Development of a structure-switching aptamer-based nanosensor for salicylic acid detection.

Salicylic acid (SA) is a phytohormone regulating immune responses against pathogens. SA and its derivatives can be found in diverse food products, medicines, cosmetics and preservatives. While salicylates have potential disease-preventative activity, they can also cause health problems to people who are hypersensitive. The current SA detection methods are costly, labor-intensive and require bulky instruments. In this study, a structure-switching aptamer-based nanopore thin film sensor was developed for cost-effective, rapid, sensitive and simple detection of SA in both buffer and plant extracts. SA is a challenging target for aptamer selection using conventional systemic evolution of ligands by exponential enrichment (SELEX) due to its small size and scarcity of reactive groups for immobilization. By immobilizing the SELEX library instead of SA and screening the library using a structure-switching SELEX approach, a high affinity SA aptamer was identified. The nanopore thin film sensor platform can detect as low as 0.1 µM SA. This is much better than the sensitivity of antibody-based detection method. This nanosensor also exhibited good selectivity among SA and its common metabolites and can detect SA in Arabidopsis and rice using only about 1 µl plant extracts within less than 30 min. The integration of SA aptamer and nanopore thin film sensor provides a promising solution for low-cost, rapid, sensitive on-site detection of SA.

Wavelet Denoising of High-Bandwidth Nanopore and Ion-Channel Signals.

Recent work has pushed the noise-limited bandwidths of solid-state nanopore conductance recordings to more than 5 MHz and of ion channel conductance recordings to more than 500 kHz through the use of integrated complementary metal-oxide-semiconductor (CMOS) integrated circuits. Despite the spectral spread of the pulse-like signals that characterize these recordings when a sinusoidal basis is employed, Bessel filters are commonly used to denoise these signals to acceptable signal-to-noise ratios (SNRs) at the cost of losing many of the faster temporal features. Here, we report improvements to the SNR that can be achieved using wavelet denoising instead of Bessel filtering. When combined with state-of-the-art high-bandwidth CMOS recording instrumentation, we can reduce baseline noise levels by over a factor of 4 compared to a 2.5 MHz Bessel filter while retaining transient properties in the signal comparable to this filter bandwidth. Similarly, for ion-channel recordings, we achieve a temporal response better than a 100 kHz Bessel filter with a noise level comparable to that achievable with a 25 kHz Bessel filter. Improvements in SNR can be used to achieve robust statistical analyses of these recordings, which may provide important insights into nanopore translocation dynamics and mechanisms of ion-channel function.

The molecularly imprinted polymer supported by anodic alumina oxide nanotubes membrane for efficient recognition of chloropropanols in vegetable oils.

A new route to synthesize a covalent interaction-based molecularly imprinted polymer (MIP) material for 3-chloro-1,2-propanediol (3-MCPD) inside the nanopores of anodic alumina oxide (AAO) is presented. A series of adsorption experiments showed MIP had good extraction capacity and selectivity for 3-MCPD. In order to evaluate the usability of the MIP nanotubes membrane, a method combining AAO@MIP membrane extraction with gas chromatography - mass spectrometry (GC-MS) detection was developed for determination of chloropropanols. The limits of detection for the proposed method were 0.072 and 0.13 µg·L-1, respectively, for 3-MCPD and 1,3-DCP. The average recoveries of 3-MCPD and 1,3-DCP spiked oil samples at three concentrations (0.01, 0.05 and 0.1 mg·kg-1) were in the range of 75.6-101.0% with a RSD of 3.3-8.4%, indicating the method would be suitable for determination of chloropropanols in vegetable oils.

An aptamer nanopore-enabled microsensor for detection of theophylline.

