Dual-responsive Poly Research Articles

Bioinspired Microgel-Loaded Smart Membrane Filtration with the Thermo- and Ion-Dual Responsive Water Gate for Selective Lead(II) Separation.

Lead (Pb2+) is a ubiquitous pollutant. Membrane filtration represents one of the most common water treatment methods, but nanofiltration and ultrafiltration require high transmembrane pressure, while microfiltration has larger pore sizes than ions, making them unfavorable for direct ion removal at low cost. Selective and direct separation of Pb2+ via membrane filtration at high efficiency without sacrificing the flux of clean water still remains challenging. Herein, inspired by the Pb2+-tolerable oleander that enriches and prevents Pb2+ in roots from permeating the plant body, a smart Pb2+-adsorptive filtration membrane with a temperature- and ion-tunable water gate was prepared by loading dual-responsive poly(N-isopropylacrylamido-co-acrylamido-benzo-18-crown-6) (PNB-5-20) microgels onto a commercial membrane. The PNB-5-20 microgel exhibits pronounced temperature-responsive swelling/deswelling (hydrodynamic diameter, 650-330 nm) with a volume phase transition temperature (VPTT) at ∼33 °C. Moreover, the microgel shows a high Pb2+-adsorption capacity (qmax, 85.4 mg/g) and good selectivity (distribution coefficient Kd ∼ 1000 mL/g) thanks to its complexation with the crown ether, as well as good Pb2+ responsiveness, having the VPTT positively shifted to 40 °C in the presence of Pb2+ with enhanced swelling behaviors. Functionalized with PNB-5-20, the smart membrane integrates Pb2+ detection, adsorption, and tunable water drainage in a single device. The membrane selectively recognizes Pb2+ in the polluted water with the gates in membrane pores switching from "open" to "closed", intercepting and adsorbing Pb2+ with water permeation reduced. Once purified, the gates can be "re-opened" by increasing the temperature. Construction of such an intelligent membrane filtration device with a tunable water gate and excellent Pb2+ recognition and adsorption performance will greatly simplify the remediation of Pb2+-polluted water.

Optimizing the boron-loaded pH/temperature dual responsive polymer for controlled release of boron from wood

ABSTRACT Disodium octoborate tetrahydrate (DOT) is a well-received and eco-friendly preservative. However, it is prone to leaching from wood in humid conditions or rainy seasons, causing problems such as decreased efficiency in resisting fungi and poor surface performance in surface finishing. To obtain enhanced leaching resistance and simultaneously achieve controlled release of DOT, a pH and temperature dual responsive poly (2-hydroxyethyl methacrylate/2-(Dimethylamino) ethyl methacrylate) (PDH) was prepared and optimized for in situ construction of DOT-loaded PDH (PDHD) in wood. Results showed that PDH displayed obvious pH and temperature-responsive swelling, and when loaded with DOT, the PDHD consequently released DOT in a pH and temperature-responsive way. Fourier transform infrared spectroscopy, Solid-13C NMR analysis and Dynamic mechanical analysis confirmed the copolymerization of 2-Hydroxyethyl methacrylate (HEMA) and 2-(Dimethylamino) ethyl methacrylate (DMAEMA), as well as the presence of crosslinked structure formed from hydrogen bond between the hydroxyl group of HEMA and the N,N-dimethylamino groups of DMAEMA. After that, the PDHD was in situ constructed in wood for controlled release of boron. During the water leaching test, the modified wood exhibited a boron fixation rate of 49.05% compared with 0.72% of the neat DOT-treated wood. Besides, it presented controlled release activity in response to pH and temperature. This work provides new approaches to the fixation of boron preservatives and notably realizes responsive releasing of boron compounds for long-term wood preservation.

