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01 October 2020, Volume 36 Issue 5

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Chemical Research in Chinese Universities Vol.36 No.5 October 2020

2020, 36(5):  0-0. 

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Review

Chemical Synthesis of Proteins Containing 300 Amino Acids

ZHANG Baochang, LI Yulei, SHI Weiwei, WANG Tongyue, ZHANG Feng, LIU Lei

2020, 36(5):  733-747.  doi:10.1007/s40242-020-0150-y

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Chemical synthesis of proteins containing up to 300 amino acids may cover 30%-50% of all the proteins encountered in biomedical studies and may provide an alternate approach to the usually used recombinant expression technology, vastly expanding the chemical space of the latter. In the present review article, we tried to survey the recent progresses made for more rapid synthesis of increasingly long peptides and more efficient ligation of multiple peptide segments. The developments of seminal methods by many research groups have greatly contributed to the recent breakthroughs in the successful total synthesis of a number of functionally important proteins, such as oligoubiquitins, bacterial GroEL/ES chaperones, and mirror-image DNA polymerases. Through these studies, a potential bottleneck has also been recognized for the chemical synthesis of large proteins, namely, how to ensure that each peptide segment from a large protein avoids unfavorable aggregation when dissolved in aqueous solution. Many new methods, such as removable backbone modification(RBM) strategy have been developed to overcome this bottleneck, while more studies need to be carried out to develop more effective and less costly methods that ultimately, may lead to fully automatable chemical synthesis of customized proteins of 300 amino acids bearing any artificial designs.



Articles

Unveiling the Hidden Movements in the Shuttling of Rotaxanes

GUO Yichang, FU Haohao, SHAO Xueguang, CAI Wensheng

2020, 36(5):  748-754.  doi:10.1007/s40242-020-0092-4

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Movements in molecular machines are usually diverse and coupled, but some of them are often implicit and hard to be observed in experiments. In the present work, the two-or three-dimensional free-energy landscapes characterizing the coupled shuttling and other movements of a series of pH-triggered rotaxanes composed of a crown ether and an H-shaped axle with distinct number of phenyl rings(n=1-3) have been explored. The results show that although the calculated free-energy barriers against shuttling in the rotaxanes(n=2 and 3) change slightly, the movements coupled with the shuttling vary significantly with the axle length. At high pH, the shuttling in the rotaxane of n=2 is coupled with the isomerization of the wheel, while the shuttling in the one of n=3 is accompanied by both the isomerization and the rotation of the macrocycle. In addition, the crown ether underwent greater conformational change during shuttling at low pH compared to that at high pH. These results indicate that disentangling the coupled movements is important to reveal the underlying molecular mechanism of the shuttling.



Acid-base Vapor Sensing Enabled by ESIPT-attributed Cd(II) Coordination Polymer with Switchable Luminescence

FU Pengyan, MO Junting, SUN Sisi, YIN Shaoyun, WANG Haiping, PAN Mei

2020, 36(5):  755-759.  doi:10.1007/s40242-020-0039-9

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Fluorescence materials based on excited state intramolecular proton transfer(ESIPT) have attracted great attention due to the unique four-level energy states. Herein, we report the assembly of a Cd-L_F coordination polymer from purposely designed L_F(H₂hpi2cf) ligand, which can present switchable luminescence behavior by gain or loss protons originated in uncoordinated ESIPT sites and serve as acid-base vapor sensors. Fabricated into in-situ grown film or transparent ink by simple methods, Cd-L_F presents facile and portable amine sensor for food spoilage detection and fluorescent anti-counterfeiting ink applications.



Mesoporous Silica Microspheres Composited with SBA-15s for Resonance Frequency Reduction in a Miniature Loudspeaker

ZHANG Xinyue, CHE Shunai

2020, 36(5):  760-767.  doi:10.1007/s40242-020-0028-z

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Microspheres composited with mesoporous SBA-15 particles and silica were investigated as fillers in miniature loudspeakers to study the factors influencing the resonance frequency offsets(RFOs). Mesoporous silica microspheres(MSMs) were prepared by self-assembling SBA-15 mesoporous silica in a microemulsion synthesis system. The formation process involved the fabrication of a stable O/W microemulsion of tetrabutyl orthosilicate(TBOS) and hexadecyltrimethylammonium bromide(C₁₆TAB) and encapsulation of SBA-15s. The RFO increased and then decreased with increasing particle size(in the length range of 0.7-5.5 μm and in the width range of 0.2-0.45 μm), increased with increasing pore size(in the range of 7.0-9.4 nm) of SBA-15s, and increased with decreasing particle size(105-900 μm) of MSMs.



Dynamic Microwave-assisted Extraction Online Coupled with QuEChERS for the Determination of Organophosphorus Pesticides in Cereals by Gas Chromatography

LI Guijie, LIU Chang, LIU Hongcheng, WANG Dawei, DING Lan

2020, 36(5):  768-773.  doi:10.1007/s40242-020-9083-8

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A rapid analytical method was first developed to detect organophosphorus pesticides(OPPs) in cereals, which used dynamic microwave assisted extraction(DMAE) coupled online with a modified quick, easy, cheap, effective, rugged, and safe(QuEChERS) method. Cereals samples were mixed with a certain amount of quartz, C₁₈ and the primary second amine(PSA), and extracted successively with the acetonitrile-water solution(80%, V/V) under microwave irradiation. The obtained eluate was directly introduced into a collection tube containing NaCl and MgSO₄. Finally, the supernate was evaporated and reconstructed, and determined by gas chromatographic spectrometry. Some factors affecting the experimental results were studied and optimized. The extraction and purification processes were carried out coinstantaneously and 12 samples could be treated in one step in 4 min. Low limits of detection(0.43-1.31 μg/kg) for OPPs were obtained in cereals. The relative standard deviations(RSDs) were 2.1%-9.3%. The recoveries of OPPs ranged from 76.1% to 100.2%. By combining the advantages of DMAE with QuEChERS, the sample pretreatment process was simple to operate, with little amount of organic solvent. The whole extraction process was completed in a closed environment, therefore it was very appropriate for daily analysis of OPPs in cereals.