This paper reports an aptamer-based nanopore thin film sensor for detecting theophylline in the buffer solution and complex fluids including plant extracts and serum samples. Compared to antibody-based detection, aptamer-based detection offers many advantages such as low cost and high stability at elevated temperatures. Experiments found that this type of sensor can readily detect theophylline at a concentration as low as 0.05µM, which is much lower than the detection limit of current lab-based equipment such as liquid chromatography (LC). Experiments also found that the aptamer-based sensor has good specificity, selectivity, and reasonable reusability with a significantly improved dynamic detection range. By using the same nanopore thin film sensors as the reference sensors to further mitigate the non-specific binding effect, the theophylline in plant extracts and serum has been detected. Only a small amount (~1µL) of plant extracts or serum samples is required to measure theophylline. Its low cost and ease-of-operation make this type of sensor suitable for point-of-care application to monitor the theophylline level of patients in real time.

Synergistic chemo-photothermal therapy of tumor by hollow carbon nanospheres.

Combined use of different therapies is conducive to improve the effectiveness of cancer therapy. The chemo-photothermal therapy is commonly used in one nanocarrier to provide an excellent synergistic effect for cancer therapy over photothermal therapy (PTT) or chemotherapy alone. In this study, biocompatible and monodisperse hollow carbon nanospheres (HCNs) were developed as a multifunctional platform for the delivery of paclitaxel (PTX) and PTT of cancer simultaneously. The mesoporous HCNs have large pore volume and proper channels for loading and release of PTX. Upon near-infrared (NIR) laser illumination, the photothermal mediator of HCNs could effectively convert absorbed light into heat, which triggered rapid release of chemotherapeutic drug from HCNs through dissociating the interactions between PTX and HCNs by heat energy. A large number of tumor cells were significantly destroyed when hct116 cells treated with PTX@HCNs were irradiated, which was mainly attribute to the synergistic result of HCNs-mediated photothermal damage and cytotoxicity of light-triggered PTX release.

Enhanced Therapeutic Treatment of Colorectal Cancer Using Surface-Modified Nanoporous Acupuncture Needles.

Acupuncture originated within the auspices of Oriental medicine, and today is used as an alternative method for treating various diseases and symptoms. The physiological mechanisms of acupuncture appear to involve the release of endogenous opiates and neurotransmitters, with the signals mediating through electrical stimulation of the central nervous system (CNS). Earlier we reported a nanoporous stainless steel acupuncture needle with enhanced therapeutic properties, evaluated by electrophysiological and behavioral responses in Sprague-Dawley (SD) rats. Herein, we investigate molecular changes in colorectal cancer (CRC) rats by acupuncture treatment using the nanoporous needles. Treatment at acupoint HT7 is found most effective at reducing average tumor size, ß-catenin expression levels, and the number of aberrant crypt foci in the colon endothelium. Surface modification of acupuncture needles further enhances the therapeutic effects of acupuncture treatment in CRC rats.

Periodic Arrays of Phosphorene Nanopores as Antidot Lattices with Tunable Properties.

A tunable band gap in phosphorene extends its applicability in nanoelectronic and optoelectronic applications. Here, we propose to tune the band gap in phosphorene by patterning antidot lattices, which are periodic arrays of holes or nanopores etched in the material, and by exploiting quantum confinement in the corresponding nanoconstrictions. We fabricated antidot lattices with radii down to 13 nm in few-layer black phosphorus flakes protected by an oxide layer and observed suppression of the in-plane phonon modes relative to the unmodified material via Raman spectroscopy. In contrast to graphene antidots, the Raman peak positions in few-layer BP antidots are unchanged, in agreement with predicted power spectra. We also use DFT calculations to predict the electronic properties of phosphorene antidot lattices and observe a band gap scaling consistent with quantum confinement effects. Deviations are attributed primarily to self-passivating edge morphologies, where each phosphorus atom has the same number of bonds per atom as the pristine material so that no dopants can saturate dangling bonds. Quantum confinement is stronger for the zigzag edge nanoconstrictions between the holes as compared to those with armchair edges, resulting in a roughly bimodal band gap distribution. Interestingly, in two of the antidot structures an unreported self-passivating reconstruction of the zigzag edge endows the systems with a metallic component. The experimental demonstration of antidots and the theoretical results provide motivation to further scale down nanofabrication of antidots in the few-nanometer size regime, where quantum confinement is particularly important.

