Polymer Nanosheet Research Articles

Mechanism of High Proton Mobility in the Two-Dimensional Nanospace at the Interlayer of a Multilayer Polymer Nanosheet Film

Mechanism of High Proton Mobility in the Two-Dimensional Nanospace at the Interlayer of a Multilayer Polymer Nanosheet Film

Ionic Covalent Organosilicon Polymer Nanosheet for Selective and Sensitive Detection of Dopamine

Ionic Covalent Organosilicon Polymer Nanosheet for Selective and Sensitive Detection of Dopamine

Renal Clearable Catalytic 2D Au-Porphyrin Coordination Polymer Augmented Photothermal-Gas Synergistic Cancer Therapy.

As a gasotransmitter, carbon monoxide (CO) possesses antitumor activity by reversing the Warburg effect at higher concentrations. The targeted delivery of carbon monoxide-releasing molecules (CORMs) using nanomaterials is an appealing option for CO administration, but how to maintain CO above the threshold concentration in tumor tissue remains a challenge. Herein, a nanozyme-catalyzed cascade reaction is proposed to promote CO release for high-efficacy photothermal therapy (PTT)-combined CO therapy of cancer. A gold-based porphyrinic coordination polymer nanosheet (Au0 -Por) is synthesized to serve as a carrier for CORM. It also possesses excellent glucose oxygenase-like activity owing to ultrasmall zero-valent gold atoms on the nanosheet. The catalytically generated H2 O2 can efficiently catalyze CORM decomposition, which enables in situ generation of sufficient CO for gas therapy. In vivo, the Au0 -Por nanosheets-enhanced photoacoustic imaging (PAI) and fluorescence imaging collectively demonstrate high tumor-targeting efficiency and nanomaterial retention. Proven to have augmented therapeutic efficacy, the nanoplatform can also be easily degraded and excreted through the kidney, indicating good biocompatibility. Thus, the application of rational designed Au0 -Por nanosheet with facile approach and biodegradable property to PAI-guided synergistic gas therapy can provide a strategy for the development of biocompatible and highly effective gaseous nanomedicine.

An organic-based amphiphilic Janus polymer nanosheet: Synthesis, properties, and microscopic dispersion interpretations

Due to the distinctive anisotropy in shapes and affluent potential in properties, amphiphilic Janus polymer nanosheets (AJPN) have attracted widespread attention. Low-cost, controllable, and precise functional polymerization remains a great challenge to conventional template methods. Herein, an organic-based AJPN was synthesized with polystyrene as the hydrophobic side and carboxyl groups presented at the hydrophilic side. Sucrose was selected as the adsorption template, which could be removed simply by water-washing. The lateral sizes could be regulated by adjusting the ultrasonic time and power after the precise construction of polymer shells. The colloidal stability and aggregation kinetics of AJPN suspension under different conditions were quantitatively measured. In particular, Rheolaser optical microrheology was pioneered to explore the authentic migration behaviors and rheological properties of AJPN aqueous solution for the first time. The results revealed that AJPN solution presented as thermodynamically unstable solid suspension, which was far different from real solution, emulsion or cross-linked hydrogel formed by common hydrophilic polymers. The carboxyl groups and the steric effect of polymer chains greatly improved the self-stability of AJPN suspension. The influences of microscopic migration of AJPN on their macroscopic dispersion in different stages were concluded, which was closely related to the applicability of nanofluid products in storage, transportation, or performance periods. Moreover, due to the amphiphilic property, Janus nature and lamellar nanomorphology, AJPN could be used as solid surfactants to reduce oil–water interfacial tension and stabilize emulsions. We hope this work can offer more opportunities for the synthesis of AJPN with different chemical compositions, and promote the development of dispersion stability of nanosheets.

Water Reduction Photocathodes Based on Ru Complex Dyes Covered with a Conjugated Polymer Nanosheet

Water Reduction Photocathodes Based on Ru Complex Dyes Covered with a Conjugated Polymer Nanosheet

An X-state solid-liquid mixture with unusual mechanical properties formed by water and coordination polymer nanosheet nanoarchitectonics.

Removal of water from a mixture of water and inorganic solids usually leads to a drastic change in the mechanical properties from liquid-like to brittle solid type. Here, we demonstrate that there is an unusual state, the X state, formed by naturally drying up a dough which is composed of Ni(H2O)2[(Ni(CN)4]·H2O nanosheets and water. This X-state mixture shows mechanical characteristics different from both pure liquids and brittle solids. The deformation curve of the X-state mixture contains three linear parts. However, the deformation is recoverable because the deformation curve can be repeated as long as fracture does not occur. The ice-like water formed among the nanosheets is believed to be an important reason for generating this X-state mixture. The unique properties of the X-state mixture may find applications, such as impact absorbents, which require materials with considerable strength, modulus and toughness.

