Chemical Structural Characterization Research Articles

Galactose-modified selenium nanoparticles for targeted delivery of doxorubicin to hepatocellular carcinoma

Galactose-modified selenium nanoparticles (GA-SeNPs) loading with doxorubicin (DOX) for hepatocellular carcinoma (HCC) therapy was investigated in this paper. Selenium nanoparticles (SeNPs) were modified with galactose as tumor targeting moiety to fabricate tumor-targeted delivery carrier GA-SeNPs, then doxorubicin was loaded onto the surface of GA-SeNPs for improving antitumor efficacy of DOX in HCC therapy. Chemical structure characterization of GA-Se@DOX showed that DOX was successfully loaded to the surface of GA-SeNPs to prepare functionalized antitumor drug delivery system GA-Se@DOX. GA-Se@DOX exhibited effective cellular uptake in HepG2 cells and entered HepG2 cells mainly by clathrin-mediated endocytosis pathway. GA-Se@DOX showed significant activity to induce the apoptosis of HepG2 cells in vitro. The western blotting result indicated that GA-Se@DOX induced HepG2 cells apoptosis via activating caspase signaling and Bcl-2 family proteins. Moreover, active targeting delivery system GA-Se@DOX exhibited excellent antitumor efficacy in vivo in comparison with passive targeting delivery system Se@DOX. Histology analysis showed that GA-Se@DOX exhibited no obvious damage to major organs including heart, liver, spleen, lung, and kidney under the experimental condition. Taken together, GA-Se@DOX may be one novel promising nanoscale drug candidate for HCC therapy.

Study on the Preparation and Chemical Structure Characterization of Melanin from Boletus griseus.

In this study, melanin (BgM) was obtained from Boletus griseus. The chemical composition and structure of BgM were characterized by UV-visible absorption spectrum, Fourier transform infrared spectrum, elemental analysis, nuclear magnetic resonance, pyrolysis gas chromatography mass spectrometry, and ultra-performance liquid chromatography–high resolution mass spectrometry. The percentage contents of C, H, N, S and O elements were 56.38%, 5.86%, 6.17%, 2.44%, and 28.04%, and the S/N and C/N ratios were 0.17 and 10.66, respectively. The UV-vis spectrum of BgM showed a maximum absorption peak at 214 nm. Characteristic absorption peaks were observed at 3426, 1600 and 1105 cm−1, and BgM contained phenolic hydroxyl, amidogen, carbonyl, methylene, and methyl groups. Moreover, BgM is an eumelanin, and its main skeleton has both a benzene ring and an indole, and the branched chain mainly consists of alkanes, alcohols, and fatty acids. BgM was hydrolyzed by H2O2 and four compounds were tentatively analyzed from the UPLC-MS/MS profile. The chemical structure of BgM was characterized as 5,6-dihydroxyindole eumelanin, and the condensed molecular formula is [C28(OR1)4(OR2)3H11O6N4]n.

Methods to prepare dopamine/polydopamine modified alginate hydrogels and their special improved properties for drug delivery

Dopamine (DA), a typical catechol-containing monomer, which has been well reported for its excellent applications in biomedical research, was used to modify alginate (ALG) hydrogel for better gel formation and performance which are needed for drug delivery. By our design, Polydopamine (PDA) particles embedded ALG hydrogel (ALG-PDA), two types of DA and ALG co-polymerized hydrogels (ALG-DA-AS, ALG-DA-SP) which were initiated by ammonia aqueous solution (AS) and sodium periodate (SP), respectively, were successfully prepared. The status of incorporated DA/PDA and their interactions with hydrogel skeleton were investigated by chemical structure, morphology and rheology characterizations. Interestingly, a self-gelation process was discovered during ALG-DA-SP preparation, which is supposed to be the crosslinking formation via the aromatic interaction and hydrogen bonding between catechol or o-benzoquinone modified ALG molecules. Such self-crosslinked structure was proved helpful to improve the structural stability of gel even in saline environment. The effects of DA, SP concentration on the self-gelation process were discussed. The good biocompatibility of PDA material was also confirmed by a cytotoxicity test. In loading and release experiments, all the modified hydrogels were proved to have better adsorption ability to gatifloxacin (GFLX) and more steady in vitro release behavior than pristine ALG hydrogel.