Polymeric lithography editor: Editing lithographic errors with nanoporous polymeric probes.

A new lithographic editing system with an ability to erase and rectify errors in microscale with real-time optical feedback is demonstrated. The erasing probe is a conically shaped hydrogel (tip size, ca. 500 nm) template-synthesized from track-etched conical glass wafers. The "nanosponge" hydrogel probe "erases" patterns by hydrating and absorbing molecules into a porous hydrogel matrix via diffusion analogous to a wet sponge. The presence of an interfacial liquid water layer between the hydrogel tip and the substrate during erasing enables frictionless, uninterrupted translation of the eraser on the substrate. The erasing capacity of the hydrogel is extremely high because of the large free volume of the hydrogel matrix. The fast frictionless translocation and interfacial hydration resulted in an extremely high erasing rate (~785 µm2/s), which is two to three orders of magnitude higher in comparison with the atomic force microscopy-based erasing (~0.1 µm2/s) experiments. The high precision and accuracy of the polymeric lithography editor (PLE) system stemmed from coupling piezoelectric actuators to an inverted optical microscope. Subsequently after erasing the patterns using agarose erasers, a polydimethylsiloxane probe fabricated from the same conical track-etched template was used to precisely redeposit molecules of interest at the erased spots. PLE also provides a continuous optical feedback throughout the entire molecular editing process-writing, erasing, and rewriting. To demonstrate its potential in device fabrication, we used PLE to electrochemically erase metallic copper thin film, forming an interdigitated array of microelectrodes for the fabrication of a functional microphotodetector device. High-throughput dot and line erasing, writing with the conical "wet nanosponge," and continuous optical feedback make PLE complementary to the existing catalog of nanolithographic/microlithographic and three-dimensional printing techniques. This new PLE technique will potentially open up many new and exciting avenues in lithography, which remain unexplored due to the inherent limitations in error rectification capabilities of the existing lithographic techniques.

Rational Design of Branched Nanoporous Gold Nanoshells with Enhanced Physico-Optical Properties for Optical Imaging and Cancer Therapy.

Reported procedures on the synthesis of gold nanoshells with smooth surfaces have merely demonstrated efficient control of shell thickness and particle size, yet no branch and nanoporous features on the nanoshell have been implemented to date. Herein, we demonstrate the ability to control the roughness and nanoscale porosity of gold nanoshells by using redox-active polymer poly(vinylphenol)-b-(styrene) nanoparticles as reducing agent and template. The porosity and size of the branches on this branched nanoporous gold nanoshell (BAuNSP) material can be facilely adjusted by control of the reaction speed or the reaction time between the redox-active polymer nanoparticles and gold ions (Au3+). Due to the strong reduction ability of the redox-active polymer, the yield of BAuNSP was virtually 100%. By taking advantage of the sharp branches and nanoporous features, BAuNSP exhibited greatly enhanced physico-optical properties, including photothermal effect, surface-enhanced Raman scattering (SERS), and photoacoustic (PA) signals. The photothermal conversion efficiency can reach as high as 75.5%, which is greater than most gold nanocrystals. Furthermore, the nanoporous nature of the shells allows for effective drug loading and controlled drug release. The thermoresponsive polymer coated on the BAuNSP surface serves as a gate keeper, governing the drug release behavior through photothermal heating. Positron emission tomography imaging demonstrated a high passive tumor accumulation of 64Cu-labeled BAuNSP. The strong SERS signal generated by the SERS-active BAuNSP in vivo, accompanied by enhanced PA signals in the tumor region, provide significant tumor information, including size, morphology, position, and boundaries between tumor and healthy tissues. In vivo tumor therapy experiments demonstrated a highly synergistic chemo-photothermal therapy effect of drug-loaded BAuNSPs, guided by three modes of optical imaging.