Two-dimensional coordination polymer-based nanosensor for sensitive and reliable nucleic acids detection in living cells

A reliable and sensitive strategy which can assess nucleic acid levels in living cells would be essential for fundamental research of biomedical applications. Some nanomaterial-based fluorescence biosensors recently developed for detecting nucleic acids, however, are often with expensive, complicated and time-consuming preparation process. Here, by using a facile bottom-up synthesis method, a two-dimensional (2D) coordination polymer (CP) nanosheet, [Cu(tz)] (Htz = 1,2,4-triazole), was successfully prepared after optimizing reaction conditions. These ultrathin CP nanosheets with thickness of 4.7 ± 1.1 nm could readily form nanosensors by assembly with DNA probes, which exhibited a low limit of detection (LOD) for p53 DNA fragment as 144 pmol/L. Furthermore, by integrating [Cu(tz)] nanosheets with hybridization chain reaction (HCR) probes, miR-21, one kind of microRNA upregulated in many cancer cells, can be sensitively detected with a LOD of 100 pmol/L and monitored in living cells, giving consistent results with those obtained by quantitative reverse-transcription polymerase chain reaction (qRT-PCR) analysis. Thus [Cu(tz)] nanosheets, which not only possess much better nucleic acids sensing performance than bulk cystals, but also exhibit nucleic acid delivery functions, could be used as a novel nanoplatform in biomedical imaging and sensing applications.

In-plane micro-supercapacitor using polymer nanosheet assembly as a weak acid solid electrolyte

In-plane micro-supercapacitors, in which the electrodes are arranged on the same plane have attracted much attention because of their light weight, simple device structure, etc. In this paper, micro-supercapacitors were fabricated by using polymer nanosheet multilayer film as a solid electrolyte. The micro-supercapacitors were fabricated by sequential deposition poly(N-dodecyl acrylamide-co-acrylic acid) monolayer onto a solid substrate with interdigitated gold electrodes. The capacitor characteristics were investigated by cyclic voltammetry under saturated humidity condition. It was revealed that the micro-supercapacitor showed a capacitance of 33 µF/cm2.

An ultrathin amino-acid based copper(II) coordination polymer nanosheet for efficient epoxidation of β-caryophyllene

• CuIle-e nanosheet and CuIle-m nanoshuttle were fabricated from natural amino acid. • Stable catalytic systems, CuIle-e /acetone/TBHP and CuIle-e /THF/O 2 /TBHP, were built. • Good yields (86.1% or 87.2%) for β-caryophyllene epoxide were achieved. • Superior recyclability of CuIle-e nanosheet was realized. Natural amino acids are important building blocks for the construction of intriguing coordination polymers (CPs) because of their abundance, inexpensiveness and environmental benignness. Herein, two copper(II) CPs, namely, 2D CuIle-e nanosheet ( e : ethanol) and 1D CuIle-m nanoshuttle ( m : methanol), were fabricated from L -isoleucine ( Ile ) and well characterized with single-crystal x-ray diffraction, XPS spectra, TEM and AFM, etc. More importantly, two novel and stable catalytic nanosystems, i.e. CuIle-e /acetone/TBHP ( tert-butyl hydroperoxide) and CuIle-e /THF/O 2 /TBHP, were thus conveniently built by using ultrathin 2D CuIle-e nanosheet (~ 2.3 nm) in suitable aprotic solvents. Under mild conditions, complete conversion of β-caryophyllene and good yields (86.1% or 87.2%) for β-caryophyllene epoxide were gained via CuIle-e /acetone/TBHP or CuIle-e /THF/O 2 (1 atm)/TBHP (10.0 mol%), respectively. Notably, ultrathin CuIle-e nanosheet showed fairly satisfactory stability, which may open a unique window for the facile fabrication of new amino-acid based CP nanosystems with outstanding catalytic performances in actual applications. Two amino acid-based ultrathin CP nanosystems, CuIle-e /acetone/TBHP and CuIle-e /THF/1 atm O 2 /TBHP, were employed for the highly efficient epoxidation of β-caryophyllene under mild conditions.

