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Microneedles (MNs) have attracted considerable attention in the pharmaceutical field as a minimally invasive delivery alternative to hypodermic needles. Current material systems of MNs have gradually shifted from metals, ceramics, and silicon to polymer in consideration of toughness and drug loading capacity. Silk fibroin (SF) is considered one of the most promising alternatives because it combines the ability to maintain the activity of biomolecules, adjustable mechanical strength, and excellent biocompatibility. However, the strength and hardness of SF MNs need to be carefully optimized to ensure skin epidermis penetration and controlled drug release, which are rarely explored in reported works. Here, the synergistic effect of glutaraldehyde-based cross-linking and water vapor annealing post-treatment is presented as an effective method to promote the formation of SF molecular networks and the mechanical strength of SF MNs. Moreover, the reinforced MN substrate is coated with a drug-loaded SF layer with low crystallinity. The drug release experiments demonstrate the successful controlled release of rhodamine B, horseradish peroxidase, and tetracycline, which suggests the great potential in the application of vaccine, antibiosis, cosmetology, and so forth.

A portable sensor for visual monitoring of Fe

Powering implanted medical devices (IMDs) is a long-term challenge since their use in biological environments requires a long-term and stable supply of power and a biocompatible and biodegradable battery system. Here, silk fibroin-based ion-exchange membranes are developed using bionics principles for reverse electrodialysis devices (REDs). Silk fibroin nanofibril (SNF) membranes are negatively and positively modified, resulting in strong cation and anion selectivity that regulates ion diffusion to generate electric power. These oppositely charged SNF membranes are assembled with Ag/AgCl electrodes into a multicompartment RED. By filling them with 10 and 0.001 mM NaCl solutions, a maximum output power density of 0.59 mW/m

Nanorobots hold great promise for integrated drug delivery systems that are responsive to molecular triggers. Herein, we successfully developed an automatic smart bionanorobot that has transport capability and recognizes and removes zinc ions from poisoned cells based on nanoscale polyhedral oligomeric silsesquioxane molecules. This intelligent bionanorobot can easily move inside and outside the cell and find zinc ions owing to its highly selective recognition to zinc ions and high cell permeability, especially the well-combined high penetration and strong binding energy. More importantly, it was also found that this intelligent bionanorobot can restore round HeLa cells to a normal fusiform cell morphology following high-concentration zinc treatment and does not interfere with cell proliferation and division. It was also shown by

Two-dimensional transition metal dichalcogenides have attracted widespread attention in cancer theranostics due to their high specific surface area and excellent photothermal conversion properties. However, their dimensions and biodegradability have limited the exploration of the therapeutic properties of transition metal dichalcogenides. Herein, we explore the mechanism of the keratin α-helix-to-random coil transition, as an actuation mechanism for the controllable design and precise synthesis of two-dimension copper sulfide nanoflakes (CuS NFs) with high absorption in the NIR-II window. Upon mixing keratin and Cu

As a kind of reactive oxygen species, peroxynitrite is related to various diseases closely such as cancer and neurodegenerative diseases. Constructing probes with highly specific ability and a wide linear detection range for peroxynitrite detection is crucial for understanding the pathogenesis of related diseases and optimizing treatments. In this work, we developed a novel luminescent ratiometric fluorescence nanoprobe (PC-CDs) based on carbon dots and phycocyanin. PC-CDs are constructed by amidation reaction between carbon dots and phycocyanin. The nanoprobe we obtained has a good ability of distinguishing peroxynitrite from other reactive oxygen species and interfering substances. Moreover, the linear range of the nanoprobe is 0.5-100 μM and the limit of detection is 0.5 μM when detecting peroxynitrite. In the spiked recovery experiments under phosphate buffered saline (PBS) environment, our nanoprobe has a good recovery performance and the recovery is 99% - 104%, which will be beneficial to the further development of peroxynitrite testing and the research progress of related diseases. Finally, we discuss the quenching mechanism of peroxynitrite for nanoprobe, and found that there is the combination of dynamic and static quenching in the quenching process.

The rapid capacity loss caused by the shuttling effect of polysulfides is one of the great challenges of Li–S batteries. In this work, we adopted a simple solid-phase sintering method to synthesize titanium disulfide (TiS2) and further demonstrated it as a superior modifier of separators for Li–S batteries. Two commonly adopted modification processes of separators, including vacuum filtration (VF) and slurry casting (SC) have been used to prepare TiS2/Celgard separators. TiS2-VF/Celgard can better restrain the polysulfide shuttling effect compared with TiS2-SC/Celgard. A TiS2-VF/Celgard-based Li–S battery has a reversible capacity of 771.6 mA h g−1, with a capacity retention of 645.6 mA h g−1 after 500 cycles at 2.0 C, corresponding to a capacity fading rate of ∼0.033% per cycle. This study has shown the potential of TiS2 as a multifunctional modifier of separators for high performance and long cycle life Li–S batteries.

