Search

[Display omitted] The advent of 3D printing technology in the 1980s enabled the fabrication of patient-specific products with precise shape, size, and complexity. A variety of 3D printing techniques, such as direct ink writing by extrusion, particle fusion printing, light-induced printing, volumetric bioprinting, and inkjet printing, have been explored recently for the purpose of developing desired 3D printed objects. Among these techniques, direct ink writing has been used extensively due to its affordability, ease of use, potential for scaling up, and faster speed. This approach saves time and resources while allowing for the flexible use of various materials. The lack of a variety of varied printing inks, however, continues to be an impediment to its widespread commercial use. Owing to their quick gelling behaviour, extrudability, and shape fidelity, injectable hydrogels have become interesting alternatives for printing inks. Hydrogel inks can be developed by either natural or synthetic polymers, or a combination of the both, to achieve the desired rheological and mechanical properties utilizing various strategies of crosslinking and incorporation of nanoparticles like nanoclay, bioactive glass, graphene oxide and silica nanoparticles. Further, various stimuli responsive hydrogel inks responding to various external stimuli (such as temperature, pH, magnetic field) can be developed to prepare engineered biostructures that can be used in healthcare sector. This review provides a spotlight on recent advancement in developing hydrogel inks and their different physicochemical aspects for developing desired engineered biostructures. Finally, we discuss the opportunities of 4D printing, current difficulties and future prospects for hydrogel inks-based 3D printing to emphasize the significant scope for future innovations. [ABSTRACT FROM AUTHOR]

Smart materials represent an elegant class of (macro)-molecules endowed with the ability to react to chemical/physical changes in the environment. Herein, we prepared new photo responsive azobenzenes possessing halogen bond donor groups. The X-ray structures of two molecules highlight supramolecular organizations governed by unusual noncovalent bonds. In azo dye I-azo-NO2, the nitro group is engaged in orthogonal H···O···I halogen and hydrogen bonding, linking the units in parallel undulating chains. As far as compound I–azo–NH–MMA is concerned, a non-centrosymmetric pattern is formed due to a very rare I···π interaction involving the alkene group supplemented by hydrogen bonds. The Cambridge Structural Database contains only four structures showing the same I···CH2=C contact. For all compounds, an 19F-NMR spectroscopic analysis confirms the formation of halogen bonds in solution through a recognition process with chloride anion, and the reversible photo-responsiveness is demonstrated upon exposing a solution to UV light irradiation. Finally, the intermediate I–azo–NH2 also shows a pronounced color change due to pH variation. These azobenzenes are thereby attractive building blocks to design future multi-stimuli responsive materials for highly functional devices.

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

Gas therapy has received widespread attention from the medical community as an emerging and promising therapeutic approach to cancer treatment. Among all gas molecules, nitric oxide (NO) was the first one to be applied in the biomedical field for its intriguing properties and unique anti-tumor mechanisms which have become a research hotspot in recent years. Despite the great progress of NO in cancer therapy, the non-specific distribution of NO in vivo and its side effects on normal tissue at high concentrations have impaired its clinical application. Therefore, it is important to develop facile NO-based nanomedicines to achieve the on-demand release of NO in tumor tissue while avoiding the leakage of NO in normal tissue, which could enhance therapeutic efficacy and reduce side effects at the same time. In recent years, numerous studies have reported the design and development of NO-based nanomedicines which were triggered by exogenous stimulus (light, ultrasound, X-ray) or tumor endogenous signals (glutathione, weak acid, glucose). In this review, we summarized the design principles and release behaviors of NO-based nanomedicines upon various stimuli and their applications in synergistic cancer therapy. We also discuss the anti-tumor mechanisms of NO-based nanomedicines in vivo for enhanced cancer therapy. Moreover, we discuss the existing challenges and further perspectives in this field in the aim of furthering its development.