Label-Free, Multiplexed, Single-Molecule Analysis of Protein-DNA Complexes with Nanopores.

Protein interactions with specific DNA sequences are crucial in the control of gene expression and the regulation of replication. Single-molecule methods offer excellent capabilities to unravel the mechanism and kinetics of these interactions. Here, we develop a nanopore approach where a target DNA sequence is contained in a hairpin followed by a ssDNA. This system allows DNA-protein complexes to be distinguished from bare DNA molecules as they are pulled through a single nanopore detector, providing both equilibrium and kinetic information. We show that this approach can be used to test the inhibitory effect of small molecules on complex formation and their mechanisms of action. In a proof of concept, we use DNAs with different sequence patterns to probe the ability of the nanopore to distinguish the effects of an inhibitor in a complex mixture of target DNAs and proteins. We anticipate that the use of this technology with arrays of thousands of nanopores will contribute to the development of transcription factor binding inhibitors.

A photoresponsive and rod-shape nanocarrier: Single wavelength of light triggered photothermal and photodynamic therapy based on AuNRs-capped & Ce6-doped mesoporous silica nanorods.

Rod-shape nanocarriers have attracted great interest because of their better cell internalization capacity and higher drug loading properties. Besides, the combination of photodynamic therapy (PDT) and photothermal therapy (PTT) holds great promise to overcome respective limitations of the anti-cancer treatment. In this work, we first report Au nanorods-capped and Ce6-doped mesoporous silica nanorods (AuNRs-Ce6-MSNRs) for the single wavelength of near infrared (NIR) light triggered combined phototherapy. AuNRs-Ce6-MSNRs are not only able to generate hyperthermia to perform PTT effect based on the AuNRs, but also can produce singlet oxygen (1O2) for PDT effect based on Ce6 after uncapping of AuNRs under the single NIR wavelength irradiation. In addition, the combined therapy can be dual-imaging guided by taking the photoacoustic (PA) and NIR fluorescence (NIRF) imaging of AuNRs and Ce6, respectively. What's more, by utilizing the special structure of MSNRs, this nanocarrier can serve as a drug delivery platform with high drug loading capacity and enhanced cellular uptake efficiency. The multi-functional nanocomposite is designed to integrate photothermal and photodynamic therapy, in vivo dual-imaging into one system, achieving synergistic anti-tumor effects both in vitro and in vivo.

Hemin on graphene nanosheets functionalized with flower-like MnO2 and hollow AuPd for the electrochemical sensing lead ion based on the specific DNAzyme.

Herein, integrated with DNAzyme highly specific to metal ions, hemin@reduced graphene oxide (hemin@rGO) functionalized with flower-like MnO2 and hollow AuPd (hAuPd-fMnO2-hemin@rGO) was used as electroactive probe and electrocatalyst to construct a universal platform for metal ion detection (lead ion Pb(2+) as the model). The proposed strategy with generality was mainly based on two aspects. Firstly, the designed probe not only showed high stability and excellent peroxidase-like activity originating from hemin, fMnO2 and hAuPd, but also possessed intrinsic redox performance from hemin, which resulted in the promotion of electron transfer and the enhancement of the response signal readout. Secondly, due to the introduction of Pb(2+), Pb(2+)-dependent DNAzyme bound in the electrode surface could be specifically identified and cleaved by Pb(2+), and the remained fragment (its supplementary sequence is a single-strand DNA S3) captured the nanocomposites S3-hAuPd-fMnO2-hemin@rGO by the hybridization reaction. Therefore, combined the cooperative catalysis of fMnO2, hAuPd and hemin to H2O2 reduction with highly specific interaction of Pb(2+)-dependent DNAzyme, the proposed Pb(2+) biosensor showed significant improvement of electrochemical analytical performance, which was involved in wide dynamic response in the range of 0.1pM-200nM, low detection limit of 0.034pM, high sensitivity and high specificity. This could facilitate the universal strategy to be a promising method for detection of other metal ions, only changing the corresponding DNAzyme specific to them.

