Smart Nanocomposites Research Articles

Production of smart nanocomposite for glass coating toward photochromic and long-persistent photoluminescent smart windows

Novel photoluminescent surface coatings were developed for simple industrial production of fluorescent photochromic and persistent photoluminescent smart materials. The photochromic fluorescent coatings are able to emit light of different color underneath an irradiation light supply, while the persistent phosphorescent coatings are able to continue the emission of light for an extended time period even after removing the irradiation light source. Photoluminescent lanthanide-doped strontium aluminum oxide (LSAO) immobilized into polystyrene (PS) nanocomposite coatings for glasses were developed by ultrasonic-assisted solution blending approach. To achieve a complete transparency for the produced coatings, the nanoparticle form of LSAO was well-dispersed in the PS matrix. LSAO nanoparticles were characterized by TEM, and the morphologies were reported on SEM, X-ray fluorescence (XRF) and EDX. The uncoated, pigment-free and photoluminescent coated glasses were colorless under normal visible daylight. Only luminescent coatings displayed bright green at lower concentrations of LSAO and bright white at higher concentrations of LSAO under ultraviolet lamp. Greenish-yellow color was also monitored in the dark for luminescent coatings. The prepared smart glasses displayed absorbance intensity at 355 nm and two emission bands at 425 and 508 nm. Both photoluminescence spectra and mechanical properties of the generated smart glasses were analyzed to display better resistance to scratching and superhydrophobic activity, compared to the uncoated glass, without adversely influencing their inherent spectral characteristics. The photoluminescent spectral studies demonstrated both photochromic fluorescent and long-persistent phosphorescent properties. The enhancement in scratch resistance and superhydrophobic properties of coated glasses can be attributed to inclusion of LSAO in polystyrene matrix. Compared to uncoated glass sample, the produced PS-LSAO nanocomposite coatings demonstrated ultraviolet protection, high durability, photostability and high reversible responsiveness to UV light without fatigue. Thus, PS-LSAO nanocomposite coatings can be applied onto a glass surface for various industrial purposes, such as solar panels, optical devices and architectural applications.

A 2D nanotheranostic platform based on graphene oxide and phase-change materials for bimodal CT/MR imaging, NIR-activated drug release, and synergistic thermo-chemotherapy.

Recent years have seen considerable progress in the development of nanomedicine by the advent of 2D nanomaterials serving as ideal platforms to integrate multiple theranostic functions. We synthesized multifunctional stimuli-responsive 2D-based smart nanocomposites (NCs), comprising gold nanoparticles (AuNPs) and superparamagnetic iron oxides (SPIOs) scaffolded within graphene oxide (GO) nanosheets, coated with doxorubicin (DOX)-loaded 1-tetradecanol (TD), and further modified with an alginate (Alg) polymer. TD is a phase-change material (PCM) that confines DOX molecules to the GO surface and melts when the temperature exceeds its melting point (Tm=39 °C), causing the PCM to release its drug payload. By virtue of their strong near-infrared (NIR) light absorption and high photothermal conversion efficiency, GO nanosheets may enable photothermal therapy (PTT) and activate a phase change to trigger DOX release. Upon NIR irradiation of NCs, a synergistic thermo-chemotherapeutic effect can be obtained by GO-mediated PTT, resulting an accelerated and controllable drug release through the PCM mechanism. The biodistribution of these NCs could also be imaged with computed tomography (CT) and magnetic resonance (MR) imaging in vitro and in vivo. Hence, this multifunctional nanotheranostic platform based on 2D nanomaterials appears a promising candidate for multimodal image-guided cancer therapy.

Mitochondria-targeted accumulation of oxygen-irrelevant free radicals for enhanced synergistic low-temperature photothermal and thermodynamic therapy