Introduction: The current work was aimed to design and synthesize novel crosslinked pH-sensitive gelatin/pectin (Ge/Pec) hydrogels using different polymeric ratios and to explore the effect of polymers and degree of crosslinking on dynamic, equilibrium swelling and in vitro release behavior of the model drug (Mannitol). Methods: The Ge/Pec based hydrogels were prepared using glutaraldehyde as the crosslinker. Various structural parameters that affect their release behavior were determined, including swelling study, porosity, sol-gel analysis, average molecular weight between crosslinks (Mc), volume fraction of polymer (V2,s), solvent interaction parameter (χ) and diffusion coefficient. The synthesized hydrogels were subjected to various characterization tools like Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and DSC differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Results: The hydrogels show highest water uptake and release at lower pH values. The FTIR spectra showed an interaction between Ge and Pec, and the drug-loaded samples also showed the drug-related peaks, indicating proper loading of the drug. DSC and TGA studies confirmed the thermal stability of hydrogel samples, while SEM showed the porous nature of hydrogels. The drug release followed non-Fickian diffusion or anomalous mechanism. Conclusion: Aforementioned characterizations reveal the successful formation of copolymer hydrogels. The pH-sensitive swelling ability and drug release behavior suggest that the rate of polymer chain relaxation and drug diffusion from these hydrogels are comparable which also predicts their possible use for site-specific drug delivery.

Traditional intravenous chemotherapy is relative to many systemic side effects, including myelosuppression, liver or kidney dysfunction, and neurotoxicity. As an alternative method, the injectable hydrogel can efficiently avoid these problems by releasing drugs topically at the tumor site. With advantages of localized drug toxicity in the tumor site, proper injectable hydrogel as the drug delivery system has become a research hotspot. Based on different types and stages of cancer, a variety of hydrogel drug delivery systems were developed, including thermosensitive, pH-sensitive, photosensitive, and dual-sensitive hydrogel. In this review, the latest developments of these hydrogels and related drug delivery systems were summarized. In summary, our increasing knowledge of injectable hydrogel for localized cancer therapy ensures us that it is a more durable and effective approach than traditional chemotherapy. Smart release system reacting to different stimuli at different time according to the micro-environment changes in the tumor site is a promising tendency for further studies.

The many postpolymerization modification opportunities of biocompatible poly(2‐alkyl/aryl‐2‐oxazoline)s (PAOx), such as thiol–ene/thiol–yne, azide–alkyne cycloadditions, amidation, and transesterification, are one of the most appealing features of this polymer class for its popularity in biomedicine. Inspired by recent reports on guanidine‐catalyzed transesterification and amidation reactions of methyl ester substrates, we explored the use of guanidines as a reactant for the modification of methyl ester functional PAOx, to obtain the respective acyl guanidines. The obtained acyl guanidines functional polymers display reactivity toward α‐haloketones, yielding imidazole functional PAOx. The obtained polymer structures are protonated in a broad pH range, and the acyl guanidine moiety is demonstrated to be a cleavable linker under basic conditions. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2616–2624 [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract This study shows how highly branched poly(N -isopropyl acrylamide) (HB-PNIPAM) with a chain pendant solvatochromic dye (Nile red) could provide a fluorescence signal, as end groups bind to bacteria and chain segments become desolvated, indicating the presence of bacteria. Vancomycin was attached to chain ends of HB-PNIPAM or as pendant groups on linear polymers each containing Nile red. Location of the dye was varied between placement in the core of the branched polymer coil or the outer domains. Both calorimetric and fluorescence data showed that branched polymers responded to binding of both the peptide target (D-Ala-D-Aa) and bacteria in a different manner than analogous linear polymers; binding and response was more extensive in the branched variant. The fluorescence data showed that only segments located in the outer domains of branched polymers responded to binding of Gram-positive bacteria with little response when linear analogous polymer or branched polymer with the dye in the inner core was exposed to Staphylococcus aureus. [ABSTRACT FROM AUTHOR]