In this work, we demonstrate the principle of mesoscopic construction of silk fibroin (SF) hybrid materials, which endows the materials with new performance. In implementing this strategy, mediating molecules, wool keratin (WK) molecules, were adopted to in-line synthesize Au nanoparticles (WK@AuNPs), which further create the stable linkage of AuNPs with SF nanofibril networks via templated β-crystallization. Fourier transform infrared spectroscopy, X-ray diffraction, and atomic force microscopy demonstrate that the mesoscopic hybrid network structure of the hybrid materials is different from neat SF materials, which gives rise to various new performances, that is, long-stable fluorescence emission. As the fluorescence emission can be characteristically annealed by Cu ions, therefore be adopted as the highly selective ion probes. Moreover, as WK@AuNPs are homogeneously connected to SF nanofibril networks, the carbonization of the materials leads to secondary hybrid materials of carbon-Au, where nano-sized Au particles are well distributed in carbonized mesoscopic conductive carbon networks. Such hybrid materials of carbon-Au can be further fabricated into electrochemical (i.e., dopamine) sensors, which are demonstrated to have excellent sensing performance.

Transmission of energy and signals through human skin is critically important for implantable devices. Because near-infrared (NIR) light can easily penetrate through human skin/tissue, in this study we report on silk fibroin (SF) up-conversion photonic amplifiers (SFUCPAs) integrated into optoelectronic devices, which provide a practical approach for subcutaneous charging and communication via NIR lasers. SFUCPAs achieve a 4 times higher fluorescence than the control, which gives rise to a 47.3 time increase in subcutaneous NIR energy conversion efficiency of a single fibrous dye-sensitized solar cell compared with the control. Moreover, the hybrid printed electrodes exhibited reversible switching to NIR exposure with a response time of ∼1.06/1.63 s for a 3 s ON/OFF switch. Owing to the flexible, biocompatible, and cost-efficient design NIR-driven optoelectronic performance, the SFUCPAs are promising for use in applications of subcutaneous medical electronics for charging, storing information, and controlling implanted devices.

The rapid capacity loss caused by the shuttling effect of polysulfides is one of the great challenges of Li-S batteries. In this work, we adopted a simple solid-phase sintering method to synthesize titanium disulfide (TiS2) and further demonstrated it as a superior modifier of separators for Li-S batteries. Two commonly adopted modification processes of separators, including vacuum filtration (VF) and slurry casting (SC) have been used to prepare TiS2/Celgard separators. TiS2-VF/Celgard can better restrain the polysulfide shuttling effect compared with TiS2-SC/Celgard. A TiS2-VF/Celgard-based Li-S battery has a reversible capacity of 771.6 mA h g-1, with a capacity retention of 645.6 mA h g-1 after 500 cycles at 2.0 C, corresponding to a capacity fading rate of ∼0.033% per cycle. This study has shown the potential of TiS2 as a multifunctional modifier of separators for high performance and long cycle life Li-S batteries.

NiCoAl layered double hydroxide nanosheets (NiCoAl-LDHNs) were prepared by a one-step solvothermal method. The shape and size of the obtained nanosheets are optimized by adjusting the solvothermal time and the molar concentration ratio of Ni2+/Co2+ to obtain the electrode material with the best performance. When the solvothermal time is 9 h and the molar concentration ratio of Ni2+/Co2+ is 1:1, NiCoAl-LDHNs has the best morphology and electrochemical performance. When assembled into a supercapacitor, NiCoAl-LDHN-9 has a high specific capacitance of 1228.5 F g−1 at 1 A g−1. As the current density is increased to 20 A g−1, the specific capacitance is 1001.8 F g−1, which still has a high capacitance retention of 81.6%. When NiCoAl-LDHN-9 was assembled into an asymmetric supercapacitor, NiCoAl-LDHN-9//AC has a specific capacitance of 102.1 F g−1 at 0.5 A g−1. The asymmetric supercapacitor devices also show excellent electrochemical performance in terms of energy density (35.9 Wh kg−1 at 225.8 W kg−1), power density (4.8 kW kg−1 at 22.2 Wh kg−1) and cycle life (capacitance retention rate after 10,000 cycles is 87.1%). Those results indicate that NiCoAl-LDHN have the potential to be promising electrode materials for high performance supercapacitors.

