Trace Explosive Detection Based on Photonic Crystal Amplified Fluorescence.

With increasing demand for public security and environmental protection, it is highly desirable to develop strategies to identify trace explosives (e. g., 2,4,6-trinitrotoluene (TNT)). Herein, we report novel photonic crystal (PC)-based sensor chips for trace TNT detection by using amplification effect of PCs on fluorescence (FL) signals. The sensor chips are constructed by integrating silica nanoparticles (NPs) modified with (3-aminopropyl)triethoxysilane (APTES) and fluorescein isothiocyanate isomer (FITC) and PC substrates. The amino groups on FITC-APTES-silica NPs can specifically bind with TNT molecules to form Meisenheimer complexes and strongly quench the FL signal of neighboring fluorophores FITC through Förster resonance energy transfer. PCs with matched PBG can amplify the FL signal of FITC-APTES-silica NPs about 24.4-fold and significantly improve sensitivity and resolution of trace TNT detection with the limit of detection of 0.23 nM. The PC-based sensor chips are stable, sensitive, and reliable TNT sensing platforms, showing great potential in homeland safety and environmental protection.

Bioinspired Supramolecular Photonic Composites: Construction and Emerging Applications.

Living organisms have evolved fascinating structural colors to survive in complex natural environments. Artificial photonic composites developed by imitating the structural colors of organisms are applied in displaying, sensing, biomedicine, and many other fields. As emerging materials, photonic composites mediated by supramolecular chemistry, namely, supramolecular photonic composites, are designed and constructed to meet emerging application needs and challenges. This review mainly introduces the constructive strategies, properties, and applications of supramolecular photonic composites. First, constructive strategies of supramolecular photonic composites are summarized, including the introduction of supramolecular polymers into colloidal photonic array templates, coassembly of colloidal particles (CPs) with supramolecular polymers, self-assembly of soft CPs, and compounding photonic elastomers with functional substances via supramolecular interactions. Supramolecular interactions endow photonic composites with attractive properties, such as stimuli-responsiveness and healability. Subsequently, the unique optical and mechanical properties of supramolecular photonic composites are summarized, and their applications in emerging fields, such as colorful coatings, real-time and visual motion monitoring, and biochemical sensors, are introduced. Finally, challenges and perspectives in supramolecular photonic composites are discussed. This article provides general strategies and considerations for the design of photonic materials based on supramolecular chemistry.

Shaping Block Copolymer Microparticles by Positively Charged Polymeric Nanoparticles.

Shape-transforming block copolymer (BCP) microparticles have attracted extensive attention due to their promising applications in nanotechnology, biomedicines, interfacial science, and other fields. As their performance is highly associated to their shape and structure, it is very important to realize the precise control of particle shape. In this report, a method is proposed to regulate the shape and structure of polystyrene-b-polydimethoxysiloxane (PS-b-PDMS) microparticles by using positively charged core-crosslinked nanoparticles (CNPs) as a cosurfactant, combining with cationic surfactant cetyltrimethylammonium bromide (CTAB). The electrostatic repulsive interactions between CNPs and CTAB dominate the shape of PS-b-PDMS particles. Upon introducing NaCl, the electrostatic repulsion is reduced, resulting in the reshape of PS-b-PDMS particles from striped Janus ellipsoids to onion-like microspheres at a critical concentration of NaCl (cNaCl ). Interestingly, it is found that the critical cNaCl first increases then reaches a plateau, with the increase in the crosslinking degree of the CNPs. The work provides a simple strategy to tailor the morphology of BCPs by manipulating the electrostatic interaction.

Bioinspired Photonic Ionogels as Interactively Visual Ionic Skin with Optical and Electrical Synergy.

With the ever-growing demands for flexible smart interactive electronics, it remains highly desirable yet challenging to design and fabricate interactive ionic skin with multiple signal synergistic outputs. Herein, high-performance photonic ionogels (PIGs) with excellent stability and synergy sensitivity are designed by locking a non-volatile and non-hygroscopic ionic liquid (IL), that is, 1-ethyl-3-methylimidazolium bis-(trifluoromethylsulfonyl)imide ([EMIm][TFSI]), into photonic elastomers based on polymer networks of poly(ethylene glycol) phenyl ether acrylate (PEGPEA). Through manipulating the degree of crosslinking, PIGs exhibit high sensitivity that can output distinct and intuitive color change in visual with the mechanochromic sensitivity of ≈1.76 nm per percent strain and clear electrical signal with the gauge factor of 1, in response to a tiny stretch of millimeter scale. Thanks to the stable photonic elastomers and IL employed, the PIGs developed in this study exhibit good performance under harsh and complex environmental conditions, including high/low temperature (from -35 °C to 100 °C), dry/wet air, and high vacuum. This study provides a novel strategy for developing integrated, stable, and multifunctional photonic ionogels for ionic skin sensors and flexible interactive devices with synergistically optical and electrical output.