Electrochemical Detection of Superoxide Anion Released by Living Cells by Manganese(III) Tetraphenyl Porphine as Superoxide Dismutase Mimic

CUI Min, REN Jujie, WEN Xiaofang, LI Na, XING Yifei, ZHANG Cong, HAN Yuanyuan, JI Xueping

2020, 36(5):  774-780.  doi:10.1007/s40242-019-0006-5

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Superoxide anion, one of the most active reactive oxygen species, is associated with the development of many diseases. So monitoring superoxide anion in living cells is of great significance for the pathological research of many diseases. In this work, a new non-enzymatic sensor for the detection of superoxide anion(O₂^·-) was developed, which was fabricated by the nanocomposites composed of manganese(III) tetraphenyl porphine(MnTPP) as super-oxide dismutase mimic and electrochemical reduced graphene oxide(ERGO) as electrode support material to modify the glassy carbon electrode(GCE). The electrochemical behavior of the fabricated electrode(MnTPP/ERGO/GCE) was performed by electrochemical impedance spectroscopy(EIS) and cyclic voltammetry(CV), which revealed that MnTPP/ERGO/GCE possessed good catalytic ability to the electrochemical reduction of O₂^·-. The MnTPP/ERGO/GCE showed excellent electroanalysis performance towards O₂^·- using the technique of differential pulse voltammetry(DPV) with a linear relationship in the range of 0.2-110.0 μmol/L, a sensitivity of 445 μA·L·mmol^-1·cm^-2 and a detection limit of 0.039 μmol/L(S/N=3). The real-time monitoring of O₂^·- from MCF-7 breast cancer cells stimulated by zymosan was realized in this work, which indicates that the MnTPP/ERGO/GCE hold potential application for electrochemical quantification of superoxide anions in biological applications.



Comparison of Two Rhodamine-Polyamine Polystyrene Solid-phase Fluorescence Sensors for Hg(II) Detection Based on Theoretical Calculation

LIU Yuanyuan, LI Yi, ZONG Linghui, ZHANG Jingyi

2020, 36(5):  781-786.  doi:10.1007/s40242-019-9258-3

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Two novel rhodamine-based polystyrene solid-phase fluorescence sensors PS-PA-I and PS-PA-II with different lengths of polyamines were synthesized for Hg(II) determination. The detection mechanism involving the Hg(II) chelation-induced spirocycle open of rhodamine was proposed with the aid of theoretical calculation. The stronger N-Hg bond and the longer polyamine chain in PS-PA-II led to a better selectivity, much higher and more quickly fluorescence response to Hg(II).



Fluorescent Aptamer-Polyethylene Glycol Functionalized Graphene Oxide Biosensor for Profenofos Detection in Food

XIONG Jin'en, LI Shuang, LI Yi, CHEN Yingli, LIU Yu, GAN Junlan, JU Jiahui, XIAN Yaoling, XIONG Xiaohui

2020, 36(5):  787-794.  doi:10.1007/s40242-019-9257-4

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A biosensor based on self-assembled ssDNA(aptamer) and polyethylene glycol functionalized graphene oxide(GO-PEG) has been designed for sensing profenofos in food. The sensor has employed the fluorescence "on/off" switching strategy in a single step in homogeneous solution. Compared to traditional detection methods, the strategy proposed here is simple, convenient, fast and sensitive. Furthermore, compared with the general aptamer-GO structure, this aptamer-GO-PEG structure is in possession of a better detection performance, which is largely attributed to the improvement of the biocompatibility and the adjustment of the adsorption capacity of GO by grafting the blocking agent PEG onto the surface of GO. Additionally, the improved biocompatibility of GO shows better stability in salt solutions and physiological solutions, which is more conducive to its practical application in foods. In this project, profenofos had been detected with the proposed strategy, and the limit of detection has been controlled to be 0.21 ng/mL. This aptasensing assay has been applied to determining profenofos in (spiked)tap water, cabbage and milk with the recovery values ranging from 93.1% to 108.5%, from 90.8% to 113.2% and from 105.9% to 114.2%, respectively.



Synthesis of Caffeic Acid Sulphonamide Derivatives and Preliminary Exploration of Their Biological Applications

PENG Xiaoyu, ZHAO Anran, HUANG Kelin, HU Tingju, LIU Buming, HUANG Yan, CHEN Hailan, CHAI Ling, LIN Cuiwu

2020, 36(5):  795-803.  doi:10.1007/s40242-020-0014-5

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Structural modification of native compounds is an effective way to develop new drugs with increased pharmacological activities and improved material characteristics. In this study, caffeic acid sulphonamide derivatives(CSs) were synthesised by conjugating sulphonamides to the backbone of caffeic acid. The structures of these derivatives were elucidated by means of Fourier transform infrared spectroscopy(FTIR), ¹H NMR, ¹³C NMR, and electrospray ionization mass spectroscopy(ESI-MS). A content determination method was established by ultraviolet detection. The lipophilicity, 2,2-diphenyl-1-picrylhydrazy free radical(DPPH) scavenging capacity, anti-coagulant effects, anti-bacterial activity, cytotoxicity, in vitro anti-proliferative activity against tumour cells, and the ability of the compounds to promote the proliferation of chondrocytes were evaluated. The results indicate that CSs exhibit strong DPPH scavenging activity, high lipophilicity, good anti-coagulant activities, wide anti-bacterial activity range, low cytotoxicity, and an excellent ability to promote chondrocyte proliferation.



Study on the Interaction and Properties of Cucurbit[8]uril with Oroxin B

XIE Jun, ZENG Zhishu, TAO Zhu, ZHANG Qianjun

2020, 36(5):  804-809.  doi:10.1007/s40242-020-0005-6

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The interaction between cucurbit[8]uril(Q[8]) and oroxin B(ORB) was investigated by UV-visible(UV-Vis) spectroscopy, isothermal titration calorimetry(ITC), mass spectrum(MS) and nuclear magnetic resonance(NMR) spectroscopy. The results showed that ORB formed a 2:1 inclusion complex with Q[8] with a binding constant of 8.266×10⁵ L²·mol^-2. ORB had good scavenging ability for 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulphonate)(ABTS) free radicals(IC₅₀=5.74 μmol/L) and the addition of Q[8] did not significantly affect the antioxidant activity of ORB(IC₅₀=5.76 μmol/L). A phase solubility experiment revealed a 1.86-fold increase in the solubility of ORB when c(Q[8])=100 μmol/L. In vitro drug release experiments showed that the release rate for ORB@Q[8] complex was lower than that of ORB in artificial intestinal juice, and higher than that of ORB in artificial gastric juice.