Paclitaxel prodrug-encapsulated polypeptide micelles with redox/pH dual responsiveness for cancer chemotherapy

Polypeptides are a highly promising carrier for delivering hydrophobic drugs, due to their excellent biocompatibility, non-toxicity, and non-immunogenicity. Herein, a redox and pH dual-responsive poly(ethylene glycol)-SS-b-polypeptide micelles encapsulated with disulfide bridged paclitaxel-pentadecanoic acid prodrug was developed for cancer chemotherapy. First of all, disulfide bridged paclitaxel-pentadecanoic acid prodrug (PTX-SS-COOH) and poly(ethylene glycol)-SS-b-polylysine-b-polyphenylalanine (mPEG-SS-b-PLys-b-PPhe, ESLP) were synthesized and confirmed via NMR, MS, FT-IR or GPC. After that, PTX-SS-COOH (PSH) embedded mPEG-SS-b-PLys-b-PPhe (ESLP/PSH) micelles were prepared by mixing method based on electrostatic interactions and hydrophobic forces. For comparison, mPEG-b-PLys-b-PPhe (ELP) was mixed with PTX-SS-COOH to generate another kind of micelles (ELP/PSH). The characterization of ESLP/PSH micelles through dynamic light scattering (DLS) and transmission electron microscopy (TEM) revealed a spherical structure with a diameter of approximately 170 nm. It is noteworthy that ESLP/PSH micelles displayed a high drug-loading rate of 22.84%, and excellent stability, which can be attributed to the specific interactions between the prodrug and copolymer. Drug release analysis demonstrated that the micelles exhibited a substantial release of PTX in the presence of GSH at pH 5.0, indicating a pH and redox dual responsiveness. In vivo pharmacokinetic study revealed the ESLP/PSH micelles had increased bioavailability and an extended circulation time. Ultimately, antitumor efficacy and systemic toxicity evaluation in 4 T1 tumor-bearing mice confirmed that ESLP/PSH micelles achieved the highest level of tumor growth inhibition (ca. 83%) and the lowest systemic toxicity in comparison with ELP/PSH micelles and commercialized Taxol®. Taken together, the dual responsive micelles represent a promising PTX formulation with potential clinical application in cancer chemotherapy.

PH and temperature dual-responsive hydrogel actuator with bidirectional bending behavior and ultra large bending angle

Smart hydrogels have received attentions for the great potentials in biomedical and robots applications. However, the deformation performance of hydrogels still needs to be improved, especially for the pH and thermal dual responsive hydrogels. In this study, a pH and temperature dual-responsive poly(acrylamide-acrylic acid-3-acrylamidophenylboronic acid)/Poly(N-isopropylacrylamide) (P(AAm-AAc-3-AAPBA)/PNIPAM) bilayer structures have been prepared by UV polymerization. The PNIPAM layer shrinks/swells when the temperature is higher/lower than the low critical solution temperature, while P(AAm-AAc-3-AAPBA) layer will swell/shrink when pH is too high/low. The volume change trend of the two layer is different, resulting in the bending behaviors of P(AAm-AAc-3-AAPBA)/PNIPAM hydrogel actuator. The bidirectional bending performance can be reversibly, repeatedly, and precisely controlled by pH and temperature-induced cooperative swelling-shrinking properties from both layers. The bending angle of the bilayer structure achieves about 1420° at the environment of pH 2 and 55 ℃. It takes about 70 s to convert the bending angle of the bilayer structures from 355° (10 ℃, pH 2) to −360° (55 ℃, pH 12). In addition, three kinds of biomimetic hydrogel structures, such as mechanical gripper, bionic flower and bionic hand, have been prepared and demonstrated good performance. The obtained P(AAm-AAc-3-AAPBA)/PNIPAM hydrogels exhibit excellent pH and thermal responsive bending properties, which enable them as an ideal smart hydrogel system.

Redox and pH Dual-Responsive Polypeptide Micelles for Doxorubicin Delivery with Enhanced Anticancer Efficacy

