Thermosensitive Nanocomposites Research Articles

Injectable Thermosensitive Nanocomposites Based on Poly(N-vinylcaprolactam) and Silica Particles for Localized Release of Hydrophilic and Hydrophobic Drugs.

The systemic delivery of drugs employed by conventional methods has shown to be less effective than a localized delivery system. Many drugs have the effectiveness reduced by fast clearance, increasing the amount required for an efficient treatment. One way to overcome this drawback is through the use of thermoresponsive polymers that undergo a sol-gel transition at physiological temperature, allowing their injection directly in the desired site. In this work, thermosensitive nanocomposites based on poly(N-vinylcaprolactam) and silica particles with 80 and 330 nm were synthesized to be employed as delivery systems for hydrophobic (naringin) and hydrophilic (doxorubicin hydrochloride) drugs. The insertion of SiO2 increased the rheological properties of the nanocomposite at 37 °C, which helps to prevent its diffusion away from the site of injection. The synthesized materials were also able to control the drug release for a period of 7 days under physiological conditions. Due to its higher hydrophobicity and better interaction with the PNVCL matrix, naringin presented a more controlled release. The Korsmeyer-Peppas model indicated different release mechanisms for each drug. At last, a preliminary in vitro study of DOX-loaded nanocomposites cultured with L929 and MB49 cells showed negligible toxic effects on healthy cells and better efficient inhibition of carcinoma cells.

Probing the Structural Dynamics of the Coil-Globule Transition of Thermosensitive Nanocomposite Hydrogels.

Nanocomposite hydrogels have emerged to exhibit multipurpose properties, boosting especially the biomaterial field. However, the development and characterization of these materials can be a challenge, especially stimuli-sensitive materials with dynamic properties in response to external stimuli. By employing UV-vis spectroscopy and NMR relaxation techniques, we could outline the formation and behavior of thermosensitive nanocomposites obtained by in situ polymerization of poly(N-vinylcaprolactam) (PNVCL) and mesoporous silica nanofibers under temperature stimuli. For instance, inorganic nanoparticles covalently linked to PNVCL changed the pattern of temperature-induced phase transition despite showing similar critical temperatures to neat PNVCL. Thermodynamic parameters indicated the formation of an interconnected system of silica and polymer chains with reduced enthalpic contribution and mobility. The investigation of water molecule and polymer segment motions also revealed that the absorption and release of water happened in a wider temperature range for the nanocomposites, and the polymer segments respond in different ways during the phase transition in the presence of silica. This set of techniques was essential to reveal the polymer motions and structural features in nanocomposite hydrogels under temperature stimuli, demonstrating its potential use as experimental guideline to study multicomponent nanocomposites with diverse functionalities and dynamic properties.

Promoting the neural differentiation of embryonic stem cells by using thermosensitive nanocomposites

Temperature-sensitive heparin mimic copolymer modified gold nanoparticles (AuNPs–pNMS) can efficiently promote the neural differentiation of embryonic stem cells.

Thermosensitive hydrogel nanocomposites with magnetic laponite nanoparticles

The thermosensitive nanocomposites based on poly (N-isopropylacrylamide) crosslinked by magnetically modified laponite have been synthesized. Using differential scanning calorimetry it was shown that all synthesized hydrogels exhibit a phase transition between the swollen and collapsed states around 32 °C and this temperature depends on the polymer cross-linking method. For hydrogels physically crosslinked by laponite, the phase transition temperature shifts toward higher temperatures compared to the chemically crosslinked hydrogels. The structure of magnetic laponite and composite hydrogels has been characterized by scanning electron microscopy and infrared spectroscopy. The combination of magnetic properties and ability to control the phase transition temperature by changing hydrogel structure suggests that the synthesized hydrogels can be potentially used as a magnetic-driven platform for targeted delivery and drug release or as actuators and elements of microfluidic devices. Thermal destruction of the physically crosslinked hydrogel with incorporated magnetic laponite is observed in the region of 300–400 °C which allows classifying them as relatively heat-resistant materials and can extend existing and open up new application areas for the developed thermosensitive nanocomposites.