Abstract: Nanotechnology, a relatively novel technique, has much potential in smart drug delivery. Development of novel nanosized particulate drug delivery systems (DDS) may help in disease prevention, diagnosis, and treatment of many of the important diseases. Nanogels have particle sizes in the 0-100 nm range, and the three-dimensional network is maintained by varying the solvent quality. This review article describes concisely the current trends and concepts involved in the design and development of nanogel DDS. This review also explores the various approaches of drug loading, release mechanisms, characterization, and biomedical applications. Optimized nanogel systems can be developed on the basis of the site of action and pattern of drug release desired for improved therapeutic benefits. This can be achieved by using the appropriate method of preparation (physical or chemical) and drug loading mechanism by modifying the geometry and surface of the nanogels. The properties of nanogels are dependent on the constituent materials/components (synthetic or natural) and on external stimuli (pH, temperature, ionic strength or incorporation of hydrophilic residues) in the case of stimuli-sensitive nanogels. Due to the high stability, biodegradability, biocompatibility, large surface area, and minimal resources required for manufacture of nanogels, their applications (such as in oral, pulmonary, nasal, ocular, and topical routes) have gained special attention in the development of pharmaceutical drug carriers.Graphical abstract: [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Nanocarriers based on β-Cyclodextrin modified with Maleic anhydride and NIPAM for dual, pH and temperature responsive drug release are reported. • Multiple functionalities conjugated to magnetic nanoparticle platform in two step one pot synthesis with urethane /urea linkages. • Simultaneous loading and release of Doxorubicin and Curcumin. • Endocytosis monitored by fluorescence. • Targeted cancer cell death in vitro manifested by significant tumor regression in vivo. Abstract Multifunctional nanoconjugates possessing an assortment of key functionalities such as magnetism, florescence, cell-targeting, pH and thermo-responsive features were developed for dual drug delivery. The novelty lies in careful conjugation of each of the functionality with magnetic Fe 3 O 4 nanoparticles by virtue of urethane linkages instead of silica in a simple one pot synthesis. Further β-cyclodextrin (CD) was utilized to carry hydrophobic as well as hydrophilic drug. Superlative release of DOX could be obtained under acidic pH conditions and elevated temperature, which coincides with the tumor microenvironment. Mathematical modelling studies revealed that the drug release kinetics followed diffusion mechanism for both hydrophobic drug and hydrophilic drug. A number of fluorophores onto a single nanoparticle produced a strong fluorescence signal to optically track the nanoconjugates. Enhanced internalization due to folate specificity could be observed by fluorescence imaging. Further their accumulation driven by magnet near tumor site led to magnetic hyperthermia. in vitro studies confirmed the nontoxicity and hemocompatibility of the nanoconjugates. Remarkable cell death was observed with drug-loaded nanoconjugates at very low concentrations in cancer cells. The internalization and cellular uptake of poor bioavailable anticancer agent curcumin were found to be remarkably enhanced on dosing the drug loaded nanoconjugates as compared to free curcumin. Site specific drug delivery due to folate conjugation and subsequent significant suppression in tumor growth was demonstrated by in vivo studies. [ABSTRACT FROM AUTHOR]