Ambient synthesis of iron-nickel amorphous coordination polymer nanosheet arrays for highly efficient oxygen evolution electrocatalysis

Two-dimensional (2D) coordination polymers, including metal-organic frameworks (MOFs) and infinite coordination polymers (ICPs), have been regarded as promising electrocatalysts. Although much effort has been devoted to investigating the electrocatalytic performance of MOFs, only a few reports are available on ICPs. Here, a facile room-temperature strategy has been developed to synthesize an iron-nickel amorphous ICP (Ni2Fe-ICP) nanosheet array on Ni foam as a self-supported electrode. Ni2Fe-ICP exhibits excellent electrocatalytic performance in the oxygen evolution reaction (OER). Specifically, Ni2Fe-ICP shows a low overpotential of 275 mV at a current density of 100 mA cm−2, outperforming commercial RuO2, and has superior stability at a high current density (150 mA cm−2 can be retained for at least 30 h). Furthermore, the real OER active species are revealed to be metal oxides that evolve during the OER process.

Fabrication of Polymer Nanosheet and Effect of Friction during Sliding between Fingertip Skins

Fabrication of Polymer Nanosheet and Effect of Friction during Sliding between Fingertip Skins

Conjugated microporous polymers as novel adsorbent materials for VOCs capture: A computational study

Conjugated microporous polymer (CMP) nanosheet containing alternative phenylene and ethynylene units were investigated computationally as efficient adsorbent materials for volatile organic compounds (VOCs) capture. The binding mechanism and electronic structures of the CMP-VOCs complexes were studied by the density-functional tight-binding method augmented with a van der Waals R−6 dispersion term. The acetic acid, acetone, ethanol, ethylacetate, and hexane molecules are considered as representative VOC molecules. We show that the VOC molecules could spontaneously adsorb to the CMP surface through H…π stacking at physisorption distances. For the CMP sheet, the phenylene moiety in the node demonstrates the strongest binding to organic molecules than the linker alkyne and the 6-member-ring regions. The number and the direction of the H atoms play important role in the CMP-VOCs binding. The average adsorption energies for different VOCs molecules are calculated to be −14∼−37 kJ/mol, demonstrating the feasibility and reliability of VOCs capture via CMP sheet. Our results might shed light on the development of novel carbon-based adsorbents for VOCs capture and removal.

Biomimetic Polyelectrolytes Based on Polymer Nanosheet Films and Their Proton Conduction Mechanism.

We report a biomimetic polyelectrolyte based on amphiphilic polymer nanosheet multilayer films. Copolymers of poly( N-dodecylacrylamide- co-vinylphosphonic acid) [p(DDA/VPA)] form a uniform monolayer at the air-water interface. By depositing such monolayers onto solid substrates using the Langmuir-Blodgett (LB) method, multilayer lamellae films with a structure similar to a bilayer membrane were fabricated. The proton conductivity at the hydrophilic interlayer of the lamellar multilayer films was studied by impedance spectroscopy under temperature- and humidity-controlled conditions. At 60 °C and 98% relative humidity (RH), the conductivity increased with increasing mole fraction of VPA ( n) up to 3.2 × 10-2 S cm-1 for n = 0.41. For a film with n = 0.45, the conductivity decreased to 2.2 × 10-2 S cm-1 despite the increase of proton sources. The reason for this decrease was evaluated by studying the effect of the distance between the VPAs ( lVPA) on the proton conductivity as well as their activation energy. We propose that for n = 0.41, lVPA is the optimal distance not only to form an efficient two-dimensional (2D) hydrogen bonding network but also to reorient water and VPA. For n = 0.45, on the other hand, the lVPA was too close for a reorientation. Therefore, we concluded that there should be an optimal distance to obtain high proton conductivity at the hydrophilic interlayer of such multilayer films.

Ultrathin and Stretchable Rechargeable Devices with Organic Polymer Nanosheets Conformable to Skin Surface.

Ultrathin flexible electronic devices have been attracting substantial attention for biomonitoring, display, wireless communication, and many other ubiquitous applications. In this article, organic robust redox-active polymer/carbon nanotube hybrid nanosheets with thickness of just 100 nm are reported as power sources for ultrathin devices conformable to skin. Regardless of the extreme thinness of the electrodes, a moderately large current density of 0.4 mA cm-2 is achieved due to the high output of the polymers (>10 A g-1 ). For the first time, the use of mechanically robust yet intrinsically soft electrodes and polymer nanosheet sealing leads to the fabrication of rechargeable devices with only 1-µm thickness and even with stretchable properties.