Microtensile Bond Strength of Resin-bonded Hightranslucency Zirconia Using Different Surface Treatments.

PURPOSE: To evaluate the effect of a novel surface treatment intended to improve bond strength to high-translucency zirconia. MATERIALS AND METHODS: Fully sintered high-translucency zirconia disks (Incoris TZI) were divided into four groups according to the surface treatment received: modified fusion sputtering technique, selective infiltration etching, low pressure particle abrasion using 30-µm alumina particles, while 50-µm particle abrasion served as control. Surface roughness was evaluated quantitatively using a contact profilometer. The disks were bonded to pre-aged composite resin disks using a light-polymerized adhesive resin (RelyX ultimate). The bilayered disks were sectioned into microbars and zirconia-resin bond strength was evaluated using the microtensile bond strength test (MTBS). The test was repeated after 3 months of water storage (37°C). Scanning electron microscopic examination of the zirconia resin interface was performed at different magnifications. A repeated measures ANOVA and Bonferroni post-hoc test were used to analyze the data (n = 20, α = 0.05). RESULTS: One-way ANOVA revealed significant differences in average surface roughness (Ra) between the tested groups (p < 0.001). The highest Ra value was recorded for fusion sputtering (12.23 ± 0.11 µm), followed by 50-µm particle abrasion (6.400 ± 0.887), then low pressure 30-µm particle abrasion (2.4 ± 0.15 µm), while the lowest surface roughness was recorded for the selective infiltration group (0.368 ± 0.04 µm). Modified fusion sputtering and selective infiltration etching produced significantly higher MTBS values at each of the tested intervals (p < 0.001) compared to particle abrasion using different particle sizes. Water storage resulted in reduction in the bond strength of 30-µm abraded specimens, which was attributed to structural defects observed at the zirconia/ resin interface. Scanning electron microscopic examination revealed a nanoporous surface characteristic of selective etching surface treatment, and modified fusion sputtering resulted in the creation of surface-fused microbeads. CONCLUSION: Within the limitations of this study, selective infiltration etching and modified fusion sputtering techniques established a strong, stable, durable bond to high-translucency zirconia.

Structural Transformation of Diblock Copolymer/Homopolymer Assemblies by Tuning Cylindrical Confinement and Interfacial Interactions.

In this study, we report the controllable structural transformation of block copolymer/homopolymer binary blends in cylindrical nanopores. Polystyrene-b-poly(4-vinylpyridine)/homopolystyrene (SVP/hPS) nanorods (NRs) can be fabricated by pouring the polymers into an anodic aluminum oxide (AAO) channel and isolated by selective removal of the AAO membrane. In this two-dimensional (2D) confinement, SVP self-assembles into NRs with concentric lamellar structure, and the internal structure can be tailored with the addition of hPS. We show that the weight fraction and molecular weight of hPS and the diameter of the channels can significantly affect the internal structure of the NRs. Moreover, mesoporous materials with tunable pore shape, size, and packing style can be prepared by selective solvent swelling of the structured NRs. In addition, these NRs can transform into spherical structures through solvent-absorption annealing, triggering the conversion from 2D to 3D confinement. More importantly, the transformation dynamics can be tuned by varying the preference property of surfactant to the polymers. It is proven that the shape and internal structure of the polymer particles are dominated by the interfacial interactions governed by the surfactants.

Sodium Hydroxide Activated Nanoporous Carbons Based on Lapsi Seed Stone.

