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Programmable materials have artificially designed physical shapes responding to external stimuli, as well as high design capability and high flexibility. Here, we propose a microfiber-shaped programmable material with an axial pattern of stimuli-responsive (SR) and nonresponsive hydrogels. The SR pre-gel solution was mixed to sodium alginate pre-gel solution for instantaneous gelation with ionic crosslinking and solidified on a nonresponsive hydrogel microfiber with a valve-controlled microfluidic system. A design of microfiber-shaped programmable material (patterned position of SR regions) could be flexibly altered by changing a coded sequence program. We confirmed that the three-dimensional (3D) coil-like structures were self-folded at the patterned SR regions responding to the thermal stimulus and that the chirality of the self-folded 3D coil-like structures depends on the condition of the stimulus to the microfiber. Finally, interaction with objects using the programmable microfiber as a soft actuator was demonstrated. Our microfiber-shaped programmable materials expand possibilities of fiber-based materials in biomimetics and soft robotics fields.

Summary Halide perovskites have recently shown potential as stimuli-responsive materials (SRMs) for a range of important technologies such as smart windows, memory devices, data storage, and sensors. Here, we overview these emerging SRMs that are based on halide perovskite systems of switchable optical and electrical properties as well as discuss their switching characteristics and practical applications. We summarize the reversible chemical and structural transformations of these materials and categorize them by their switching mechanisms. Furthermore, to guide the community’s search for new designs of stimuli-responsive halide perovskites, we outline several important criteria for effective switchable materials. Finally, we provide our perspective on the current challenges and future developments of these emerging materials.

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.

Microneedle (MN) patches consisting of miniature needles have emerged as a promising tool to perforate the stratum corneum and translocate biomolecules into the dermis in a minimally invasive manner. Stimuli-responsive MN patches represent emerging drug delivery systems that release cargos on-demand as a response to internal or external triggers. In this review, a variety of stimuli-responsive MN patches for controlled drug release are introduced, covering the mechanisms of action toward different indications. Future opportunities and challenges with respect to clinical translation are also discussed.

Supramolecular self-assemblies and co-assemblies possess multiple noncovalent interactions, highly ordered structures, and multifunctional properties. Yet, the fundamental understanding of their "structure-property relationship" remains very challenging. Herein, two kinetically controlled supramolecular charge transfer (CT) complexes were conceptualized from a trimorphic molecular donor denoted as "twisted aromatic hydrocarbon" (TAH), with p-fluoranil (TFQ) and p-chloranil (TCQ) in water, organic solvent, and solvent-free methods. Elucidating their co-assembling mechanism revealed that segmentation of the TAH with molecules having planar deficient cores spontaneously formed a distinct "H-type mixed stack" and "J-type segregated stack", regulated by blue/red-shifted charge-transfer and π-π stacking including weak C-H···F and C-H···O noncovalent interactions. By utilizing the structural transformational ability of the self-assembled TAH, the mechanistic aspects for the rapid nanoscopic co-assembly formation were precisely demonstrated experimentally and theoretically. The trimorphs and co-crystals of TAH could be disassembled resulting in turn-on emission by applying various external stimuli and being repeatedly reconfigured, thus providing a unique structure-property relationship and new TAH-based materials. This unique concept offers color-specific polymorphism and CT-complex formation strategy involving a simple class of functional materials having cooperative network forming ability using the twisted molecular donor.

Nano- and microgels are promising soft polymer materials for different application fields: stabilizers, sensors, catalysts, selective sorbents, drug delivery carriers etc. They are composed of cross-linked polymer chains swollen with a solvent. The building blocks, synthesis approaches and architecture of nano- and microgels are reviewed. The mechanisms of responsiveness to various stimuli are described, examples of applications are provided. Micro- and nanogels are good objects for learning projects and the ideas for learning projects with microgels are described.

A dual stimuli-responsive nanoplatform was rationally designed for controlled drug delivery. The nanosheets of graphene oxide (GO) were first modified with aminated mesoporous silica (NH2-mSiO2), and then methotrexate (MTX) was loaded into the mesopores of mSiO2. Alginate (Alg) acted as the "gatekeeper" was then anchored to the MTX-loaded GO/NH2-mSiO2 by amidation reaction, achieving the encapsulation of MTX in the core-shell structured GO/mSiO2@Alg. Due to the high pH sensitivity of amide bond and the excellent photothermal conversion ability of GO, the constructed nanoplatform could be used for pH and near-infrared (NIR) controlled delivery of MTX. The results of cell viability test demonstrate the high inhibitory rate of the dual stimuli-responsive nanoplatform toward hepatoma (HepG2) cells.

