Changchun University of Technology

enables CFNs to act as an outstanding contrast agent for MRI in vitro and in vivo. These findings certify the potential of such "all in one" nanotheranostic agent integrated PDT, photoenhanced CDT, photothermal therapy (PTT), and MRI imaging capabilities along with modulating the tumor microenvironment function in theranostics of cancer.

A new type of carbon dots (CD-Asp) with targeting function toward brain cancer glioma was synthesized via a straightforward pyrolysis route by using D-glucose and L-aspartic acid as starting materials. The as-prepared CD-Asp exhibits not only excellent biocompatibility and tunable full-color emission, but also significant capability of targeting C6 glioma cells without the aid of any extra targeting molecules. In vivo fluorescence images showed high-contrast biodistribution of CD-Asp 15 min after tail vein injection. A much stronger fluorescent signal was detected in the glioma site than that in normal brain, indicating their ability to freely penetrate the blood-brain barrier and precisely targeting glioma tissue. However, its counterparts, the CDs synthesized from D-glucose (CD-G), L-asparic acid (CD-A), or D-glucose and L-glutamic acid (CD-Glu) have no or low selectivity for glioma. Therefore, CD-Asp could act as a fluorescence imaging and targeting agent for noninvasive glioma diagnosis. This work highlights the potential application of CDs for constructing an intelligent nanomedicine with integration of diagnostic, targeting, and therapeutic functions.

Development of a controllable drug delivery system is imperative and important to reduce the side-effects and enhance the therapeutic efficacy of drugs. Metal-organic frameworks (MOFs) and nanoscale MOFs (NMOFs), as porous hybrids constructed by polydentate bridging ligands and metal-connecting nodes, have attracted significant attention from the scientific community due to their tailorable compositions and structures, excellent porosity, and easier surface modification. Significant progress has been achieved in the past decade, but most attempts still remain in the proof-of-concept stage. This review highlights the latest advances in NMOFs for drug delivery systems and classifies the current drug-loading method into three strategies according to the location of the cargos and cargo-carrier interactions: encapsulation strategy, direct assembly strategy, and post-synthesis strategy. Each feature and the latest advances in these strategies are highlighted. Finally, the challenges and future perspectives in this field have been discussed.

Two-photon polymerization (TPP) is a powerful and potential technology to fabricate true three-dimensional (3D) micro/nanostructures of various materials with subdiffraction-limit resolution. And it has been applied to microoptics, electronics, communications, biomedicine, microfluidic devices, MEMS and metamaterials. These applications, such as microoptics and photon crystals, put forward rigorous requirements on the processing accuracy of TPP, including the dimensional accuracy, shape accuracy and surface roughness and the processing accuracy influences their performance, even invalidate them. In order to fabricate precise 3D micro/nanostructures, the factors influencing the processing accuracy need to be considered comprehensively and systematically. In this paper, we review the basis of TPP micro/nanofabrication, including mechanism of TPP, experimental set-up for TPP and scaling laws of resolution of TPP. Then, we discuss the factors influencing the processing accuracy. Finally, we summarize the methods reported lately to improve the processing accuracy from improving the resolution and changing spatial arrangement of voxels.

Nitrogen-doped species (NDs) are theoretically accepted as a determinant of the catalytic activity of metal-free N-doped carbon (NC) catalysts for oxygen reduction reaction (ORR). However, direct relationships between ND type and ORR activity have been difficult to extract because the complexity of carbon matrix impairs efforts to expose specific NDs. Herein, we demonstrate the fabrication of a 3D hierarchically porous NC catalyst with micro-, meso-, and macroporosity in one structure, in which sufficient exposure and availability of inner-pore catalytic sites can be achieved due to its super-high surface area (2191 cm(2) g(-1) ) and interconnected pore system. More importantly, in-situ formation of graphitic-N species (GNs) on the surface of NC stimulated by KOH activation enables us to experimentally reveal the catalytic nature of GNs for ORR, which is of great significance for the design and development of advanced metal-free NC electrocatalysts.

