Hollow Nanocones Research Articles

Facile Synthesis of Organic–Inorganic Hybrid Layered Rare‐Earth Hydroxide Nanocone for Multifunctional Drug Delivery System with Fluorescence Probe and Simultaneous Magnetic Resonance Imaging

AbstractTo fulfill the emerging demand for drug therapy, the Y/Tb/Gd ternary layered rare‐earth hydroxide nanocone is developed as a new multifunctional delivery system for one of the most popular drugs, aspirin. Dodecyl sulfate intercalation is firstly used for the drug carrier which can form hollow nanocones and owns low binding energy, leading to the facile synthesis of organic–inorganic hybrid drug delivery system. The aspirin can be loaded rapidly (as short as 5 min) and released continuously (as long as 48 h) by YTG system through anion exchange, which will be favorable for sustained therapy. Meanwhile, the intercalated aspirin can enhance the green light luminescence of Tb3+ with peak position at 543 nm through energy transfer, which can be utilized as fluorescence probe to monitor the drug loading and release process. The magnetization of Gd3+ can also be improved by structural evolution induced by aspirin intercalation, which can be applied as magnetic resonance imaging contrast agent simultaneously. The current research provides a novel pathway for the invention of multifunctional drug delivery system, which hopefully is to be put into service in biomedical fields in the near future.

Plasmonic Sensor and Surface Enhanced Fluorescence Imaging Based on Hollow Nanocone Arrays

Hollow nanocone arrays are fabricated by a low-cost and efficient colloidal lithography (CL) technique. The hollow nanocone arrays are then reversed to make only the tips contact the substrate. The optical properties of the obverse and inverse hollow nanocone arrays are determined by the surrounding environment, showing different reflection spectra and structure dependence. The inverse hollow nanocone arrays show a relative index sensitivity of 70% per RIU with strict linearity. The fluorescence of fluorophore or staining cells can be facilely enhanced by placing them on the tips of the hollow nanocone arrays, while having no quenching effect. The study of the obverse and inverse hollow nanocone arrays can benefit the understanding of the effect of the environment on the plasmonic resonances. The hollow nanocone arrays are promising to serve as high-performance plasmonic sensors and versatile substrates for surface-enhanced fluorescence imaging.

Fabrication of Hollow Nanocones Membrane with an Extraordinary Surface Area as CO2 Sucker.

Recently, more and more attention has been paid to the development of eco-friendly solid sorbents that are cost-effective, noncorrosive, have a high gas capacity, and have low renewable energy for CO2 capture. Here, we claimed the fabrication of a three-dimensional (3D) film of hollow nanocones with a large surface area (949.5 m2/g), a large contact angle of 136.3°, and high surface energy. The synthetic technique is based on an electrochemical polymerization process followed by a novel and simple strategy for pulling off the formed layers as a membrane. Although the polymer-coated substrates were reported previously, the membrane formation has not been reported elsewhere. The detachable capability of the manufactured layer as a membrane braked the previous boundaries and allows the membrane’s uses in a wide range of applications. This 3D hollow nanocones membrane offer advantages over conventional ones in that they combine a π-electron-rich (aromatic ring), hydrophobicity, a large surface area, multiple amino groups, and a large pore volume. These substantial features are vital for CO2 capturing and storage. Furthermore, the hydrophobicity characteristic and application of the formed polymer as a CO2 sucker were investigated. These results demonstrated the potential of the synthesized 3D hollow polymer to be used for CO2 capturing with a gas capacity of about 68 mg/g and regeneration ability without the need for heat up.

Hierarchical Control of Plasmonic Nanochemistry in Microreactor.

A microreactor that can confine chemical reactions exclusively in tiny vessels with the volume of ∼0.015 μm3 is introduced. Aluminum inversed hollow nanocone arrays (IHNAs) are fabricated by a simple and efficient colloidal lithography method. Ag and Au nanoparticles (NPs), as well as polypyrrole, grow exclusively in the conic cavities under light illumination. The photocatalytic effect arising from the plasmonic enhanced electric fields (E-fields) of IHNAs boosts the reactions and is in charge of the submicrometer site-selectivity. By partially inhibiting light to IHNAs, various hierarchical patterns at the macro-, micro-, and sub-microscale are obtained, inspiring a facile patterning technique by varying the light source. In addition, the Al IHNA films are transferred to flexible and curved substrates with unchanged performances, showing high flexibility for wide applications. Microreactors based on the IHNAs will contribute to the control of chemical reactions at different dimensions and offer great potentials in developing novel nanofabrication techniques.