Syntheses and Insecticidal Activity of Spirocyclic Tetronic Acid Derivatives Containing Oxime Ether Moiety

ZHAO Yang, CHENG Jingli, XIE Zhengang, FANG Shaowei, ZHAO Jinhao

2020, 36(5):  810-815.  doi:10.1007/s40242-020-0003-8

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In order to develop novel spirocyclic tetronic acid lead compounds, a series of new spirocyclic tetronic acid derivatives containing oxime ether moiety was synthesized and bioassayed. The structures of 16 target compounds were characterized by ¹H NMR spectra, ¹³C NMR spectra and high-resolution mass spectrometer(HRMS). Preliminary bioassays indicated that most of the title compounds displayed excellent insecticidal activity against Aphis fabae and Nilaparvata lugens at 100 mg/L. In particular, compound 6k showed the similar activity(LC₅₀=6.87 mg/L) against A. fabae as the spirotetramat(LC₅₀=4.56 mg/L) and had better effects(LC₅₀=1.64 mg/L) against N. lugens in comparison with spirotetramat(LC₅₀=7.90 mg/L). The study showed that compound 6k exhibited more promising and broad-spectrum insecticide activity and may serve as a new insecticidal agent for sucking pests.



Catalyst-free 2+2 Photodimerization of 1,4-Bis[2-(4-pyridyl)ethenyl]-benzene in Solution Under Low Power UV Irradiation

CHU Ning, XU Shuping, XU Weiqing

2020, 36(5):  816-820.  doi:10.1007/s40242-020-9116-3

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Two different kinds of configurations of 1,4-bis[2-(4-pyridyl)ethenyl]-benzene(trans-bpeb and cis-bpeb) were achieved, and a bpeb dimer was synthesized in dimethyl sulfoxide(DMSO). Compared with the previous work that synthesized the bpeb dimer or polymer in crystal with a template agent needed, the reaction occurred in a solution phase in the present method. A hand-held ultraviolet lamp(365 nm) with the power of 12 W and the Watt density of 0.35 mW/cm² can realize the photodimerization of bpeb, instead of the high-power mercury lamp in most previous studies. Unlike other 2+2 cycloaddition in liquid state using catalysts even noble metals, no catalysts were required here, which is cost-saving. Only the trans-pbeb can start the cycloaddition and the formation of the close J-aggregations of trans-pbeb in DMSO is a precondition for explaining the 2+2 photodimerization. The productivity for the 2+2 cycloaddition product was achieved as 55.6%.



Self-assembly Palladacycle Thiophene Imine Monolayer-Investigating on Catalytic Activity and Mechanism for Coupling Reaction

LI Lun, XUE Xiaoxia, SUN Yimeng, ZHAO Wuduo, LI Tiesheng, LIU Minghua, WU Yangjie

2020, 36(5):  821-828.  doi:10.1007/s40242-020-9087-4

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An ordered cyclopallated thiophene imine self-assembly monolayer(Si@Pd3TI) was designed and fabricated. It was characterized by water contact angle(WCA), ultraviolet-visible spectroscopy(UV), cyclic voltammetry(CV), infrared(IR) spectrum, atomic force microscopy(AFM) and X-ray photoelectron spectroscopy(XPS). Its ca-talytic performance for Suzuki coupling reaction and catalytic mechanism were systematic investigated. Si@Pd3TI was validated as a heterogeneous catalyst identified by poisoning tests, hot filtration test and three-phase test. The heterogeneous catalytic mechanism was investigated by WCA, UV, Raman spectrum(RS), AFM, XPS and density functional theory(DFT). The catalytic mechanism proceeded via surface-catalysis process, on which the Pd(II)/Pd(I)/Pd(0) synergistic active center acted likely as "multimetallic cluster". It played a great role for cataly-zing coupling reaction, in which the real active species was Pd(I).



Synthesis and Biological Evaluation of Novel Anthranilic Diamides Containing N-H/CH₃-1H-Pyrazole

ZHANG Xiulan, ZHANG Huan, LIU Jingbo, XIONG Lixia, LI Zhengming

2020, 36(5):  829-834.  doi:10.1007/s40242-020-9037-1

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In order to systematically study the structure-activity relationship of anthranilic diamides and develop insecticides with simple structure and high efficiency, a series of novel anthranilic diamides containing N-H/CH₃-1H-pyrazole was designed and synthesized. Their chemical structures were characterized by ¹H NMR spectra, high resolution mass spectrometry(HRMS) or ¹³C NMR spectra. The preliminary bioassay results indicated that all title compounds displayed moderate insecticidal activity against oriental armyworm(Mythimna separata) at 200 mg/L and fungicidal activities against six kinds of fungi at 50 mg/L, especially compound 5i showed 50% insecticidal activity at 25 mg/L. In addition, some compounds exhibited certain antitumor activities. It was demonstrated that the introduction of CH₃ group into pyrazole ring was superior to H for the insecticidal activity.



Ball-milling Synthesis of Tetrahydroquinolines via ‘One-pot’ Three-component Diels-Alder Reaction Catalyzed by Phosphotungstic Acid

WANG Zeyou, SHEN Guodong, HUANG Xianqiang, GONG Shuwen, YANG Bingchuan, SUN Zhenzhen, ZHANG Zuhao, LIU Wanxing

2020, 36(5):  835-842.  doi:10.1007/s40242-020-9019-3

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We reported an economic and practical ball-milling method for the synthesis of tetrahydroquinoline derivatives via a ‘one-pot’ three-component Diels-Alder reaction of anilines, aldehydes and alkenes catalyzed by phosphotungstic acid at room temperature. For this reaction, a simple ‘one-pot’ ball-milling operation was conducted, readily available starting materials were employed, ‘one-pot’ conditions were applied, and the most important was to use inexpensive and environmentally friendly catalyst phosphotungstic acid. Various tetrahydroquinolines, which might be potentially applicable in the pharmaceutical and biochemical areas, were conveniently synthesized in mo-derate to excellent yields.