The advent of hydrogel-based strain sensors has attracted immense research interest in artificial intelligence, wearable devices, and health-monitoring systems. However, the integration of the synergistic characteristics of good mechanical properties, self-adhesiveness, self-healing capability and high strain sensitivity for fabricating hydrogel-based strain sensors is still a challenge. Here, a multifunctional conductive hydrogel composed of a polyacrylamide (PAAm)/chitosan (CS) hybrid network is fabricated for wearable strain sensors. The PAAm network is cross-linked by hydrophobic associations, and the CS network is ionically cross-linked by carboxyl-functionalized multi-walled carbon nanotubes (c-MWCNTs). These two networks are further interlocked by physical entanglement and hydrogen bond interactions. The obtained hydrogels exhibit excellent flexibility, puncture resistance and self-healing capability because of the efficient energy dissipation of the dynamic cross-linking network. Moreover, the hydrogels exhibit self-adhesive behavior on various materials, including polytetrafluoroethylene, wood, glass, aluminum, rubber and skin. Notably, the hydrogels can be applied as soft human-motion sensors for real-time and accurate detection of both large-scale and small human activities, including joint motions, speaking, breathing, and even subtle blood pulsation. Therefore, it is anticipated that the flexible, self-adhesive, self-healing and conductive hydrogel-based strain sensor will have promising applications in artificial intelligence, soft robots, biomimetic prostheses, and personal health care.

A facile and cost-efficient hydrothermal and lyophilization two-step strategy has been developed to prepare three-dimensional (3D) SnO2/rGO composites as NO2 gas sensor. In the present study, two different metal salt precursors (Sn(2+) and Sn(4+)) were used to prepare the 3D porous composites. It was found that the products prepared from different tin salts exhibited different sensing performance for NO2 detection. The scanning electron microscopy and transmission electron microscopy characterizations clearly show the macroporous 3D hybrids, nanoporous structure of reduce graphene oxide (rGO), and the supported SnO2 nanocrystals with an average size of 2-7 nm. The specific surface area and porosity properties of the 3D mesoporous composites were analyzed by Braunauer-Emmett-Teller method. The results showed that the SnO2/rGO composite synthesized from Sn(4+) precursor (SnO2/rGO-4) has large surface area (441.9 m(2)/g), which is beneficial for its application as a gas sensing material. The gas sensing platform fabricated from the SnO2/rGO-4 composite exhibited a good linearity for NO2 detection, and the limit of detection was calculated to be as low as about 2 ppm at low temperature. The present work demonstrates that the 3D mesoporous SnO2/rGO composites with extremely large surface area and stable nanostructure are excellent candidate materials for gas sensing.

It is an emerging focus to develop a simple and straightforward strategy to synthesize multifunctional nanomedicines for cancer imaging and treatment. In this work, a new carbon dot (named CyCD) with intrinsic theranostic properties was prepared from a hydrophobic cyanine dye [2-((E)-2-((E)-2-chloro-3-((E)-2-(1-(2-hydroxyethyl)-3,3-dimethylindolin-2-ylidene) ethylidene)cyclohex-1-en-1-yl)vinyl)-1-(2-hydroxyethyl)-3,3-dimethyl-3H-indol-1-ium iodide, CyOH] and poly(ethylene glycol) (PEG800) via a simple solvothermal process. The as-prepared CyCD is well dispersed in water media with an average diameter of 2.9 ± 0.5 nm; it possesses favorable hydrophilicity and excellent photostability. More importantly, the strong absorption and near-IR (NIR) emission within the range from 600 to 900 nm, along with preferential uptake at tumors and high photothermal conversion efficiency (η = 38.7%), facilitate CyCD to act as an ideal theranostic agent for NIR fluorescent imaging and photothermal therapy in vitro and in vivo. This work highlights theranostic CDs as an excellent candidate for efficient cancer imaging and therapy.

