Thermoresponsive Nanocomposites Research Articles

A thermoresponsive nanocomposite integrates NIR-II-absorbing small molecule with lonidamine for pyroptosis-promoted synergistic immunotherapy

Photothermal immunotherapy is regarded as the ideal cancer therapeutic modality to against malignant solid tumors; however, its therapeutic benefits are often modest and require improvement. In this study, a thermoresponsive nanoparticle (BTN@LND) composed of a photothermal agent (PTA) and pyroptosis inducer (lonidamine) were developed to enhance immunotherapy applications. Specifically, our “two-step” donor engineering strategy produced the strong NIR-II-absorbing organic small-molecule PTA (BTN) that exhibited high NIR-II photothermal performance (ε1064 = 1.51 × 104 M−1 cm−1, η = 75.8%), and this facilitates the diagnosis and treatment of deep tumor tissue. Moreover, the fabricated thermally responsive lipid nanoplatform based on BTN efficiently delivered lonidamine to the tumor site and achieved spatiotemporal release triggered by the NIR-II photothermal effect. In vitro and in vivo experiments demonstrated that the NIR-II photothermal therapy (PTT)-mediated on-demand release of cargo effectively faciliated tumor cell pyroptosis, thereby intensifying the immunogenic cell death (ICD) process to promote antitumor immunotherapy. As a result, this intelligent component bearing photothermal and chemotherapy can maximally suppress the growth of tumors, thus providing a promising approach for pyroptosis/NIR-II PTT synergistic therapy against tumors.Graphical

A novel responsive stabilizing Janus nanosilica as a nanoplugging agent in water-based drilling fluids for exploiting hostile shale environments

Thermo-responsive nanocomposites have recently emerged as potential nanoplugging agents for shale stabilization in high-temperature water-based drilling fluids (WBDFs). However, their inhibitory properties have not been very effective in high-temperature drilling operations. Thermo-responsive Janus nanocomposites are expected to strongly interact with clay particles from the inward hemisphere of nanomaterials, which drive the establishment of a tighter hydrophobic membrane over the shale surface at the outward hemisphere under geothermal conditions for shale stabilization. This work combines the synergistic benefits of thermo-responsive and zwitterionic nanomaterials to synchronously enhance the chemical inhibitions and plugging performances in shale under harsh conditions. A novel thermo-responsive Janus nanosilica (TRJS) exhibiting zwitterionic character was synthesized, characterized, and assessed as shale stabilizer for WBDFs at high temperatures. Compared to pristine nanosilica (SiNP) and symmetrical thermo-responsive nanosilica (TRS), TRJS exhibited anti-polyelectrolyte behaviour, in which electrolyte ions screened the electrostatic attraction between the charged particles, potentially stabilizing nanomaterial in hostile shaly environments (i.e., up to saturated brine or API brine). Macroscopically, TRJS exhibited higher chemical inhibition than SiNP and TRS in brine, prompting a better capability to control pressure penetration. TRJS adsorbed onto the clay surface via chemisorption and hydrogen bonding, and the interactions became substantial in brine, according to the results of electrophoretic mobility, surface wettability, and X-ray diffraction. Thus, contributing to the firm trapping of TRJS into the nanopore structure of the shale, triggering the formation of a tight hydrophobic membrane over the shale surface from the outward hemisphere. The addition of TRJS into WBDF had no deleterious effect on fluid properties after hot-treatment at 190 °C, implying that TRJS could find potential use as a shale stabilizer in WBDFs in hostile environments.