Development of smart switchable surfaces to solve the inevitable bacteria attachment and colonization has attracted much attention; however, it proves very challenging to achieve on-demand regeneration for noncontaminated surfaces. We herein report a smart, host-guest interaction-mediated photo/temperature dual-controlled antibacterial surface, topologically combining stimuli-responsive polymers with nanobactericide. From the point of view of long-chain polymer design, the peculiar hydration layer generated by hydrophilic poly(2-hydroxyethyl methacrylate) (polyHEMA) segments severs the route of initial bacterial attachment and subsequent proliferation, while the synergistic effect on chain conformation transformation poly(N-isopropylacrylamide) (polyNIPAM) and guest complex dissociation azobenzene/cyclodextrin (Azo/CD) complex greatly promotes the on-demand bacterial release in response to the switch of temperature and UV light. Therefore, the resulting surface exhibits triple successive antimicrobial functions simultaneously: (i) resists ∼84.9% of initial bacterial attachment, (ii) kills ∼93.2% of inevitable bacteria attack, and (iii) releases over 94.9% of killed bacteria even after three cycles. The detailed results not only present a potential and promising strategy to develop renewable antibacterial surfaces with successive antimicrobial functions but also contribute a new antimicrobial platform to biomedical or surgical applications.

Radical anions are important for various uses. However, their generation and stabilization under ambient conditions, which are essential for actual applications, are challenging. A photogenerated N...

Over the past few decades, advanced polymeric materials have gained popularity in the development of sustainable agricultural applications. Smart polymeric systems have extensively contributed to the agricultural industry by increasing the efficiency of pesticides, herbicides, and fertilizers by facilitating controlled release systems and, therefore, enabling lower doses to be used. Superabsorbent polymeric materials have been used as soil conditioners to control the impact of drought, whereas polycationic polymers have been utilized for plant bioengineering. These functions in the environment are complemented by applications within plants as part of the developing range of tools for genetically transforming plants in order to increase productivity and disease resistance. This Review will summarize and discuss the recent developments in the design and application of advanced polymeric systems for precision agriculture related applications. The design criteria of the polymers employed to date, such as polymer structure, as well as the properties of polymer nanoparticles including shape and size will be discussed, and the key findings in the related area will be highlighted. Finally, we will identify future directions for the exploration of functional polymers with the ultimate aim of advancing sustainable agriculture.\ud \ud

Diabetes is a serious global disease that threatens more than 400 million people’s health. Therefore, timely detection of body’s glucose level becomes extremely important for control, diagnosis and treatment of diabetes. Based on the feature of stimuli-responsive volume phase transition of hydrogel materials, this review will provide a systematic summary of glucose detection devices in recent years, including hydrogel preparation methods based on glucose-sensitive pattern, detection mechanisms based on signal transduction, current and emerging devices based on different body fluids and discuss the challenge, prospect the future development trend in the end.

Nanomedicines afford unique advantages in therapeutic intervention against tumors. However, conventional nanomedicines have failed to achieve the desired effect against cancers because of the presence of complicated physiological fluids and the tumor microenvironment. Stimuli-responsive drug-delivery systems have emerged as potential tools for advanced treatment of cancers. Versatile nano-carriers co-triggered by multiple stimuli in different levels of organisms (eg, extracorporeal, tumor tissue, cell, subcellular organelles) have aroused widespread interest because they can overcome sequential physiological and pathological barriers to deliver diverse therapeutic “payloads” to the desired targets. Furthermore, multiple stimuli-responsive drug-delivery systems (MSR-DDSs) offer a good platform for co-delivery of agents and reversing multidrug resistance. This review affords a comprehensive overview on the “landscape” of MSR-DDSs against tumors, highlights the design strategies of MSR-DDSs in recent years, discusses the putative advantage of oncotherapy or the obstacles that so far have hindered the clinical translation of MSR-DDSs.

Stimuli-responsive emulsifiers have emerged as a class of smart agents that can permit regulated stabilization and destabilization of emulsions, which is essential for food, cosmetic, pharmaceutical, and petroleum industries. Here, we report the synthesis of novel "smart" hydroxyapatite (HaP) magnetic nanoparticles and their corresponding stimuli-responsive Pickering emulsions and explore their movement under confined spaces using a microfluidic platform. Pickering emulsions prepared with our magnetic stearic acid-functionalized Fe2O3@HaP nanoparticles exhibited pronounced pH-responsive behavior. We observed that the diameter of emulsion droplets decreases with an increase in pH. Swift demulsification was achieved by lowering the pH, whereas the reformation of emulsions was achieved by increasing the pH; this emulsification-demulsification cycling was successful for at least ten cycles. We used a microfluidic platform to test the stability of the emulsions under flowing conditions and their response to a magnetic field. We observed that the emulsion stability was diminished and droplet coalescence was enhanced by the application of the magnetic field. The smart nanoparticles we developed and their HaP-based emulsions present promising materials for pharmaceutical and petroleum industries, where responsive emulsions with controlled stabilities are required.

Smart fibers with reversible optical properties have received extensive attention due to their wide potential for application in human health monitoring and wearable devices. However, achieving multi-stimuli-responsive luminescent fibers via a facile manufacturing process is challenging. Herein, novel independent multi-stimuli-responsive luminescent fibers are successfully fabricated via a facile wet-spinning process. The color of the fibers responds to ultraviolet (UV) and heat independently and in combination. The fibers emit bright red light emission (λem = 627 nm) after excitation (λex = 330 nm) which is attributed to Y2O2S:Eu3+,Mg2+,Ti4+ ceramics. The as-prepared fibers possess a tensile strength of around 9.39 MPa. The experimental results demonstrate that the multi-stimuli-responsive persistent luminescent fibers coupled with the facile preparation process make the multi-stimuli-responsive luminescent fibers a potential candidate for application in anti-counterfeiting and UV/heat detection devices.