A novel stimuli-responsive magnetite nanocomposite as de novo drug delivery system for cancer chemotherapy is developed successfully through the incorporation of magnetite nanoparticles into PEG-b-(PNIPAAm-b-PAA)2 copolymer. The chemical structures of samples were characterized using FTIR and 1H NMR spectroscopies. Furthermore, thermal property, morphology, size, and magnetic properties of the nanocomposite were investigated. The DOX loading and encapsulation efficiencies as well as stimuli-responsive drug release ability of the nanosystem were studied. As results, at pH 5.3 and temperature of 41°C the nanocomposite exhibited higher drug release values, which qualified it for cancer chemotherapy according to especial features of cancerous tissue. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Stimuli responsive chitosan PVP hydrogel are prepared for wound healing applications. • Thermal analysis showed hydrogel as thermally more stable than individual chitosan and PVP. • Antimicrobial analysis revealed antibacterial activity against E. coli. • The hydrogels showed responsive swelling behavior against different media. • The distinctive pH behavior of hydrogels showed significant release profile (91.2%) of silver sulfadiazine in PBS. Abstract Stimuli responsive chitosan (CS) and poly (N-vinyl-2-pyrrolidone) (PVP) have attained hydrogel properties in the presence of 74% neutralized poly acrylic acid (PAA) which can be exploited for wound healing applications. The FTIR spectra confirmed the presence of all specific functional groups and the developed interactions in the hydrogels. The thermal analysis explained that the hydrogel samples are thermally more stable than individual chitosan and PVP. The antimicrobial analysis revealed that all the samples show antibacterial activity against E. coli and the biodegradation analysis is performed to confirm the hydrogels degradation. The hydrogels showed enhanced responsive swelling behavior against different media depending upon the amount of PVP. The %age swelling in water is decreased with the increase in the amount of PVP. The most considerable swelling behavior is observed against pH, as they manifested low swelling at acidic pH and high swelling at neutral pH while at pH 8, the prominent values are obtained. This distinctive behavior of hydrogels and their biocompatibility made them pertinent to drug delivery and their release profile is examined spectrophotometrically using silver sulfadiazine (antibiotic for burnt wounds) showed 91.2% of drug release for a period of 1 h in phosphate buffer saline (PBS) in a consistent and controlled manner. [ABSTRACT FROM AUTHOR]

The popularity of hydrogels as biomaterials lies in their tunable physical properties, ability to encapsulate small molecules and macromolecular drugs, water holding capacity, flexibility, and controllable degradability. Functionalization strategies to overcome the deficiencies of conventional hydrogels and expand the role of advanced hydrogels such as DNA hydrogels are extensively discussed in this review. Different types of cross-linking techniques, materials utilized, procedures, advantages, and disadvantages covering hydrogels are tabulated. The application of hydrogels, particularly in buccal, oral, vaginal, and transdermal drug delivery systems, are described. The review also focuses on composite hydrogels with enhanced properties that are being developed to meet the diverse demand of wound dressing materials. The unique advantages of hydrogel nanoparticles in targeted and intracellular delivery of various therapeutic agents are explained. Furthermore, different types of hydrogel-based materials utilized for tissue engineering applications and fabrication of contact lens are discussed. The article also provides an overview of selected examples of commercial products launched particularly in the area of oral and ocular drug delivery systems and wound dressing materials. Hydrogels can be prepared with a wide variety of properties, achieving biostable, bioresorbable, and biodegradable polymer matrices, whose mechanical properties and degree of swelling are tailored with a specific application. These unique features give them a promising future in the fields of drug delivery systems and applied biomedicine.

The development and comparison of latent fingerprint (LFP) are crucial for the detection and identification of LFP. However, research on stable, clear, and no background interference's fluorescent materials for LFP recognition are scarce. In this study, lignin-derived carbon dots (CDs) with orange red emission were synthesized and combined with polyvinyl alcohol (PVA) matrix for identification of LFP and ink-free printing. The physicochemical and microstructure of the CDs and CDs/PVA nanocomposite have been precisely elucidated by TEM, FT-IR, XPS, SEM, and TGA to verify the reaction of CDs with PVA forming hydrogen bonds. The effect of CDs on the mechanical properties of PVA nanocomposite was studied. The tensile strength and elongation at break of PVA nanocomposite were increased by 113.01 % and 175.26 %, respectively. The shape memory and fluorescence properties of CDs/PVA nanocomposite were studied under different conditions such as water, acid, alkali and heat. The fluorescence intensity of CDs/PVA nanocomposites was enhanced due to the deprotonation of CDs surface under alkaline conditions. By coating CDs/PVA solution on LFP, a stable fluorescent fingerprint with clear ridge details was formed on the composite film, and it is applied to letterpress printing and gravure printing, enabling personal identification and ink-free printing. Obviously, the nanocomposite film prepared herein has multiple functions, providing potential for the design and manufacture of advanced all-round personal information identification and encryption applications in extremely harsh high temperature and strong alkaline environments. [Display omitted] • Lignin-derived tangerine carbon dots were prepared by a solvothermal method. • Lignin-derived CDs/PVA nanocomposites were formed by compositing CDs with PVA. • Transfer, collection and detection of LFPs and ink-free printing were realized. [ABSTRACT FROM AUTHOR]