Hafnium-doped nano-magnetite/poly(N-vinylcaprolactam) composites for doxorubicin release

In this work, thermo-responsive nanocomposites based on hafnium-dope magnetite (Hf0.6Fe2.4O4) nanoparticles and poly(vinylcaprolactam) (PNVCL) were prepared for the targeted delivery of doxorubicin (DOX). First, the hafnium-doped magnetite nanoparticles were synthesized by the inverse chemical co-precipitation method and then functionalized with vinyltrimethoxysilane (VTMS) to endow with vinyl groups which are susceptible to free radical polymerization. Then the “grafting from” approach was used to graft PNVCL onto VTMS-functionalized Hf0.6Fe2.4O4. These nanocomposites were characterized by X-ray diffraction (XRD), Fourier-transformed infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), vibrating sample magnetometry (VSM), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). DOX molecules were loaded onto the nanocomposites and the DOX release studies were carried out at different temperature (25 and 37 °C) in phosphate buffer solution 5.8. The XRD and XPS results demonstrated the incorporation of hafnium into the structure of magnetite. TEM images showed semi-spherical Hf0.6Fe2.4O4 nanoparticles surrounded by a layer of PNVCL while the XPS studies demonstrated the covalent interaction between the nanoparticles and the polymer. Finally, the PNVCL-modified Hf0.6Fe2.4O4 nanoparticles showed a sustained release of this drug during the first 24 h at 37 °C reaching up to 70% of cumulative drug release which make them suitable as drug delivery systems.

Thermo‐Responsive Nanocomposite Bioink with Growth‐Factor Holding and its Application to Bone Regeneration (Small 9/2023)

Thermo-Responsive Nanocomposite Bioinks Poly(organophosphazene)-based thermo-responsive nanocomposite bioink, with tunable mechanical property under a moderate temperature range, exhibits good 3D printing outcomes without additional chemical crosslinking process. The bioink encapsulates growth factors through physical interaction, exhibiting biological activities and therapeutic potential for bone defect repair. More details can be found in article number 2203464 by Soo-Chang Song and co-workers.

Thermo-Responsive Nanocomposite Bioink with Growth-Factor Holding and its Application to Bone Regeneration.

Three-dimensional (3D) bioprinting, which is being increasingly used in tissue engineering, requires bioinks with tunable mechanical properties, biological activities, and mechanical strength for in vivo implantation. Herein, a growth-factor-holding poly(organophosphazene)-based thermo-responsive nanocomposite (TNC) bioink system is developed. The mechanical properties of the TNC bioink are easily controlled within a moderate temperature range (5-37°C). During printing, the mechanical properties of the TNC bioink, which determine the 3D printing resolution, can be tuned by varying the temperature (15-30°C). After printing, TNC bioink scaffolds exhibit maximum stiffness at 37°C. Additionally, because of its shear-thinning and self-healing properties, TNC bioinks can be extruded smoothly, demonstrating good printing outcomes. TNC bioink loaded with bone morphogenetic protein-2(BMP-2) and transforming growth factor-beta1 (TGF-β1), key growth factors for osteogenesis, is used to print a scaffold that can stimulate biological activity. A biological scaffold printed using TNC bioink loaded with both growth factors and implanted on a rat calvarial defect model reveals significantly improved bone regenerative effects. The TNC bioink system is a promising next-generation bioink platform because its mechanical properties can be tuned easily for high-resolution 3D bioprinting with long-term stability and its growth-factor holding capability has strong clinical applicability.

In Situ Monitoring of Intracellular ATP Variation Based on a Thermoregulated Polymer Nanocomposite.

It is necessary to develop reliable chemiluminescence strategies for determination of intracellular adenosine triphosphate (ATP), which is vital in life science and clinical diagnosis. However, the current chemiluminescence methods based on firefly luciferase suffered from low delivery efficiency, unsatisfied targeting performance, and autohydrolysis in living biosystem. To circumvent these drawbacks, a thermoresponsive polymer nanocomposite modified with firefly luciferase and ATP aptamer (PFLNC@aptamer) was fabricated, which targeted ATP and determined the intracellular ATP levels via measuring the chemiluminescence signals at different temperatures. The PFLNC@aptamer exhibited capability for the enzymolysis efficiency regulation, increased 21.0% with temperature change from 37.0 to 25.0 °C. The ATP detection limit was 3.3 nM with a linear relationship from 10.0 nM to 0.1 mM. Moreover, the thermoresponsive nanocomposite could also effectively avoid the interference during delivering firefly luciferase into the living cells and effectively discriminate ATP via the immobilized ATP aptamer, which further confirmed its reliability for practical applications. It paves a specific avenue for effective intracellular ATP monitoring in fundamental and applied research.