Термочутливі та рН-чутливі гідрогелеві нанокомпозити з магнітним лапонітом

Термочутливі та рН-чутливі гідрогелеві нанокомпозити з магнітним лапонітом

An ultra-small thermosensitive nanocomposite with a Mo154-core as a comprehensive platform for NIR-triggered photothermal-chemotherapy.

A uniform ultra-small (<10 nm) nanosized dendritic composite was reported for combined photothermal-chemotherapy, wherein a giant ring-like polymolybdate cluster was introduced for the first time as a photothermal therapeutic agent. The giant polyoxometalate cluster possesses strong absorption characteristics in the near infrared region, whereas it has never been applied for biomaterials due to its sensitivity towards environment and structural instability under physiological conditions. Herein, a cationic dendron bearing triethylene glycol monomethyl ether terminal groups was used to cover a giant polyanionic cluster Mo154 surface through a simple electrostatic interaction. Arising from their assembly, the formed core-shell supramolecular composite that has uniform size, precise chemical composition and definite molecular weight not only exhibited mono-dispersion and low cytotoxicity, but also imparted anticancer drug loading and thermoresponsive properties, thus leading to NIR-controlled drug release. When irradiated with an 808 nm NIR laser, the formed complex had significant in vivo photothermal-chemotherapeutic effects on tumor tissue, which makes it a promising material for applications in nanomedicine.

Swelling behavior of thermosensitive nanocomposite hydrogels composed of oligo(ethylene glycol) methacrylates and clay

Novel thermosensitive nanocomposite (NC) hydrogels have been synthesized by copolymerization of 2-(2-methoxyethoxy) ethyl methacrylate (MEO2MA), oligo(ethylene glycol) methacrylate (OEGMA), and using inorganic clay as cross-linker via in-situ free radical polymerization. The structure and morphology of clay/P(MEO2MA-co-OEGMA) NC hydrogels were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM), and the results indicated that the inorganic clay was uniformly dispersed in the NC hydrogels and obviously affected the network structure. Furthermore, physical properties such as equilibrium swelling/deswelling ratio, water retention, reversible thermosensitivity, and temperature dependence behaviors of NC hydrogels with different chemical compositions (molar ratio of comonomer, clay, and mass fraction of polymer) were investigated carefully. Moreover, the deswelling kinetics at specific temperature was studied, and the deswelling rates were well described with a first-order kinetics equation. The results indicated that the obtained NC hydrogels showed a controllable equilibrium swelling/deswelling behavior and possessed remarkable thermosensitivity. In addition, when the molar ratio of MEO2MA and OEGMA was 80mol%: 20mol%, the equilibrium swelling ratio of NC hydrogels with 5wt% clay reached 1640%, which is four times higher than that of N,N′-methylenebisacrylamide cross-linked hydrogels (410%). Consequently, this novel clay/P(MEO2MA-co-OEGMA) NC hydrogel with interesting thermosensitive properties would be promising for potential applications, such as stimuli-responsive valve, drug delivery system, artificial muscle, and biosensor.

A novel nanocomposite hydrogel with precisely tunable UCST and LCST.

Novel thermosensitive nanocomposite (NC) hydrogels consisting of organic/inorganic networks are prepared via in situ free radical polymerization of 2-(2-methoxyethoxy) ethyl methacrylate (MEO2 MA) and oligo(ethylene glycol) methacrylate (OEGMA) in the presence of inorganic cross-linker clay in aqueous solution. The obtained clay/P(MEO2 MA-co-OEGMA) hydrogels exhibit double volume phase transition temperatures, an upper critical solution temperature (UCST), and a lower critical solution temperature (LCST), which can be controlled between 5 and 85 °C by varying the fraction of OEGMA units and the weight percentage of cross-linker clay. These new types of NC hydrogels with excellent reversible thermosensitivity are promising for temperature-sensitive applications such as smart optical switches.