BackgroundAlthough lower temperature (< 45 °C) photothermal therapy (LPTT) have attracted enormous attention in cancer therapy, the therapeutic effect is still unsatisfying when applying LPTT alone. Therefore, combining with other therapies is urgently needed to improve the therapeutic effect of LPTT. Recently reported oxygen-irrelevant free radicals based thermodynamic therapy (TDT) exhibit promising potential for hypoxic tumor treatment. However, overexpression of glutathione (GSH) in cancer cells would potently scavenge the free radicals before their arrival to the specific site and dramatically diminish the therapeutic efficacy.Methods and resultsIn this work, a core–shell nanoplatform with an appropriate size composed of arginine–glycine–aspartate (RGD) functioned polydopamine (PDA) as a shell and a triphenylphosphonium (TPP) modified hollow mesoporous manganese dioxide (H-mMnO2) as a core was designed and fabricated for the first time. This nanostructure endows a size-controllable hollow cavity mMnO2 and thickness-tunable PDA layers, which effectively prevented the pre-matured release of encapsulated azo initiator 2,2′-azobis[2-(2-imidazolin-2-yl) propane] dihydrochloride (AIBI) and revealed pH/NIR dual-responsive release performance. With the mitochondria-targeting ability of TPP, the smart nanocomposites (AIBI@H-mMnO2-TPP@PDA-RGD, AHTPR) could efficiently induce mitochondrial associated apoptosis in cancer cells at relatively low temperatures (< 45 °C) via selectively releasing oxygen-irrelevant free radicals in mitochondria and facilitating the depletion of intracellular GSH, exhibiting the advantages of mitochondria-targeted LPTT/TDT. More importantly, remarkable inhibition of tumor growth was observed in a subcutaneous xenograft model of osteosarcoma (OS) with negligible side effects.ConclusionsThe synergistic therapy efficacy was confirmed by effectively inducing cancer cell death in vitro and completely eradicating the tumors in vivo. Additionally, the excellent biosafety and biocompatibility of the nanoplatforms were confirmed both in vitro and in vivo. Taken together, the current study provides a novel paradigm toward oxygen-independent free-radical-based cancer therapy, especially for the treatment of hypoxic solid tumors.Graphical

Carbon-Based Nanocomposite Smart Sensors for the Rapid Detection of Mycotoxins.

Carbon-based nanomaterials have become the subject of intensive interest because their intriguing physical and chemical properties are different from those of their bulk counterparts, leading to novel applications in smart sensors. Mycotoxins are secondary metabolites with different structures and toxic effects produced by fungi. Mycotoxins have low molecular weights and highly diverse molecular structures, which can induce a spectrum of biological effects in humans and animals even at low concentrations. A tremendous amount of biosensor platforms based on various carbon nanocomposites have been developed for the determination of mycotoxins. Therefore, the contents of this review are based on a balanced combination of our own studies and selected research studies performed by academic groups worldwide. We first address the vital preparation methods of biorecognition unit (antibodies, aptamers, molecularly imprinted polymers)-functionalized carbon-based nanomaterials for sensing mycotoxins. Then, we summarize various types of smart sensors for the detection of mycotoxins. We expect future research on smart sensors to show a significant impact on the detection of mycotoxins in food products.

Reflection and transmission of waves at the common interface of piezoelectric half-spaces with microstructure

The present article deals with the reflection and transmission of waves at an interface of piezoelectric (ALN & PZT-5T) half-spaces with microstructures. Unlike the classical piezoelectric material, in the considered media, five coupled waves (2 bulk and 3 surface) [namely the Quasi-longitudinal wave (QP), Quasi-transverse wave (QSV), Electric-acoustic wave (EA), P-type surface wave (SP) and S-type surface wave (SS)] are generated in response to an oblique incident Quasi plane wave. The main objective of this study is to investigate the influence of the characteristic length of microstructure, the inertial characteristic length and flexoelectric coefficients on the reflection and transmission coefficients. For this purpose, the linear algebraic equation, continuity conditions at the common interface are contracted. The linear system of equations comprising the reflection and transmission coefficients is derived, which is solved by using the Cramer's rule. The consequence of this electromechanical phenomenon may be advantageous in certain engineering applications that involve smart nano-composites.