Synthesis of green thermo-responsive amphoteric terpolymer functionalized silica nanocomposite derived from waste vegetable oil triglycerides for enhanced oil recovery (EOR)

Despite the high efficiency of polymer flooding as a chemical enhanced oil recovery (CEOR) technique, the low thermal stability and poor salt resistance of widely applied partially hydrolyzed polyacrylamide (HPAM) limited the application of this technique in oil reservoirs at harsh reservoir conditions of high–temperature and high–salinity (HTHS). These inadequacies of HPAM, result in the urge for an environmentally friendly polymer with good viscosifying properties and a substantial effect on mobility ratio at HTHS reservoir conditions. In this research, a high oleic acid waste vegetable oil (WVO) is utilized to synthesize a novel environmentally benign, thermo-responsive amphoteric nanocomposite for EOR applications at HTHS reservoir conditions. A green route transesterification reaction has been utilized to synthesize a novel thermo-sensitive monomer from WVO. The existence of unsaturated fatty acids isolated double bonds and acryloyl functional groups in the synthesized monomer has been confirmed using different characterization methods. The reactive acryloyl double bond in the synthesized monomer has been copolymerized with acrylamide, acrylacyloxyethyltrimethyl ammonium chloride, and 2-acrylamide-2-methylpropane sulfonic acid in presence of dimethylphenylvinylsilane via free radical emulsion polymerization. The synthesized nanocomposite has been characterized by FTIR, 1H NMR, SEM, EDX, TEM, and DLS. The thermal stability of the nanocomposite has been evaluated by TGA and DTA analysis. The results indicated that nanocomposite solution exhibited a pouncing thermo-thickening behaviour and superior viscosifying properties even at an ultra-low polymer concentration of 0.04 wt% as the temperature increased from 25 to 100 °C, with increasing salinity from 10,000 to 230,000 ppm as well as salt-free solutions. Flooding experiments demonstrated that the oil recovery factor reached 15.4 ± 0.1 % using low nanocomposite concentrations of 0.04 wt%, 22.6 ± 0.3 % using nanocomposite concentrations of 0.06 wt% and 25 ± 0.2 % using 0.1 wt% nanocomposite concentrations evaluated under hostile conditions of 100 °C and salinity of about 230,000 ppm. This research offers a new direction for the synthesis of a novel green, high molecular weight thermoresponsive nanocomposite for EOR application at extremely harsh reservoir conditions via WVO valorization.

Novel Photo- and Thermo-Responsive Nanocomposite Hydrogels Based on Functionalized rGO and Modified SIS/Chitosan Polymers for Localized Treatment of Malignant Cutaneous Melanoma.

Melanoma is an aggressive type of skin cancer that accounts for over 75% of skin cancer deaths despite comprising less than 5% of all skin cancers. Despite promising improvements in surgical approaches for melanoma resection, the survival of undetectable microtumor residues has remained a concern. As a result, hyperthermia- and drug-based therapies have grown as attractive techniques to target and treat cancer. In this work, we aim to develop a stimuli-responsive hydrogel based on chitosan methacrylate (ChiMA), porcine small intestine submucosa methacrylate (SISMA), and doxorubicin-functionalized reduced graphene oxide (rGO-DOX) that eliminates microtumor residues from surgically resected melanoma through the coupled effect of NIR light-induced photothermal therapy and heat-induced doxorubicin release. Furthermore, we developed an in silico model to optimize heat and mass transport and evaluate the proposed chemo/photothermal therapy in vitro over melanoma cell cultures.

Precision Control of Programmable Actuation of Thermoresponsive Nanocomposite Hydrogels with Multilateral Engineering.