Multi-layered PLLA-nanosheets loaded with FGF-2 induce robust bone regeneration with controlled release in critical-sized mouse femoral defects

To overcome clinical issues caused by large bone defects and subsequent nonunion, various approaches to bone regeneration have been researched, including tissue engineering, biomaterials, stem cells and drug screening. Previously, we developed a free-standing biodegradable polymer nanosheet composed of poly(L-lactic acid) (PLLA) using a simple fabrication process consisting of spin-coating and peeling techniques. We reported that sandwich-type PLLA nanosheets loaded with recombinant human bone morphogenetic protein-2 (rhBMP-2) displayed long-lasting, sustained release of rhBMP-2, and markedly enhanced bone regeneration in mouse calvarial bone defects. Here, we fabricated multi-layered nanosheets loaded with fibroblast growth factor-2 (FGF-2), and investigated their application for long bone regeneration. Subcutaneously implanted tri-layered PLLA nanosheets displayed sustained release of loaded rhFGF-2 for about 2 weeks. Next, we prepared critical-sized mouse femoral defects and implanted mono- or tri-layered nanosheets, or a gelatin hydrogel with rhFGF-2. Amongst these conditions, the tri-layered nanosheet most efficiently induced bone regeneration. Indeed, bone regeneration was enhanced even after 4 weeks in the tri-layered nanosheet group, and was accompanied by FGFR1 activation and subsequent osteoblast differentiation. Multi-layered PLLA nanosheets loaded with rhFGF-2 may be useful for bone regenerative medicine. Furthermore, the multi-layered PLLA nanosheet structure may potentially be applied as a potent sustained-release carrier. Statements of SignificanceHere, we describe multi-layered poly(L-lactic acid) (PLLA) nanosheets loaded with recombinant human fibroblast growth factor-2 (rhFGF-2) as a modified sustained-release carrier for bone regeneration. In vivo imaging system analysis revealed that subcutaneously implanted tri-layered PLLA nanosheets displayed sustained release of loaded rhFGF-2 for 2 weeks. In critical-sized mouse femoral defects, tri-layered nanosheets loaded with rhFGF-2 most efficiently induced bone regeneration. Notably, bone regeneration was enhanced even after 4 weeks in the tri-layered nanosheet group, and was accompanied by FGFR1 activation and subsequent osteoblast differentiation. Multi-layered PLLA nanosheets loaded with rhFGF-2 may be useful for bone regenerative medicine. Furthermore, the multi-layered PLLA nanosheet structure may potentially be applied as a potent sustained-release carrier.

(Invited) Ultra-Flexible Polymer Nanosheet for Bio and Electronics Applications

Integration of flexible devices into the living system is expected for advancing medical and healthcare devices, which will realize investigation of biological information at nano-biointerface. Such devices should be compatible to physical and mechanical properties of biological tissues. In this talk, we introduce free-standing polymeric ultra-thin films (referred to as “polymer nanosheets”) as a unique platform of ultra-flexible devices, which comprise tens- to hundreds-of-nanometer thickness close to the scale of biomembranes1. Various polymers (e.g., biodegradable polymers, conductive polymers, elastomers) are applicable as building blocks of polymer nanosheets; those are processed by spincoating, layer-by-layer and gravure coating techniques. The resulting nanosheets showed flexible and physically adhesive property owing to their ultra-thin structure. Polymer nanosheets are also functionalized by printing conductive polymers, nanomaterials or embedding thermo-sensitive dyes2-4. These nanosheet-based devices revealed several types of physiological properties in living organisms at different length scale from cell to tissue to body via functionalized interface, exemplified by temperature mapping of living muscle tissues and electromyogram of human bodies. The nanosheet technology will open a new avenue in the field of biotechnology and biomedicine. References T. Fujie, Polym. J., 2016, 48, 773.A. Zucca, K. Yamagishi, T. Fujie, S. Takeoka, V. Mattoli, F. Greco, J. Mater. Chem. C, 2015, 3, 6539.T. Miyagawa, T. Fujie, Ferdinandus, T. T. Vo Doan, H. Sato, S. Takeoka, ACS Appl. Mater. Interfaces, 2016, 8, 33377.M. Okamoto, M. Kurotobi, S. Takeoka, J. Sugano, E. Iwase, H. Iwata, T. Fujie, J. Mater. Chem. C, 2017, 5, 1321.