Shaping Block Copolymer Microparticles by pH-Responsive Core-Cross-Linked Polymeric Nanoparticles.

Block copolymer microparticles with controllable morphology have drawn widespread attention owing to their promising applications in photonic materials, energy storage, and other areas. Hence, it is highly desired to achieve a controllable transformation of microparticle morphology. In this work, we report a simple method to shape the morphology of polystyrene-block-poly(dimethylsiloxane) (PS-b-PDMS) microparticles, by employing core-cross-linked polymeric nanoparticles (CNPs) as cosurfactants which are synthesized through cross-linking P4VP segment of PS-block-poly(4-vinylpyridine) (PS-b-P4VP). The addition of pH-responsive CNPs makes the shape of pH-inert PS-b-PDMS microparticles sensitive to pH value. The PS-b-PDMS microparticles transformed from elongated Janus pupa-like particles to onion-like particles by decreasing the pH value of the aqueous phase. The deformation mechanism is investigated by changing pH value, the weight fraction of CNPs, and surfactant property. This study provides a facile strategy to deform microparticles of pH-inert BCPs by tuning pH value, which is anticipated to be applicable to other non-pH-responsive BCP microparticles.

Structure-Controlled Preparation of Multicompartment Micelles with Tunable Emission through Hydrodynamics-Dependent Self-Assembly in Microfluidic Chips.

Multicompartment micelles (MCMs) attracted much attention since they have subdivided domains that could be employed to encapsulate and transport diverse compounds simultaneously. Usually, preparation of MCMs relied on precise synthesis of block copolymers (BCPs) and elegant control of assembly kinetics, making it difficult to successively produce MCMs. Herein, we report a facile yet effective method for preparing MCMs by adjusting the hydrodynamics in microfluidic channels. It was found that well-defined MCMs were formed through hydrodynamics-dependent secondary assembly in microfluidic chips. By adjusting the flow diffusion process by varying the flow rate ratio and total flow rate, both the internal structure and size of MCMs could be effectively changed. A product diagram of micellar morphologies associated to the initial polymer concentration and flow rate ratio of water/BCPs solution was constructed. More interestingly, quantum dots (QDs) could be selectively loaded into different domains of the MCMs. Consequently, the Förster resonance energy transfer among QDs could be effectively suppressed. Thus, the emission spectrum of MCMs/QDs hybrid particles could be easily tuned by changing the ratio of QDs, showing great potential application in photonics and sensors.

NIR-Light-Activated Ratiometric Fluorescent Hybrid Micelles for High Spatiotemporally Controlled Biological Imaging and Chemotherapy.

Intelligent-responsive imaging-therapy strategy has shown great significance for biomedicine. However, it is still a challenge to construct spatiotemporally controlled imaging-therapy systems triggered by near infrared (NIR) light. In this work, NIR-light-activated ratiometric fluorescent hybrid micelles (RFHM) are prepared via the co-assembly of upconversion nanoparticles (UCNPs), doxorubicin (DOX), and UV-light-responsive amphiphilic block copolymer for the spatiotemporally controlled imaging and chemotherapy. Upon NIR light irradiation, UCNPs can convert NIR light to UV light. The emitted UV light induces the photoreaction of copolymer to further trigger ratiometric fluorescence imaging and degradation of hybrid micelles, resulting in rapid DOX release from hybrid micelles for antitumor therapy. The animal experiments reveal that NIR light can not only remotely regulate the ratiometric fluorescence imaging of RFHM in tumor tissue, but also trigger DOX release from RFHM to inhibit tumor growth. Therefore, this study provides a new strategy to achieve high spatial-temporal-controlled biological imaging and chemotherapy.

Tunable Photonic Microspheres of Comb-Like Supramolecules.