Multifunctional nanocomposites have drawn great attention in clinical applications because of their ability to integrate diagnostic and therapeutic functions. Manganese dioxide (MnO2), owing to its biocompatibility and magnetic resonance imaging (MRI) properties, has been widely applied in biomedical research. Our previous work on biogenic MnO2 nanoparticles (Bio-MnO2 NPs) revealed that intrinsic photothermal properties and stimuli-responsive MRI imaging are particularly promising for the development of theranostic systems. However, further improvement in the photothermal therapy (PTT) performance of Bio-MnO2 NPs is still required. Herein, we have improved the PTT efficiency of Bio-MnO2 NPs by in situ synthesis of fluorescent polydopamine (PDA) while generating additional stimuli responsive fluorescence properties in this system, thus further broadening the scope of their theranostic functions. These synthesis conditions are mild and green. The fluorescence of PDA was quenched by capping Bio-MnO2 NPs and could be recovered upon degradation of Bio-MnO2 NPs inside tumour cells. Additionally, Mn2+ released from the nanoparticles can support T1-weighted MR imaging. Compared to the Bio-MnO2 NPs alone, the integration of Bio-MnO2 NPs and PDA significantly enhances the photothermal performance in vitro and in vivo. With their high biocompatibility, these multifunctional composite nanodevices hold great potential for fluorescence imaging and MRI-guided photothermal therapy.

Molecular self-assembly is a widespread natural phenomenon and has inspired several researchers to synthesize a compendium of nano/microstructures with widespread applications. Biomolecules like proteins, peptides and lipids are used as building blocks to fabricate various nanomaterials. Supramolecular peptide self-assembly continue to play a significant role in forming diverse nanostructures with numerous biomedical applications; however, dipeptides offer distinctive supremacy in their ability to self-assemble and produce a variety of nanostructures. Though several reviews have articulated the progress in the field of longer peptides or polymers and their self-assembling behavior, there is a paucity of reviews or literature covering the emerging field of dipeptide-based nanostructures. In this review, our goal is to present the recent advancements in dipeptide-based nanostructures with their potential applications.

Stimuli-responsive polymers (SRPs) are capable of changing their solubility, conformation, and volume in response to external stimuli. By understanding the nature of the responsivity and the synthetic challenges, new SRPs can be synthesized with enhanced responsivities at scales that will allow their use in the real world. In this review, many fundamental concepts and recent advances in SRPs for sensing and actuation are presented. A variety of sensors that can respond to physiologically relevant species and stimuli are reviewed, including temperature/pH, proteins, glucose and ions. The review also includes examples of the use of SRPs for artificial muscles, soft robots, cell culture, and drug delivery.

The combination of polymerization-induced self-assembly (PISA) and post-polymerization modification is a versatile route to prepare core-functionalized nanoaggregates. PISA is a useful approach for preparing in situ self-assembled nano-objects, in which morphological nanostructures are tunable with a high solid concentration that can afford scale-up syntheses. Herein, the preparation via PISA of diblock copolymers that have functional groups in their structures to be further post-functionalized using active modifiers has been reviewed. The resulting multifunctional nanoaggregates exhibit great potential for use in a wide range of applications, for example, crosslinked nano-objects having improved stability, stimuli responsive vehicles for drug delivery, and fluorescent nanomaterials for bioimaging.

Traditional textiles with hydrophilic properties can absorb sweat secreted from the skin, but cause an undesirable cold sensation and adhere to the skin. Textiles with an effect similar to an air conditioner and sensing properties have attracted great interest because of their desirable performance, comfort, and energy-saving properties. However, fabricating functional textiles with moisture management and pH identification properties remains a difficult challenge. Herein, we demonstrate a fluorine-free hydrophobic loofah fabric with embedded thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) microspheres as microplugs, which endowed it with directional liquid transport and body temperature regulation depending on the temperature. Based on the phase separation of the microplugs and capillary gradients, the microplugs of the self-venting textile are opened and generate drying and cooling effects via high moisture transport in hot weather, whereas the pores of the microplugs close to retain heat in cold weather. Moreover, the multifunctional loofah textile exhibits hydrophobic or hydrophilic behaviour for droplets with different pH values, which can provide real-time liquid signal detection. The water repellency and the wicking, permeability, and mechanical properties of the hydrophobic outer surface of the loofah textile are not affected by harsh conditions. This study not only provides ideas for the design and preparation of textiles for personal comfort, but also environmentally friendly and acid/alkali-protective clothing with great potential applications in demanding situations.

Responsive polymers with properties designed to interact with their surrounding environment are enabling “smart” design features for custom biomaterials. Numerous applications are being innovated, ranging from diagnostics and imaging to tissue engineering and drug delivery. Herein, I feature a collection of research articles published in ACS Macro Letters that highlight an array of innovative chemical attributes such as pH-triggered hydrolytic degradation, reduction-based release, photomodulation, glucose responsiveness, thermal sensitivity, and membrane permeating peptides. The chemical, physical, mechanical, and morphological properties of polymeric structures can be custom tailored to enhance numerous features such as biological delivery, pharmaceutical potency and safety, disease diagnosis, and antigen/biomaker detection.