The chemotherapeutic drug of doxorubicin (DOX) has witnessed widespread applications for treating various cancers. DOX-treated dying cells bear cellular modifications which allow enhanced presentation of tumor antigen and neighboring dendritic cell activation. Furthermore, DOX also facilitate the immune-mediated clearance of tumor cells. However, disadvantages such as severe off-target toxicity, and prominent hydrophobicity have resulted in unsatisfactory clinical therapeutic outcomes. The effective delivery of DOX drug molecules is still challenging despite the rapid advances in nanotechnology and biomaterials. Huge progress has been witnessed in DOX nanoprodrugs owing to their brilliant benefits such as tumor stimuli-responsive drug release capacity, high drug loading efficiency and so on. This review summarized recent progresses of DOX prodrug-based nanomedicines to provide deep insights into future development and inspire researchers to explore DOX nanoprodrugs with real clinical applications. [Display omitted] • DOX nanoprodrugs have been applied for the treatment of various kinds of cancers, such as ovarian, breast, lung and leukemia among others. • DOXnanoprodrugs possess various advantages, such as tumor stimuli-responsive drug release capacity, high drug loading, among others. • Mechanisms of stimuli-responsive DOX release have been summarized. [ABSTRACT FROM AUTHOR]

[Display omitted] • Lanthanide-based hydrogel possessed reversible luminescent switching property. • Dual-stimuli luminescent switching enables flexible anti-counterfeiting designs. • Advanced luminescent hydrogel effectively protects data security. The development of data protection materials with low cost is still challenging in the era of big data and artificial intelligence. Herein, the luminescent hydrogel with luminescent switching property was prepared by the introduction of lanthanide complex into poly(vinyl alcohol) gelation matrix. The developed luminescent hydrogel showed good reversible luminescent switching behavior under the stimulation of HCl/NH 3 and Fe3+/EDTA2-, respectively. It enables the hydrogel to be applied as reversible data security storage material with low cost. The results showed that the input and erasure of data was reversible. Moreover, the fabricated data was invisible under daylight whereas it was visible under UV light. It is suitable for data protection. Furthermore, the combination of dual-stimuli was demonstrated to improve the security level of data effectively. The hydrogel also exhibited good stability against UV irradiation. The findings suggested that the stimuli-responsive luminescent hydrogel has potential application in data protection. [ABSTRACT FROM AUTHOR]

Spurred by significant progress in materials chemistry and drug delivery, charge-reversal nanocarriers are being developed to deliver anticancer formulations in spatial-, temporal- and dosage-controlled approaches. Charge-reversal nanoparticles can release their drug payload in response to specific stimuli that alter the charge on their surface. They can elude clearance from the circulation and be activated by protonation, enzymatic cleavage, or a molecular conformational change. In this review, we discuss the physiological basis for, and recent advances in the design of charge-reversal nanoparticles that are able to control drug biodistribution in response to specific stimuli, endogenous factors (changes in pH, redox gradients, or enzyme concentration) or exogenous factors (light or thermos-stimulation).

Stimuli-responsive controlled-release nanocarriers are promising vehicles for delivery of bioactive molecules that can minimize side effects and maximize efficiency. The release of the drug occurs when the nanocarrier is triggered by an internal or external stimulus. Mesoporous silica nanoparticles (MSN) can have drugs and bioactive cargos loaded into the high-capacity pores, and their release can be triggered by activation of a variety of stimulus-responsive molecular “gatekeepers” or “nanovalves.” In this mini-review, we discuss the basic concepts of MSN in targeted drug-release systems and cover different stimulus-responsive gatekeepers. Internal stimuli include redox, enzymes, and pH, while external stimuli include light, ultrasound, and magnetic fields, and temperature can either be internal or external.