Photonic crystals (PCs) are ideal candidates for reflective color pigments with high color purity and brightness due to tunable optical stop band. Herein, the generation of PC microspheres through 3D confined supramolecular assembly of block copolymers (polystyrene-block-poly(2-vinylpyridine), PS-b-P2VP) and small molecules (3-n-pentadecylphenol, PDP) in emulsion droplets is demonstrated. The intrinsic structural colors of the PC microspheres are effectively regulated by tuning hydrogen-bonding interaction between P2VP blocks and PDP, where reflected color can be readily tuned across the whole visible spectrum range. Also, the effects of both PDP and homopolymer (hPS) on periodic structure and optical properties of the microspheres are investigated. Moreover, the spectral results of finite element method (FEM) simulation agree well with the variation of structural colors by tuning the periodicity in PC microspheres. The supramolecular microspheres with tunable intrinsic structural color can be potentially useful in the various practical applications including display, anti-counterfeit printing and painting.

Solvent Quality-Mediated Regioselective Modification of Gold Nanorods with Thiol-Terminated Polymers.

Modification of nanorods (NRs) with functional polymer ligands is of great significance to enhance their surface chemistry and prompt their applications in many fields (e.g., photothermal therapy, bioimaging, and catalysis). However, the regioselective modification of AuNRs still remains a great challenge. Herein, we introduce a facile yet versatile strategy to achieve the regioselective modification of AuNRs through a solvent quality-mediated strategy. By employing a poor solvent of the original ligand cetyltrimethylammonium bromide (CTAB) as the medium in the modification, polymer ligands would selectively graft onto the two ends of AuNRs, while polymer ligands would graft onto the entire surface when employing a good solvent. This strategy demonstrates good reproducibility and is applicable to both hydrophilic and hydrophobic polymer ligand modifications. Moreover, by combing our strategy with the preoccupation route, the two ends and sidewall of AuNRs modified by two different polymers form an "ABA"-type building block, which can further self-assemble into well-ordered superstructures. Our finding provides a new opportunity for multifunctionalization of NRs.

Kinetic Control of Length and Morphology of Segmented Polymeric Nanofibers in Microfluidic Chips.

In this work, we report an approach to prepare segmented polymer nanofibers (SPNFs) composed of rodlike subunits by kinetically controlled self-assembly of polystyrene-b-poly(4-vinylpyridine)-based supramolecules in microfluidic chips. The length and morphology of the SPNFs could be effectively adjusted by changing the total flow rate (Vtotal) and the molar ratio (x) of 4-vinylpyridine (4VP) unit to a hydrogen-bonding molecule, 3-n-pentadecyphenol. Moreover, the subunits of SPNFs could transform from short rods to spheres when the interfacial tension between PS core and solvent increased. On the contrary, the SPNFs elongated along the major axis when the interfacial tension decreased. This work not only offers mechanism insights into the hierarchical self-assembly of block copolymer-based supramolecules but also provides a versatile and effective method for kinetically controlling the hierarchical structures of assemblies.

Flow-Induced Micellar Morphological Transformation in Microfluidic Chips under Nonequilibrium State: From Aggregates to Spherical Micelles.

Self-assembly of block copolymers (BCPs) in microfluidic chips is a versatile yet effective route to produce micellar aggregates with various controllable sizes and morphologies. In this study, the morphological transformation of the BCP of polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) assemblies from irregular aggregates to multicompartment micelles and ultimately to ordered spherical micelles is demonstrated in microfluidic chips. Our experimental and computational simulation results indicate that the transverse diffusion of solvents plays an important role in the morphological transformation of PS-b-P4VP assemblies in the confined flow condition. We find that the mixing time (tmix) between a BCP/tetrahydrofuran (THF) solution and water affects the morphological transformation. Micellar morphologies are intended to transform from aggregates to ordered spherical structures under a relatively long mixing time (tmix). In addition, it is observed that the size of the micelles decreases with the increase of the flow velocity ratio by tuning the hydrodynamic conditions of the flows. Moreover, by adjusting the initial polymer solution concentration, temperature, and weight fraction of the introduced homopolystyrene (hPS), which can affect the viscosity of the BCP solution, the flow diffusion in the microfluidic chip and the resulted micellar structures can also be readily adjusted. The current study provides a new flow-driven method to adjust the micellar ordered structural transformation under the nonequilibrium state.