Promotion Mechanism of H₂O for Stereoselectivity in Pd(II)-catalyzed C-H Arylation of Diarylphosphinamides with Arylboronic Acids

CAI Yanchun, JIAO Long, QIU Xuepeng, DU Zhijun

2020, 36(5):  843-846.  doi:10.1007/s40242-019-9013-9

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On the basis of a series of control experiments and nuclear magnetic resonance analyses, it is discovered that Boc-protected amino acid ligand coordinated to Pd center is partly replaced by N,N-dimethylformamide, and H₂O can inhibit coordination of N,N-dimethylformamide to Pd center. The novel action mechanism perfectly explains H₂O promotion for stereoselectivity in Pd(II)-catalyzed C-H arylation of diarylphosphinamides with arylboronic acids.



Green and Efficient Synthesis of 3-Pyrazolyl Indoles in Water

ZHAO Yanhui, YU Haifeng, LIAO Peiqiu, WANG Wenju

2020, 36(5):  847-852.  doi:10.1007/s40242-019-0011-8

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A green and efficient synthesis of 3-pyrazolyl indoles was developed by the cyclocondensation reaction of β-ethylthio-β-indolyl-α,β-unsaturated ketones with semicarbazide hydrochloride as hydrazine equivalent in the presence of 3 equiv. of PEG-400(1a/PEG mole ratio of 1:3) in reflux water. This procedure did not require toxic hydrazine and product purification, eliminating the use of toxic liquid chemicals.



Design, Synthesis and Biological Activities of Novel N-Aryl-1H-pyrazole-5-carboxylate Derivatives

ZHANG Xiulan, ZHANG Huan, MA Jinlong, YU Shujing, LI Zhengming

2020, 36(5):  853-858.  doi:10.1007/s40242-019-9274-3

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In an attempt to search for potent fungicide, a series of novel N-aryl-1H-pyrazole-5-carboxylate derivatives was designed and synthesized. Their chemical structures were characterized by ¹H NMR spectra and high resolution mass spectrometry(HRMS). The preliminary bioassay results indicated that some target compounds displayed better fungicidal activities against certain fungi at 50 μg/mL or favorable antitumor activities at 5 μg/mLcompared with chlorothalonil and 5-fluorouracil, respectively. The structure-activity relationship demonstrated that the introduction of ester group and amide bond was favorable to the improvement of activities against Physalospora piricola and Phytophthora capsici.



Highly Active Pd-PEPPSI Complexes for Suzuki-Miyaura Cross-coupling of Aryl Chlorides: an Investigation on the Effect of Electronic Properties

ZHANG Yingying, HAN Fangwai, ZHANG Mengyao, ZHANG Huixin, LI Ying, WANG Ru, ZENG Yongfei, LIU Guiyan

2020, 36(5):  859-864.  doi:10.1007/s40242-019-9222-2

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Three new Pd-pyridine enhanced precatalyst preparation stabilization and initiation(PEPPSI) complexes with halogen groups on the N-heterocyclic carbene and pyridine were prepared. Their structures have been clearly characterized by nuclear magnetic resonance spectroscopy and X-ray single-crystal diffraction. The effects of the electronic properties of halogen groups on the catalytic activity in the Suzuki-Miyaura cross-coupling of aryl chlorides were investigated. These Pd-PEPPSI complexes could catalyze the cross-coupling reaction efficiently with a low catalyst loading(0.05%, molar ratio) at room temperature and the products were obtained in high yields.



Baeyer-Villiger Oxidation of Cyclic Ketones Catalyzed by Amino Acid Ionic Liquids

YU Fengli, CHI Yujie, GAO Chong, CHEN Ruirui, XIE Congxia, YU Shitao

2020, 36(5):  865-869.  doi:10.1007/s40242-019-9186-z

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A series of amino-acid-based ionic liquids was synthesized via one-step protonation of the corresponding L-amino acid by utilizing an array of proton sources. The catalytic activity of the amino-acid-based ionic liquids for the Baeyer-Villiger oxidation of cyclic ketones was investigated using cyclopentanone as a model cycloketone. The proline-based ionic liquid [ProH]CF₃SO₃ was shown to exhibit the best catalytic activity. The reaction condition was optimized to give the following reagent ratio of n(cyclopentanone):n(catalyst):n(H₂O₂)=1:0.06:4, 60℃ and 6 h. Under the optimum conditions, the conversion of cyclopentanone was 96.57% and the selectivity for δ-valerolactone was 73.01%. The catalytic activity was shown to be constant after 4 cycles. A simple treatment was allowed for the recover and the reuse of [ProH]CF₃SO₃. The successful utilization of [ProH]CF₃SO₃ to catalyze a host of cyclic ketones via Baeyer-Villiger oxidation clearly demonstrated the capacity of [ProH]CF₃SO₃ to tolerate variation in the substrate.



Reduction Removal of Cr(VI) from Wastewater by CO₂^·- Deriving from Formate Anion Based on Activated Carbon Catalyzed Persulfate

ZHOU Rui, LI Tingting, ZHANG Lijian, JIAO Xinqian

2020, 36(5):  870-876.  doi:10.1007/s40242-020-0169-0

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As a strong reducing radical, carbon dioxide anion radical(CO₂^·-) can be generated by initiating sulfate radical(SO₄^·-) in the presence of formate anions(FA) for Cr(VI) reduction. Moreover, activated carbon(AC)-catalyzed persulfate(PS) oxidation is an economically justifiable, environmentally friendly, and easy-to-scale-up method to produce SO₄^·-. The complete removal of Cr(VI) was achieved within 280 min for an initial Cr(VI) concentration of 50 mg/L under the optional condition of c(AC)=1 g/L, [PS]₀=10 mmol/L, [FA]₀=10 mmol/L, T=30℃, and unadjusted pH. When the molar ratio of FA to PS was greater than or equal to 1, the system maintained a strong reduction state. The mechanism investigation confirmed that FA was converted to carboxyl anion radical(CO₂^·-) as the predominant radical for Cr(VI) reduction. This novel system may offer a potential platform technology for Cr(VI) wastewater treatment.