Herein, redox and pH dual-responsive poly(glutamic acid) micelle-encapsulated doxorubicin (DOX) was developed in this report. First, methoxy poly(ethylene glycol)-block-poly(glutamic acid) (PEG-SS-PG) linked by a disulfide bond was synthesized through ring-opening polymerization of l-glutamic acid γ-benzyl ester carboxyanhydride using terminal aminosylated poly(ethylene glycol) (PEG-SS-NH2) as an initiator. After that, PEG-SS-PG was assembled with doxorubicin (DOX) by a simple mixing to form tight PEG-SS-PG/DOX micelles by virtue of the electrostatic interaction between carboxylic acid groups of PEG-SS-PG and amine groups of DOX. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) characterization indicated that the micelles have a spherical structure with an average particle size of about 70 nm. The drug loading efficiency (DLE) was measured to be 92.3 wt %. The release behavior of PEG-SS-PG/DOX was checked in the presence of glutathione (GSH) and different pH. The results showed that about 90% DOX was released within 36 h under the combined action of high GSH concentration and low pH, while less than 25% DOX was released at pH 7.4 in the absence of GSH. These data confirmed the glutathione and pH dual-responsiveness of PEG-SS-PG/DOX micelles. The micelles could be internalized by cancer cells, as revealed by confocal laser scanning microscopy (CLSM) and flow cytometry (FCM). The pharmacokinetics and biodistribution of the PEG-SS-PG/DOX micelles were further investigated in detail. Compared with free DOX, PEG-SS-PG/DOX micelles improved the biodistribution of DOX and prolonged blood circulation time. Finally, in vivo antitumor efficacy was studied using 4T1 breast tumor-bearing BALB/c mice. It was found that the tumor inhibition rate of PEG-SS-PG/DOX was up to 86.32%, indicating greatly effective antitumor performance. Taken together, PEG-SS-PG micelles can encapsulate DOX via electrostatic interaction to form tight micelles and possess redox and pH dual-responsive release of DOX and highly effective inhibition of tumor growth, which have potential application for the treatment of tumors.

Dual-Responsive Amphiphilic P(DMAEMA-co-LMA-co-OEGMA) Terpolymer Nano-Assemblies in Aqueous Media.

This work reports on the synthesis and self-assembly of a novel series of dual-responsive poly[2-(dimethylamino)ethylmethacrylate-co-laurylmethacrylate-co-(oligoethyleneglycol)methacrylate], P(DMAEMA-co-LMA-co-OEGMA)statistical terpolymers in aqueous solutions. Five P(DMAEMA-co-LMA-co-OEGMA) amphiphilic terpolymers, having different content of the three monomers, were synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. The success of the synthesis was confirmed by the molecular characterization of the terpolymers via size exclusion chromatography (SEC) for the determination of molecular weights and the molecular weight distributions. By using nuclear magnetic resonance (1H-NMR) and Fourier-transform infrared (FTIR) spectroscopy, it was possible to determine the exact composition of the terpolymers. Dynamic light scattering (DLS) and fluorescence spectroscopy (FS) indicated the formation of P(DMAEMA-co-LMA-co-OEGMA) unimolecular or multichain aggregates in aqueous solutions, as a response to pH, temperature and ionic strength changes, with their dimensions being largely affected. The amphiphilic terpolymers were able to encapsulate the hydrophobic drug curcumin (CUR) and demonstrate stability to fetal bovine serum (FBS) solutions. These terpolymer aggregates were studied by DLS, FS and UV-Vis, and it was found that they may have been used as potential nanocarriers for drug delivery and bio-imaging applications.

Synthesis and characterization of dual-responsive poly(N-vinylcaprolactam-co-N-methylolacrylamide) nanogels

ABSTRACT This article reports the synthesis of poly(N-vinylcaprolactam-co-N-methylolacrylamide) (P(NVCL-co-NMA)) nanogels and investigates their thermo-/pH-responsive behavior. The formation of nanogels was synthesized using free radical emulsion polymerization by varying the monomer composition of NVCL:NMA, and their molecular structure was characterized by 1H-NMR and FTIR. It was found that the nanogels were successfully prepared, and the nanogels exhibited LCST-type phase transition behavior. Cloud point transition temperature (Tc) was studied as a function of copolymer composition, MBA concentration, and pH of the solution by exploring their changes in turbidity using UV–vis spectrophotometer. Our studies reveal that Tc nanogels increased with increasing concentration of NMA, which is due to the hydrophilicity of NMA. Our research also demonstrated that the increase in MBA percentage could decrease the Tc of the synthesized nanogels. Interestingly, P(NVCL-co-NMA) nanogels showed not only a thermoresponsive behavior but also a pH response with increasing Tc in a strong acidic environment owing to the H-bonds within the polymer chains. The results show that nanogels with initial monomer composition of NVCL and NMA of 75% and 25%, respectively, and using 4% of MBA showed Tc around 35°C at pH 7.4. In addition, DLS studies also confirmed this result since the particle sizes became much larger after surpassing the temperature of 35°C. Due to this founding, such nanogels might have potential application in controlled release. Nevertheless, further studies regarding the adjustment of Tc are still needed.