Shape-Anisotropic Diblock Copolymer Particles with Varied Internal Structures.

Anisotropic polymer particles have promising applications in various fields, whereas their preparation usually suffers from tedious procedures. Here, we introduce a facile strategy to fabricate novel shape-anisotropic particles with varied internal structures via self-assembly of block copolymers (BCPs), with perfluorooctane (PFO) as the liquid template in emulsion droplets. By increasing the volume ratio of PFO to polystyrene- block-poly(4-vinylpyridine) (PS- b-P4VP) or decreasing the initial concentration of the BCPs, the self-assembled polymer particles change from spherical core-shell structures to anisotropic particles. Moreover, the anisotropic shape and internal structure of the polymer particles, including cone-like particles with alternative PS and P4VP lamellas, crescent-shaped particles with cylindrical P4VP domains, and plate-like particles with spherical P4VP domains, can be obtained by changing the block ratio or molecular weight or by adding a hydrogen-bonding agent. Based on the in situ optical microscopy investigation of the morphology evolution of the emulsion droplet, we conclude that both kinetic and thermodynamic factors during emulsion evolution determine the formation of shape-anisotropic polymeric particles with controllable internal structures.

Kinetically Controlled Self-Assembly of Block Copolymers into Segmented Wormlike Micelles in Microfluidic Chips.

Kinetically controlled self-assembly of block copolymers (BCPs) in solution is an efficient route to fabricate complex hierarchical colloids which are of great importance for nanoencapsulation, microreactors, and biomimics. Herein, segmented wormlike micelles (SWMs) with controllable size are generated by the self-assembly of polystyrene- block-poly(4-vinyl pyridine) in microfluidic channel. Different from the assembly of BCPs off-chip at the same solution properties, it is found that the fabricated SWMs are kinetically controlled assemblies with thermodynamic metastable structures, which are formed by the orderly aggregation of preformed spherical micelles because of the fast mixing process in microfluidic channels. Moreover, by manipulating the total flow velocity of water and BCPs solution or their flow velocity ratio, both of the percentages of SWMs among the whole assemblies and their sizes can be effectively tuned. On the basis of electron microscopy and dynamic light scatting investigations, a product diagram of micellar morphologies associated to initial polymer concentration and flow velocity ratio of water/BCPs solution was constructed, which is important for the rational design and fabrication of complex hierarchical BCP colloids.

Responsive Photonic Hydrogel-Based Colorimetric Sensors for Detection of Aldehydes in Aqueous Solution.

In this work, we present a fast and efficient strategy for the preparation of responsive photonic hydrogels for aldehyde sensing by combining the self-assembly of monodisperse carbon-encapsulated Fe3O4 nanoparticles (NPs) and in situ photopolymerization of polyacrylamide (PAM) hydrogels. The responsive photonic hydrogels exhibit structural color variation after being treated with formaldehyde aqueous solution, which can be attributed to the chemical reaction between the amide groups in the hydrogels and the formaldehyde. We have also shown that the photonic hydrogels can be used to determine the concentration of formaldehyde and to differentiate aldehydes through a facile reflection spectra shift and color change. This study provides a facile strategy for the visualized determination of aldehyde in aqueous solution.

Id4 promotes cisplatin resistance in lung cancer through the p38 MAPK pathway.

Inhibitor of differentiation 4 (Id4) plays an important role in tumorigenesis, but its role in cancer chemoresistance remains unclear. Our study showed that Id4 expression in cisplatin-resistant A549/DDP cells was higher than that in parental A549 cells. Moreover, overexpression of Id4 in A549 cells results in cisplatin resistance and apoptosis inhibition, while increasing the IC50 for cisplatin through activation of phospho-p38 MAPK. However, Id4 knockdown in A549/DDP cells was shown to resensitize A549/DDP cells to cisplatin and induce apoptosis, as well as decrease the IC50 for cisplatin through inactivation of phospho-p38 MAPK. In addition, a p38 MAPK inhibitor (SB202190) could partly reverse both Id4-reduced apoptosis and Id4-induced cisplatin resistance. These results suggest that Id4 inhibits cisplatin-induced apoptosis in human lung adenocarcinoma, partially through activation of the p38 MAPK pathway. Our research indicates that Id4 may be a new target for non-small-cell lung cancer treatment.

