Synthesis of PAA-g-PNIPAM well-defined graft polymer by sequential RAFT and SET-LRP and its application in preparing size-controlled super-paramagnetic Fe3O4 nanoparticles as a stabilizer

Controllable Regulation of Diesel Oil-in-Water Pickering Emulsion Stability by Multiresponsive Recyclable Magnetic Polymer Brush Microvessels

To ensure safety and efficiency in the production and transportation of fuel oil, there is an urgent demand to develop intelligent emulsifiers to deal with this challenge. Fe3O4@PDA-P(NIPAM-b-MAA-b-LMA) (MNPDNML) microspheres were prepared by modifying polydopamine and the triblock polymer brush P(NIPAM-b-MAA-b-LMA) on the surface of Fe3O4 nanoparticles via oxidative autopolymerization and SI-RAFT polymerization. Therefore, the MNPDNML microspheres exhibited sensitive stimulus-responsive behavior to pH, temperature, near-infrared (NIR) laser radiation, and magnetic fields. The stability state of the emulsion could be modulated by changing pH, temperature, magnetic field, and NIR radiation, and the reversible switching of emulsification/breaking behavior could be reached at least 10 times. This "intelligent emulsifier" exhibited high emulsification efficiency, long-term stability, and on-demand emulsification/breaking properties. It was notable that MNPDNML microspheres showed excellent emulsification ability for olive oil, kerosene, gasoline, and crude oil, which allowed the material to be widely used in the controlled transportation and separation of fuel oil.

Temperature-responsive and biocompatible nanocarriers based on clay nanotubes for controlled anti-cancer drug release

Administration of temperature-responsive drug carriers that release anticancer drugs at high temperatures can benefit hyperthermia therapies because of the synergistic effect of anticancer drug molecules and high temperature on killing the cancer cells. In this study, we design and characterize a new temperature-responsive nanocarrier based on a naturally occurring and biocompatible clay mineral, halloysite nanotubes. Poly(N-isopropylacrylamide) brushes were grown on the surface of halloysite nanotubes using a combination of mussel-inspired dopamine polymerization and surface-initiated atom transfer radical polymerization. The chemical structure of the hybrid materials was investigated using X-ray photoelectron spectroscopy, thermogravimetric analysis and energy-dispersive X-ray spectroscopy. The hybrid material was shown to have a phase transition temperature of about 32 °C, corresponding to a 40 nm thick polymer layer surrounding the nanotubes. Cell studies suggested that grafting of poly(N-isopropylacrylamide) brushes on the polydopamine-modified halloysite nanotubes suppresses the cytotoxicity caused by the polydopamine interlayer and drug release studies on nanotubes loaded with doxorubicin showed that thanks to the poly(N-isopropylacrylamide) brushes a temperature-dependent drug release is observed. Finally, a fluorescent dye molecule was covalently attached to the polymer-grafted nanotubes and stimulated emission depletion nanoscopy was used to confirm the internalization of the nanotubes in HeLa cells.

Cellulose nanocrystals reinforced highly stretchable thermal-sensitive hydrogel with ultra-high drug loading

Hydrogels often have poor mechanical properties which limit their application in load-bearing tissues such as muscle and cartilage. In this work, a near-infrared light-triggered stretchable thermal-sensitive hydrogel with ultra-high drug loading was developed by a combination of natural polymeric nanocrystals, a network of synthetic thermo-responsive polymer, and magnetic Fe₃O₄ nanoparticles. The hydrogels comprise cellulose nanocrystals (CNCs) decorated with Fe₃O₄ nanoparticles (Fe₃O₄/CNCs) dispersed homogeneously in poly(N-isopropylacrylamide) (PNIPAm) networks. The composite hydrogels exhibit an extensibility of 2200%. Drug loading of vancomycin (VCM) reached a high value of 10.18 g g^-1 due to the dispersion of Fe₃O₄/CNCs and the interactions between the CNCs and the PNIPAm network. Importantly, the hydrogels demonstrated a thermo-response triggered by NIR, with the temperature increasing from 26 to 41 °C within 60 s. The hydrogels have high biocompatibility evidenced by cell proliferation tests, illustrating that these hydrogels are promising as dressings for wound closure, and wound healing.

Temperature-Responsive Magnetic Nanoparticles for Enabling Affinity Separation of Extracellular Vesicles

Small magnetic nanoparticles that have surfaces decorated with stimuli-responsive polymers can be reversibly aggregated via a stimulus, such as temperature, to enable efficient and rapid biomarker separation. To fully realize the potential of these particles, the synthesis needs to be highly reproducible and scalable to large quantity. We have developed a new synthesis for temperature-responsive magnetic nanoparticles via an in situ co-precipitation process of Fe2+/Fe3+ salts at room temperature with poly(acrylic acid)- block-poly( N-isopropylacrylamide) diblock co-polymer template, synthesized via the reversible addition-fragmentation chain-transfer polymerization method. These particles were 56% polymer by weight with a 6.5:1 Fe/COOH ratio and demonstrated remarkable stability over a 2 month period. The hydrodynamic diameter remained constant at ∼28 nm with a consistent transition temperature of 34 °C, and the magnetic particle separation efficiency at 40 °C was ≥95% over the 2 month span. These properties were maintained for all large-scale synthesis batches. To demonstrate the practical utility of the stimuli-responsive magnetic nanoparticles, the particles were incorporated into a temperature-responsive binary reagent system and efficiently separated a model protein biomarker (mouse IgG) as well as purified extracellular vesicles derived from a human biofluid, seminal plasma. The ease of using these particles will prove beneficial for various biomedical applications.