Horseradish peroxidase (HRP)-mediated oxidation of tyrosine-conjugated biodynamer containing acylhydrazone linkages and ovalbumin (OVA)/reduced ovalbumin (rOVA) generated protein nanogels through simultaneous tyrosine coupling and thiol cross-linking in the presence of H

Light- and temperature-responsive poly(N-isopropylacrylamide-co-nitrobenzyl methacrylate) (pNIPAm-co-NBMA) microgels were synthesized via free-radical precipitation polymerization and exhibited a h...

In the past few years four-dimensional (4D) printing technologies have attained worldwide interest and they are now considered the "next big thing". The aim of this research is to provide three selected examples of stimuli-responsive polymer (SRP) applications additively manufactured (AM) by the fused filament fabrication (FFF) technique. To that end, a CCT BLUE filament of thermo-responsive polymer was chosen to produce a water temperature indicator, which changes colour from blue to white when temperature increases; a CCU RED filament of photo-responsive polymer was used to produce a sunlight / UV indicator bracelet; a transparent PLA CLEAR polymer, a CCU RED photo-responsive polymer, and an electrical conductive PLA polymer were selected to produce a smart business card stand. The temperature indicator capability was analysed based on examining colour changes as a function of temperature changes. The sunlight/UV indicator capability was analysed based on the inspection of colour change as a function of absorbed sun/ultraviolet light. The electrical conductivity of the conductive PLA polymer was examined by performing resistance measurements. All three objects were successfully produced and their functionality was demonstrated. We hope that these examples will catalyse the expansion of FFF 4D printed SRP applications, as much work remains to be done in designing the parts and developing FFF printing parameters that take advantage of the stimuli-responsive materials currently being developed for FFF technology.

Rheumatoid arthritis (RA) is a long-term inflammatory disease derived from an autoimmune disorder of the synovial membrane. Current therapeutic strategies for RA mainly aim to hamper the macrophages' proliferation and reduce the production of pro-inflammatory cytokines. Therefore, the accumulation of therapeutic agents targeted at the inflammatory site should be a crucial therapeutic strategy. Nowadays, the nanocarrier system incorporated with stimuli-responsive property is being intensively studied, showing the potentially tremendous value of specific therapy. Stimuli-responsive (i.e., pH, temperature, light, redox, and enzyme) polymeric nanomaterials, as an important component of nanoparticulate carriers, have been intensively developed for various diseases treatment. A survey of the literature suggests that the use of targeted nanocarriers to deliver therapeutic agents (nanotherapeutics) in the treatment of inflammatory arthritis remains largely unexplored. The lack of suitable stimuli-sensitive polymeric nanomaterials is one of the limitations. Herein, we provide an overview of drug delivery systems prepared from commonly used stimuli-sensitive polymeric nanomaterials and some inorganic agents that have potential in the treatment of RA. The current situation and challenges are also discussed to stimulate a novel thinking about the development of nanomedicine.

With growing interest in polymers of natural origin, innumerable polysaccharides have gained attention for their biomedical application. Pullulan, one of the FDA approved nutraceuticals, possesses multiple unique properties which make them highly advantageous for biomedical applications. This present review encompasses the sources, production, properties and applications of pullulan. It highlights various pullulan based stimuli-responsive systems (temperature, pH, ultrasound, magnetic), subcellular targeted systems (mitochondria, Golgi apparatus/endoplasmic reticulum, lysosome, endosome), lipid-vesicular systems (solid-lipid nanoparticles, liposomes), polymeric nanofibres, micelles, inorganic (SPIONs, gold and silver nanoparticles), carbon-based nanoplatforms (carbon nanotubes, fullerenes, nanodiamonds) and quantum dots. This article also gives insight into different biomedical, therapeutic and diagnostic applications of pullulan viz., imaging, tumor targeting, stem cell therapy, gene therapy, vaccine delivery, cosmetic applications, protein delivery, tissue engineering, photodynamic therapy and chaperone-like activities. The review also includes the toxicological profile of pullulan which is helpful for the development of suitable delivery systems for clinical applications.

We demonstrate a new fabrication technology to realize “intelligent”, transdermal, minimally invasive microneedle array ( i $\mu $ NA) by crosslinking a hydrogel, Polyethylene Glycol Diacrylate (PEGDA) by photo-polymerization using Digital Light Processing (DLP) based 3D printing. The photo-polymerization conditions have been optimized so that the mutually exclusive requirements of excellent mechanical strength while retaining hydrogel properties of PEGDA are met which would allow swelling/delivery of therapeutic cargo of diclofenac sodium via diffusion. An array having 100 microneedles arranged in a $10\times 10$ array was successfully 3D printed which efficiently penetrated human skin during ex vivo characterization. In vitro drug release studies demonstrated that the PEGDA based i $\mu $ NA behaves as a stimuli responsive device showing distinct release characteristics from external stimuli such as temperature and pH. [2020-0133]

Over the last decade, stimuli-responsive microemulsions, that is, those that switch between stable and unstable states in response to certain stimuli, have attracted considerable attention because of their unique properties and potential for diverse applications. Herein, we highlight the recent advances in the development of microemulsions responsive to external triggers such as pH, redox reactions, light, CO2 gas, magnetic field and temperature; discuss the corresponding responses; and reveal important composition–microstructure–macroscopic property relationships to suggest future research directions and potential applications.