Hydrogels capable of stimuli-responsive deformation are widely explored as intelligent actuators for diverse applications. It is still a significant challenge, however, to “program” these hydrogels to undergo highly specific and extensive shape changes with precision, because the mechanical properties and deformation mechanism of the hydrogels are inherently coupled. Herein, two engineering strategies are simultaneously employed to develop thermoresponsive poly(N-isopropyl acrylamide) (PNIPAm)-based hydrogels capable of programmable actuation. First, PNIPAm is copolymerized with poly(ethylene glycol) diacrylate (PEGDA) with varying molecular weights and concentrations. In addition, graphene oxide (GO) or reduced graphene oxide (rGO) is incorporated to generate nanocomposite hydrogels. These strategies combine to allow the refined control of mechanical and diffusional properties of hydrogels over a broad range, which also directly influences variable thermoresponsive actuation. It is expected that this comprehensive design principle can be applied to a wide range of hydrogels for programmable actuation.

Development and bioevaluation of controlled release 5-aminoisoquinoline nanocomposite: a synergistic anticancer activity against human colon cancer

<abstract> <p>The current study presents a bimodal therapeutic platform for cancer treatment. Bimodal implies that the presented drug loaded core-shell structure is capable of elevating the tumor tissue temperature (hyperthermia) through the superparamagnetic iron oxide core and simultaneously release a Poly (ADP-ribose) polymerase-1(PARP-1)-modifying agent from the thermoresponsive shell. Magnetic thermoresponsive nanocomposite MTN was synthesized via an in situ free radical polymerization of thermo-responsive (N-isopropylacrylamide) (NIPAAm) monomer in the presence of 11-nm monodisperse SPIONs. The composite was allowed to swell in various concentrations of the PARP inhibitor: 5-aminoisoquinoline (5-AIQ) forming drug-loaded magnetic thermoresponsive nanocomposite (MTN-5.AIQ). Structural characterization of the formed composite is studied via various experimental tools. To assess the coil to globule transition temperature, the lower critical solution temperature (LCST) is determined by differential scanning calorimetry (DSC) method and the cloud point (Tp) is determined by turbidometry. Magnetic thermoresponsive nanocomposite (MTN) is formed with excellent potential for hyperthermia. A high drug loading efficiency (85.72%) is obtained with convenient temperature dependent drug release kinetics. Biocompatibility and cytotoxic efficacy are tested on an in vivo and in vitro colorectal-adenocarcinoma model, respectively. MTN.5-AIQ administration exhibits normal hepatic and renal functions as well as lower toxic effect on normal tissue. In addition, the composite effectively inhibits Caco-2 cells viability upon incubation. Based on the obtained results, the proposed therapeutic platform can be considered as a novel, promising candidate for dual therapy of colorectal adenocarcinoma exhibiting a PARP-1 overexpression. as well as increased the inhabiting efficacy of 5-AIQ.</p> </abstract>

Improved Treatment on Ocular Inflammation with Rationally Designed Thermoresponsive Nanocomposite Formulation

AbstractCataract is the principal cause of preventable blindness in older people globally. Intraocular surgeries stimulate multiple postoperative inflammatory responses. The current clinical treatment by dropping prednisolone acetate (PA) and levofloxacin (LF) suffers from drawbacks, such as low bioavailability and poor patient compliance. This study aims to develop a rationally designed thermoresponsive formulation combining PA and LF using nancomposites of mesoporous silica nanoparticle (MSN) and thermo‐nanogel (thermogel) (PA@MSN‐LF@Thermogel). The in vitro release profiles of PA and LF from PA@MSN‐LF@Thermogel are tailor‐made to adapt to wound healing by a sustained release of 28 days. PA@MSN‐LF@Thermogel exhibits little cytotoxicity to human Tenon's fibroblasts and human corneal epithelial cells, while presents excellent in vitro antibacterial effectiveness to Staphylococcus bacteria. After implanted into the rabbit eye by a subconjunctival injection, PA@MSN‐LF@Thermogel displays overwhelming anti‐inflammatory and antibacterial effectiveness up to 21 days using only one‐eighth of the total dose, compared with PA and LF eye drops. The formulation does not cause any ocular hypertension and noticeable histopathological abnormality which indicate good biosafety. This thermoresponsive nanocomposite formulation is thus a promising drug delivery alternative for treatment of postoperative inflammation after intraocular surgeries.