Photo- and thermo-responsive microgels with supramolecular crosslinks for wavelength tunability of the volume phase transition temperature.

Functional microgels have powerful applications, especially due to their quick responsiveness to different external stimuli such as temperature, pH, ionic strength, solvent composition and light. Here, we describe the synthesis of novel dual-responsive poly(N-isopropylacrylamide) (PNIPAM) microgels and demonstrate that, in addition to temperature, light changes their properties. The crosslinks inside the microgels were achieved by the host-guest interactions between the trans azobenzene (transAzo) and β-cyclodextrin (βCD) units. transAzo can be photoisomerized to cisAzo which exhibits significant lower binding affinity to βCD. As a consequence, the crosslink density, and thus several microgel properties, can be controlled by light irradiation. Surprisingly, this irradiation with light can significantly change the volume phase transition temperature (VPTT) by several degrees centigrade, presumably due to the fact that the polar βCD shields the transAzo bound to it, whereas the unbound cisAzo is rather apolar. As a result, continuous irradiation with specific wavelengths until reaching the respective photostationary state allows for a full control over the VPTT within the physiologically relevant range between 32 °C and 38 °C.

Multiresponsive Microgels: Toward an Independent Tuning of Swelling and Surface Properties.

Dual-responsive poly-(N-isopropylacrylamide) (PNIPAM) microgels surface-functionalized with polyethylene glycol (PEG) or poly-2-dimethylaminoethyl methacrylate (PDMAEMA) were developed to enable the swelling behavior and surface properties of the microgels to be tuned independently. The thermo-triggered swelling and pH-triggered surface properties of the microgels were investigated in aqueous suspensions using dynamic light scattering and on substrates using the surface forces apparatus. Grafting polymer chains on the microgel surface did not impede the thermo-triggered swelling behavior of the microgels in suspensions and immobilized on substrates. An unprecedented decoupling of the swelling behavior and surface properties could be obtained. More particularly, the thermo-triggered swelling behavior of the PNIPAM underlying microstructure could be tuned below and above the phase transition temperature with no change in the surface potential and adhesion provided by the surface non-responsive PEG.

Self-bleaching dual responsive poly(ionic liquid) with optical bistability toward climate-adaptable solar modulation

In the development of smart windows, functional polymer materials play a crucial role, which can provide a more comfortable indoor environment for people to enjoy a better lifestyle. However, many of the implied smart windows that have been studied to date respond to only one stimulus, but studies on dual-responsive smart windows have been increasing. The growing interest in multi-responsive smart windows is due to the many opportunities in terms of utility and activity that they offer. Herein, our group has adopted a strategy to combine the thermo- and electro-chromic as well as electrolyte properties in one single molecule. Dual-responsive poly(ionic liquid) (PIL) 6 based electrolyte was synthesized via radical polymerization of poly(ethylene glycol) diacrylate (PEGDA) with N-isopropylacrylamide (NIPAM) with viologen based electroactive monomer utilizing AIBN as an initiator in DMSO. One single molecule (all-in-one) single-layer device consisting of ITO/smart PIL/ITO was assembled on a glass substrate, that can enhance its optical efficiency and characteristics of phase shift. The proposed electrochromic device exhibits tunable transparency and electrochromic properties due to the thermo-responsive property of PNIPAM and the bistable electrochromic property of a viologen-based electroactive monomer, respectively. Consequently, the acquired dual-responsive properties of smart PIL 6 for the development of bistability smart windows can not only control solar energy input but can also provide a more comfortable color tone to boost people's feelings and emotions in indoor environments.