Introduction: Nanocarrier-based delivery systems offer multiple benefits to overcome limitations of the traditional drug dosage forms, such as protection of the drug, enhanced bioavailability, targeted delivery to disease site, etc. Nanocarriers have exhibited tremendous successes in targeted delivery of therapeutics to the desired tissues and cells with improved bioavailability, high drug loading capacity, enhanced intracellular delivery, and better therapeutic effect. A specific design of stimuli-responsive nanocarriers allows for changing their structural and physicochemical properties in response to exogenous and endogenous stimuli. These nanocarriers show a promise in site specific controlled release of therapeutics under certain physiological conditions or external stimuli. Areas covered: This review highlights recent progresses on the multifunctional and stimuli-sensitive nanocarriers for targeted therapeutic drug delivery applications. Expert opinion: The progress from single functional to multifunctional nanocarriers has shown tremendous potential for targeted delivery of therapeutics. On our opinion, the future of targeted delivery of drugs, nucleic acids, and other substances belongs to the site-targeted multifunctional and stimuli-based nanoparticles with controlled release. Targeting of nanocarriers to the disease site enhance the efficacy of the treatment by delivering more therapeutics specifically to the affected cells and substantially limiting adverse side effects upon healthy organs, tissues, and cells.

Shape-memory polymers (SMPs) enable the production of stimuli-responsive polymer-based materials with the ability to undergo a large recoverable deformation upon the application of an external stimulus. Academic and industrial research interest in the shape-memory effects (SMEs) of these SMP-based materials is growing for task-specific applications. This mini-review covers interesting aspects of SMP-based materials, their properties, how they may be investigated and highlights examples of the potential applications of these materials.

A novel multi-stimuli-responsive theranostic nanomedicine was designed and fabricated by the conjugation of a thiol end-capped poly(N-isopropylacrylamide-block-acrylic acid) (HS-PNIPAAm-b-PAA) onto...

We demonstrate microfluidic manufacturing of glutathione (GSH)-responsive polymer nanoparticles (PNPs) with controlled

Purpose The purpose of this paper is to study the shape memory properties of SMP samples produced through a MEAM process. Fused deposition modeling or, as it will be referred to in this paper, material extrusion additive manufacturing (MEAM) is a technique in which polymeric materials are extruded though a nozzle creating parts via accumulation and joining of different layers. These layers are fused together to build three-dimensional objects. Shape memory polymers (SMP) are stimulus responsive materials, which have the ability to recover their pre-programmed form after being exposed to a large strain. To induce its shape memory recovery movement, an external stimulus such as heat needs to be applied. Design/methodology/approach This project investigates and characterizes the influence of print orientation and infill percentage on shape recovery properties. The analyzed shape recovery properties are shape recovery force, shape recovery speed and time elapsed before activation. To determine whether the analyzed factors produce a significant variation on shape recovery properties, t-tests were performed with a 95% confidence factor between each analyzed level. Findings Results proved that print angle and infill percentage do have a significant impact on recovery properties of the manufactured specimens. Originality/value The manufacturing of SMP objects through a MEAM process has a vast potential for different applications; however, the shape recovery properties of these objects need to be analyzed before any practical use can be developed. These have not been studied as a function of print parameters, which is the focus of this study.

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., Graphical abstract Image, graphical abstract

Smart drug delivery nano-systems show significant changes in their physical or chemical properties in response to slight change in environmental physical and/or chemical signals, and further releasing drugs adjusted to the progression of the disease at the right target and rate intelligently. Two-dimensional materials possess dramatic status extend all over various scientific and technological disciplines by reason of their exceptional unique properties in application of smart drug delivery nano-systems. In this review, we summarized current progress to highlight various kinds of two-dimensional materials drug carriers which are widely explored in smart drug delivery systems as well as classification of stimuli responsive two-dimensional materials and the advantages and disadvantages of their applications. Consequently, we anticipate that this review might inspire the development of new two-dimensional materials with smart drug delivery systems, and deepen researchers’ understanding of smart nano-carries based on two-dimensional materials., Graphical abstract The fabrication, encapsulation, various stimuli response and applications of 2D materials smart drug delivery systems were reviewed. With unique 2D structure and sensitive response to external stimuli, 2D materials are expected to conquer any obstacle in maximizing the therapeutic effect of drugs.Image 1, Highlights • Introduction to the exfoliation method of two-dimensional materials for biomedical applications. • Summary of the encapsulation of two-dimensional materials smart drug delivery systems. • Discussion of the classification of stimuli responsive two-dimensional materials smart drug delivery systems. • Overview of the application of two-dimensional materials smart drug delivery systems.