Development of Silver Nanoparticles/Gelatin Thermoresponsive Nanocomposites: Characterization and Antimicrobial Activity.

Skin and soft tissue infections involve microbial invasion of the skin and underlying soft tissues. To overcome this problem, nanocomposites were obtained using gelatin as a biopolymer scaffold and silver nanoparticles as a wide spectrum antimicrobial agent. Water and glycerol have been used as solvents for the gelatin hydrogel synthesis. This mixture led to a stable and homogeneous biomaterial with improved mechanical properties. Silver nanoparticles were characterized using SEM, EDS and TEM. Moreover, the AgNp/gelatin nanocomposite obtained using these nanoparticles was characterized using SEM and FTIR. Moreover, mechanical and swelling properties were studied. The storage modulus was 3000 Pa for gelatin hydrogels and reached 5800 Pa for AgNp/gelatin nanocomposite. Silver nanoparticles have been studied as an alternative to antibiotics. Importantly, the rate of silver release was modulated as a function of the temperature of the nanocomposite. Thus, the silver release from the nanocomposites at 24 °C and 38 °C was analyzed by atomic absorption spectroscopy. The silver release reached 25% after 24 h at 24 °C, while a 75% release was achieved at 38°C in the same period, showing the material thermoresponsive behavior. AgNp/gelatin nanocomposite showed a deleterious effect over 99.99% of Pseudomonas aeruginosa and Staphylococcus aureus, leading to a material with antimicrobial properties. AgNp/gelatin nanocomposite with improved mechanical properties and silver nanoparticles as a source of silver ions has been synthesized. The properties of the nanocomposite with controlled silver delivery result in a more efficient topical pharmaceutical form for wound healing applications.

Bone Morphogenetic Protein-9-Stimulated Adipocyte-Derived Mesenchymal Progenitors Entrapped in a Thermoresponsive Nanocomposite Scaffold Facilitate Cranial Defect Repair.

Due to availability and ease of harvest, adipose tissue is a favorable source of progenitor cells in regenerative medicine, but has yet to be optimized for osteogenic differentiation. The purpose of this study was to test cranial bone healing in a surgical defect model utilizing bone morphogenetic protein-9 (BMP-9) transduced immortalized murine adipocyte (iMAD) progenitor cells in a citrate-based, phase-changing, poly(polyethylene glycol citrate-co-N-isopropylacrylamide) (PPCN)-gelatin scaffold. Mesenchymal progenitor iMAD cells were transduced with adenovirus expressing either BMP-9 or green fluorescent protein control. Twelve mice underwent craniectomy to achieve a critical-sized cranial defect. The iMAD cells were mixed with the PPCN-gelatin scaffold and injected into the defects. MicroCT imaging was performed in 2-week intervals for 12 weeks to track defect healing. Histologic analysis was performed on skull sections harvested after the final imaging at 12 weeks to assess quality and maturity of newly formed bone. Both the BMP-9 group and control group had similar initial defect sizes (P = 0.21). At each time point, the BMP-9 group demonstrated smaller defect size, higher percentage defect healed, and larger percentage defect change over time. At the end of the 12-week period, the BMP-9 group demonstrated mean defect closure of 27.39%, while the control group showed only a 9.89% defect closure (P < 0.05). The BMP-9-transduced iMADs combined with a PPCN-gelatin scaffold promote in vivo osteogenesis and exhibited significantly greater osteogenesis compared to control. Adipose-derived iMADs are a promising source of mesenchymal stem cells for further studies in regenerative medicine, specifically bone engineering with the aim of potential craniofacial applications.

Directed Printing and Reconfiguration of Thermoresponsive Silica‐pNIPAM Nanocomposites

Front Cover: In article number 1900191, Bhuvnesh Bharti and co-workers present a new approach for printing silica poly(N-isopropylacrylamide) thermoresponsive nanocomposites into monolayer networks using laser as a remote crosslinking source. The reconfiguration of the printed structure upon heating is pre-programmed by the geometry of the printed network, which provides a new design principle for fabricating adaptive materials with shape-changing abilities.