Nanoporous activated carbons (ACs) were prepared from Lapsi (Choerospondias axillaris) seed powder by chemical activation with sodium hydroxide (NaOH) at different NaOH impregnation ratios. The prepared ACs were characterized by Fourier transform-infrared (FTIR) spectroscopy, Raman scattering, X-ray diffraction (XRD), and scanning electron microscopy (SEM). Semi-quantitative information on the surface properties was obtained by estimating iodine number. FTIR spectra showed the presence of oxygenated functional groups such as hydroxyl, carbonyl, and carboxyl in the prepared ACs. Raman scattering showed clear D and G bands in the spectra. The intensity ratio of G and D band peak intensity was ca. 1.39 at lowest NaOH and Lapsi seed powder ratio 0.25:1 showing high graphitic degree. This ratio decreased with increase in the NaOH impregnation ratio and reached minimum ca. 0.94 (comparable with commercial AC) at NaOH and Lapsi seed powder ratio 1:1 demonstrating that higher NaOH impregnation reduces the graphitic structure of the carbon. XRD patterns showed two broad peaks at diffraction angles of approximately 25 and 43 degrees indicating the amorphous structure. Surface properties of the ACs (BET surface area, pore volume, and pore size distributions) were evaluated by nitrogen adsorption-desorption isotherm. Our ACs showed strong methylene blue adsorption property (maximum methylene blue is ca. 200 mg/g). Judging from the iodine number and methylene blue values, structure, and surface areas, it can be concluded that NaOH impregnation ratio is one of the key parameters to tune the surface properties of Lapsi seed stone-based activated carbons.

Biomimetic Nanoporous Anodic Alumina Distributed Bragg Reflectors in the Form of Films and Microsized Particles for Sensing Applications.

In this study, we produce for the first time biomimetic films and microsized particles based on nanoporous anodic alumina distributed Bragg reflectors (NAA-DBRs) by a rational galvanostatic pulse-anodization approach. These biomimetic photonic structures can feature a broad range of vivid bright colors, which can be tuned across the UV-visible spectrum by engineering their nanoporous structure through different anodization parameters. The effective medium of NAA-DBRs films is systematically assessed as a function of the anodization period, the anodization temperature, and the current density ratio by reflectometric interference spectroscopy (RIfS). This analysis makes it possible to establish the most sensitive structure toward changes in its effective medium. Subsequently, specific detection of vitamin C molecules is demonstrated. The obtained results reveal that NAA-DBRs with optimized structure can achieve a low limit of detection for vitamin C molecules as low as 20 nM, a sensitivity of 227±4 nm µM(-1), and a linearity of 0.9985. Finally, as proof of concept, we developed a new photonic nanomaterial based on NAA-DBR microsized particles, which could provide new opportunities to produce microsized photonic analytical tools.

Hyaluronic acid-modified Fe3O4@Au core/shell nanostars for multimodal imaging and photothermal therapy of tumors.

Development of multifunctional theranostic nanoplatforms for diagnosis and therapy of cancer still remains a great challenge. In this work, we report the use of hyaluronic acid-modified Fe3O4@Au core/shell nanostars (Fe3O4@Au-HA NSs) for tri-mode magnetic resonance (MR), computed tomography (CT), and thermal imaging and photothermal therapy of tumors. In our approach, hydrothermally synthesized Fe3O4@Ag nanoparticles (NPs) were used as seeds to form Fe3O4@Au NSs in the growth solution. Further sequential modification of polyethyleneimine (PEI) and HA affords the NSs with excellent colloidal stability, good biocompatibility, and targeting specificity to CD44 receptor-overexpressing cancer cells. With the Fe3O4 core NPs and the star-shaped Au shell, the formed Fe3O4@Au-HA NSs are able to be used as a nanoprobe for efficient MR and CT imaging of cancer cells in vitro and the xenografted tumor model in vivo. Likewise, the NIR absorption property enables the developed Fe3O4@Au-HA NSs to be used as a nanoprobe for thermal imaging of tumors in vivo and photothermal ablation of cancer cells in vitro and xenografted tumor model in vivo. This study demonstrates a unique multifunctional theranostic nanoplatform for multi-mode imaging and photothermal therapy of tumors, which may find applications in theranostics of different types of cancer.