Deposition of Phosphate Nanoparticles onto Textile Fabrics via Sol-gel Method and Their Kinetics Desorption Studies

Mohamed El MESSOUDI, Aicha BOUKHRISS, Laila SADALLAH, Laila SAJID, M'hamed El KOUALI, Said GMOUH

2020, 36(5):  877-884.  doi:10.1007/s40242-020-0045-y

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In this paper, phosphate nanoparticles were coated on cotton(CO) and polyester(PES) textile surfaces by sol-gel method using tetraethylorthosilicate(TEOS) and chloropropyltriethoxysilane(CPTS) as silica precursors. The deposited nanoparticles were observed with scanning electronic microscopy energy-dispersive X-ray spectroscopy (SEM-EDX). The release kinetics of phosphorus(P) from these textiles into the aqueous medium(Aq), acid(Ac), and basic(Ba) artificial sweats were then studied. The released amount of phosphorus was evaluated by the inductively coupled plasma(ICP) according to ISO NF EN 16711-2 procedure. The results revealed that the release of P into the aqueous medium is lower than in the artificial sweat. The kinetics data[the phosphorus desorption amount(mg/g) as a function of time] were modeled according to five models:the first order, the second order, the third order, simple Elovich and parabolic diffusion. The suitable model was chosen based on the coefficient of determination(R²) and the calculation of the sum of the absolute errors(EABS), which describes the error between the theoretical and experimental values. SEM observations were also carried out on the fabrics after desorption in order to show the impact of desorption on their morphology. Furthermore, the impact of P release on the tensile strength of CO and PES fabrics was investigated using a uniaxial tensile test. The thermal stability of all samples before and after desorption was assessed by thermogravimetric analysis(ATG).



Reaction Mechanism of H₂-Assisted C₃H₆-SCR over Ag-Ce_xZr Catalyst as Investigated by In situ FTIR

DUAN Jun, ZHAO Ling, GAO Shengjun, ZHANG Yu

2020, 36(5):  885-893.  doi:10.1007/s40242-020-0026-1

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A series of silver-doped cerium zirconium oxide(Ag-Ce_xZr) samples was synthesized successfully for selective catalytic reduction of nitric oxide(NO) with hydrogen and propene(H₂/C₃H₆-SCR) under excess oxygen condition. The catalytic activity test proved that Ag-Ce_0.4Zr exhibited the best C₃H₆-SCR activity. Hydrogen(H₂) significantly enhanced NO conversion and widened the temperature window. Multi-technology characterizations were conducted to ascertain the properties of fabricated catalysts including X-ray diffraction(XRD), Fourier transform infrared spectrometry(FTIR), scanning electron microscopy(SEM) and H₂ temperature programmed reduction (H₂-TPR). In situ FTIR results demonstrated that various types of nitrates and chelating nitrite were generated on Ag-Ce_xZr after introduction of NO. Besides, adding H₂ could increase the concentration of bidentate nitrate and chelated bidentate nitrate dramatically, especially for Ag-Ce_0.4Zr catalyst. Transient reaction between pre-adsorbing NO and C₃H₆/C₃H₆+H₂ illuminated that the most active intermediate was chelating nitrite,which was promoted significantly by H₂ participation. Furthermore, adding H₂ improved the formation of organo-nitro(R-NO₂), which was the key intermediate in C₃H₆-SCR. The reaction mechanism over Ag-Ce_xZr catalysts was proposed at 200℃ as follows:nitric oxide(NO)+propene(C₃H₆)+hydrogen(H₂)+oxygen(O₂)→chelating nitrite(NO₂^-)+acrylate-type species(C_xH_yO_z)→organo-nitro(R-NO₂)→isocyanate(-NCO)+cyanide(-CN)→nitrogen(N₂).



Investigation on the Relationship Between Carbon Cores and Fluorescence Moieties by Measurement of Fluorescence Anisotropy of CDs with Different Sizes

WANG Yijie, WANG Lei, WANG Haiyu

2020, 36(5):  894-900.  doi:10.1007/s40242-020-9109-2

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Carbon dots(CDs) have been considered as a marvellous photoluminescence(PL) material, and their PL mechanism remains debatable. The carbon core, as an essential part of CDs, apparently plays an intricate role in the PL of CDs. However, the influence of the core on the PL and the relationship between the core and fluorescence moiety are still unclear. Here, we investigated the influence of carbon cores with different sizes on the rotational motion of fluorescence moieties to determine the relationship between carbon cores and fluorescence moieties. CDs with different size distributions were synthesized by controlling carbonization time. The core sizes and rotational correlation time(RCT) of the CD samples were measured by transmission electron microscopy(TEM) and fluorescence anisotropy measurement, respectively. And the rotating unit radius were calculated from the RCT. The experimental results show that the rotational motion of the fluorescence moiety is independent of the carbon core sizes and it possesses total rotational freedom. This work is helpful for understanding the connection between the carbon core and fluorescence moiety and its influence on the PL properties of CDs.