The occasional use of chemical warfare agents (CWAs) by rogue states in current conflicts provides a reminder that these hazards are a real threat. Although hazmat suits made of fully impermeable b...

Thermo- and pH-responsive polyrotaxane (PR)-based triblock copolymers were synthesized by atom transfer radical polymerization (ATRP) of N-isopropylacrylamide initiated with polypsudorotaxanes whic...

Made available in DSpace on 2020-12-12T02:10:06Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-01-01 Stimuli-responsive drug-delivery nanocarriers (DDNs) have been increasingly reported in the literature as an alternative for breast cancer therapy. Stimuli-responsive DDNs are developed with materials that present a drastic change in response to intrinsic/chemical stimuli (pH, redox and enzyme) and extrinsic/physical stimuli (ultrasound, Near-infrared (NIR) light, magnetic field and electric current). In addition, they can be developed using different strategies, such as functionalization with signaling molecules, leading to several advantages, such as (a) improved pharmaceutical properties of liposoluble drugs, (b) selectivity with the tumor tissue decreasing systemic toxic effects, (c) controlled release upon different stimuli, which are all fundamental to improving the therapeutic effectiveness of breast cancer treatment. Therefore, this review summarizes the use of stimuli-responsive DDNs in the treatment of breast cancer. We have divided the discussions into intrinsic and extrinsic stimuli and have separately detailed them regarding their definitions and applications. Finally, we aim to address the ability of these stimuli-responsive DDNs to control the drug release in vitro and the influence on breast cancer therapy, evaluated in vivo in breast cancer models. Department of Drugs and Medicines Faculdade de Ciências Farmacêuticas UNESP-Univ. Estadual Paulista, Campus Araraquara College of Pharmacy Dentistry and Nursing Department of Pharmacy Federal University of Ceará Graduation Program in Pharmaceutical Sciences State University of Paraíba Department of Drugs and Medicines Faculdade de Ciências Farmacêuticas UNESP-Univ. Estadual Paulista, Campus Araraquara

Among modern drug formulations, stimuli-responsive hydrogels also called "smart hydrogels" deserve a special attention. The basic feature of this system is the ability to change their mechanical properties, swelling ability, hydrophilicity, bioactive molecules permeability, etc., influenced by various stimuli, such as temperature, pH, electromagnetic radiation, magnetic field and biological factors. Therefore, stimuli-responsive matrices can be potentially used in tissue engineering, cell cultures and technology of innovative drug delivery systems (DDSs), releasing the active substances under the control of internal or external stimuli. Moreover, smart hydrogels can be used as injectable DDSs, due to gel-sol transition connected with in situ cross-linking process. Innovative smart hydrogel DDSs can be utilized as matrices for targeted therapy, which enhances the effectiveness of tumor chemotherapy and subsequently limits systemic toxicity. External stimulus sensitivity allows remote control over the drug release profile and gel formation. On the other hand, internal factors provide drg accumulation in tumor tissue and reduce the concentration of active drug form in healthy tissue. In this report, we summarise the basic knowledge and chemical strategies for the synthetic smart hydrogel DDSs applied in antitumor therapy.

Stimuli-responsive nano-assemblies are emerging as promising drug delivery systems (DDSs) with spatial and temporal tenability, which can undergo structural transition for controlled drug release upon excitation by either exogenous or endogenous stimuli. Particularly, exogenous stimuli-responsive nano-assemblies based remotely controlled DDSs, have received much attention due to their accuracy and reliability realized by tunable exogenous triggers such as light, magnetic field, or temperature. In this review, we will briefly introduce the current state-of-the-art technologies of nano-assembly synthesis and summarize the recent advances in remotely controlled nano-assembly-based DDSs activated by different exogenous stimuli or endogenous/exogenous dual-stimuli. Furthermore, the pioneering progress in bio-cleanable stimuli-responsive nano-assemblies that holds great relevance to clinical translation will be described. Finally, we will conclude with our perspectives on current issues and future development of this field. The objective of this review is to outline current advances of nano-assemblies as remotely controlled DDSs, in hopes of accelerating the future development of intelligent nanomedicines.

Despite high drug-loading capacity, the ocular surface retention and corneal permeability of conventional nano eye drops are still unsatisfactory, thereby limiting therapeutic efficacy. Therefore, the objective of this study was to formulate dexamethasone loaded temperature-sensitive, pH-sensitive and ion-sensitive nanogels by incorporating stimuli-responsive elements, in order to enhance the ocular surface retention and corneal permeability of the encapsulated drug. The nanogels showed excellent rheological properties, along with good strength and viscosity under physiological conditions. Both in vitro and in vivo studies showed that the nanogels enhanced the ocular surface retention and corneal permeability of drugs. The temperature-sensitive gel showed the optimum behavior. The stimuli-responsive nanogels are stable delivery systems that can release drugs into the posterior ocular segment in a targeted and sustained manner.