The influence of nanopore dimensions on the electrochemical properties of nanopore arrays studied by impedance spectroscopy.

The understanding of the electrochemical properties of nanopores is the key factor for better understanding their performance and applications for nanopore-based sensing devices. In this study, the influence of pore dimensions of nanoporous alumina (NPA) membranes prepared by an anodization process and their electrochemical properties as a sensing platform using impedance spectroscopy was explored. NPA with four different pore diameters (25 nm, 45 nm and 65 nm) and lengths (5 µm to 20 µm) was used and their electrochemical properties were explored using different concentration of electrolyte solution (NaCl) ranging from 1 to 100 µM. Our results show that the impedance and resistance of nanopores are influenced by the concentration and ion species of electrolytes, while the capacitance is independent of them. It was found that nanopore diameters also have a significant influence on impedance due to changes in the thickness of the double layer inside the pores.

LaF3:Ln mesoporous spheres: controllable synthesis, tunable luminescence and application for dual-modal chemo-/photo-thermal therapy.

In this report, uniform LaF(3):Ln mesoporous spheres have been synthesized by a facile and mild in situ ion-exchange method using yolk-like La(OH)3:Ln mesoporous spheres as templates, which were prepared through a self-produced bubble-template route. It was found that the structures of the final LaF(3):Ln can simply be tuned by adding a polyetherimide (PEI) reagent. LaF(3):Ln hollow mesoporous spheres (HMSs) and LaF(3):Ln flower-like mesoporous spheres (FMSs) were obtained when assisted by PEI and in the absence of PEI. The up-conversion (UC) luminescence results reveal that the doping of Nd(3+) ions in LaF(3):Ln can markedly influence the UC emissions of the products. It is interesting that an obvious thermal effect is achieved due to the energy back-transfer from Tm(3+) to Nd(3+) ions under 980 nm near-infrared (NIR) irradiation. The LaF(3):Yb/Er/Tm/Nd HMSs show good biocompatibility and sustained doxorubicin (DOX) release properties. In particular, upon 980 nm NIR irradiation, the photothermal effect arising from the Nd(3+) doping induces a faster DOX release from the drug release system. Moreover, UC luminescence images of LaF(3):Yb/Er/Tm/Nd HMSs uptaken by MCF-7 cells exhibit apparent green emission under 980 nm NIR irradiation. Such a multifunctional carrier combining UC luminescence and hyperthermia with the chemotherapeutic drugs should be of high potential for the simultaneous anti-cancer therapy and cell imaging.

Three-dimensional block copolymer nanostructures by the solvent-annealing-induced wetting in anodic aluminum oxide templates.

Block copolymers have been extensively studied over the last few decades because they can self-assemble into well-ordered nanoscale structures. The morphologies of block copolymers in confined geometries, however, are still not fully understood. In this work, the fabrication and morphologies of three-dimensional polystyrene-block-polydimethylsiloxane (PS-b-PDMS) nanostructures confined in the nanopores of anodic aluminum oxide (AAO) templates are studied. It is discovered that the block copolymers can wet the nanopores using a novel solvent-annealing-induced nanowetting in templates (SAINT) method. The unique advantage of this method is that the problem of thermal degradation can be avoided. In addition, the morphologies of PS-b-PDMS nanostructures can be controlled by changing the wetting conditions. Different solvents are used as the annealing solvent, including toluene, hexane, and a co-solvent of toluene and hexane. When the block copolymer wets the nanopores in toluene vapors, a perpendicular morphology is observed. When the block copolymer wets the nanopores in co-solvent vapors (toluene/hexane = 3:2), unusual circular and helical morphologies are obtained. These three-dimensional nanostructures can serve as naontemplates for refilling with other functional materials, such as Au, Ag, ZnO, and TiO2 .