Fabrication of Z-Scheme WO₃/KNbO₃ Photocatalyst with Enhanced Separation of Charge Carriers

ZHENG Xiuzhen, HAN Huijuan, YE Xiangju, MENG Sugang, ZHAO Shuangshuang, WANG Xiangxiang, CHEN Shifu

2020, 36(5):  901-907.  doi:10.1007/s40242-020-9106-5

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Z-Scheme photocatalysts as a research focus perform strong redox capability and high photocatalytic performance. WO₃/KNbO₃ photocatalysts were fabricated by ball milling method, and performed higher photocatalytic activity in liquid degradation(rhodamine B, methylene blue and bisphenol A), compared with WO₃ or KNbO₃ monomer. This is due to that Z-scheme heterojunction is formed between WO₃ and KNbO₃, and the holes photo-excited in valence band of KNbO₃ are quickly combined with the electrons in conduction band of WO₃. The electrons accumulated in conduction band of KNbO₃ show high reducibility, thereby reducing O₂ to ^·O₂^-, and the holes in valence band of WO₃ show high oxidative to oxidize H₂O to ^·OH, respectively. Furthermore, it is proved by means of electron spin resonance(ESR) spectra, terephthalic acid photoluminescence probing technique(TA-PL), and UV-Vis absorption spectra of nitroblue tetrazolium. This work indicates that the fabrication of Z-scheme structure can improve the photocatalytic activity by efficiently separating the photogenerated electrons and holes in the photocatalytic reaction system, which is helpful to deeply understand the migration mechanism of photoexcited carrier(band-band transfer and Z-scheme transfer) in heterojunction photocatalysts.



Mechanism of Lithium and Cobalt Recovery from Spent Lithium-ion Batteries by Sulfation Roasting Process

YU Yueshan, WANG Dahui, CHEN Huaijing, ZHANG Xiaodong, XU Li, YANG Lixin

2020, 36(5):  908-914.  doi:10.1007/s40242-019-0010-9

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Different from the traditional pyrometallurgical recovery process of Li and Co from spent lithium-ion batteries, a new recovery method for Li and Co was established by converting LiCoO₂ into water-soluble metal sulfates by roasting a mixture of LiCoO₂ and NaHSO₄·H₂O. The evolution law of the mixture with increased roasting temperature was investigated by thermogravimetry-differential scanning calorimetry(TG-DSC), in situ X-ray diffraction(XRD), XRD, and X-ray photoelectron spectroscopy(XPS). The results show that the phase transition of LiCoO₂ mixed with NaHSO₄·H₂O with increased temperature proceeded as follows:LiCoO₂, NaHSO₄·H₂O→LiCoO₂, NaHSO₄→Li_1-xCoO₂, LiNaSO₄, Na₂S₂O₇, Na₂SO₄→Li_1-xCoO₂, Co₃O₄, LiNaSO₄, Na₂SO₄→Co₃O₄, LiNaSO₄. The reaction mechanism of this roasting process may be as follows:LiCoO₂+NaHSO₄·H₂O→1/2Li₂SO₄+ 1/2Na₂SO₄+1/3Co₃O₄+1/12O₂+3/2H₂O, Li₂SO₄+Na₂SO₄=2LiNaSO₄.



Theoretical Design and Adsorption Properties of Molecularly Imprinted Polymers Obtained from Chloramphenicol and Acrylamide

LIU Junbo, ZHAO Wensi, TANG Shanshan, JIN Ruifa

2020, 36(5):  915-920.  doi:10.1007/s40242-019-9267-2

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Molecular simulations are widely used to model molecularly imprinted polymers(MIPs) in order to enhance their adsorption and selectivity. In this study, chloramphenicol(CAP) and acrylamide(AM) were used as the template and functional monomer, respectively, and pentaerythritol triacrylate(PETA), ethylene glycol dimethacrylate (EGDMA), and trimethylolpropane trimethylacrylate(TRIM) were used as cross-linking agents. The ωB97XD/6-31G(d,p) density functional theory method was employed to simulate binding sites, binding energy, the number of hydrogen bonds, the imprinted molar ratio, which produced the most stable complex, and the interaction mechanism. The cross-linking agent was optimized based on the binding energy. The atoms in molecules theory were used to study the nature of the imprinting effects. The theoretical calculations revealed that CAP and AM formed ordered complexes via hydrogen bonding interactions when the molar ratio between CAP and AM was 1:7 using TRIM as the cross-linking agent. The CAP-AM complex(molar ratio 1:7) had the most stable structure, the largest number of hydrogen bonds, and the smallest ∆E. The experimental results indicate that the CAP-MIPs formed perfect microspheres with an average particle size of 314 nm. Scatchard plot analysis showed that the CAP-MIPs had only one type of binding site over the studied concentration ranges. The dissociation equilibrium constant and maximum apparent adsorption capacities were 1887.35 mg/L(5.84 mmol/L) and 155.56 mg/g(0.482 mmol/g), respectively.



Solubility of Potassium Acetate in Water, 2,2,2-Trifluoroethanol, Ethanol and Their Binary Mixtures at 288.15—333.15 K

WU Xi, YANG Shuaishuai, XU Shiming, ZHANG Xinjie

2020, 36(5):  921-926.  doi:10.1007/s40242-019-9193-3

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The potassium acetate solutions are new potential working fluids for the closed-type reverse electrodialysis(RED) power generation system driven by thermal energy. In this paper, the solubilities of potassium acetate in water, 2,2,2-trifluoroethanol, ethanol and their binary mixtures were measured by using the laser dynamic method over the temperature range of 288.15 to 333.15 K under atmospheric pressure. The results indicate that the solubility of potassium acetate solution is influenced by both the solvent components and solution temperature evidently. Besides, it is found that the measured solubility data of the potassium acetate-water-2,2,2-trifluoroethanol solutions as per the laser dynamic method are slightly larger than that of the data obtained as per the static method. Finally, five correlation models, including the Van't Hoff model, Modified Apelblat model, Yaws model, λh model and Modified Apelblat-Jouyban-Acree model, were used to correlate the measured solubility data of those potassium acetate solutions, with the relative standard deviations within 0.23% to 1.58%.