Alkane elimination reactions of amino-amino-bis(phenols) H2L1-4, Salan H2L5, and methoxy-β-diimines HL6,7 with lanthanide tris(alkyl)s, Ln(CH2SiMe3)3(THF)2 (Ln = Y, Lu), respectively, afforded a series of lanthanide alkyl complexes 1−8 with the release of tetramethylsilane. Complexes 1−6 are THF-solvated mono(alkyl)s stabilized by O,N,N,O-tetradentate ligands. Complexes 1−3 and 5 adopt twisted octahedral geometry, whereas 4 contains a tetragonal bipyramidal core. Bearing a monoanionic moiety L6 (L7), complex 7 (8) is a THF-free bis(alkyl). In complex 7, the O,N,N-tridentate ligand combined with two alkyl species forms a tetrahedral coordination core. Complexes 1, 2, and 3 displayed modest activity but high stereoselectivity for the polymerization of rac-lactide to give heterotactic polylactide with the racemic enchainment of monomer units Pr ranging from 0.95 to 0.99, the highest value reached to date. Complex 5 exhibited almost the same level of activity albeit with relatively low selectivity. In contrast, dramatic decreases in activity and stereoselectivity were found for complex 4. The Salan yttrium alkyl complex 6 was active but nonselective. Bis(alkyl) complexes 7 and 8 were more active than 1−3 toward polymerization of rac-LA, however, to afford atactic polylactides due to di-active sites. The ligand framework, especially the "bridge" between the two nitrogen atoms, played a significant role in governing the selectivity of the corresponding complexes via changing the geometry of the metal center. The NMR spectrum of the active species of the rac-lactide oligomer attached to complex 1 demonstrated a coordination−insertion mechanism. In addition it also confirmed that the geometry of the metal center of complex 1 in the solid state was retained in solution (THF) during the polymerization, which contributed significantly to the high selectivity of the complex.

Biomimetic skin-like electric materials have been rapidly developed for human–machine interfaces, health monitoring, and soft robots. However, achieving a combination of mechanical and sensory properties like those of human skin remains a challenge. Here, a bioinspired physical cross-linking hydrogel sensor is designed and fabricated on the basis of an ionic conductive hydrogel with hybrid latex particles in a physically cross-linked network. The hydrogels exhibit excellent mechanical adaptability similar to that of human skin, including a low modulus, excellent stretchability, robust elasticity, rapid self-recoverability, and a good antifatigue property. Moreover, the addition of LiCl gives the hydrogel ideal ionic conducive behavior as a high-performance wearable sensor. The hydrogel-based sensor exhibits high sensitivity (GF = 5.44) over a broad strain window (0.25–2000%), excellent pressure sensing capability, a rapid response time, negligible hysteresis, and good durability. As a result, the hydrogel sensor can monitor various human motions, including large-scale joint bending, running and jumping, and tiny phonating and breathing. Therefore, the strategy will broaden the path for the new generation of biomimetic sensors with skin-like mechanical and strain and pressure sensing performances.

Federated learning (FL) is a promising new technology in the field of IoT intelligence. However, exchanging model-related data in FL may leak the sensitive information of participants. To address this problem, we propose a novel privacy-preserving FL framework based on an innovative chained secure multiparty computing technique, named chain-PPFL. Our scheme mainly leverages two mechanisms: 1) single-masking mechanism that protects information exchanged between participants and 2) chained-communication mechanism that enables masked information to be transferred between participants with a serial chain frame. We conduct extensive simulation-based experiments using two public data sets (MNIST and CIFAR-100) by comparing both training accuracy and leak defence with other state-of-the-art schemes. We set two data sample distributions (IID and NonIID) and three training models (CNN, MLP, and L-BFGS) in our experiments. The experimental results demonstrate that the chain-PPFL scheme can achieve practical privacy preservation (equivalent to differential privacy with ∈ approaching zero) for FL with some cost of communication and without impairing the accuracy and convergence speed of the training model.