Aerosol-Processed Thermosensitive Nanocomposites for Controlled Drug Release.

In this study, an ambient-spark-produced iron (Fe)-nanoparticle-laden nitrogen gas was mixed with an atomized solution of N-isopropylacrylamide (NIPAM)-polydimethylsiloxane (PDMS). The Fe nanoparticles reacted with NIPAM-PDMS in the atomized droplets to form encapsulated Fe nanoparticles, i.e., Fe@NIPAM-PDMS nanocomposites, whose size distribution was unimodal (showing only a NIPAM-PDMS-like distribution, with the Fe distribution eliminated). By varying processing temperatures, it was possible to obtain Fe@NIPAM-PDMS nanocomposites with different sizes and morphologies. This is further attributed to the quantitative incorporation of Fe nanoparticles into atomized NIPAM-PDMS-doxorubicin (DOX) droplets. The Fe@NIPAM-PDMS-DOX nanocomposites released different amounts of DOX under a magnetothermal effect, which produced different levels of cytotoxic effects on the targeted HeLa cells. The thermosensitivity makes these nanocomposites an ideal candidate for important applications such as controlled drug delivery.

Study on partition and release of molecules in superabsorbent thermosensitive nanocomposites

Nanocomposites are synthesized by in-situ polymerization of conducting polymers: polyaniline (PANI) or poly(N-methylaniline) (PNMANI) inside thermosensitive hydrogels based on poly(N-isopropylacrylamide) (PNIPAM) homopolymer and copolymers with 2-acrylamido-2-methyl propane sulfonic acid (AMPS). Large swelling capacities (up to 25,000%) are measured for a nanocomposite based on a hydrogel containing only 2% of anionic monomer units. Dynamic swelling experiences show that water intake follows a non-Fickian mechanism. Drug release kinetics and partition coefficients ( K) of model compounds (Methyl Orange, Ruthenium-tris(2,2′-bipyridyl) ion, Dansyl Chloride) and pharmaceuticals (Tryptophan, Propranolol Chloride, Riboflavin) were measured. Log K values were determined by UV–visible or fluorescence spectroscopy, below and above the phase transition temperature of the materials. Large values of log K (>3) were measured for tryptophan while the same material shows small log K (1.5) for riboflavin. Depending on the nanocomposite/solute interactions, the partition increases or decreases upon phase transition. Several nanocomposites studied show potential for application in the separation of solutes or water purification. Additionally, it is possible to synthesize nanocomposites which show different partition coefficients for the same molecule. In that way, a specific pattern could be measured for each molecule allowing its identification.

Thermo-Sensitive Poly(&lt;I&gt;N&lt;/I&gt;-Isopropylacrylamide)/Mesoporous Silica Nanocomposites as Controlled Delivery Carriers: Loading and Release Behaviors for Drug Ibuprofen

Thermo-sensitive nanocomposites based on mesoporous silica SBA-15 and poly(N-isopropylacrylamide) (PNIPAAm) have been synthesized via in situ radical polymerization in mesopores. The resultant materials were used as carriers to construct temperature-responsive controlled drug delivery systems. Loading of model drug ibuprofen (IBU) was ascertained by IR and UV-vis/DRS spectroscopy, and the mesostructure and pore properties of the delivery system were characterized by small-angle XRD and N2 adsorption-desorption experiment. Study on drug uptake indicated that higher polymer content in the composite, higher IBU concentration in loading solution and lower loading temperature below the lower critical solution temperature (LCST) could increase the loading amount of IBU by means of interaction between IBU and polymer and trap effect of the polymer chains in pores. Different from the uptake of IBU, however, the release of drug followed a positive temperature-responsive manner, that is, the release was accelerated upon heating above the LCST, while decelerated and lasted for a longer period of time below the LCST. This feature allows the material to function as a reversible fast/slow transition switch or rate regulator responsive to environmental temperature and to be potentially interesting in controlled delivery and other smart application fields.