Delivery of Doxorubicin for Human Cervical Carcinoma Targeting Therapy by Folic Acid-Modified Selenium Nanoparticles.

Cancer-specific drug delivery represents an attractive approach to preventing undesirable side effects and increasing the accumulation of the drug in tumors. The surface modification of selenium nanoparticles (SeNPs) with targeting moieties thus represents an effective strategy for cancer therapy. In this study, SeNPs were modified with folic acid (FA), whose receptors were overexpressed on the surface of cancer cells, including human cervical carcinoma HeLa cells, to fabricate tumor-targeting delivery carrier FA-SeNPs nanoparticles. Then, the anticancer drug doxorubicin (DOX) was loaded onto the surface of the FA-SeNPs for improving the antitumor efficacy of DOX in human cervical carcinoma therapy. The chemical structure characterization of FA-Se@DOX showed that DOX was successfully loaded to the surface of FA-SeNPs to prepare FA-Se@DOX nanoparticles. FA-Se@DOX exhibited significant cellular uptake in human cervical carcinoma HeLa cells (folate receptor overexpressing cells) in comparison with lung cancer A549 cells (folate receptor deficiency cells), and entered HeLa cells mainly by the clathrin-mediated endocytosis pathway. Compared to free DOX or Se@DOX at the equivalent dose of DOX, FA-Se@DOX showed obvious activity to inhibit HeLa cells’ proliferation and induce the apoptosis of HeLa cells. More importantly, FA-Se@DOX could specifically accumulate in the tumor site, which contributed to the significant antitumor efficacy of FA-Se@DOX in vivo. Taken together, FA-Se@DOX may be one novel promising drug candidate for human cervical carcinoma therapy.

Functionalized selenium nanoparticles for targeted delivery of doxorubicin to improve non-small-cell lung cancer therapy.

BackgroundSelenium nanoparticles (SeNPs) loaded with chemotherapeutic drugs provided a novel perspective for cancer therapy.Materials and methodsHere, SeNPs were modified with cyclic peptide (Arg–Gly–Asp–d-Phe–Cys [RGDfC]) to fabricate tumor-targeting delivery carrier RGDfC-SeNPs and, then, doxorubicin (DOX) was loaded to the surface of RGDfC-SeNPs for improving the antitumor efficacy of DOX in non-small-cell lung carcinoma therapy.ResultsThe chemical structure characterization of RGDfC-Se@DOX showed that DOX was successfully loaded to the surface of RGDfC-SeNPs to prepare functionalized antitumor drug delivery system RGDfC-Se@DOX. RGDfC-Se@DOX exhibited effective cellular uptake in A549 cells and entered A549 cells mainly by clathrin-mediated endocytosis pathway. Compared to free DOX or Se@DOX at the equivalent dose of DOX, RGDfC-Se@DOX showed greater activity to inhibit A549 cells’ proliferation and migration/invasion and induce A549 cells’ apoptosis. More importantly, compared with passive targeting delivery system Se@DOX, active targeting delivery system RGDfC-Se@DOX exhibited more significant antitumor efficacy in vivo.ConclusionTaken together, RGDfC-Se@DOX may be a novel promising drug candidate for the lung carcinoma therapy.