Logic gate nanocarriers based on pH and ROS dual sensitive poly(orthoester-thioether) for enhanced anticancer drug delivery

The traditional poly(orthoesters) nanoparticles degrade very slowly at acidic pH due to surface erosion. While the amphiphilic poly(orthoesters) micelles lack stability. Therefore, to improve the stability of carriers and drug release capacity, we synthesized a new type of pH and ROS dual responsive poly(orthoester-thioether) (PSOE) with orthoester and thioether in main chain to build logic gate nanoparticles by transesterification between an orthoester and a diol. The self-assembled PSOE nanospheres (PSOE NPs) kept stable under physiological condition, while degraded rapidly in the presence of hydrogen peroxide and acidic pH because hydrophobic-to-hydrophilic transition upon stimulation by hydrogen peroxide, resulted in rapid degradation of orthoester. The drug release profiles demonstrated that doxorubicin release from PSOE NPs was significantly accelerated under mildly acidic and ROS condition. In vitro cell experiments revealed that DOX-loaded PSOE NPs exhibited efficient antitumor effect against monolayer cells and three-dimensional multicellular spheroids. Therefore, pH and ROS dual responsive PSOE NPs may be a promising candidate for efficient drug delivery.

Fabrication of PNIPAM-chitosan/decatungstoeuropate/silica nanocomposite for thermo/pH dual-stimuli-responsive and luminescent drug delivery system

A luminescent and dual-stimuli-responsive nanocomposite based on mesoporous silica, poly (N-isopropylacrylamide)-chitosan and decatungstoeuropate was prepared. To fabricate the nanocomposite, the mesoporous silica nanoparticles were coated with thermo/pH dual-responsive poly (N-isopropylacrylamide)-chitosan and the luminescent decatungstoeuropate particles were grafted onto copolymers. The designed nanocarrier could show exhibit good red luminescence as well as obvious thermo/pH stimuli-responsive properties, which could be employed as a drug storage reservoir for the loading and release of anticancer drug doxorubicin (DOX). The research indicated that the releases of DOX were thermo/pH dependent and high temperatures/acidic conditions were favorable for the fast release of drug. In vitro cytotoxicity tests revealed that the drug delivery carrier displayed excellent biocompatible and the composites loaded with DOX showed significant suppression effect on HeLa cells. Luminescence spectra showed that the composite containing decatungstoeuropate displayed fine red luminescence at various temperatures and pH values, which could be utilized as a potential labeling material in field of medicine.

CRGD mediated redox and pH dual responsive poly(amidoamine) dendrimer-poly(ethylene glycol) conjugates for efficiently intracellular antitumor drug delivery

To improve antitumor efficiency of chemotherapy and reduce side effect, according to the physiological characteristics of tumor tissues and tumor intracellular microenvironment, a multifunctional drug delivery system with properties of long circulation, active targeting, redox and pH triggered drug release was established based on the Generation 4 polyamidoamine dendrimer (PAMAM). First, the redox cleavable disulfide bonds (SS) were introduced for linking polyethylene glycol (PEG) with PAMAM to form PAMAM-S-S-PEG (PSSP). Then cRGD peptide was applied to the PEG end of PSSP to construct RGD-PSSP conjugates. Finally, encapsulating the antitumor chemotherapy drug doxorubicin (DOX) into the hydrophobic cavity of RGD-PSSP conjugates constructed the RGD-PSSP/DOX drug delivery system. The in vitro experiments displayed that RGD-PSSP/DOX NPs showed obviously redox and pH dual sensitive drug release profile. MTT and cell uptake observation elucidated cRGD modification could increase the cytotoxicity, and promote the uptake of B16 cells and HUVEC cells both overexpressing integrin ανβ3on cell membrane. Cell uptake mechanism investigation further revealed that RGD-PSSP/DOX interacted with plasma membrane via specific recognition of cRGD peptide with integrin ανβ3, and was subsequently internalized mainly through clathrin- and caveolin-mediated endocytosis. Remarkably, RGD-PSSP/DOX presented superior anticancer activity and lower heart and kidney toxicity in vivo, which could be regarded as a potential candidate for efficient antitumor chemotherapy drug delivery.