Temperature-Responsive Nanocomposites Based on Mesoporous SBA-15 Silica and PNIPAAm: Synthesis and Characterization

Thermosensitive nanocomposites based on mesoporous SBA-15 silica and poly(N-isopropylacrylamide) (PNIPAAm) have been synthesized via in situ polymerization of monomers deposited on the pore walls. ...

Triple-Shape Capability of Thermo-sensitive Nanocomposites from Multiphase Polymer Networks and Magnetic Nanoparticles

AbstractThermo-sensitive multiphase polymer networks with triple-shape capability have been recently introduced as a new class of active polymers that can change on demand from a first shape A to a second shape B and from there to a permanent shape C. Such multiphase polymer networks consist of covalent cross-links that determine shape C and at least two phase-segregated domains with distinct thermal transitions Ttrans,A and Ttrans,B , that are associated to shape A and B. In general the application of a two step programming or a one step programming procedure is required for creation of triple-shape functionality. In this study we report about a series of CLEGC nanocomposites consisting of silica coated nanoparticles (SNP) incorporated in a multiphase graft polymer network matrix from crystallisable poly(ε-caprolactone) diisocyanatoethyl methacrylate (PCLDIMA) and poly(ethylene glycol) monomethyl ether monomethacrylate (PEGMA) forming crystallisable side chains. These CLEGC nanocomposites were designed to enabling non contact activation of triple-shape effect in alternating magnetic field. Composites with variable PCLDIMA content ranging from 30 wt-% and 70 wt-% and different SNP amounts (0 wt-%, 2.5 wt-%, 5 wt-% and 10 wt-%) were realized by thermally induced polymerization. The thermal and mechanical properties of the CLEG nanocomposites were explored by means of DSC, DMTA and tensile tests. The triple-shape properties were quantified in cyclic, thermomechanical experiments, which consisted of a two step programming procedure and a recovery module under stress-free conditions for recovery of shapes B and C. While the thermal properties and the Young’s modulus of the investigated polymer networks were found to be independent from the incorporated amount of SNP, the elongation at break (εB) decreases with increasing nanoparticle content. All investigated composites exhibit excellent triple-shape properties showing a well separated two step shape recovery process.

Thermosensitive Nanostructures Comprising Gold Nanoparticles Grafted with Block Copolymers

AbstractBinary thermosensitive nanocomposites are fabricated by grafting block copolymers of poly(N‐isopropylacrylamide) and poly(methoxy‐oligo(ethylene glycol) methacrylate) onto gold nanoparticles through consecutive, surface‐initiated, atom‐transfer radical polymerization (ATRP). These Au@copolymer nanocomposites display a well‐defined core/shell nanostructure and have two thermosensitive points near 33 and 55 °C in an aqueous suspension corresponding to the thermally induced conformational transition of inner homopolymer segments and outer oligo(ethylene glycol)‐containing copolymer layer, respectively. Silver nanoparticles trapped within Au@copolymer nanocomposites with weakly crosslinked shells display thermally modulated catalytic activity as heterogeneous catalysts because of the thermosensitive collapse of the polymer layers.

Structure and property of Cu-based thermosensitive nanocomposite

The Cu-based thermosensitive nanocomposites are made by high energy ball milling. The microstructures and properties of Cu-based thermosensitive nanocomposites are studied by transmission electron microscopy(TEM) and themosensitivity test. The effects of milling time on the microstructures and the thermosensitivity of Cu-based nanocomposite material are researched. The results show that the Cu-based nanocomposite can be made by high energy ball milling. As the milling time increases, the copper particle size decreases in the nanocomposite, then the thermoexpansivity of nanocomposite increases. The nanocomposite is of best thermoexpansivity when the milling time is up to 100 h. At 35–45 °C, the nanocomposite shows good thermosensitivity.