Formation and shape transition of porous polyurea of exotic forms through interfacial polymerization of toluene diisocyanate in aqueous solution of ethylenediamine and their characterization

Polyureas (PU) are of prime importance for a great number of applications from protective coatings and catalyst support to biomaterials for hydrogels and drug release. Novel physical and chemical methods of their synthesis have been great interests in order to obtain these materials of different morphologies with different surface and structural properties. Herein, PUs with exotic structures, including bead-skewer and string-form, are prepared through a very simple interfacial polymerization of toluene diisocyanate (TDI), by adding it into an aqueous solution of ethylenediamine (EDA) at constant rate. The effects of experimental conditions, including EDA/TDI ratio, polymerization temperature, pore size of syringe needle for TDI addition and the addition rate, on the morphology of PU materials were studied. The results showed that bead-skewer PU was obtained with EDA/TDI ratio at 1.43–1.51, and string-form PU achieved with the same ratio at 1.59–2.20. A hard shell was first formed on the surface of TDI once extruded out of the syringe needle. The size of bead-skewer and string-form PU was easily adjusted. Their chemical structure characterization by NMR confirmed that a PU shell was formed in the early stage of the polymerization, owing to the reaction of TDI with EDA. PU materials thus prepared are macroporous regardless of their shape. This paper provides therefore a novel and simple way to the preparation of porous PU with specific shapes, such as bead-skewer and string-form, along with the formation and shape transition mechanism of the materials.

An innovative approach for the chemical structural characterization of poly(styrene 4‐vinylpyridine) copolymers by matrix‐assisted laser desorption/ionization time of flight mass spectrometry

ABSTACTPoly(styrene‐co‐4‐vinylpyridine) random copolymers with different molar composition were synthesized by nitroxide‐mediated controlled‐radical polymerization using 2,2,5‐trimethyl‐4‐phenyl‐3‐azahexane‐3‐nitroxide (TIPNO) as a mediator. We record the matrix‐assisted laser desorption/ionization time of flight (MALDI‐TOF) spectra under various conditions, and we find (at last) that they show mostly intact ions [using 2(‐4‐hydroxyphenylazo‐)benzoic acid as MALDI matrix]. Spectra are highly resolved, and thus they allow for the determination of all end‐groups, even some less‐abundant ones. Spectra are dominated by intact “dormant” copolymer chains terminated with TIPNO at one end and with (4‐Bromo‐phenyl)ethyl group (starting fragment) at the other one. Applying the mass analysis of copolymers (MACO) statistical model to the spectra, we show that the MACO/MALDI‐TOF mass spectrometry (MS) analysis can be successfully applied to copolymers having a difference between the mass of the comonomers as small as 1 g mol−1 (the styrene and 4‐vinylpyridine units are 104.15 and 105.15 g/mol, respectively), which results in overlapping isotopic patterns. The results are accurate: chemical composition evaluated by means of MS agrees with that calculated by 1H‐nuclear magnetic resonance, for all copolymers investigated. This analytical method allows to extract detailed information on the composition of the copolymer samples and their structure. Glass transition temperatures of copolymers were also determined by differential scanning calorimetry. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 46976.

Synthesis, characterization and antibacterial properties of reverse osmosis membranes from cellulose bromoacetate

The antibacterial alkyl bromide groups were introduced into cellulose diacetate (CDA) through the esterification between highly active bromoacetyl bromide and hydroxyl groups under mild conditions and the modified cellulose acetate reverse osmosis membrane (Br-CA-RO) was obtained subsequently after phase inversion process. The results of FTIR and 1H-NMR indicated the existence of alkyl bromide groups in the modified CDA powder. The optical density method was used to confirm its antibacterial ability. The chemical structure and morphology characterization demonstrated that the anchoring of bromoacetyl groups as antibacterial part brought out minimal alteration on membrane chemical structure and its asymmetric structure, but the regularity and density of membranes increased with the degree of esterification. The property testing results showed that the whole physical performance was enhanced with the thermal stability getting slightly worse. Both the flux and salt rejection of Br-CA-RO increased after modification and the latter was close to that of cellulose triacetate RO membrane. The dynamic contact antibacterial testing implied that Br-CA-RO showed much higher antibacterial ability than unmodified RO membranes, and its relative bactericidal rates against E. coli (gram negative) and S. aureus (gram positive) were higher than 73.0% and 93.5%, respectively. This method offers a new approach for antibacterial and functional modification of CA-RO membranes.