Doxorubicin is still used as a first-line drug in current therapeutics for numerous types of malignant tumours (including lymphoma, transplantable leukaemia and solid tumour). Nevertheless, to overcome the serious side effects like cardiotoxicity and myelosuppression caused by effective doses of doxorubicin remains as a world-class puzzle. In recent years, the usage of biocompatible polymeric nanomaterials to form an intelligently sensitive carrier for the targeted release in tumour microenvironment has attracted wide attention. These different intelligent polymeric micelles (PMs) could change the pharmacokinetics process of drugs or respond in the special microenvironment of tumour site to maximise the efficacy and reduce the toxicity of doxorubicin in other tissues and organs. Several intelligent PMs have already been in the clinical research stage and planned for market. Therefore, related research remains active, and the latest nanotechnology approaches for doxorubicin delivery are always in the spotlight. Centring on the model drugs doxorubicin, this review summarised the mechanisms of PMs, classified the polymers used in the application of doxorubicin delivery and discussed some interesting and imaginative smart PMs in recent years.

Ample evidence has demonstrated that biological cells not only react to biochemical cues from the surrounding microenvironments but also sensitively detect the mechanical properties of the extracellular matrix and neighboring cells to adapt their shape, function, and fate. Mechanical aspects in biology, called mechanobiology, have been attracting biologists, chemists, physicists, and mechanical engineers. However, most in vitro studies to date have heavily relied on covalently cross-linked hydrogels with prefixed and hence unchangeable mechanical properties, although the mechanical properties of the cellular microenvironment are never uniform or static. From this context, stimuli-responsive hydrogels are highly attractive as surrogate materials that can simulate dynamic physical microenvironments in vivo. This review tries to provide a comprehensive overview of previous achievements, present pitfalls and challenges, and future perspectives on the recent development of stimuli-responsive hydrogel materials for the dynamic control of cell behavior. Stimulus-responsive hydrogels are highly attractive as the surrogate materials that can simulate dynamic mechanical microenvironments surrounding biological cells in vivo. This review tries to provide with comprehensive overviews on the previous achievements, present pitfalls and challenges, and future perspectives on the recent development on stimulus-responsive hydrogel materials for the dynamic control of cell behaviors.

Nanodrug delivery systems have been widely researched to achieve efficient antitumor drug delivery. However, the controlled drug delivery at tumor cells remains the main challenge for antitumor therapy. Herein, a pH and reduction-responsive nanocarrier based on green tea polyphenols was employed as a smart excipient for chemotherapy drug delivery. Paclitaxel, as a chemotherapy drug, was loaded in the nanocarrier, noted as green tea polyphenol/paclitaxel. The green tea polyphenol/paclitaxel kept constant diameter at physiological condition (i.e. pH 7.4), while gradually enlarged at acid environment (pH = 5.5) and the reductive environment. The in vitro paclitaxel release results indicated that the release of paclitaxel from the green tea polyphenol/paclitaxel at pH 7.4 was slow, whereas obviously accelerated at the acid environment (pH = 5.5) and the reductive environment. The in vitro antitumor assay showed more efficient tumor cells inhibition of green tea polyphenol/paclitaxel than free paclitaxel. Meanwhile, due to the proper size (∼100 nm), green tea polyphenol/paclitaxel could effectively accumulate at tumor sites. In the in vivo mice bearing A549 xenograft mouse models, green tea polyphenol/paclitaxel exhibited satisfactory antitumor effect and depressed system toxicity when compared with free paclitaxel, owing to the enhanced paclitaxel accumulation and controlled paclitaxel release in the tumor cells. With simple compositions and satisfactory antitumor effects, this green tea polyphenol-based nanocarrier can be a promising nanodrug delivery system for the therapy of cancers.

Ferrites have been serving as clinical elements over the past few years as contrasting agents in MRI, gene transfection, gene consignment and to attach cytotoxic drugs for targeted drug delivery. I...

Inspired by desert resurrection plant, Rose of Jericho, this study developed a new porous material with programmable multiple-stimuli responsive features. The first one is reversible shape-memory transformation of experiencing extremely large deformations upon dehydration and rehydration; superior to the plant, the aerogels display controllable responsiveness based on moisture amount with fast actuation. The second one is switchable flexibility depending on the polarity of exposed fluids; these aerogels are reversibly compressible with outstanding flexibility in polar solvents but sustain incompressibility with high stiffness in nonpolar solvents. The third one is programmable shape morphing capability driven by imbibition of liquid droplet; mimicking the movement of the plant but in different mechanisms, the aerogels can evolve into programmed V-shape or U-shape by simply controlling the liquid imbibition location. These multiple-stimuli responsive features arise from the unique ensemble of the porous morphology, and the interactions between solvent molecules and the chemical structures of the porous material engineered by two-step crosslinking mechanism. It can be foreseen that the synergistic effect of the intriguing features could allow for the applications of the aerogels as smart sensors/actuators, soft robotics, and biomedical devices, all of which typically require smart adaptability to external stimuli and/or extreme environments.