Glycoprotein-based bioimaging of HeLa cancer cells by folate receptor and folate decorated graphene quantum dots

Folate receptor (FR, 38 kDa) is a glycosylphosphatidylinositol glycoprotein which overexpressed on the surface of various cancer cells and has been utilized for wide applications. Folic acid (FA) functionalized nitrogen doped graphene quantum dots wrapped terbium (III) tungstate nanoparticles (Tb2(WO4)3NPs@N-GQDs-FA or Tb-W@GQDs-FA) as a smart nanocomposite was synthesized and used for specific imaging of folate receptor (FR) positive HeLa cancer cells. The mechanism of action is based on the attachment of FA decorated nanomaterials to the FR on the surface of cancer cells. This bioimaging probe emits fluorescence emission at 450 nm upon excitation on 345 nm. Flow cytometry and fluorescence microscopy techniques were applied to evaluate the efficiency of uptake of Tb-W@GQDs-FA to the cancer cells. Also, the selective attachment of Tb-W@GQDs-FA particles towards FR-positive HeLa cancer cells was verified by incubation of Tb-W@GQDs-FA with FR-negative normal cells. The cellular toxicity of the produced Tb-W@GQDs-FA nanocomposite was evaluated and results approved its biocompatible nature at the concentration of about 400 µg/mL. In conclusion, Tb-W@GQDs-FA could be effectively applied for noninvasive bio-imaging of HeLa cancer cells.

Chemosensor-Anchored Halloysite Nanotubes for Detection and Removal of Hypochlorite in Water

Preparation of a smart tool for simultaneous detection and removal of hypochlorite (ClO–) in water, a kind of serious persistent pollutant in industrial wastewater and even in tap water, is a puzzling issue in the chemosensing field. Here, halloysite nanotubes (HNTs), a natural product with excellent dispersibility in water, were employed as the scaffold to solve the urgent problem. The diaminomaleonitrile moiety, accompanying with the coumarin derivative as a chemosensor unit, was decorated on the surface of the HNTs. The diaminomaleonitrile group can be transferred into substituted imidazole formation and thereby triggers strong fluorescence emission upon ClO–, which triggers a dramatically “turn-on” fluorescence change and reduce ClO– into eco-friendly chloridion (Cl–). The detection and removal capacities show high selectivity over other commonly used ions. These results suggest that the smart nanocomposite can be used in the synchronous detection and removal of ClO– in water, which may pave a path in water quality monitoring and treatment.

Magnetoresponsive smart nanocomposites with highly cross‐linked polymer matrix

We propose a coarse‐grained model, which is used for mesoscale simulation of nanocomposites based on a highly cross‐linked polymer network with embedded magnetic nanoparticles (MNPs) whose structure is represented as a set of connected magnetic dipoles. All the simulations are carried out with reactive dissipative particle dynamics, taking into account the interaction of MNPs with an external magnetic field. To study the effect of the spatial organization of MNPs, the network formation from polymerizing monomers is simulated both in the field and without it. Under the influence of the field, the nanoparticles are organized into filamentous aggregates that induce the anisotropic structure of the polymer matrix and affect the network topology. The stress–strain curves demonstrate that the ordering of MNPs also causes anisotropy of mechanical properties and leads to an increase in Young's modulus for uniaxial tension along the long aggregate axis. When monomers polymerize in the presence of MNPs at zero applied field, the filler particles remain disordered and Young's modulus of such a composite can exhibit a weak linear decrease with increasing filler content. This behavior is well attributed to the reduction in the number of load‐bearing chains in the simulation box. Additionally, the role of the polymer/MNP interface is studied. To this end, the corresponding interaction parameters are varied. It is found that the interface can provide an additional contribution to the tensile rigidity of composites.

Chemosensitivity assessments of curdlan-doped smart nanocomposites containing erlotinib HCl

Curdlan (CN)-doped montmorillonite/poly(N-isopropylacrylamide-co-N,N′-methylene-bis-acrylamide) [CN/MT/P(NIPA-co-MBA)] smart nanocomposites (NCs) were developed for efficient erlotinib HCl (ERL) delivery to lung cancer cells. The placebo NCs demonstrated excellent biodegradability, pH/thermo-responsive swelling profiles and declined molar mass (M¯c) between the crosslinks with increasing temperature. The XRD, FTIR, DSC, TGA, and SEM analyses revealed the architectural chemistry of these NC scaffolds. The NCs loaded with ERL (F-1-F-3) displayed acceptable diameter (734–1120 nm) and zeta potential (+1.16 to −11.17 mV), outstanding drug entrapping capability (DEE, 78–99%) and sustained biphasic ERL elution patterns (Q8h, 53–91%). The ERL release kinetics of the optimal matrices (F-3) obeyed Higuchi model and their transport occurred through anomalous diffusion. The mucin adsorption behaviour of these matrices followed Freudlich isotherms. As compared to pure ERL, the formulation (F-3) displayed an improved anti-proliferative potential and induced apoptosis more effectively on A549 cells. Thus, the CN-doped smart NCs could be utilized as promising drug-cargoes for lung cancer therapy.