Novel Magnet and Thermoresponsive Chemosensory Electrospinning Fluorescent Nanofibers and Their Sensing Capability for Metal Ions

Novel multifunctional switchable chemosensors based on fluorescent electrospun (ES) nanofibers with sensitivity toward magnetism, temperature, and mercury ions (Hg²⁺) were prepared using blends of poly(N-isopropylacrylamide)-co-(N-methylolacrylamide)-co-(Acrylic acid), the fluorescent probe 1-benzoyl-3-[2-(2-allyl-1,3-dioxo-2,3-dihydro-1Hbenzo[de]isoquinolin-6-ylamino)-ethyl]-thiourea (BNPTU), and magnetite nanoparticles (NPs), and a single-capillary spinneret. The moieties of N-isopropylacrylamide, N-methylolacrylamide, acrylic acid, BNPTU, and Iron oxide (Fe₃O₄) NPs were designed to provide thermoresponsiveness, chemical cross-linking, Fe₃O₄ NPs dispersion, Hg²⁺ sensing, and magnetism, respectively. The prepared nanofibers exhibited ultrasensitivity to Hg²⁺ (as low as 10⁻³ M) because of an 80-nm blueshift of the emission maximum (from green to blue) and 1.6-fold enhancement of the emission intensity, as well as substantial volume (or hydrophilic to hydrophobic) changes between 30 and 60 °C, attributed to the low critical solution temperature of the thermoresponsive N-isopropylacrylamide moiety. Such temperature-dependent variations in the presence of Hg²⁺ engendered distinct on–off switching of photoluminescence. The magnetic ES nanofibers can be collected using a magnet rather than being extracted through alternative methods. The results indicate that the prepared multifunctional fluorescent ES nanofibrous membranes can be used as naked eye sensors and have the potential for application in multifunctional environmental sensing devices for detecting metal ions, temperature, and magnetism as well as for water purification sensing filters.

Reversible Regulation of Thermoresponsive Property of Dithiomaleimide-Containing Copolymers via Sequential Thiol Exchange Reactions

The facile and efficient functionalization of thermoresponsive polymers based on sequential, reversible thiol-exchange reactions is reported. Well-defined dithiomaleimide-containing polymers have been synthesized via Cu(0)-mediated SET-LRP and characterized by ¹H NMR and size exclusion chromatography (SEC). The resulting thermosensitive copolymers were subsequently reacted with various thiols to demonstrate the applicability of the strategy, and the thiol-exchange reaction was found to be very fast and efficient. The cloud point of the prepared copolymers can be continually and reversibly tuned, and desirable functionality can be dynamically exchanged upon sequential addition of functional thiol reagents. Through the substitution by thioglucose, an ON-to-OFF switch for fluorescence of the copolymers along with the generation of a glycopolymer was achieved.

PHEA-g-PDMAEA well-defined graft copolymers: SET-LRP synthesis, self-catalyzed hydrolysis, and quaternization

This article reports the synthesis of well-defined graft copolymers containing a PHEA backbone and degradable PDMAEA side chains, by the combination of RAFT polymerization, SET-LRP, and the grafting-from strategy.

Synthesis of amphiphilic nanoparticles and multi-block hydrophilic copolymers by a facile and effective “living” radical polymerization in water

A convenient and robust approach using MANDC-COOH as the initiator and oxidatively stable Cu(OAc)₂as the catalyst to synthesize amphiphilic nanoparticles and hydrophilic multi-block copolymers was successfully developed in water.

Constructing nanosized CdTe nanocrystal clusters with thermo-responsive photoluminescence characteristics

Photoluminescence clusters of CdTe nanocrystals self-assembled by PNAEAM-b-PNIPAM copolymers represent sensitive and reversible thermo-responsive properties in aqueous solutions.

Synthesis and self-assembly of PMBTFVB-g-PNIPAM fluorine-containing amphiphilic graft copolymer

This article reports the synthesis of an amphiphilic graft copolymer containing a perfluorocyclobutyl (PFCB) aryl ether-based backbone and poly(N-isopropylacrylamide) side chains by a combination of thermal step-growth cycloaddition polymerization and atom transfer radical polymerization (ATRP).

A novel methacrylate with a bisphosphonate group: RAFT polymerization and flame retardant property of the resultant polymers

In this work, a novel methacrylate monomer with a bisphosphonate group was synthesized and then polymerized by RAFT polymerization to obtain well-defined polymers with better thermal and flame-retardant properties.