In this work, Ag/TiO2 nanoheterostructures with Ag nanocrystals well-grown on TiO2-based nanofiber mats have been achieved by means of a novel and straighforward protocol combining an electrospinning technique and a solvothermal process. The experimental results indicated that the morphology and size of the secondary Ag nanostructures could be tailored by altering the experimental parameters, such as the reaction time and solvent as well as the reducing agent in the solvothermal treatment. The investigation of photocatalytic ability showed that the Ag/TiO2 nanoheterostructures possess an excellent photocatalytic activity superior to the pure TiO2 nanofiber for the degradation of Rhodamine B (RB) dye driven by visible light. The results indicated that Ag might be responsible for the visible light induced photocatalytic degradation by improving the photogenerated electrons and holes separation as well as charge migration, allowing both the electrons and holes to partake in the overall photocatalytic reaction. In addition, Ag has a good light absorption capability, extending the response of TiO2 to visible light. Finally, the corresponding possible mechanism related to the photocatalytic performance of the Ag/TiO2 nanoheterostructures was discussed in detail. Additionally, the separation and recovery process of the Ag/TiO2 nanoheterostructures might be easily acheived by sedimentation without a decrease in the photocatalytic ability because of their particular one-dimensional nanostructured nature.

This review examines the current status (from 2016 to December 2018) of the electroanalytical application of boron-doped diamond (BDD), in view of its advantages and challenges for electroanalytical applications.

A straightforward nanoprecipitating method was developed to prepare water dispersible curcumin (CCM)-loaded nanoscale zeolitic imidazolate framework-8 (CCM@NZIF-8) nanoparticles (NPs). The as-synthesized CCM@NZIF-8 NPs possess high drug encapsulation efficiency (88.2%), good chemical stability and fast drug release in tumor acidic microenvironments. Confocal laser scanning microscopy and cytotoxicity experiments reveal that NZIF-8 based nanocarriers promote the cellular uptake of CCM and result in higher cytotoxicity of CCM@NZIF-8 than that of free CCM toward HeLa cells. The in vivo anticancer experiments indicate that CCM@NZIF-8 NPs exhibit much higher antitumor efficacy than free CCM. This work highlights the potential of using nanoscale metal organic framworks (NMOFs) as a simple and stable platform for developing a highly efficient drug delivery system in cancer treatment.

This study demonstrates high contrast and sensitivity by designing a dual-emissive hydrogel particle system, whose two emissions respond to pH and temperature strongly and independently. It describes the photoluminescence (PL) response of poly(N-isopropylacrylamide) (PNIPAM)-based core/shell hydrogel nanoparticles with dual emission, which is obtained by emulsion polymerization with potassium persulfate, consisting of the thermo- and pH-responsive copolymers of PNIPAM and poly(acrylic acid) (PAA). A red-emission rare-earth complex and a blue-emission quaternary ammonium tetraphenylethylene derivative (d-TPE) with similar excitation wavelengths are inserted into the core and shell of the hydrogel nanoparticles, respectively. The PL intensities of the nanoparticles exhibit a linear temperature response in the range from 10 to 80 °C with a change as large as a factor of 5. In addition, the blue emission from the shell exhibits a linear pH response between pH 6.5 and 7.6 with a resolution of 0.1 unit, while the red emission from the core is pH-independent. These stimuli-responsive PL nanoparticles have potential applications in biology and chemistry, including bio- and chemosensors, biological imaging, cancer diagnosis, and externally activated release of anticancer drugs.

Owing to their extensive practical applications and fundamental importance, the controllable synthesis of well-faceted anatase TiO(2) crystal with high percentage of reactive facets has attracted increasing attention. Here, nano-sized anatase TiO(2) sheets mainly dominated by {001} facets had been prepared on graphene sheets by using a facile solvothermal synthetic route. The percentage of {001} facets in TiO(2) nanosheets was calculated to be ca. 64%. The morphologies, structural properties, growth procedures and photocatalytic activities of the resultant TiO(2)/graphene nanocomposites were investigated. In comparison with commercial P25 and pure TiO(2) nanosheets, the composite exhibited significant improvement in photocatalytic degradation of the azo dye Rhodamine B under visible light irradiation. The enhancement of photocatalytic activity and stability was attributed to the effective charge anti-recombination of graphene and the high catalytic activity of {001} facets.