Preparation of pH-Responsive Doxorubicin Nanocapsules by Combining High-gravity Antisolvent Precipitation with In-situ Polymerization for Intracellular Anticancer Drug Delivery

LIU Jie, CHEN Bo, ZHANG Jianjun

2020, 36(5):  927-933.  doi:10.1007/s40242-020-0007-4

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Owing to the low pH value in tumor and cancer cells, drug delivery systems based on pH-responsive polymer nanocarriers have been extensively explored for anticancer chemotherapy. Herein, we developed a pH-responsive doxorubicin(DOX) nanocapsule(named as DNanoCapsule) prepared by combining in-situ polymerization technique with high-gravity antisolvent precipitation technique through an amphiphilic polymerized surface ligand. DNanoCapsules show an obvious spherical core-shell structure with a single DOX nanoparticle encapsulated in the polymer layer. Dissolution rate studies prove that the DNanoCapsules have robust drug-release profiles under acidic environments due to the division of the pH-sensitive cross-linker, which triggers the collapse of the polymer layer. The in vitro investigations demonstrated that the DNanoCapsules exhibited high cellular uptake efficiency and cytotoxicity for both HeLa and MCF-7 cancer cells. Therefore, this work may provide a promising strategy to design and develop various stimuli-responsive drug nanocapsules for the treatment of cancer or other diseases.



Aerobic Oxidation of Alcohols to Aldehydes and Ketones with Recyclable Pd Catalysts on Cross-linked 1,10-Phenanthroline Polymers

LI Ruyue, WU Mingwei, PAN Biwei, LI Meng, HUANG Jun

2020, 36(5):  934-939.  doi:10.1007/s40242-020-9115-4

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A 1,10-phenanthroline based polymer named PPPhen(i.e., polymer from pyrene 1,10-phenanthrolin) was prepared by the Friedel-Crafts reaction of 1,10-phenanthroline and pyrene cross-linked with dimethoxymethane. The related Pd catalyst Pd@PPPhen was prepared by supporting Pd nanoparticles(NPs) on the PPPhen material. PPPhen and Pd@PPPhen were characterized by means of scanning electron microscopy(SEM), transmission electron microscopy, N₂ adsorption-desorption, Fourier-transform infrared and X-ray photoelectron spectroscopy analyses. The results showed that PPPhen polymer was highly porous and that the phenanthroline group can enhance the stability of the Pd nanoparticles. Pd@PPPhen also exhibited good catalytic activity in the aerobic oxidation of alcohols to aldehydes and ketones, and Pd@PPPhen was recyclable with durable activity and retentive structures.



Thermally Conductive Study of Polyethylene/Al₂O₃ Composite Networks Cross-linked by Electron Beam Irradiation

SHI Chengying, YANG Jiayu, LIU Yang, WANG Yanmiao, XU Wenge, XU Yiquan, HU Wei, LIU Baijun

2020, 36(5):  940-945.  doi:10.1007/s40242-019-0008-3

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The surface-modified Al₂O₃ particles were introduced into polyethylene(PE) to enhance the thermal conductivity, and PE/Al₂O₃ cross-linked networks with improved thermal and mechanical properties were prepared through electron beam(EB) irradiation technology. The incorporation of reactive irradiation sensitizer was useful in fabricating a high degree of cross-linking(DC) PE networks under a low irradiation dose. In the PE sample containing 2% sensitizer, DC ca.67.1% could be obtained under 60 kGy(1 kGy=1000 J/kg). EB-irradiation greatly improved the tensile stress of PE-based samples, and the tensile stresses of the samples with 0.2%-5% TMPTA(trimethylolpro-pane triacrylate) under 60 kGy were 24.61-27.77 MPa. All the EB-irradiated samples had higher Vicat softening temperatures than the samples without irradiation. After treatment at 120 kGy, the Vicat softening temperatures of PE-Al₂O₃-44/TMPTA-2 increased from 127℃ to 130.4℃. SEM images revealed that PE-Al₂O₃-50 samples with increased amount of Al₂O₃ particles showed a conduction "pathway," and thermal conductivity reached 0.67 W/(m·K). Thus, high-performance pipes were extruded, which could satisfy the static hydraulic blasting test and exhibit improved thermal conduction capability.



Highly Uniform Alkali Doped Cobalt Oxide Derived from Anionic Metal-Organic Framework: Improving Activity and Water Tolerance for CO Oxidation

LEI Huijin, ZHANG Xinlu, JIN Jiongke, WANG Shuhua, DING Shunmin, ZHANG Ning, CHEN Chao

2020, 36(5):  946-954.  doi:10.1007/s40242-020-0024-3

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A sequence of alkali metal cation-exchanged Co metal-organic frameworks(Co-MOFs), therein after denoted as M@Co-MOF, M=Na⁺, K⁺, Rb⁺, and Cs⁺, was prepared and used as the precursors to obtain the corresponding alkali doped cobalt oxide(defined as M/Co₃O₄, M=Na⁺, K⁺, Rb⁺, and Cs⁺) through calcination under air atmosphere. The cobalt oxide modified by uniform alkali metals exhibited a significant promotion of catalytic activity for CO oxidation. The activity of M/Co₃O₄ decreased in the order of Cs⁺ > Na⁺ > K⁺ > Rb⁺. Experimental and theoretical results revealed that the anionic skeleton of Co-MOF could facilely adsorb alkali metal cations and play a crucial role in the formation of highly uniform alkali doped cobalt oxide. The further characterizations, such as temperature-programmed reduction of H₂(H₂-TPR), oxygen temperature-programmed desorption(O₂-TPD), X-ray photoelectron spectroscopy(XPS), and in situ diffuse reflectance infrared Fourier transform(DRIFT) spectra demonstrated that the enhanced catalytic activity is originated from the interfacial electron transfer as well as weakened the Co-O bond strength, which promoted oxygen desorption from Co₃O₄ and formation of cobalt species with the lower valence state. The Cs/Co₃O₄ catalyst was maintained for 60 h without deactivation and still showed a high activity in the presence of water.