Oxygen Self‐Sufficient Nanoplatform for Enhanced and Selective Antibacterial Photodynamic Therapy against Anaerobe‐Induced Periodontal Disease

AbstractThe hypoxic microenvironment, continuous oxygen consumption, and poor excitation light penetration depth during antimicrobial photodynamic therapy (aPDT) tremendously hinder the effects on bacterial inactivation. Herein, a smart nanocomposite with oxygen‐self‐generation is presented for enhanced and selective antibacterial properties against anaerobe‐induced periodontal diseases. By encapsulating Fe3O4 nanoparticles, Chlorin e6 and Coumarin 6 in the amphiphilic silane, combined light (red and infrared) stimulated aPDT is realized due to the increased conjugate structure, the corresponding red‐shifted absorption, and the magnetic navigation performance. To address the hypoxic microenvironment problem, further modification of MnO2 nanolayer on the composites is carried out, and catalytical activity is involved for the decomposition of hydrogen peroxide produced in the metabolic processing, providing sufficient oxygen for aPDT in infection sites. Experiments in the cellular level and animal model proved that the rising oxygen content could effectively relieve the hypoxia in a periodontal pocket and enhance the ROS production, remarkably boosting aPDT efficacy. The increasing local level of oxygen also shows the selective inhibition of pathogenic and anaerobic bacteria, which determines the success of periodontitis treatment. Therefore, this finding is promising for combating anaerobic pathogens with enhanced and selective properties in periodontal diseases, even in other bacteria‐induced infections, for future clinical application.

Graphene-Based Scaffolds for Regenerative Medicine.

Leading-edge regenerative medicine can take advantage of improved knowledge of key roles played, both in stem cell fate determination and in cell growth/differentiation, by mechano-transduction and other physicochemical stimuli from the tissue environment. This prompted advanced nanomaterials research to provide tissue engineers with next-generation scaffolds consisting of smart nanocomposites and/or hydrogels with nanofillers, where balanced combinations of specific matrices and nanomaterials can mediate and finely tune such stimuli and cues. In this review, we focus on graphene-based nanomaterials as, in addition to modulating nanotopography, elastic modulus and viscoelastic features of the scaffold, they can also regulate its conductivity. This feature is crucial to the determination and differentiation of some cell lineages and is of special interest to neural regenerative medicine. Hereafter we depict relevant properties of such nanofillers, illustrate how problems related to their eventual cytotoxicity are solved via enhanced synthesis, purification and derivatization protocols, and finally provide examples of successful applications in regenerative medicine on a number of tissues.

Interpenetrating polymer network/functionalized‐reduced graphene oxide nanocomposite: As an advanced functional material

AbstractIn this report, smart polyurethane‐polystyrene interpenetrating polymer network (IPN)‐based nanocomposites were fabricated using simultaneous polymerization technique with different doses of functionalized reduced graphene oxide (f‐RGO). RGO was functionalized with monoglyceride of sunflower oil in the presence of toluene diisocyanate. Successful functionalization of RGO was supported by Fourier‐transform infrared spectroscopy, X‐Ray diffraction, and transmission electron microscopy analyses. Most interestingly, the fabricated IPN‐based nanocomposites showed significant enhancements in mechanical (tensile strength: 165%; elongation at break: 198%; toughness: 340%) and thermal (thermally stable up to 262°C) properties upon incorporation of 1 weight% of f‐RGO. Moreover, the fabricated nanocomposites exhibited outstanding chemical resistance, self‐cleaning behavior through surface hydrophobicity (static contact angle: 125.6–136.5°), multi‐stimuli responsive shape memory effect (100% recovery within 33–44 s by microwave and 265–308 s by sunlight) and thermally actuated artificial muscle‐like behavior. Therefore, the studied smart nanocomposites with the aforementioned properties hold significant potential for possible advanced applications.