Video-assisted thoracoscopic surgery thymectomy versus open thymectomy in patients with myasthenia gravis: a meta-analysis.

BACKGROUND: Video-assisted thoracoscopic surgery (VATS) thymectomy has become a feasible treatment for myasthenia gravis (MG) in recent years. The objective of the present meta-analysis was to evaluate the perioperative characteristics, safety, and completely stable remission rate in patients with MG who received VATS or open thymectomy (OT). METHODS: We searched PubMed, Embase, ScienceDirect, Web of Science, and CNKI for related articles using combinations of the search terms video-assisted thoracoscopic thymectomy, transsternal thymectomy, and MG. The inter-study heterogeneity was assessed by χ2-based Q statistics, and the extent of inconsistency was generated by I2 statistics. RESULTS: A total of 12 studies with 1173 patients were included, and there was no difference in the operation time (p = 0.08) and ICU time (p = 0.14) between the two groups, but VATS thymectomy was associated with less intra-operation blood loss and hospital time (p < 0.00001). VATS was also associated with lower rates of total complication (OR =0.59; 95% CI, 0.37-0.94; p = 0.03) and myasthenic crisis (OR = 0.51; 95% CI, 0.28-0.92; p = 0.03), but the rates of pneumonia (OR = 0.59; 95% CI, 0.29-1.32; p = 0.21) and complete remission rate (CSR) (OR = 0.64; 95% CI, 0.38-1.09; p = 0.10) had no obvious differences between the VATS and OT groups. CONCLUSION: Patients with MG undergoing VATS thymectomy achieved better surgical outcomes and fewer complications than those who received OT.

Plasmonic gold nanocrystals coupled with photonic crystal seamlessly on TiO2 nanotube photoelectrodes for efficient visible light photoelectrochemical water splitting.

A visible light responsive plasmonic photocatalytic composite material is designed by rationally selecting Au nanocrystals and assembling them with the TiO(2)-based photonic crystal substrate. The selection of the Au nanocrystals is so that their surface plasmonic resonance (SPR) wavelength matches the photonic band gap of the photonic crystal and thus that the SPR of the Au receives remarkable assistance from the photonic crystal substrate. The design of the composite material is expected to significantly increase the Au SPR intensity and consequently boost the hot electron injection from the Au nanocrystals into the conduction band of TiO(2), leading to a considerably enhanced water splitting performance of the material under visible light. A proof-of-concept example is provided by assembling 20 nm Au nanocrystals, with a SPR peak at 556 nm, onto the photonic crystal which is seamlessly connected on TiO(2) nanotube array. Under visible light illumination (>420 nm), the designed material produced a photocurrent density of ~150 µA cm(-2), which is the highest value ever reported in any plasmonic Au/TiO(2) system under visible light irradiation due to the photonic crystal-assisted SPR. This work contributes to the rational design of the visible light responsive plasmonic photocatalytic composite material based on wide band gap metal oxides for photoelectrochemical applications.

Photon Management Enabled by Opal and Inverse Opal Photonic Crystals: from Photocatalysis to Photoluminescence Regulation.

Light is a promising renewable energy source and can be converted into heat, electricity, and chemical energy. However, the efficiency of light-energy conversion is largely hindered by limited light-absorption coefficients and the low quantum yield of current-generation materials. Photonic crystals (PCs) can adjust the propagation and distribution of photons because of their unique periodic structures, which offers a compelling platform for photon management. The periodicity of materials with an alternating refractive index can be used to manipulate the dispersion of photons to generate the photonic bandgap (PBG), in which light is reflected. The slow photon effect, i. e., photon propagation at a reduced group velocity near the edges of the PBG, is widely regarded as another valuable optical property for manipulating light. Furthermore, multiple light scattering can increase the optical path, which is a vital optical property for PCs. Recently, the light reflected by PBG, the slow photon effect, and multiple light scattering have been exploited to improve light utilization efficiency in photoelectrochemistry, materials chemistry, and biomedicine to enhance light-energy conversion efficiency. In this review, the fabrication of opal or inverse opal PCs and the theory for improving the light utilization efficiency of photocatalysis, solar cells, and photoluminescence regulation are discussed. We envision photon management of opal or inverse opal PCs may provide a promising avenue for light-assisted applications to improve light-energy-conversion efficiency.