A synthetic route for redox-sensitive and non-sensitive core multi-shell (CMS) carriers with sizes below 20 nm and narrow molecular weight distributions was established. Cyclic voltammetric measurements were conducted characterizing the redox potentials of reduction-sensitive CMS while showcasing its reducibility through glutathione and tris(2-carboxyethyl)-phosphine as a proof of concept. Measurements of reduction-initiated release of the model dye Nile red by time-dependent fluorescence spectroscopy showed a pronounced release for the redox-sensitive CMS nanocarrier (up to 90% within 24 h) while the non-sensitive nanocarriers showed no release in PBS. Penetration experiments using ex vivo human skin showed that the redox-sensitive CMS nanocarrier could deliver higher percentages of the loaded macrocyclic dye meso-tetra (m-hydroxyphenyl) porphyrin (mTHPP) to the skin as compared to the non-sensitive CMS nanocarrier. Encapsulation experiments showed that these CMS nanocarriers can encapsulate dyes or drugs with different molecular weights and hydrophobicity. A drug content of 1 to 6 wt% was achieved for the anti-inflammatory drugs dexamethasone and rapamycin as well as fluorescent dyes such as Nile red and porphyrins. These results show that redox-initiated drug release is a promising strategy to improve the topical drug delivery of macrolide drugs.

The presence of leaky vasculature and the lack of lymphatic drainage of small structures by the solid tumors formulate nanoparticles as promising delivery vehicles in cancer therapy. In particular, among various nanoparticles, the mesoporous silica nanoparticles (MSN) exhibit numerous outstanding features, including mechanical thermal and chemical stability, huge surface area and ordered porous interior to store different anti-cancer therapeutics with high loading capacity and tunable release mechanisms. Furthermore, one can easily decorate the surface of MSN by attaching ligands for active targeting specifically to the cancer region exploiting overexpressed receptors. The controlled release of drugs to the disease site without any leakage to healthy tissues can be achieved by employing environment responsive gatekeepers for the end-capping of MSN. To achieve precise cancer chemotherapy, the most desired delivery system should possess high loading efficiency, site-specificity and capacity of controlled release. In this review we will focus on multimodal decorations of MSN, which is the most demanding ongoing approach related to MSN application in cancer therapy. Herein, we will report about the recently tried efforts for multimodal modifications of MSN, exploiting both the active targeting and stimuli responsive behavior simultaneously, along with individual targeted delivery and stimuli responsive cancer therapy using MSN.

Abstract Orally administrable drug delivery vehicles are developed to manage incurable inflammatory bowel disease (IBD), however, their therapeutic outcomes are compromised by the side effects of systemic drug exposure. Herein, we use hyaluronic acid functionalized porous silicon nanoparticle to bridge enzyme-responsive hydrogel and pH-responsive polymer, generating a hierarchical structured (nano-in-nano-in-micro) vehicle with programmed properties to fully and sequentially overcome the multiple obstacles for efficiently delivering drugs locally to inflamed sites of intestine. After oral administration, the pH-responsive matrix protects the embedded hybrid nanoparticles containing drug loaded hydrogels against the spatially variable physiological environments of the gastrointestinal tract until they reach the inflamed sites of intestine, preventing premature drug release. The negatively charged hybrid nanoparticles selectively target the inflamed sites of intestine, and gradually release drug in response to the microenvironment of inflamed intestine. Overall, the developed hierarchical structured and programmed vehicles load, protect, transport and release drugs locally to inflamed sites of intestine, contributing to superior therapeutic outcomes. Such strategy could also inspire the development of numerous hierarchical structured vehicles by other porous nanoparticles and stimuli-responsive materials for the local delivery of various drugs to treat plenty of inflammatory gastrointestinal diseases, including IBD, gastrointestinal cancers and viral infections. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