Highlights Materials with contradictory performance were prepared using wool keratin (WK).WK used for in situ preparation of AuNPs and N-doped carbon precursor as well.Two- and three-electrode flexible strip sensors designed for pH and UA detection. Electronic supplementary material The online version of this article (10.1007/s40820-020-00459-5) contains supplementary material, which is available to authorized users., Flexible biosensors with high accuracy and reliable operation in detecting pH and uric acid levels in body fluids are fabricated using well-engineered metal-doped porous carbon as electrode material. The gold nanoparticles@N-doped carbon in situ are prepared using wool keratin as both a novel carbon precursor and a stabilizer. The conducting electrode material is fabricated at 500 °C under customized parameters, which mimics A–B type (two different repeating units) polymeric material and displays excellent deprotonation performance (pH sensitivity). The obtained pH sensor exhibits high pH sensitivity of 57 mV/pH unit and insignificant relative standard deviation of 0.088%. Conversely, the composite carbon material with sp2 structure prepared at 700 °C is doped with nitrogen and gold nanoparticles, which exhibits good conductivity and electrocatalytic activity for uric acid oxidation. The uric acid sensor has linear response over a range of 1–150 µM and a limit of detection 0.1 µM. These results will provide new avenues where biological material will be the best start, which can be useful to target contradictory applications through molecular engineering at mesoscale. Electronic supplementary material The online version of this article (10.1007/s40820-020-00459-5) contains supplementary material, which is available to authorized users.

Transient devices have attracted extensive interest because they allow changes in physical form and device function under the control of external stimuli or related commands and have very broad application prospects for information security, biomedical care and the environment. Transient bioelectrical devices were fabricated inspired by a silkworm moth breaking out of its cocoon, which has shown many advantages, including the use of mild stimulation, biocompatible materials, a simple process, and a universal strategy. For the fabrication of the transient devices, heat-sensitive microspheres with a 9.3 mol L−1 LiBr solution in wax shells were prepared by microfluidic technology, which were then assembled into silk fibroin (SF) electronic materials/devices, such as SF conductive film, an LED circuit on SF film, and a Ag/SF film/Pt/SF film memristor. The contribution from the LiBr/wax microspheres to the transient time of the SF films upon exposure to heat was quantitatively investigated. This approach was applied to transiently dissolve a flexible Ag-nanowire resistance circuit line on a SF substrate. Moreover, memristors constructed with a functional layer of SF were destroyed by melting the LiBr/wax microspheres. This technique paves the way for realizing transient bioelectrical devices inspired by biological behavior, which have been well optimized by nature via evolution.

Two-photon fluorescent (TPF) Bombyx mori silk fibers were acquired for bioimaging by molecular recognition functionalization. In this context, 2,7-bis((E)-4-((E)-4-nitrostyryl)styryl)-9,9-dioctyl-9H-fluorene (NF) was adopted to functionalize silkworm silk fibers. NF exhibits a large two-photon absorption cross section, but has a low TPF quantum yield in the solid form due to the side-by-side (π–π) molecular stacking. In terms of the molecular recognition between the nitro groups of NF and the amide groups of silk fibroin, the silk fibers acquire the two-photon fluorescent emission with a significant enhancement of 350% in TPF quantum yield of NF molecules, compared with the solid state. For comparison, two other molecules, 2,7-bis((E)-4-methylstyryl)-9,9-dioctyl-9H-fluorene (MF1) and 2,7-bis((E)-4-((E)-4-methylstyryl)styryl)-9,9-dioctyl-9H-fluorene (MF2), were selected for similar experiments. These molecules show little effect due to the lack of molecular recognition. The TPF silk scaffolds were obtained, and high quality imaging of NF in cell culture was finally achieved, which has extremely relevant implications for biomedical applications.

Solid photothermal materials with favorable biocompatibility and modifiable mechanical properties demonstrate obvious superiority and growing demand. In this work, polydopamine (PDA) induced functionalization of regenerated silk fibroin (RSF) fibers has satisfactory photothermal conversion ability and flexibility. Based on multilevel engineering, RSF solution containing PDA nanoparticles is wet spun to PDA-incorporating RSF (PDA@RSF) fibers, and then the fibers are coated with PDA via oxidative self-polymerization of dopamine to form PDA@RSF-PDA (PRP) fibers. During the wet spinning process, PDA is to adjust the mechanical properties of RSF by affecting its hierarchical structure. Meanwhile, coated PDA gives the PRP fibers extensive absorption of near-infrared light and sunlight, which is further fabricated into PRP fibrous membranes. The temperature of PRP fibrous membranes can be adjusted and increases to about 50 °C within 360 s under 808 nm laser irradiation with a power density of 0.6 W cm

A compact evanescent wave detection platform (EWDP) is developed for the detection of fluorescence gold nanoclusters. The EWDP employs a simple optical system and a Si-based photodetector SOP-1000 assembly to improve the optical efficiency and detection sensitivity. A microfluidic sample cell is also used to decrease the amount of analyte to 200 μL (The volume of sample cell is really about 30 μL). On this basis, we design a strategy for detecting dopamine (DA) based on the photoinduced electron transfer (PET) quenching mechanism. By introduction of tyrosinase (TYR) during the detection, the testing time is shortened to 1 min. The fluorescence emission signal decreased dramatically and the quenching ratio (F0–F)/F0 is linearly related to the concentration of DA in the range of 0.03–60 μM with a detection limit of 0.03 μM. Additionally, this detection platform has potential applications for DA fast detection in the microsamples.