Deep Eutectic Solvent-assisted Synthesis of Nitrogen-doped Carbon Quantum Dots for Cell Imaging

LI Long, HUANG Yan, ZHAO Pei, MIAO Haochi, ZHAO Ting

2020, 36(5):  955-961.  doi:10.1007/s40242-020-0015-4

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Carbon quantum dots(CQDs) are widely used in fluorescence imaging due to their negligible toxicity, low-cost and excellent fluorescence properties. The fluorescence properties of CQDs are greatly affected by the synthesis method, passivation agent and reaction media. In this study, the nitrogen-doped CQDs(N-CQDs) were synthesized by a facile microwave-assisted method with citric acid(CA) as a carbon source and deep eutectic solvents as a N-dopant as well as the reaction solvent. After detailed characterizations, the as-prepared N-CQDs exhibited near spherical morphology with an average size of (2.64±0.55) nm. Besides, the abundant hydrophilic functional groups including hydroxyl, carboxyl, amine and quaternary ammonium were present on the surface of the N-CQDs. The N-CQDs displayed the excitation-dependent fluorescence feature under the excitation wavelength of 350-480 nm. Moreover, the N-CQDs could be efficiently uptaken by RAW264.7 cells and emitted bright green light. Meanwhile, the resultant N-CQDs showed the low cytotoxicity in living cells, suggesting the great potential in bio-imaging applications.



Strong and Injectable Hydrogels Based on Multivalent Metal Ion-Peptide Cross-linking

YU Wenting, XUE Bin, ZHU Zhenshu, SHEN Ziqin, QIN Meng, WANG Wei, CAO Yi

2020, 36(5):  962-969.  doi:10.1007/s40242-020-9100-y

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Injectable hydrogels are ideal biomaterials for delivering cells, growth factors and drugs specifically to localized lesions and subsequent controlled release. Many factors can affect the efficacy of injectable hydrogels. To avoid potential damage to encapsulated cells or drugs, injectable hydrogels should be highly dynamic so that they can undergo shear-thinning at low strain rates and rapidly reform after injection. However, dynamic hydrogels are often mechanically weak, leading to the leakage of encapsulated cells or drugs. Here we demonstrated a convenient method to improve the mechanical strength without jeopardizing the dynamic properties of hydrogels by using metal ion-peptide crosslinkers containing multiple metal ion-ligand bonds. We showed that the dynamic properties of the hydrogels correlated with the intrinsic dynamics of the metal-ligand bonds and were not affected by the formation of multivalent binding. Yet, the mechanical stability of the hydrogels was significantly improved due to the increased thermodynamic stability of the crosslinkers. We further showed that the drug release rates were slowed down by the formation of multivalent crosslinkers. Our results highlight the importance of ligand valency to the mechanical response of hydrogels and provide a universal route to rationally tune the dynamic and mechanical properties of injectable hydrogels.



Preparation and Characterization of CaO/ZnO Core-shell Structured Nanoparticles

WANG Lili, LIU Yanan, PENG Xiaoxing, SUN Yuanqing, LIU Xiaohua, LIU Huimin, LIN Quan, SUN Hongchen, YANG Bai, LI Xiangwei

2020, 36(5):  970-975.  doi:10.1007/s40242-020-9029-1

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Residual bacteria and microleakage in a complicated root canal can often result in reinfection of the periapical tissues. To promote the antibacterial and sealing effects of a root canal filling, core-shell structured CaO/ZnO nanospheres were synthesized using a precipitation method based on a traditional root canal sealer, zinc oxide-eugenol(ZOE). The obtained CaO/ZnO particles had a size of 80-90 nm and a core-shell structure. The film thickness, flow rate, pH, and calcium ion release of the core-shell structured CaO/ZnO nanospheres-eugenol paste were tested. The pH and calcium ion release results showed a slight increase in the prepared nanospheres, with a flow rate of 24.22 mm and a formed film thickness of 30 μm, which are basically consistent with ISO 6876:2001 standards(regarding dental root canal sealing materials). Cytotoxicity tests showed that the cytocompatibility of the CaO/ZnO nanospheres-eugenol paste was much higher than that of the ZOE or iRoot SP groups(P<0.05). A comparison of the sealing ability and antibacterial activity showed that the core-shell structured CaO/ZnO nano-spheres-eugenol paste had significantly better effects than the ZOE and iRoot SP sealers(P<0.05). The core-shell structured CaO/ZnO nanosphere paste displayed excellent sealing and antibacterial properties, and it has promising application potential in endodontics.



Introduction of H₂SO₄ and H₃PO₄ into Crystalline Porous Organic Salts(CPOS-1) for Outstanding Proton Conductivity

WANG Yuxia, YAN Tingting, BEN Teng

2020, 36(5):  976-980.  doi:10.1007/s40242-020-9276-1

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To improve the proton conduction of crystalline porous organic salts(CPOS-1), H₂SO₄ and H₃PO₄ were introduced into the channel to obtain H₂SO₄@CPOS-1 and H₃PO₄@CPOS-1. Compared to CPOS-1, the proton conductivities of H₂SO₄@CPOS-1 and H₃PO₄@CPOS-1 increased two orders of magnitude and one order of magnitude at 303 K and 100% RH, respectively. It can be attributed to the increasing concentration of the protons, which dissociates from the acids.



Highlights

Encapsulation and Release of Circulating Tumor Cells Using 3D DNA Hydrogels

GUO Zijian

2020, 36(5):  981-982.  doi:10.1007/s40242-020-0251-7

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To minimize the concomitant cell damage in the capture process of circulating tumor cells(CTCs) in conventional methods, Zuo et al. proposed to use aptamer-trigger-clamped hybridization chain reaction method to encapsulate CTCs by in-situ forming 3D DNA hydrogel. The 3D porous DNA hydrogel on cell membrane minimizes cell damage, and the CTCs can be readily released by the ATP triggered dis-assembly of DNA hydrogel for subsequent culture and live cell analysis. This work has been published online in the Nature Protocols in June 22, 2020.



Unraveling the Dynamics of Antibody-Antigen Interaction by DNA Origami

NIE Zhou

2020, 36(5):  983-984.  doi:10.1007/s40242-020-0252-6

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To investigate the dynamic interaction between antibody and antigen, Fan et al. rationally designed a triangular DNA origami framework to spatially organize the antigenic epitopes at the nanoscale and thus to monitor the transient binding kinetics of the dynamic antigen-antibody complexes at room temperature. This study provides a straightforward, designable and programmable strategy to investigate the transition kinetics of antibody-antigen interaction at a single-molecule level and improve the understanding toward the design of the next-generation antibodies and vaccines for various biomedical applications. This work has been published online in Nature Communications on June 19, 2020.