Silver and palladium nanoparticle embedded poly(n-isopropylacrylamide-co-2-acrylamido-2-methylpropane sulfonic acid) hybrid microgel catalyst with pH and temperature dependent catalytic activity

Here in, we demonstrate facile fabrication of silver and palladium nanoparticles in dual responsive poly(N-isopropylacrylamide- co-2-Acrylamido-2-methylpropane sulfonic acid) microgel with temperature- and pH-dependent catalytic potential. Palladium-based catalyst showed better catalytic efficiency as compared to silver-based catalyst for degradation of Rhodamine-B and P-Nitrophenol in aqueous medium under the same set of reaction conditions. The responsive nature of the microgel was found to be useful to tune the catalytic activity of the as-prepared catalysts, and reduction rate was enhanced with the pH and temperature elevation of the reaction medium; however, the increasing trend was slowed in the volume phase transition region of the microgel. Under a specific set of reaction conditions, the reduction of Rhodamine-B was as fast as 0.968 and 0.571 min−1 when catalyzed with palladium and silver based catalysts, respectively. The hydrodynamic radius of the particles of microgel support was found to be in the range of 65-180 nm when pH and temperature of the medium were varied in the range of 2-12 and 25-45, respectively. The estimated diameter of silver and palladium nanoparticles fabricated in the microgel support under the same set of reaction conditions was 9-15 and 7-11 nm, respectively.

One-pot quaternization of dual-responsive poly(vinyl alcohol) with AIEgens for pH-switchable imaging and killing of bacteria

Dual-responsive poly(vinyl alcohol) derivatives bearing AIEgens and quaternary ammonium moieties were prepared through a facile one-pot quaternization for the pH-switchable imaging and killing of bacteria.

PH and thermal dual-responsive poly(NIPAM-co-GMA)-coated magnetic nanoparticles via surface-initiated RAFT polymerization for controlled drug delivery.

Herein, a novel type of multifunctional magnetic nanoparticles with dual thermal and pH-responsive behavior was fabricated as the carrier for delivery of doxorubicin (DOX). Fe3O4@SiO2 magnetic nanoparticles, were grafted with polymer brushes consisting of poly (NIPAM-co-GMA) (PNG) chains via surface initiated reversible addition-fragmentation chain transfer (SI-RAFT) polymerization. The polymer brushes were then modified with hydrazine groups as DOX binding sites. The prepared multifunctional magnetic nanoparticles were characterized by FT-IR, 1H NMR, XPS, TGA, DLS, VSM, GPC, TEM, and XRD analysis. The in vitro drug release of the multifunctional magnetic nanoparticles was examined at 37 °C (above LCST) and 25 °C (below LCST) in different pH media and exhibited excellent pH- and thermo-sensitive behavior. The results show that the Fe3O4@SiO2@PNG-Hy fabricated via SI-RAFT polymerization is a viable candidate material for tumor treatment studies.

Polymer microspheres with high drug-loading capacity via dual-modal drug-loading for modulating controlled release property in pH/reduction dual-responsive tumor-specific intracellular triggered doxorubicin release

pH/Reduction dual-responsive poly(4-formylphenyl acrylate-co-acryloyl-β-cyclodextrin) (P(FPA-co-ACD)) microspheres were synthesized as multi-functional vehicle for tumor-specific intracellular triggered doxorubicin (DOX) release, via emulsion copolymerization of acryloyl-β-cyclodextrin (ACD) and 4-formylphenyl acrylate (FPA), with N,N-bis(acryloyl)cystamine (BACy) as crosslinker. In comparison with the drug delivery system (DDS) via mono-modal drug-loading, the DOX/P(FPA-co-ACD)C via only covalent conjugation, or the DOX/P(FPA-co-ACD)N via only host-guest inclusion, the dual-modal drug-loaded DDS, DOX/P(FPA-co-ACD)C+N, were fabricated with a higher drug-loading capacity (DLC) of >53% via both acid-labile Schiff-base conjugation and host-guest inclusion complexation. Furthermore, the DOX release rate from the DOX/P(FPA-co-ACD)C+N was faster than the DOX/P(FPA-co-ACD)C but slower than the DOX/P(FPA-co-ACD)N in the simulated tumor intracellular microenvironment, demonstrating the controlled release behavior of such DDS could be modulated with dual-modal drug-loading.