Unfolded protein response (UPR) and endoplasmic reticulum (ER)-phagy are essential for cell homeostasis. Quantum dots (QDs), which have been widely used for biomedical applications, can accumulate in the kidney tissues and may cause renal dysfunction. However, the molecular mechanism of QDs-induced nephrotoxicity is still obscure. The present study was aimed to elucidate the role and mechanism of UPR and ER-phagy in QDs-induced nephrotoxicity. Herein, human embyronic kidney (HEK) cells were exposed to 15, 30, 45, and 60 nM cadmium telluride (CdTe)-QDs for 12 and 24 h. And CdTe-QDs (30-60 nM) inhibited the HEK cell viability. The clathrin-dependent endocytosis was determined as the main pathway of CdTe-QDs cellular uptake. Within cells, CdTe-QDs disrupted ER ultrastructure and induced UPR and FAM134B-dependent ER-phagy. Blocking UPR with inhibitors or siRNA rescued the FAM134B-dependent ER-phagy, which was triggered by CdTe-QDs. Moreover, suppression of UPR or FAM134B-dependent ER-phagy restored the cell vability. In vivo, mice were intravenously injected with 8 and 16 nmol/kg body weight CdTe-QDs for 24 h. Kidney was shown as one of highest distributed organs of CdTe-QDs, resulting in renal dysfunction, as well as UPR and FAM134B-dependent ER-phagy in it. Thus, for the first time, we demonstrated that ER-phagy can be triggered by nanomaterials both in vitro and in vivo. In addition, blocking of UPR and ER-phagy showed protective effects against CdTe-QDs-induced toxicity in kideny cells. Notably, a secreted alkaline phosphatase reporter gene system has been developed as a sensitive and rapid method for evaluating the ER quality under the exposure of nanomaterials.

A novel flower-like polyaniline/graphene hybrid (PANI-ATRGO) is prepared by a one-pot synthesis and used as electrode materials for supercapacitors. The structure, formation mechanism and electrochemical properties of such unique architecture are systematically investigated by combining Fourier transform infrared spectroscopy, Ultraviolet–visible absorption spectroscopy, Raman spectroscope, X-ray diffraction and electrochemical techniques. The results suggest that “V-type” amino groups of ATRGO and supermolecular assembly between PANI chains play the key role in the formation of flower-like nanostructures. Compare to pristine PANI (487 F g −1 at 1 A g −1 ), PANI-ATRGO electrode materials exhibit a remarkable improvement of the specific capacitance (1510 F g −1 at 1 A g −1 ) for supercapacitor in addition to excellent rate capacity and long-term cycling stability. Moreover, it is found that flower-like PANI-ATRGO hybrids exhibit better electrochemical properties than the corresponding nanorod-array hybrids in our previous study. This reveals the significance of controlling the hierarchical structure of hybrid materials in the development of high-performance supercapacitor.

Turning insulating silk fibroin materials into conductive ones turns out to be the essential step toward achieving active silk flexible electronics. This work aims to acquire electrically conductive biocompatible fibers of regenerated Bombyx mori silk fibroin (SF) materials based on carbon nanotubes (CNTs) templated nucleation reconstruction of silk fibroin networks. The electronical conductivity of the reconstructed mesoscopic functional fibers can be tuned by the density of the incorporated CNTs. It follows that the hybrid fibers experience an abrupt increase in conductivity when exceeding the percolation threshold of CNTs >35 wt%, which leads to the highest conductivity of 638.9 S m-1 among organic-carbon-based hybrid fibers, and 8 times higher than the best available materials of the similar types. In addition, the silk-CNT mesoscopic hybrid materials achieve some new functionalities, i.e., humidity-responsive conductivity, which is attributed to the coupling of the humidity inducing cyclic contraction of SFs and the conductivity of CNTs. The silk-CNT materials, as a type of biocompatible electronic functional fibrous material for pressure and electric response humidity sensing, are further fabricated into a smart facial mask to implement respiration condition monitoring for remote diagnosis and medication.