Anthracene-substituted acylhydrazone derivative ( AHP-T8 ) exhibits multi-stimuli-responsive fluorescence switching behaviors. The AHP-T8 exhibits mechanofluorochromism in that grinding and heating could change the emission colors. The transformation of crystalline features and amorphous state between the xerogel and ground states might be attributed to the mechanochromic luminescence properties. Protonation-deprotonation has a significant effect on the frontier molecular orbitals, resulting in AHP-T8 exhibiting remarkable and reversible acid/base stimulated fluorescence switching properties in both organogel and solid state. The multi-stimuli responsive fluorescence properties reveal that AHP-T8 may be a potential candidate for applications in sensing, security label and a fluorescence indicator for acids/bases. [ABSTRACT FROM AUTHOR]

The cavities of metallosupramolecular cages can be used to mimic the central spaces of naturally occurring proteins and bind a wide variety of molecular guests. A range of potential applications have arisen from this capacity for host–guest chemistry. However, to truly harness the opportunities thus afforded, methodologies to controllably allow the release and reuptake of guests from the cavities of metallosupramolecular cages are required. Methods to accomplish this have centered upon reversibly altering the character of either the guest or host. This minireview outlines the current approaches used to carry out the binding and release of guests from metallosupramolecular hosts using important examples from the field. The cavities of metallosupramolecular cages can be used to mimic the central spaces of naturally occurring proteins and bind a wide variety of molecular guests. However, in order to more fully mimic Nature mechanisms that allow for the binding and release of guest molecules are required. This minireview outlines the current approaches used to carry out the binding and release of guests from metallosupramolecular hosts. [ABSTRACT FROM AUTHOR]

Abstract: The design and synthesis of a series of zwitterionic ionic liquids (ZILs) to understand the structure–property relationship towards an increase of the thermal stability, a variation of the glass transition temperature, the shape‐tuning of nanostructured aggregates and the tuning of the stimuli responsiveness are demonstrated. The substitution reaction of imidazole with various aliphatic and aromatic bromides followed by the reaction of the corresponding substituted imidazoles with bromoalkyl carboxylic acids of varying spacer length produces the ZILs. In aqueous solution, a ZIL molecule either exist in its ionic liquid (substituted imidazolium bromide) form or its zwitterionic (substituted imidazolium alkyl carboxylate) form with an isoelectric point (pI) depending on the pH value of the solution. Upon changing the pH to near or above the pI, the aqueous ZIL solution undergoes transition from a transparent to a turbid phase due to the formation of insoluble hierarchical nanostructured aggregates of various morphologies, such as spheres, tripods, tetrapods, fern‐like, flower‐like, dendrites etc. depending on the pH of the solution and the nature of the alkyl/vinyl/aryl substituents. Upon heating the solution a phase transition occurs from turbid to transparent, exhibiting a distinct reversible upper critical solution temperature (UCST)‐type cloud point (Tcp). It is observed that the cloud point varies with the nature of the substituent, an increase of the concentration of the ZIL as well as with changes of the pH of the solution. [ABSTRACT FROM AUTHOR]

Abstract: Layer‐by‐layer (LbL) films of micelles of poly[2‐(dimethylamino)ethyl methacrylate]‐b‐poly[(2‐(diethylamino)ethyl methacrylate)] (PDMA‐b‐PDEA) and poly(sodium 4‐styrenesulfonate) (PSS) with remarkably different pH‐stability and release properties are obtained via tuning film deposition conditions in a narrow pH and temperature range. Multilayers constructed at pH 8.5/25 °C or pH 8/30 °C completely disintegrate at physiologically related conditions, whereas film deposition at pH 8/25 °C produces stable films under the same conditions. Importantly, despite their stability, pH 8/25 °C multilayers release a considerable amount of pyrene at moderately acidic pH due to disintegration of the micellar cores. The amount of pyrene increases significantly at body temperature due to lower critical solution temperature (LCST)‐type phase behavior of PDMA coronal chains. The difference in properties of multilayers is explained by the extent of association among the layers which can be tuned by film deposition conditions in a narrow pH and temperature range due to dual responsive, that is, pH and temperature behavior of PDMA‐b‐PDEA micelles. [ABSTRACT FROM AUTHOR]