The re-emergence of room temperature liquid metals presents an exciting paradigm for an ideal combination of metallic and fluidic properties. The unique fluid metal features of non-hazardous Ga-based liquid metals, including high surface energy, low viscosity, electrical and thermal conductivity, a wide temperature range of the liquid state, and desirable chemical activity for many applications, have led to remarkable possibilities for harnessing their properties and achieving unique functionalities. The realization of their stimulus-responsivity and multi-functionality make Ga-based liquid metals an attractive family of ‘smart materials’ that could act as the basis of countless applications in new frontiers, covering a wide range from materials science and engineering to medicine. Constructing hybrids of Ga-based liquid metals with other functional materials can further extend the field-responsive capacity of liquid metals to incredible levels. An increasing number of reports have revealed Ga-based liquid metals and their hybrids as remarkable soft smart-response materials. Nevertheless, the mechanisms underlying their stimulus–response activities, their interactions with other functional entities, and efficient tuning in their intimate integration, still require further exploration. Considering the applications of Ga-based liquid metals and their hybrids, this review focuses on their field-responsive physical and chemical properties. The recent field-responsive reports are comprehensively presented. The analysis of their responsive properties and the types of field applied in each case are discussed, so that a critical outlook on this field can be established.

Background: In the field of drug delivery, smart and intelligent approaches have gained significant attention among researchers in order to improve the efficacy of conventional dosage forms. Material science has played a key role in developing these intelligent systems that can deliver therapeutic cargo on-demand. Stimuli responsive material based drug delivery systems have emerged as one of the most promising innovative tools for site-specific delivery. Several endogenous and exogenous stimuli have been exploited to devise “stimuli-responsive” materials for targeted drug delivery. Methods: For better understanding, these novel systems have been broadly classified into two categories: Internally Regulated Systems (pH, ionic strength, glucose, enzymes, and endogenous receptors) and Externally Regulated Systems (Light, magnetic field, electric field, ultrasound, and temperature). This review has followed a systematic approach through separately describing the design, development, and applications of each stimuli-responsive system in a constructive manner. Results: The development includes synthesis and characterization of each system, which has been discussed in a structured manner. From advantages to drawbacks, a detailed description has been included for each smart stimuli responsive material. For a complete review in this niche area of drug delivery, a wide range of therapeutic applications including recent advancement of these smart materials have been incorporated. Conclusion: From the current scenario to future development, a precise overview of each type of system has been discussed in this article. In summary, it is expected that researchers working in this novel area will be highly benefited from this scientific review.

In recent years, much progress has been motivated in stimuli-responsive nanocarriers, which could response to the intrinsic physicochemical and pathological factors in diseased regions to increase the specificity of drug delivery. Currently, numerous nanocarriers have been engineered with physicochemical changes in responding to external stimuli, such as ultrasound, thermal, light and magnetic field, as well as internal stimuli, including pH, redox potential, hypoxia and enzyme, etc. Nanocarriers could respond to stimuli in tumor microenvironments or inside cancer cells for on-demanded drug delivery and accumulation, controlled drug release, activation of bioactive compounds, probes and targeting ligands, as well as size, charge and conformation conversion, etc., leading to sensing and signaling, overcoming multidrug resistance, accurate diagnosis and precision therapy. This review has summarized the general strategies of developing stimuli-responsive nanocarriers and recent advances, presented their applications in drug delivery, tumor imaging, therapy and theranostics, illustrated the progress of clinical translation and made prospects.

Peptides have attracted great interests due to their potential for versatile application in preparation of drug carriers because of their specific targeting capability to desired tissues and bioresponsiveness toward various biological molecules such as enzymes for selective cleavage or bio-responsive folding into specific conformation. Therefore, the introduction of peptides as a gatekeeper on the surface would provide MSNs with triggered release property of guest molecules in response to a variety of biological stimuli including specific enzymes at specific target sites. In this review, we discuss the recent progress of peptide gatekeepers on MSNs by classification of the stimuli for triggering the release of payloads from the mesopore. We also describe the on-off gatekeepers by employing the motif of conformational transformation of peptides in response to external stimuli. The myriad biological functions of peptides by interaction with biomolecules, cells and organs endow the peptide gatekeepers on MSNs with great potential to construct smart nanocarriers.

Polymeric membranes are used on huge scales for kidney dialysis, wastewater treatment, and drinking water production. However, almost all polymeric membranes are fabricated by a process reliant on the use of unsustainable, expensive, and reprotoxic dipolar aprotic solvents. In this work, we propose an aqueous phase separation approach for preparing porous membrane films. Poly(4-vinylpyridine) (P4VP), a pH-responsive polymer, is first dissolved at low pH where the polymer is charged and subsequently cast as a thin film. Switching to a high pH where the polymer is uncharged and insoluble results in controlled phase separation and solidification of the polymer into porous membrane structures. This approach gives a large degree of control over membrane structure, leading to symmetric porous microfiltration membranes and asymmetric dense nanofiltration membranes. Moreover, the use of a pH-responsive polymer leads directly to a pH-responsive membrane, where the degree of responsive behavior can be tuned by the degree of cross-linking. Such responsive behavior allows effective cleaning of the membrane, without the use of harsh chemicals. This work outlines an approach toward preparing membranes in a more sustainable fashion—an approach that allows control over the membrane structure and one that naturally leads to advanced membranes with responsive properties.