external stimuli. The decoration morphologies are predictable since the assemblies of dopant BCPs around pore edges are closely related to their self‐assemblies in solution. The coassembly between different BCPs in the hybrid membrane for the control of pore morphology is featured, and the parameter settings, including block incompatibility and molecular architecture for the construction of a specific pore, are determined. Results show that harnessed dopant BCPs in the hybrid membrane can enhance pore formation and induce directional pore shape and functionality transformation. Diversified pore decorations exhibit potential that can be further explored in selective solute transport and the design of stimuli‐responsive smart nanodevices. [ABSTRACT FROM AUTHOR]

Development of macromolecules provides applicable platforms for the delivery of therapeutics. In this general overview, we focus on the design principles of synthetic polymers, with disulfide bonds located in either the polymer backbone or side chains. We also discuss the role of disulfide bonds, as well as the remaining questions to better understand their applications in therapeutic delivery systems. [ABSTRACT FROM AUTHOR]