A series of functional polyacetylenes bearing the fluorene moiety with different conjugated lengths and terminal substituents, poly[2-ethynyl-7-(4-nitrostyryl)-9,9-dioctyl-9H-fluorene] (P1), poly[2-ethynyl-7-(4-(4-nitrostyryl)styryl)-9,9-dioctyl-9H-fluorene] (P2), poly[2-ethynyl-7-(4-(4-methoxystyryl)styryl)-9,9-dioctyl-9H-fluorene] (P3), poly[2-ethynyl-7-(4-(4-methylstyryl)styryl)-9,9-dioctyl-9H-fluorene] (P4), and poly[2-ethynyl-7-(4-(4-methylstyryl)styryl)-9,9-didodecyl-9H-fluorene] (P5), were designed and prepared using [Rh(nbd)Cl]2 as the catalyst. Their structures and properties were characterized and evaluated by FTIR, NMR, UV, FL, GPC and TGA analyses. The optical limiting properties were investigated using 450 fs laser pulses at 780 nm. These results show that the incorporation of styryl/stilbene functionalized polyfluorenylacetylenes has endowed resultant polyacetylenes with novel near-infrared laser protection properties and enhanced thermal stability. The optical limiting mechanism for laser protection was studied. It was found that the optical limiting properties mainly originated from two-photon absorption (TPA) of molecules in the resulting polyacetylenes. Additionally, it was also found that the functionalized polyacetylene with a longer fluorene-based conjugated chromophore and a stronger terminal electron acceptor group exhibits better optical limiting properties because of the larger π-electron delocalization and dipolar effect.

Silk fibers spun by silkworms or spiders at ambient temperature display unique mechanical strength, excellent biocompatibility and optical transparency, which offer unconventional interfaces to soft and curved biological systems. In comparison with conventional materials, the performance of soft matter, i.e., animal silks, is mainly determined by the structure at the mesoscale. To further extend the applications, functionalization of silk materials becomes is required, and mesoscopic material assembly (MMA) was developed for this task. This feature article provides an overview on the principles and strategies concerning MMA, and some typical examples of functionalizing silk fibroin materials. The main strategies of MMA include in vivo and in vitro assemblies, and can be implemented by the three different paths: (1) molecular recognition, (2) surface functionalization of nanomaterials, or (3) foreign molecule mediation. The cases include the functionalization of silk fibroin materials by one/two-photon fluorescent molecules, quantum dots (QDs) and gold clusters, etc. The applications of these functionalized materials in bio waveguide, white-light-emitting devices, bioimaging, were also highlighted. MMA provides a practical tool for the production of the functionalized biocompatible materials, which can be further applied to fabricate high-performance bio integrated devices used in consumer electronics, and biomedical diagnosis, as well as human-machine interfaces.

To fabricate biocompatible composite films with tunable performance, both silk fibroin (SF, β-crystallite rich) and keratin (α-helix rich) materials are engineered at the mesoscale based on the molecular synergy. While SF materials display a hierarchical structure initiated from the β-crystallite molecular networks, keratin materials reveal the networks crossly linked by disulfide bonding. It is surprising to see that the β-crystallites of SF materials induce the conversion of the free unfolded molecular chains of keratin to β-folding (β-crystallites) in the SF/keratin composites. Furthermore, the α-helices from the keratin components in the SF/keratin composites can transit to β-sheets under stress, which gives rise to the strain-hardening, and a better flexibility and elasticity. It follows that the tensile and biodegradable performance of the SF/keratin composites can be programmed by adjusting the ratio of SF versus keratin in the composites. Raising the SF ratio in the composite films increases the density of β-crystallites in the networks, giving rise to the enhanced toughness and reduced biodegradation rate, but poor deformation recovery. On the other hand, increasing the ratio of keratin in the composite films increases the extensibility, strain-hardening effect. These make them excel bio-optical materials with controllable properties.

Here a biomimetic approach is presented to fabricate nanodragon fruits featured by a multitude of tiny quantum dot ZnO seeds embedded in mesosilica (SiO2) flesh then enclosed in amorphous calcium phosphate (ACP) shell. The nanodragon fruits give rise to a new class of hybrid ZnO/SiO2@ACP nanocomplex with multimoidal capability: cellular delivering, intracellular targeting, and subcellular imaging. With this particular design, the unusual fluorescent stability of ZnO quantum dots (QDs) in aqueous solution, the specific color selection of the functional ZnO QD seeds, and the stability of transient ACP over a long period of time are made possible. In addition, the nanodragon fruits, capable of targeting mitochondria, have elevated biocompatibility, thus can be of enormous potential applications in treating mitochondrial diseases including inflammation, neurodegeneration, obesity, diabetes, cardiovascular diseases, and cancer. As numerous human disorders are often associated with cellular dysfunctions, this biocompatible carrying platform, capable of delivering, targeting, and imaging subcellular organelles, is therefore highly desirable for efficacious therapeutic and diagnostic treatment.