A copper mesh with dendritic copper-oxide core-shell structure is prepared using an additive-free electrochemical deposition strategy for on-demand oil-water separation. Electrochemical manipulation of the oxidation state of the copper oxide shell phase results in opposite affinities towards water and oil. The copper mesh can be tuned to manifest both superhydrophobic and superoleophilic properties to enable oil-removal. Conversely, switching to superhydrophilic and underwater superoleophobic allows water-removal. These changes correspond to the application of small reduction voltages (<1.5 V) and subsequent air drying. In the oil-removal mode, heavy oil selectively passes through the mesh while water is retained; in water-removal mode, the mesh allows water to permeate but blocks light oil. The smart membrane achieved separation efficiencies higher than 98% for a series of oil-water mixtures. The separation efficiency remains high with less than 5% variation after 30 cycles of oil-water separation in both modes. The switchable wetting mechanism is demonstrated with the aid of microstructural and electrochemical analysis and based on the well-known Cassie-Baxter and Wenzel theories. The selective removal of water or oil from the oil-water mixtures is driven solely by gravity and yields high efficiency and recyclability. The potential applications for the relevant technologies include oil spills cleanup, fuel purification, and wastewater treatment. [ABSTRACT FROM AUTHOR]

While providing the ability to magnetically enhance delivery rates, ferrogels have not been able to produce the various types of regulated delivery profiles likely needed to direct complex biological processes. For example, magnetically triggered release after prolonged periods of payload retention have not been demonstrated and little has been accomplished towards remotely controlling release rate through alterations in the magnetic signal. Also, strategies do not exist for magnetically coordinating multi-drug sequences. The purpose of this study was to develop these capabilities through improved ferrogel design and investigating how alterations in the magnetic signal impact release characteristics. Results show that delivery rate can be remotely regulated using the frequency of magnetic stimulation. When using an optimized biphasic ferrogel design, stimulation at optimized frequencies enabled magnetically triggered deliveries after a delay of 5 days that were 690- to 1950-fold higher than unstimulated baseline values. Also, a sequence of two payloads was produced by allowing one payload to initially diffuse out of the ferrogel, followed by magnetically triggered release of a different payload on day 5. Finally, it was demonstrated that two payloads could be sequentially triggered for release by first stimulating at a frequency tuned to preferentially release one payload (after 24 h), followed by stimulation at a different frequency tuned to preferentially release the other payload (After 4 days). The strategies developed here may expand the utility of ferrogels in clinical scenarios where the timing and sequence of biological events can be tuned to optimize therapeutic outcome. [ABSTRACT FROM AUTHOR]

Non-communicable diseases including cancer, cardiovascular disease, diabetes, and neuropathy are chronic in nature. Treatment of these diseases with traditional delivery systems is limited due to lack of site-specificity, non-spatiotemporal release and insufficient doses. Numerous responsive delivery systems which respond to both physiological and external stimuli have been reported in the literature. However, effective strategies incorporating a multifactorial approach are required to control these complex wounds. This can be achieved by fabricating spatiotemporal release systems, multimodal systems or dual/multi-stimuli responsive delivery systems loaded with one or more bioactive components. Critically, these next generation stimuli responsive delivery systems that are at present not feasible are required to treat chronic wounds. This review provides a critical assessment of recent developments in the field of responsive delivery systems, highlighting their limitations and providing a perspective on how these challenges can be overcome. [ABSTRACT FROM AUTHOR]