Microstructural Engineering of Heterogeneous P−S−Co Interface for Oxygen and Hydrogen Evolution

AbstractFabricating and engineering heterointerface was an effective approach to improve electrochemical activity of catalysts through modulating their atomic arrangement and chemical states. Herein, cobalt phosphide and cobalt sulfide (CoP/CoSx) heterostructure hollow nanocones were fabricated by an in situ ion intercalation template‐assisted method. The microstructure of the heterointerface could be adjusted by changing the molar ratio of S/P. Electrochemical investigation revealed that the disordered structures at the heterointerface could influence the catalytic behavior of active sites. Rationally engineering the disordered structure could improve the electrocatalytic activity for oxygen and hydrogen evolution reactions (OER/HER). The optimized CoP/CoSx heterostructure exhibited favorable catalytic activity for OER, which delivered an overpotential at 10 mA cm−2 of 313 mV and a Tafel slope (93 mV dec−1) in alkaline media. Meanwhile, the optimized CoP/CoSx heterostructure also exhibited superior HER performance under acidic condition.

Volume-Enhanced Raman Scattering Detection of Viruses.

Virus detection and analysis are of critical importance in biological fields and medicine. Surface-enhanced Raman scattering (SERS) has shown great promise in small molecule and even single molecule detection, and can provide fingerprint signals of molecules. Despite the powerful detection capabilities of SERS, the size discrepancy between the SERS "hot spots" (generally, <10 nm) and viruses (usually, sub-100 nm) yields poor detection reliability of viruses. Inspired by the concept of molecular imprinting, a volume-enhanced Raman scattering (VERS) substrate composed of hollow nanocones at the bottom of microbowls (HNCMB) is developed. The hollow nanocones of the resulting VERS substrates serve a twofold purpose: 1) extending the region of Raman signal enhancement from the nanocone surface (e.g., surface "hot spots") to the hollow area within the cone (e.g., volume "hot spots")-a novel method of Raman signal enhancement, and 2) directing analyte such as viruses of a wide range of sizes to those VERS "hot spots" while simultaneously increasing the surface area contributing to SERS. Using HNCMB VERS substrates, greatly improved Raman signals of single viruses are demonstrated, an achievement with important implications in disease diagnostics and monitoring, biomedical fields, as well as in clinical treatment.

Free-Standing Plasmonic Chiral Metamaterials with 3D Resonance Cavities.

Hollow nanocone array (HNCA) films (cm × cm), composed of two Ag and Au nanoshells, are fabricated via a low-cost and efficient colloidal lithography technique. The relative position of the Ag and Au nanoshells can be controlled to generate various chiral asymmetries. A pronounced chiroptical response is observed in the ultraviolet-visible region with the anisotropy factor up to 10-1, which is rooted in the asymmetric current oscillations and electric field distributions. Beyond previous reports on plasmonic chiral metamaterials, the HNCA can be free-standing and further transferred to other functional and flexible substrates, such as polydimethylsiloxane (PDMS), highly curved surfaces, prepatterned films, and hydrogels, while keeping the original features. The good transferability would make HNCA more flexible in specific applications. Furthermore, the chiral HNCAs offer a series of chiral resonance cavities, which are conducive for the research of chiral sensing, confinement, chiral signal transmission, and amplification. Overall, this work provides a scalable metamaterial to tune the plasmonic chiral response, and HNCA would be a promising candidate of the components in chiral optical devices and sensors.

Light Trapping in Plasmonic Nanovessels

Inverse hollow nanocone arrays are fabricated by an efficient colloidal lithography technique and a facile transfer process. These structures have the peculiar features of nanobeakers, which may be promising reaction vessels. Local field distribution near this beaker and the influence on optical properties are investigated. A majority of light at the resonance wavelength can be trapped in the cavity due to multiple internal reflections in the cone and coupling with the surface plasmon of the nanostructures. Due to the strongly enhanced electric field distributed in air, the resonant reflection dip shows sensitive response to changes of the surrounding environment, with excellent linearity and relative sensitivity up to 62% per refractive index unit (RIU). Moreover, the Raman signal becomes much weaker when excited at the resonance wavelength, demonstrating the strong ability of trapping light. This nanostructure and the investigation of the plasmonic performances may contribute to the generation of nanovessels for optical tweezers and plasmon‐assisted chemistry.