Thermoresponsive nanocomposites incorporating microplasma synthesized magnetic nanoparticles—Synthesis and potential applications

The requirement for novel therapeutic and diagnostic techniques for biomedical applications has driven the development of multifunctional composite materials. This, in turn, has necessitated the use of novel synthesis and processing techniques for scalable nanocomposite production with tuneable material properties. Atmospheric Pressure Microplasma (APM) is a synthesis technique which has received considerable interest in recent years as a viable route for fabrication of nanoparticles (NPs) and NP/polymer composites. Here, we employ APM synthesis of NPs in solutions demonstrating, for the first time, the in situ synthesis of magnetic NPs (Fe3O4) in a hydrogel; fabricating a magnetic thermo‐responsive hydrogel (poly (N‐isopropylacrylamde)) composite. This demonstrates the applicability of our APM process for producing materials which are potentially relevant to the health sector.

Lipid-coated superparamagnetic nanoparticles for thermoresponsive cancer treatment

Poor aqueous solubility, chemical instability, and indiscriminate cytotoxicity have limited clinical development of camptothecin (CPT) as potent anticancer therapeutic. This research aimed at fabricating thermoresponsive nanocomposites that enhance solubility and stability of CPT in aqueous milieu and enable stimulus-induced drug release using magnetic hyperthermia. 1,2-Dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and l-α-dipalmitoylphosphatidyl glycerol (DPPG) (1:1, mol/mol) were immobilized on the surface of superparamagnetic Fe3O4 nanoparticles (SPIONs) via high affinity avidin-biotin interactions. Heating behavior was assessed using the MFG-1000 magnetic field generator. Encapsulation efficiency and drug release were quantified by fluorescence spectroscopy. Anticancer efficacy of medicated nanoparticles was measured in vitro using Jurkat cells. The results revealed that drug incorporation did not significantly alter particle size, zeta potential, magnetization, and heating properties of lipid-coated SPIONs. Drug loading efficiency was 93.2 ± 5.1%. Drug release from medicated nanoparticles was significantly faster at temperatures above the lipid transition temperature, reaching 37.8 ± 2.6% of incorporated payload after 12 min under therapeutically relevant hyperthermia (i.e., 42 °C). Medicated SPIONs induced greater cytotoxicity than CPT in solution suggesting synergistic activity of magnetically-induced hyperthermia and drug-induced apoptosis. These results underline the opportunity for thermoresponsive phospholipid-coated SPIONs to enable clinical development of highly lipophilic and chemically unstable drugs such as CPT for stimulus-induced cancer treatment.

Ultrastiff, Thermoresponsive Nanocomposite Hydrogels Composed of Ternary Polymer–Clay–Silica Networks

Anomalous increases in mechanical stiffness and tensile strength were achieved in a poly(N-isopropylacrylamide) nanocomposite gel (NC gel) by incorporating a small amount of silica through the sol–gel reaction of tetraethyl orthosilicate in the polymer–clay network. The resulting NC-Si gels, with ternary polymer–clay–silica structures, exhibited very high tensile moduli (∼3500 kPa) and strengths (∼1700 kPa), as well as well-defined thermoresponsive swelling/deswelling behavior, through the incorporation of 0.2–2.5 wt % silica (relative to the gel weight). The reinforcing efficiency of in situ formed silica in the NC gel is more than 50 times that of clay, while the incorporation of preformed silica nanoparticles led to no observable changes in mechanical properties. The controllable range of hydrogel tensile mechanical properties was significantly extended by the preparation of NC-Si gels. The ternary polymer–clay–silica network structure was proposed on the basis of optical transmittance, TEM, EDS, and 2...

Highly Efficient Thermoresponsive Nanocomposite for Controlled Release Applications.

