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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.

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.

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 Cp*-Rh based D-shaped binuclear metallacycle and a template-free molecular Borromean ring (BR) were obtained in high yield using the semi-rigid thioether dipyridyl ligand 1,4-bis[(pyridin-4-ylthio)methyl]benzene (Bptmb). The topological transformation from a binuclear metallacycle and a BR to tetranuclear metallacycles was realized via the controlled oxidation of thioethers. The strategy used in this work can be regarded as a new form of stimuli-responsive post-synthesis modification (PSM).

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...

Rational molecular design enables the development of stimuli-responsive supramolecular hydrogels. Biocompatible supramolecular hydrogels have great potential for medicinal and pharmaceutical applic...

With the incessant improvement of requirements for optical anti-counterfeiting technology, it is essential to develop multifunctional luminescent materials with multiple models and adjustable lumin...

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.

A wide variety of synthetic molecular machines has been designed and synthesized to construct nanometer-scale assemblies whose molecular motions can be precisely controlled by external stimuli. A h...

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.

CRISPR-Cas9 promotes changes in identity or abundance of nucleic acids in live cells and is a programmable modality of broad biotechnological and therapeutic interest. To reduce off-target effects, tools for conditional control of CRISPR-Cas9 functions are under active research, such as stimuli-responsive guide RNA (gRNA). However, the types of physiologically relevant stimuli that can trigger gRNA are largely limited due to the lack of a versatile synthetic approach in chemistry to introduce diverse labile modifications into gRNA. In this work, we developed such a general method to prepare stimuli-responsive gRNA based on site-specific derivatization of 2′-O-methylribonucleotide phosphorothioate (PS-2′-OMe). We demonstrated CRISPR-Cas9-mediated gene editing in human cells triggered by oxidative stress and visible light, respectively. Our study tackles the synthetic challenge and paves the way for chemically modified RNA to play more active roles in gene therapy., Conditional control of CRISPR-Cas9 activity by reactive oxygen species and visible light is achieved using stimuli-responsive guide RNA synthesized by a general method based on RNA 2′-O-methylribonucleotide phosphorothioate.

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.

Gels prepared from low-molecular-weight gelators (LMWGs) represent versatile soft materials. Self-assembly of LMWGs forms nanofibers and above critical gelation concentrations, the entanglement of which leads to self-supporting gels. Owing to the dynamic properties of the self-assembly process, stimuli-responsive LMWGs have prospered in the last decade. In addition, incorporating multiple LMWGs into one system brings the opportunity to achieve sophisticated designs and functions. This review covers recent advances in the field of supramolecular gels, from stimuli-responsive gelators to multicomponent systems that are self-sorting and/or co-assembling.

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...

DNA nanostructures have recently attracted increasing interest in biological and biomedical applications by virtue of their unique properties, such as structural programmability, multi-functionality, stimuli-responsive behaviors, and excellent biocompatibility. In particular, the intelligent responsiveness of smart DNA nanostructures to specific stimuli has facilitated their extensive development in the field of high-performance biosensing and controllable drug delivery. This minireview begins with different self-assembly strategies for the construction of various DNA nanostructures, followed by the introduction of a variety of stimuli-responsive functional DNA nanostructures for assembling metastable soft materials and for facilitating amplified biosensing. The recent achievements of smart DNA nanostructures for controllable drug delivery are highlighted. Finally, the current challenges and possible developments of this promising research are discussed in the fields of intelligent nanomedicine.

Stimuli responsive nanocarriers proved to be an efficient system in accurate diagnosis and targeted delivery of therapeutic moieties. Enzymes have been researched widely as successful targeting age...

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.

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.

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.

Water-soluble microgels have been known for over than three decades. Initially introduced as thermoresponsive polymer colloids with tunable softness, these macromolecular objects become a versatile platform for a broad range of potential applications due to the bursting growth of the diversity of their chemical architecture through the years. The recent progress in the design of stimuli-responsive microgels together with the notable examples of their applications is discussed in this paper.

Recent innovations in genome editing have enabled the precise manipulation of the genetic information of mammalians, and benefitted the development of next-generation gene therapy. Despite these advances, several barriers to the clinical translation of genome editing remain, including the intracellular delivery of genome editing machinery, and the risk of off-target editing effect. Here, we review the recent advance of spatiotemporal delivery of CRISPR/Cas9 genome editing machinery, which is composed of programmable Cas9 nuclease and a single-guide RNA (sgRNA) using stimuli-responsive nanoparticles. We discuss the specific chemistries that have been used for controlled Cas9/sgRNA delivery and intracellular release in the presence of endogenous or external signals. These methodologies can leverage biological signals found locally within disease cells, or exogenous signals administrated with spatiotemporal control, through which an improved genome editing could be achieved. We also discuss the future in exploiting these approaches for fundamental biomedical applications and therapeutic genome editing.