Smart Nanocomposite Nonwoven Wearable Fabrics Embedding Phase Change Materials for Highly Efficient Energy Conversion-Storage and Use as a Stretchable Conductor.

Flexible and intelligent electronics are highly demanded in wearable devices and systems, but it is still challenging to fabricate conductive textiles with good stretchability, multifunctionality, and responsiveness to multistimuli. Therefore, kinds of smart conductive fabrics with high stretchability and thermal properties, good washability, excellent shape stability, rapid responsiveness to external stimuli (e.g., electrical and photonic), and outstanding energy conversion and storage properties were designed and prepared. The nonwoven smart fabrics were fabricated by electrospinning of a solution of multiwalled carbon nanotubes (MWCNTs)/lauric acid (LA)/thermoplastic polyurethane (PU) and dip-coating conductive polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) on the obtained nanofibers. The smart textiles showed tunable temperature and phase change enthalpy that responded to external stimuli such as electrical voltage, infrared light, and sunlight. At the same time, they realized the storage and conversion of energy reversibly with a high efficiency. The elastic fabrics could also be used as a stretchable conductor in a range of deformation. The integrative functions of the smart fabrics promise them great potential in wearable systems and intelligent protective garments.

Enhanced Corrosion Protection of A-36 Steel Using Epoxy-Reinforced CSA-Doped Polyaniline-SnO2 Nanocomposite Smart Coatings

Reinforced epoxy polymer nanocomposites have been employed as anti-corrosion coatings on various metallic substrates due to their beneficial characteristics and high electrochemical performances. In this work, we explore the anti-corrosion behavior of reinforced epoxy (EP) polymer nanocomposite consists of polyaniline (PANI)-tin oxide (SnO2) doped with camphor sulfonic acid (CSA). PANI-SnO2 nanocomposites doped with CSA were prepared by in situ chemical oxidative polymerization of aniline in the presence of SnO2 nanoparticles. The morphological and structural features of the prepared nanocomposites were investigated through scanning electron microcopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). Further, the coatings of these PANI:SnO2 nanocomposites with epoxy were employed on A-36 steel (carbon steel) substrates to investigate their corrosion protection behavior. The effect of SnO2 presence in the composite towards enhancing the corrosion protection was discussed through the Tafel polarization, polarization resistance, and electrochemical impedance spectroscopy (EIS) as well as oxygen gas permeability studies. Successful formation of potential barriers and their corrosion inhibition abilities were discussed. The EP:PANI:SnO2 composite coatings demonstrate an excellent corrosion inhibition efficiency of 98% in comparison to neat epoxy (43%). The investigation on mechanical properties of these coatings indicates improved adhesion, Young’s modulus, and tensile strength due to the presence of SnO2 nanoparticles. Owing to their enhanced conductivity, superior electrochemical performance and excellent mechanical properties, these EP:PANI:SnO2 nanocomposite coatings could form smart anti-corrosion formulations in protecting A-36 steel against harsh environments.

Smart nanocomposites of chitosan/alginate nanoparticles loaded with copper oxide as alternative nanofertilizers

A chitosan and sodium alginate complex acts as a biodegradable shell to release nanoscaled nutrients, CuO nanoparticles, as an alternative smart delivery nanofertilizer.

Alginate/chitosan-based hydrogel loaded with gene vectors to deliver polydeoxyribonucleotide for effective wound healing.

Timely and effective wound treatment is of great significance in acute bleeding caused by accidents and chronic wounds such as diabetic foot ulcers, venous leg ulcers, pressure sores. A hydrogel as wound dressing can provide a suitable microenvironment for wound healing and prevent bacteria and dust from reaching the wound. The loading of therapeutic factors in the hydrogel has been proved to accelerate wound healing. Polydeoxyribonucleotide (PDRN), as a series of nucleic acid fragments extracted from salmon, has the functions of improving angiogenesis, promoting cell activity, increasing collagen synthesis, and developing the anti-inflammatory response. These effects have positive implications for wound healing. But naked PDRN is difficult to take up by cells. Inspired by gene vectors, we prepared a PDRN-loaded CaCO3 nanoparticle (PCNP) to improve the delivery efficiency of PDRN. PCNPs were encapsulated in an alginate/chitosan-based hydrogel (Gel@PCNPs). The prepared hydrogel has plasticity and is suitable for various irregular wounds. The released gene carrier, PCNP, can be effectively taken up by skin fibroblasts. Under the action of PDRN, the wound healing rate has been confirmed to be significantly accelerated. We believe that this polysaccharide-based hydrogel loaded with PDRN vectors is a promising wound dressing.