Highly efficient magnetic release from nanocomposite microparticles is shown, which are made of Poly (N-isopropylacrylamide) hydrogel with embedded iron nanowires. A simple microfluidic technique was adopted to fabricate the microparticles with a high control of the nanowire concentration and in a relatively short time compared to chemical synthesis methods. The thermoresponsive microparticles were used for the remotely triggered release of Rhodamine (B). With a magnetic field of only 1 mT and 20 kHz a drug release of 6.5% and 70% was achieved in the continuous and pulsatile modes, respectively. Those release values are similar to the ones commonly obtained using superparamagnetic beads but accomplished with a magnetic field of five orders of magnitude lower power. The high efficiency is a result of the high remanent magnetization of the nanowires, which produce a large torque when exposed to a magnetic field. This causes the nanowires to vibrate, resulting in friction losses and heating. For comparison, microparticles with superparamagnetic beads were also fabricated and tested; while those worked at 73 mT and 600 kHz, no release was observed at the low field conditions. Cytotoxicity assays showed similar and high cell viability for microparticles with nanowires and beads.

Abatement of aqueous anionic contaminants by thermo-responsive nanocomposites: (Poly(N-isopropylacrylamide))-co-silylanized Magnesium/Aluminun layered double hydroxides

A series of novel thermo-responsive composite sorbents, were prepared by free-radical co-polymerization of N-isopropylacrylamide (NIPAm) and the silylanized Mg/Al layered double hydroxides (SiLDHs), named as PNIPAm-co-SiLDHs. For keeping the high affinity of Mg/Al layered double hydroxides towards anions, the layered structure of LDHs was assumed to be reserved in PNIPAm-co-SiLDHs by the silanization of the wet LDH plates as evidenced by the X-ray powder diffraction. The sorption capacity of PNIPAm-co-SiLDH (13.5mg/g) for Orange-II from water was found to be seven times higher than that of PNIPAm (2.0mg/g), and the sorption capacities of arsenate onto PNIPAm-co-SiLDH are also greater than that onto PNIPAm, for both As(III) and As(V). These sorption results suggest that reserved LDH structure played a significant role in enhancing the sorption capacities. NO3− intercalated LDHs composite showed the stronger sorption capacity for Orange-II than that of CO32−. After sorption, the PNIPAm-co-SiLDH may be removed from water because of its gel-like nature, and may be easily regenerated contributing to the accelerated desorption of anionic contaminants from PNIPAm-co-SiLDHs by the unique phase-transfer feature through slightly heating (to 40°C). These recyclable and regeneratable properties of thermo-responsive nanocomposites facilitate its potential application in the in-situ remediation of organic and inorganic anions from contaminated water.

Self-assembly of thermoresponsive nanocomposites and their applications for sensing daunorubicin with DNA

Poly(N-isopropylacrylamide)-co-poly(methylmethacrylate) (PNIPAM-co-PMMA) nanofibers were fabricated by electrospinning. The titanium dioxide (TiO2) nanoparticles that grafted with thermoresponsive poly(N-isopropylacrylamide) (PNIPAM-gTiO2) were synthesized in our previous report (Gong et al., J. Mater. Chem. 22 (2012) 16872–16879). The blends of PNIPAM-co-PMMA nanofibers with PNIPAM-g-TiO2 nanoparticles (PNIPAM-g-TiO2/PNIPAM-co-PMMA) have been characterized and utilized as detection for daunorubicin. The biorecognition of daunorubicin was measured by electrochemical analysis. Because of the surface grafting polymer, both the nanocomposites of PNIPAM-g-TiO2/PNIPAM-co-PMMA and the PNIPAM-g-TiO2 nanoparticles have remarkable enhancement effect on the biorecognition of daunorubicin. Moreover, with the adding DNA, the biorecognition of the daunorubicin can be enhanced from 4% to 31.1%. It was found the self-assembly process occurred amongst the nanocomposites, daunorubicin and the DNA as the temperatures above the critical solution temperature (LCST) of the composites. These are suggested to be the potential valuable applications of sensor in the drug bioanalysis fields.