Hydrogen peroxide (H2O2) is widely involved in various physiological or pathological processes such as cell differentiation, proliferation, tumorigenesis, and immune responses. The accurate detection of H2O2 is highly required in many situations ranging from chemical sensing to biomedical diagnosis. However, it is exceedingly challenging to develop a single sensor that can respond to H2O2 in different conditions. Herein, a three-in-one stimulus-responsive nanoplatform (Au@MnO2@Raman reporter) was designed for colorimetry/SERS/MR tri-channel H2O2 detection which satisfied different applications. The MnO2 shell acted as a distance mediator between the gold nanoparticle (Au NP) core and the Raman reporter layer. In the presence of H2O2, the MnO2 shell is degraded, thus releasing the Mn2+ and Au NP core, which act as magnetic resonance (MR) and colorimetry signals, respectively. Simultaneously, the Raman reporters adsorb on the exposed Au NPs, resulting in the surface-enhanced Raman scattering (SERS) effect. The Au NP-based colorimetric assay was employed as H2O2 sensors for glucose detection while the turn-on signals of SERS and MR were used for H2O2 sensing and imaging in live cells and tumors, showing great versatility and flexibility of the multichannel probes in diverse situations.

In this work, a series of oxidized starch-based bio-nanocomposites (OS/CuO) were prepared and investigated as colon drug delivery vehicles. The appearance of peaks at 400–800 cm−1 of FTIR spectrum,...

This Review presents polysaccharides, oligosaccharides, nucleic acids, peptides, and proteins as functional stimuli-responsive polymer scaffolds that yield hydrogels with controlled stiffness. Different physical or chemical triggers can be used to structurally reconfigure the crosslinking units and control the stiffness of the hydrogels. The integration of stimuli-responsive supramolecular complexes and stimuli-responsive biomolecular units as crosslinkers leads to hybrid hydrogels undergoing reversible triggered transitions across different stiffness states. Different applications of stimuli-responsive biomolecule-based hydrogels are discussed. The assembly of stimuli-responsive biomolecule-based hydrogel films on surfaces and their applications are discussed. The coating of drug-loaded nanoparticles with stimuli-responsive hydrogels for controlled drug release is also presented.

This Minireview summarizes the recent progress of stimuli-responsive purely organic phosphorescence materials. Organic phosphorescence is closely related to the intermolecular interactions, because such interactions are beneficial to promote spin orbital coupling (SOC) and boost intersystem cross (ISC) efficiency and finally are conducive to satisfactory phosphorescence. It is found that the intermolecular interactions, which are essential for organic phosphorescence, are easily disturbed by external stimuli such as mechanical force, photon, acid, chemical vapor, leading to the luminescence change. According to this principle, various purely organic phosphorescence materials sensitive to external stimuli have been developed. This Minireview categorizes reported stimuli-responsive purely organic phosphorescence materials on the basis of different stimuli, including mechanochromism, mechanoluminescence, photoactivity, acid-responsiveness and other stimuli. Some prospective strategies for constructing stimuli-responsive purely organic phosphorescence molecules are provided.

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

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.

Resistance to anticancer drugs and their incomplete delivery to the cancerous tissue are the main causes of the chemotherapy failure. In this regard, colloidal systems offer a promising prospect to...

Circulating fetal nucleated cells (CFCs) carrying whole genomic coding of the fetus in maternal blood have been pursued as ideal biomarkers for noninvasive prenatal testing (NIPT). However, a significant limitation is the need to enrich sufficient cells in quantity and purity for fetal genetic disorder diagnosis. This study for the first time demonstrates a stimuli-responsive ligand enabling interface on array patterned microfluidic chip (NIPT-Chip) for high efficient isolation and release of CFCs in untreated whole blood. Deterministic lateral displacement (DLD)-array was patterned in the chip to increase collision frequency between CFCs and surface-anchored antibody to achieve high efficient cell capture. More importantly, the stimuli-responsive interface enables gentle release of captured CFCs through a thiol exchange reaction for downstream gene analysis of NIPT. With the advantages of simple processing, efficient isolation, and gentle release, NIPT-Chip offers great potential for clinical translation of circulating fetal cell-based NIPT.

Herein, we synthesized poly(vinyl alcohol) (PVA) decorated chitosan grafted poly(NIPAM-co-AAc) hydrogels through free-radical copolymerization. Increased PVA concentration revealed enhancement of t...

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.

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.

Mixed valency is a well-known phenomenon in which charge distributions can change via intervalence charge transfer. In addition, there are many other ubiquitous phenomena for charges such as proton...