Vanadium pentoxide (V2O5) has attracted much attention for energy storage application because of its high Faradaic activity and stable crystal structure, which make it a promising electrode material for supercapacitors. However, the low electronic conductivity and small lithium-ion diffusion coefficient of V2O5 limit its practical applications. To overcome these limitations, a facile and efficient method is here demonstrated for the fabrication of V2O5/reduced graphene oxide (rGO) nanocomposites as electrode materials for supercapacitors. With this method, the reduction of graphene oxide can be achieved in a cost-effective and environmentally friendly solvent, without the addition of any other toxic reducing agent. Importantly, this solvent can control the formation of the uniform rodlike V2O5 nanocrystals on the surface of rGO. Compared to pure V2O5 microspheres, the V2O5/rGO nanocomposites exhibited a higher specific capacitance of 537 F g(-1) at a current density of 1 A g(-1) in neutral aqueous electrolytes, a higher energy density of 74.58 Wh kg(-1) at a power density of 500 W kg(-1), and better stability even after 1000 charge/discharge cycles. Their excellent performances can be attributed to the synergistic effect of rGO and rodlike V2O5 nanocrystals. Such impressive results may promote new opportunities for these electrode materials in high-energy-density storage systems.

Wet-resistant flexible electronics have gained impressive attention as underwater wearable sensors, all-weather electronic skins, and implantable bioelectrodes. However, fabricating a stable and nonswelling hydrogel-based electronic device used in diverse liquid media is challenging and promising for the progress of wet-resistance electronics. Herein, a solvent-resistant and tough hydrogel conductor is successfully prepared and exhibits fatigue resistance, antifreezing behavior, and nonswelling and wet-adhesion performances in organic and aqueous solutions. Moreover, the hydrogels are utilized as all-weather wearable sensors featuring high sensitivity, reliability, and wide sensing ranges for monitoring and distinguishing various physiological signals and human motions. Furthermore, the hydrogel sensors can even achieve accurate and stable mechanical sensing of pressure, bending, and stretching in diverse solvents consisting of water, chloroform, hexane, and dodecane. It is envisioned that the solvent-resistant and antifreezing hydrogel conductor can present promising feasibility as all-weather electronic skins, intelligent sensors in solvents, and soft robots in various harsh liquid environments.

Phosphoric acid-doped polybenzimidazole (PA-PBI) used in high-temperature proton exchange membranes (HT-PEMs) frequently suffers from a serious loss of mechanical strength because of the "plasticizing effect" of the dopant acid. Conventional cross-linking approaches generally enhance membrane stability. However, acid doping levels (ADLs) and consequently proton conductivity inevitably decrease. This is due to the formation of more compact molecular structures and a reduced amount of functional imidazole units, caused by their consumption in introducing the cross-linker. To resolve the common problems of current PA-PBI-based HT-PEMs, herein, a highly acidophilic imidazole-rich cross-linked network with superior "antiplasticizing" ability is constructed based on a novel multifunctional cross-linker. This unique bischloro/bibenzimidazole ("A2B2-type") molecular structure has extremely high reactivity, including "self-reaction" among the cross-linkers and "inter-reaction" between the cross-linker and PBI molecules. The resulting imidazole-rich cross-linked membranes exhibit the desired combination of high ADLs, high conductivity, outstanding dimensional–mechanical stability, and excellent fuel cell performance. In comparison to a corresponding linear PBI membrane, one membrane with a high content of the cross-linker of 30% has a 100 wt % increased acid uptake, a doubling in proton conductivity at 200 °C, and a maximum power density of 533 mW·cm–2 at 160 °C without humidification.

Bioinspired strategies have drawn much attention for designing intelligent hydrogels with promising performance. Herein, we present a bioinspired adhesive hydrogel driven by adenine and thymine, which are the basic units of DNA. The adhesive hydrogel exhibited promising adhesive property for the surface of various solid materials, including muscle tissues, plastics, rubbers, glasses, metals, ceramics, carnelians, and woods. The maximum peeling strength of hydrogels was 330 N m–1 on aluminum, superior to that of PAAm hydrogels with 70 N m–1. The strong adhesive behavior remained more than 30 times repeated peeling tests. Moreover, the swelling behavior, morphological structure, mechanical strength, and peeling adhesive strength were also investigated and confirmed the formation and various characteristics of adhesive hydrogels driven by adenine and thymine. Thus, the biomimetic strategy to design promising adhesive hydrogels can provide various opportunities in tissue engineering, such as wound dressing, bioglues, and tissue adhesives.