2-(4-((4-Chloro-6-((3',6'-dihydroxy-3-oxospiro [isoindoline-1,9'-xanthen]-2-yl)amino)-1,3,5-triazin-2-yl)amino)benzoyl)-N-phenylhydrazine-1-carbothioamide (PCFH) is prepared for the detection of Hg2+ by hydrogen-induced emission (HIE). In the presence of blood serum, PCFH has a strong fluorescence response to Hg2+ in ethanol/H2O (90/10, v/v), while the fluorescence with other metal ions, including Cu2+, is much weaker. PCFH coordinates better with Hg2+ than Cu2+, which gives rise to specificity of detection. Through spectroscopic techniques and molecular dynamics simulations, the mechanism of HIE reveals that the interactions between polar bonds of PCFH and protein in blood serum via hydrogen bonding can efficiently enhance the specificity and sensitivity of detection. As the results of the interactions, the free rotation of two plenary structures of PCFH linked by C C bonds is restricted, which leads to increased planarity, and the protein destroys the coordination between Cu2+ and PCFH. The development of cells under Hg2+ pollution is monitored, and the concentrations of Hg2+ in deformed and dead cells are 0.47 μM and 0.88 μM respectively. The HIE effects found here will promote new ideas in the design of new types of fluorescence probes for Hg2+ and other metal ions.

A multisite-targeting polymer with the ability of both fluorescence and targeting recognition was successfully synthesized by using fluorescein as the fluorescent group and folic acid as the targeted group. The chemical structure of fluorescent monomer and polymer was characterized and analyzed by FTIR and 1H NMR. The cytotoxicity and biocompatibility of this polymer were characterized by MTT assay and hemolysis rate respectively. The cell viability was 85 % and the hemolysis rate of erythrocyte was only 0.147 % even at the concentration of PFLAC was 10−4 mol/L. The polymer has also been applied to cell imaging for the identification of human colorectal cancer cells. Interestingly, the results show that the polymer was able to enter into the specific cell with an excellent targeting ability.

Free lead and zinc ions are toxic to living cells and environment, we develop a multi-responsive fluorescence probe based on water-soluble double hydrophilic block copolymer. The polymer sensor with Schiff moiety can sensitively, selectively and simultaneously fluorescence probe Zn2+ (green) and Pb2+ (blue) through the different fluorescence color. The linear concentration ranges for Pd2+ and Zn2+ were 0.8–10.0 μM and 0–10.0 μM with the detection limits of 0.7 μM and 0.2 μM, respectively. The probe responding to Na+, Mn2+, Fe2+, Fe3+, Cu2+, Zn2+, Cd2+, Al3+, Cr3+, Co2+, Ni2+, Ag+, Ca2+, K+, Mg2+, Ba2+, Hg2+, and Pb2+ displays almost no significant interference with the assay process. The sensing mechanism of the PSAM probe to Pb2+ and Zn2+ was investigated by Job's plot experiment, 1H NMR analysis and density functional theory (DFT), the results show that the nitrogen atom of CH N and oxygen atom of OH may recognize with ions and the Job's plots for the PSAM complexes demonstrate 1:1 complexation, respectively. To achieve its application, the chemosensor is successfully applied to monitor Pd2+and Zn2+ in tap and lake water samples, its ability to monitor free Pd2+ and Zn2+ ions in living cells or in vivo is also validated by the intracellular imaging.

Graphitic nitrogen-doped hierarchical porous carbon nanosheets for supercapacitor application were derived from an easily obtained and green silk by simultaneous ZnCl2 activation and FeCl3 graphitization at different heating temperatures. By increasing the heating temperature from 700 to 850 °C, the degree of graphitization and BET surface area rose to their highest levels, while the nitrogen doping content was maintained at 2.24 wt%. Carbonized silk at 850 °C displays a nanosheet morphology and a considerable specific surface area (1285.31 m2 g−1), and it was fabricated into a supercapacitor as an electrode material, exhibiting superior electrochemical performance with a high specific capacitance of 178 F g−1 at 0.5 A g−1 and an excellent rate capability (81% capacitance retention ratio even at 20 A g−1) in 1 mol L−1 H2SO4 electrolyte. A symmetric supercapacitor using carbonized silk at 850 °C as the electrodes has an excellent specific energy of 14.33 W h kg−1 at a power density of 251 W kg−1 operated over a wide voltage range of 2.0 V in aqueous neutral Na2SO4 electrolyte.