An investigation into size‐dependent dynamic thermo‐electromechanical response of piezoelectric‐laminated sandwich smart nanocomposites

An investigation into size‐dependent dynamic thermo‐electromechanical response of piezoelectric‐laminated sandwich smart nanocomposites

Micromechanical technique based prediction of effective properties for hybrid smart nanocomposites

The domain of carbon nanotube (CNT) reinforced composites is a colossal and convoluted area of research. The modeling of composite materials under deformation plays a vital role in structural design. A new model that comprises CNT and piezoelectric fibers reinforced in a hybrid smart composite has been proposed, and its effective properties are determined. The resulting composite can be regarded as a cylindrical composite with continuous parallel PZT fiber embedded inside the CNT-reinforced hybrid nanocomposite. The strength of a material based on the micromechanics technique is used to evaluate the proposed hybrid smart nanocomposite's effective elastic and piezoelectric properties. The results illustrate that the introduction of CNTs as reinforcing fibers in the proposed composites has significantly improved the effective elastic and piezoelectric properties. The effects of CNT content and volume fractions were investigated in a hybrid smart nanocomposite.

Thermo-resistive and thermo-piezoresistive sensitivity of carbon nanostructure engineered thermoplastic composites processed via additive manufacturing

We experimentally examine the thermo-resistive and thermo-piezoresistive sensitivity of multiwall carbon nanotube (MWCNT)/polypropylene random copolymer (PPR) nanocomposites processed via fused filament fabrication (FFF) process. The filament feedstocks were fabricated by melt blending of neat PPR with a predetermined amount of MWCNTs (either 4, 6 or 8 wt%) using a twin-screw extruder. Thermo-resistive characteristics of MWCNT/PPR composites were measured under both constrained and unconstrained heating from approximately 30-100 °C. For all MWCNT concentrations considered here, negative temperature coefficients of resistivity (TCR) were observed for both constrained and unconstrained heating, as a consequence of thermal fluctuation-induced tunneling at MWCNT junctions. The highest thermo-resistive sensitivity was measured for the composite with the lowest MWCNT concentration (4 wt%) under unconstrained conditions, reporting a TCR of −12,800 × 10−6/°C, which is higher in magnitude than that of other polymer nanocomposites reported in the literature. Moreover, the MWCNT/PPR composites exhibit strong thermo-piezoresistive response under tensile loading. For 4 wt% MWCNT loading, the gauge factor (measured over 0–20% strain range) of the composite increased from 27.8 to 52.3 when the temperature was raised from 30 °C to 60 °C. Our results further evince higher thermo-piezoresistive sensitivity i.e., a gauge factor as high as 395 at 60 °C. The electron tunneling and hopping, both thermally-assisted and activated by mechanical deformation of the PPR matrix, significantly increase the thermo-piezoresistance with the increase in temperature in this range. The excellent thermo-resistive and thermo-piezoresistive characteristics of MWCNT/PPR composites reported in this study would enable the development of smart nanocomposites for self-sensing both temperature and strain/damage state.

Micromechanical analysis of quantum dot-embedded smart nanocomposite materials

A general micromechanical model based on asymptotic homogenization technique is developed for the analysis of anisotropic quantum dot-embedded smart nanocomposites with piezoelectrically active constituents. The governing equations are derived with unit-cell problem formulations that are universal in nature and can be applied to study various 3D material structures of interest. The work continues to illustrate the effectiveness of the model by analyzing the elastic, piezoelectric, and dielectric properties of ZnO quantum dot (QD) fiber-reinforced polymer nanocomposites of laminated structure. The evaluation of these properties are accomplished by imposing homogeneous displacement and electric potential fields as boundary conditions. . The effective material properties are calculated in relation to volume fraction of participating material constituents (fiber, polymer, QD). The micromechanically-obtained results are then compared with those of the numerically obtained results in ABAQUS finite element method. The results demonstrate a close agreement between the analytical and numerical models.