Two-Dimensional Proton Conduction in Biomimetic Polymer Electrolytes Prepared the Polymer Nanosheet Multilayer Film

1．Introduction Organic materials which efficiently transport protons are used in various energy harvesting such as fuel cells and ATP production. Recently, it has been reported that proton transport in the organic materials can be controlled by electric field. [1] In general, protons are transported in two dimension in the protonic transistor, which suggest the importance of fabricating two dimensional proton conductive channel. Biological membrane is a good example for such two dimensional proton conduction. Thus we mimicked the proton conduction at the biological membrane by using polymer nanosheet multilayer film. [2] [3] In this study, we introduce amphoteric group, phosphonic acid to the polymer nanosheet multilayer film. The proton conductivity through the interlayer of the multilayer film was studied by impedance spectroscopy and the mechanism of two dimensional conduction was proposed. 2．Experiment N-dodecylacryamide-co-phosphonic acid copolymers, [p(DDA/VPA)] (Fig. 1) were synthesized by free radical copolymerization of DDA with VPA in ethanol. The monolayer properties of p(DDA/VPA) were investigated by π−A isotherm measurements. The polymer was depositioned on a substrate using the Langmuir-Blodgett (LB) method and film was characterized by X-ray diffraction (XRD) measurement. p(DDA/VPA) was deposited on the substrate with comb-type Au electrode to study the proton conductivity by impedance measurements. 3．Result and discussion The syntheses of p(DDA/VPA) copolymer were confirmed from 1H-NMR and FT-IR. The mole fractions of VPA in the copolymers (n) were determined to be 0.19〜0.52, by elemental analysis. π-A isotherms in all copolymers showed a steep rise in surface pressure and relatively high collapse pressure, indicating that the copolymers formed a densely packed polymer monolayer. The average limiting surface area of VPA suggested that the VPA units were located below the water surface. The lamellar structure of the nanosheet multilayer film prepared using the LB was confirmed by X-ray diffraction measurement. Because the interlayer space increased with n, p(DDA/VPA) formed a multilayer in which a phosphonic acid group is sandwiched between hydrophilic sites (Fig. 2). The proton conductivity parallel to the lamellar plane direction increased with VPA content until n = 0.41 and became 2.6 × 10-2 S cm-1 at 60 ˚C and 98% RH(Fig. 3). Interestingly, the conductivity of n = 0.45 decreased to 1.0×10-2 S cm-1 nevertheless the number of proton source was increased. From the result, we suggest that there is an optimal distance of acid group to achieve a high proton conduction in two dimensional nanospaces. [4] 5．Acknowledgments This work was supported by the Research Program “Dynamic Alliance for Open Innovation Bridging Human, Environment and Materials” within the “Network Joint Research Center for Materials and Devices”. 6．References [1] C. Zhong, et al. Nat. Comm, 2011, 2, 476. [2] T. Sato et al., Langmuir, 2017, 33 (45), 12897–12902. [3] T. Sato et al., Langmuir, 2015, 31 (18), 5174–5180. [4] V. B. P. Leite et al., Phys. Rev. E, 1998, 57, 6835-6839 Figure 1

Polymer Nanosheet Containing Star-Like Copolymers: A Novel Scalable Controlled Release System.

Poly(ε-caprolactone) (PCL)-based nanomaterials, such as nanoparticles and liposomes, have exhibited great potential as controlled release systems, but the difficulties in large-scale fabrication limit their practical applications. Among the various methods being developed to fabricate polymer nanosheets (PNSs) for different applications, such as Langmuir-Blodgett technique and layer-by-layer assembly, are very effort consuming, and only a few PNSs can be obtained. In this paper, poly(ε-caprolactone)-based PNSs with adjustable thickness are obtained in large quantity by simple water exposure of multilayer polymer films, which are fabricated via a layer multiplying coextrusion method. The PNS is also demonstrated as a novel controlled guest release system, in which release kinetics are adjustable by the nanosheet thickness, pH values of the media, and the presence of protecting layers. Theoretical simulations, including Korsmeyer-Peppas model and Finite-element analysis, are also employed to discern the observed guest-release mechanisms.

A high-capacity and long-life aqueous rechargeable zinc battery using a porous metal–organic coordination polymer nanosheet cathode

Aqueous zinc ion batteries (AZIBs) have received increasing attention because of their low cost, environmental benefits and material abundance.

Sandwich-type PLLA-nanosheets loaded with BMP-2 induce bone regeneration in critical-sized mouse calvarial defects.

Here we describe sandwich-type poly(L-lactic acid) (PLLA) nanosheets loaded with recombinant human bone morphogenetic protein-2 (rhBMP-2) as a novel method for bone regeneration. Biodegradable 60-nm-thick PLLA nanosheets display strong adhesion without any adhesive agent. The sandwich-type PLLA nanosheets displayed constant and sustained release of the loaded rhBMP-2 for over 2months in vitro. The nanosheets with rhBMP-2 markedly enhanced bone regeneration when they were implanted into critical-sized defects in mouse calvariae. In addition to their application for bone regeneration, PLLA nanosheets may be useful for various purposes in combination with various drugs or molecules, because they displays excellent capacity as a sustained-release carrier.