A study on the cross-linking of fluorinated acrylate and siloxane waterborne polyurethanes was carried out in order to produce a material with improved waterproof property. Trimethylolpropane-tris-(β-N-aziridinyl) propionate was employed as a simple, fast curing and low cost crosslinking agent. It follows that the acquired polyurethane film had the lowest water absorption and highest water contact angles so far among this series of compounds, and has better mechanical/thermal properties once the fluoride acrylic monomer content reaches 8 wt% and polyether modified polydimethylsiloxane content is 10 wt%. Once the crosslinked structure is acquired, the overall performance of the polyurethane films are enhanced, i.e. the water absorption decreases to 3.48% and n-heptane swelling decreases to 1.02%, the hardness reaches 6H and the tensile strength also rises to 33.2 MPa. Such eco-friendly crosslinked polyurethane films with outstanding waterproof property can find various applications in corrosion protection and optoelectronic devices.

A series of modified waterborne polyurethanes were synthesized using a self-emulsifying method for high performance waterproof coatings, such as fluoride polyurethane (FPU), siloxane modified waterborne polyurethane (SPU) and the polyurethane containing fluorine and siloxane (FSPU). The structures of waterborne polyurethane were designed from scratch, and the contents of fluoride acrylic monomer (FMA) and siloxane contents (HO-PDMS) segments in FSPU were adjusted for high performance waterproof. It's found that the sample has lowest water absorption, higher water contact angles, and better mechanical/thermal properties, when the FMA content is 20 wt% and HO-PDMS content is 3 wt%. The mechanisms of improvement of contact angles were investigated, due to the vinyl group crosslinking, higher temperature can significantly improve the hydrophobicity of the films in emulsion polymerization and film forming process. Optimized FSPU has a promising future as a kind of waterborne waterproof coatings.

In this study, we demonstrate the enhancement of the electrochromic performance of tungsten oxide (WO3) by crystal network topology modification. This is achieved by constructing various crystalline morphologies and patterns of the films. Different mesoscopic crystalline networks of WO3 were acquired on transparent conducting fluorine-doped tin oxide (FTO) by a crystal-seed-assisted hydrothermal process. The modification of the crystal network topology and crystal growth habit of WO3 films was achieved by adding different concentrations of oxalic acid and HCl, and controlling the growth time. The influence of the topological patterns on the corresponding electrochromic performance of WO3 films was examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and in situ reflectance spectroscopy. It follows that four different topological patterns of WO3 microstructures, namely random “rocks” of the seed layers, micro-urchin, small peony, and blooming peony were obtained by adding different concentrations of oxalic acid and hydrochloric acid. It is found that pH and oxalic acid are both the key modifying factors of the habit and topology of the crystal networks. Consequently, the urchin-like pattern gives rise to a high efficiency in optical modulation and coloration due to its similarity to micro-sized antennas, which may facilitate the emission and absorption of charged particles and electrochemical reactions at the WO3 surfaces.

For many functional materials, the functionality that is critical to macroscopic behavior begins to manifest itself at the mesoscale. To control the macroscopic properties, knowledge of the structural characteristics in relation to the properties of the mesoscopic materials is crucial. To a large extent, the mesoscopic structure of the crystal networks in supramolecular materials determines the materials' macroscopic properties. This review therefore aims to provide a comprehensive survey of the structural characteristics of crystal networks in correlation with the macroscopic properties/performance and the formation mechanisms of supramolecular gels. In the mesoscopic engineering of soft materials, a strategy constituting a materials engineering triangle is typically adopted. This is applied to engineer soft materials based on a thorough understanding of the correlation between the structure and performance of the materials, as well as the formation kinetics. First, the hierarchy of the crystal network structures, such as the crystal network and domain network, determine the basic key features of crystal networks. Concerning the formation mechanism of the crystal networks, herein, the basic mechanisms of crystal nucleation and growth are first reviewed, and then the review is further extended to the formation of multi-level crystal networks. Consequently, the engineering of mesoscopic materials can be implemented by controlling the crystal network formation. Practical strategies include the application of various stimuli, such as additives, sonication, seeding, and thermodynamic driving force, which allow the tuning and reconstructing of the mesoscopic network structure of supramolecular gels, which leads to a controllable performance of the supramolecular materials. In general, gaining a comprehensive understanding of crystal networks will help in identifying new and robust approaches to engineer and functionalize supramolecular materials in the long term.