Poly(cystine-PCL) based pH/redox dual-responsive nanocarriers for enhanced tumor therapy.

Functional polymeric drug delivery systems have generated enormous interest due to their excellent features. This paper reports the development of a novel pH and redox dual-sensitive polymer for anticancer paclitaxel (PTX) delivery applications. The polymer was prepared by polycondensation of disulfide bond-containing dimethyl l-cystinate (Cys) and polycaprolactone (PCL) oligomer via a pH-responsive imine bond. Using the nanoprecipitation method, the polymer can be formulated as nanoparticles (poly(Cys-PCL)/PTX NPs) with a diameter less than 100 nm, as measured by TEM and DLS. The NPs release PTX significantly faster at mildly acidic pH and high concentrations of GSH, exhibiting almost no burst release under the physiological conditions of plasma. Notably, the NPs efficiently deliver PTX to the tumor cells, which was more cytotoxic to 4T1 cancer cells than the pure PTX alone. In vivo results reveal an excellent tumor inhibiting ability, good drug tolerability and biosafety of poly(Cys-PCL)/PTX NPs. Overall, the poly(Cys-PCL)/PTX NPs platform may have greater potential in enhancing cancer therapy.

Temperature/pH dual-responsive poly (N-isopropylacrylamide)/chitosan-coated luminescent composite nanospheres: Fabrication and controllable luminescence

Thermo/pH dual-responsive luminescent composites consisting of lanthanide-polyoxometalates and Poly (N-isopropylacrylamide)/Chitosan were synthesized. The dual-responsive nanoparticles are characterized by the FT-IR, UV–vis, TEM, SEM, TGA, DLS and luminescence. The prepared composites exhibit the thermo/pH-responsive properties and the controllable and switchable luminescence in solution in response to the simple changes in temperature and pH values. For instance, the composite hydrogels exhibit intense red luminescence under UV irradiation below 34 °C, and the luminescence become much weaker in solution above 34 °C. Moreover, the hydrogel could not show red luminescence in the buffer solution with low pH value. However, it shows bright red luminescence in neutral and alkaline buffer solution. The possible reasons for controllable luminescence are discussed in the research. The results suggest that the multifunctional nanoparticles could be potentially used in biomedical fields such as luminescent switches, biological labeling and imaging.

Temperature and Recognition Dual Responsive Poly(N-Isopropylacrylamide) and Poly(N,N-Dimethylacrylamide) with Adamantyl Side Group.

A series of copolymers with an adamantyl side group (poly(NIPAM-co-AdMA) and poly(DMAM-co-AdMA)) were prepared by radical copolymerization of N-isopropylacrylamide (NIPAM) and N,N-dimethylacrylamide (DMAM) with a 2-methyl-2-adamantylmethacrylate (AdMA) monomer. The structure and composition of the as-synthesized copolymers were characterized by Fourier transform infrared (FT-IR) spectroscopy, proton nuclear magnetic resonance (1H NMR) spectroscopy, gel permeation chromatography (GPC), thermogravimetric analysis (TGA), and elemental analysis. Temperature and recognition dual responsivity of the copolymers was investigated by cloud point (Tcp) and dynamic light scattering (DLS), respectively. The results show that the as-synthesized copolymers are a kind of temperature-responsive polymer with a lower critical solution temperature (LCST). Tcp was approximately consistent with the critical temperature of intermolecular copolymer association (Tass) from DLS. For these copolymers, Tcp decreases with increasing content of AdMA unit in the copolymers. After the addition of β-cyclodextrins (β-CD), Tcp increases, and the increment of Tcp values gradually became large with increasing content of AdMA in the copolymers. It is host-guest molecular recognition of β-CD and adamantyl groups that endows the as-synthesized copolymers with recognition-tunable thermosensitivity.