Smart pattern display by tuning the surface plasmon resonance of hollow nanocone arrays.

Patterns of hollow nanocone array films can be hidden in air and made to appear due to a solvent, enabling a smart method to hide information that can be recovered by a change of the environment.

Hollow LiMn2O4 Nanocones as Superior Cathode Materials for Lithium‐Ion Batteries with Enhanced Power and Cycle Performances

Single-crystalline LiMn(2)O(4) hollow nanocones are synthesized via a template-engaged low-temperature lithiation reaction. When applied as cathode materials for lithium-ion batteries, they can deliver a high specific capacity of 127.1 mAh g(-1) at 0.1 C and the capacity still maintains 100 mAh g(-1) even at 50°C. After over 1000 cycles at 5°C, 94.8% of the initial capacity is retained.

Resonant Optical Transmission through Topologically Continuous Films

A continuous thick (≥ 100 nm) Ag film is generally optically nontransparent, but here we show that via a dedicated structuring it can be made transparent. The enhanced optical transmission is realized by preparing metal films with a periodic array of hollow nanocones via an inexpensive and versatile colloidal lithography technique. These topologically continuous films possess the structural feature of sharp top tips and bottom nanoholes, leading to an effective resonance mode of coupling between the surface plasmons around the holes and cone tips. This introduces a resonant optical transmission that is much affected by the thickness and height of the hollow nanocones. Moreover, the topologically continuous films are highly sensitive to the surrounding environment, indicating great potential for plasmonic sensors. The experimental results are in good agreement with numerical simulations. On the basis of the hollow element and enhanced optical performance, hollow nanocone array films can be used as photosensitive microreactors, isolated cell culture bases, etc. This provides a combination of high optical sensitivity and chemistry in microcavities.

Mesoporous CeO2 nanoparticles assembled by hollow nanostructures: formation mechanism and enhanced catalytic properties

In this paper, novel hierarchically mesoporous CeO2 nanoparticles assembled by hollow nanocones were prepared through a facile solvothermal strategy using Ce(HCOO)3 as the precursor.

Hydrothermal synthesis of hollow Mn2O3 nanocones as anode material for Li-ion batteries

Novel Mn2O3 hollow nanocones have been successfully prepared as a lithium ion batteries anode material by a hydrothermal then annealing process, which exhibited a high specific capacity of ∼900 mA h g−1 at 50 mA g−1 with intriguing rate performance and cycling stability.

Fabrication of highly ordered CuInSe 2 films with hollow nanocones for anti-reflection

Highly ordered CuInSe 2 films with hollow nanocones were fabricated by electron beam evaporation and nanospheres lithograph. From the AFM analyses, polystyrene nanospheres with diameter of 220 nm are assembled regularly on glass substrates. After reaction ion etching under different powers and residues removal, different and new surface morphologies of substrates have been obtained, such as smooth nanocones and hollow nanocones. The diffuse reflection spectra demonstrate that films on the substrates with periodic nanopatterned structure have less reflection over wavelengths ranged from 200 nm to 2500 nm due to light trapping. Especially, reflection for hollow nanocone arrays has the larger suppression value than nanocone-patterned films, which proves that surface pattern of hollow nanocones has better anti-reflection effect. Furthermore, while hollow depth increases from 6 nm to 9 nm, its optical antireflective effect becomes remarkable. These results could yield new options for solar-cell design with higher energy conversion efficiency.

Selective heterogeneous oriented attachment of manganese oxide nanorods in water: toward 3D nanoarchitectures

MnOOH and MnO2 polymorphs are synthesized using a reaction between Mn2+and MnO4− in water at low temperature (95 °C). Nanoparticles are characterized using powder XRD, TEM and electron diffraction. Depending on the acidity of the aging medium, γ-MnO2 compounds are shown to be obtained as nanorods (final pH = 2.0) or hollow nanocones (3.6 ≤ final pH ≤ 4.5). The external faces of the cones originate from heterogeneous oriented attachment of α-MnOOH nanorods on early cones. The selective attachment between (−110)γ–MnO2 and (101)α–MnOOH faces is discussed by taking into account the surface charge of the primary particles and the reactivity of the Mn–OHx surface groups. This study underlines the role of the electrostatic repulsions and the surface reactivity in the oriented attachment mechanism in water for oxides.