We have prepared nitrogen and oxygen enriched hierarchically porous carbon (NOHPC) based on a concept of neutralization reaction. The reactant of KOH and the reaction product of KCl mixed in soybean flour acts as chemical activators and porogens during carbonization, which play different roles to produce the hierarchical porous structure containing macropores, mesopores and micropores. After the investigation of the effect of the reaction pH and carbonization temperature on the structure, the optimized NOHPC with reaction pH at 11.5 and carbonization temperature at 900 °C has a large area (2404.3 m2 g−1), with a high pore volume of 1.31 cm3 g−1, a nitrogen content (0.42%) and an oxygen content (32.1%). When assembling supercapacitors, NOHPC has a extremely large specific capacitance (381 F g−1 at 1 A g−1) and large energy density (20.78–15.42 Wh kg−1), and possesses good rate performance. Particularly, the symmetric supercapacitor assembled based on NOHPC-900-11.5 has a good cycle stability in the voltage range of 0–1.8 V in a two-electrode system with 1 M Na2SO4 as the electrolyte. It is worth noting that when Tetraethylazanium tetrafluoroborate (TEATFB) in propylene carbonate and 1-ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide (EMIMNTF2) are selected as electrolyte, high energy densities of 31.4 Wh kg−1 and 71.6 Wh kg−1 are achieved. The above results indicate that NOHPC prepared based on neutralization reaction is superior energy storage materials. This work has universal significance in producing high performance porous carbons from biomass.

This review provides a comprehensive survey of the structural characteristics of crystal networks of silk soft fibrous materials in correlation with the macroscopic properties/performance and the network formation mechanisms. The correlation between the hierarchical mesoscopic structures and the mechanical properties of silk soft fibrous materials including silk fibroin hydrogels and naturally spun silk fibers are addressed based on the hierarchical crystal network models. Namely, two types of hierarchical networks are identified: the weak nanofibril-nanofibril interaction case (i.e., silk fibroin hydrogels), and the strong nanofibril-nanofibril interaction case (i.e., silk fibers). The macroscopic properties, i.e., the rheological/mechanical properties, can be controlled in terms of tuning different levels of hierarchical network structures by ultrasonication-induced gelation, introducing the initial nucleation centers, etc. Such controls take effect by different mesoscale assembly pathways, which are found to occur via different routes of the nucleation and growth processes. Furthermore, the hierarchical network model of soft fibrous materials can be applied to explain the superior mechanical properties and the unique strain-hardening behaviors of spider silk fibers within the framework of hierarchical breaking mechanism. Obviously, a knowledge of crystal networks will allow the prediction of the performance and engineering strategy of silk fibrous materials in generals.

This novel materials assembly technology endows the designated materials with additional/enhanced performance by fixing "functional components" into the materials. Such functional components are molecularly recognized and accommodated by the designated materials. In this regard, two-photon fluorescence (TPF) organic molecules and CdTe quantum dots (QDs) are adopted as functional components to functionalize silk fibers and films. TPF organic molecules, such as, 2,7-bis[2-(4-nitrophenyl) ethenyl]-9,9-dibutylfluorene (NM), exhibit TPF emission quenching because of the molecular stacking that leads to aggregation in the solid form. The specific recognition between -NO2 in the annealed fluorescent molecules and the -NH groups in the silk fibroin molecules decouples the aggregated molecules. This gives rise to a significant increase in the TPF quantum yields of the silk fibers. Similarly, as another type of functional components, CdTe quantum dots (QDs) with different sizes were also adopted in the silk functionalization method. Compared to QDs in solution the fluorescence properties of functionalized silk materials display a long stability at room temperature. As the functional materials are well dispersed at high quantum yields in the biocompatible silk a TPF microscope can be used to pursue 3D high-resolution imaging in real time of the TPF-silk scaffold.

The fabrication of bio-hybrid functional films is demonstrated by applying a materials assembly technique. Based on the hierarchical structures of silk fibroin materials, functional molecular/materials, i.e., quantum dots (QDs), can be fixed to amino acid groups in silk fibroin films. It follows that white-light-emitting QD silk hybrid films are obtained by hydrogen bond molecular recognition to the –COO– groups functionalized to blue luminescent ZnSe (5.2 nm) and yellow luminescent CdTe (4.1 nm) QDs in a molar ratio of 30:1 of ZnSe to CdTe QDs. Simultaneously, a systematic blue shift in the emission peak is observed from the QD solution to QDs silk fibroin films. The significant blue shift hints the appearance of the strong interaction between QDs and silk fibroins, which causes strong white-light-emitting uniform silk films. The molecular recognized interactions are confirmed by high resolution transmission electron microscopy, field scanning electron microscope, and attenuated total internal reflectance Fourier transform infrared spectroscopy. The QD silk films show unique advantages, including simple preparation, tunable white-light emission, easy manipulation, and low fabrication costs, which make it a promising candidate for multicomponent optodevices.