Synthesis and Characterization of Terpolymers of poly(L-lactide-glycolide-ε-caprolactone)

Random terpolymers of poly(L-lactide-glycolide-ε-caprolactone) (PLLGC) was prepared by ring-opening polymerization of L-lactide, glycolide and ε-caprolactone monomers initiated with stannous octanoate. Fourier transform infrared spectra, nuclear magnetic resonance and gel permeation chromatography were employed to characterize the obtained PLLGC terpolymers. The effects of polymerization temperature, reaction time, the amount of initiator and the polymerization pressure on the weight average molecular mass and polydispersity index of the PLLGC were investigated. In addition, the water contact angle of the PLLGC was also tested. The characterization of chemical structure showed that the PLLGC was successfully synthesized. For instance, a PLLGC terpolymer with a weight average molecular mass of about 12.435 × 104 Da and a polydispersity index of 1.28 was obtained when the polymerization was conducted with a molar ratio of monomer to initiator ([M]/[I]) of 2000, polymerization temperature of 140 °C, polymerization pressure of 5.0 Pa and reaction time of 24 h. The random incorporation of ε-CL monomer units decreased the wettability of the PLGA copolymers.

Development of Amoxicillin-Loaded Electrospun Polyurethane/Chitosan/ $\beta$ -Tricalcium Phosphate Scaffold for Bone Tissue Regeneration.

Biocompatible nanocomposite electrospun fibers containing Polyurethane/Chitosan/ $\beta $ -Tri calcium phosphate with diverse concentrations were designed and produced through the electrospinning process for bone tissue engineering applications. After the production process, density measurement, viscosity, electrical conductivity, and tensile strength measurement tests were carried out as physical analyses of blended solutions. The chemical structural characterization was scrutinized using Fourier transform infrared spectrometer (FTIR), and scanning electron microscopy (SEM) was used to observe the morphological details of developed electrospun scaffolds. Cell viability, attachment, and proliferation were performed using a L929 fibroblast cell line. Based on the physical, SEM, FTIR analysis, and cell culture studies, preferable nanofiber composition was selected for further studies. Amoxicillin (AMX) was loaded to that selected nanofiber composition for examination of the drug release. In comparison with other studies on similar AMX controlled products, higher drug loading and encapsulation efficiencies were obtained. It has been clearly found that the developed nanofiber composites have potential for bone tissue engineering applications.

Interface Design for Metal Halide Perovskite Solar Cells

With the rise of thin-film photovoltaics, the research community brought the interfaces within the device into the spotlight for performance enhancements. This Perspective lays out why this notion is especially applicable for solar cells based on metal halide perovskite (MHP) absorber materials, for which we reach a significant improvement of device functionality and stability through the means of engineering the energetics and electronic properties at the interface. After examining recent key developments in chemical and electronic structure characterization of MHPs that led to this avenue, we will iterate the next steps toward interlayer tailoring and analysis. The future goal is to derive a comprehensive model for interface energetics in perovskite solar cells and to set up respective design rules for stable high-efficiency cells. This approach also pertains to the broader scope of MHP-based optoelectronic devices for which charge carrier transport across the interfaces and surface recombination play a...

Structural, dielectric and humidity properties of Al-Ni-Zn ferrite prepared by co-precipitation method

Al0,2Ni0,3Zn0,5Fe2O4 ferrite nanoparticles have been synthesized by chemical co-precipitation method and structural characterization has been analyzed using X-Ray diffraction (XRD) and scanning electron microscopy (SEM). XRD analysis indicates that Al0,2Ni0,3Zn0,5Fe2O4 ferrite nanoparticles crystallize in the cubic spinel phase. To determine the electrical properties of the sample, the real and imaginary parts of the dielectric constant have been investigated to a frequency range from 20 Hz to 10 MHz for 31 test frequencies. These measurements have been also repeated for different temperatures. The impedance analysis of the sample was carried out using Nyquist curves. The variation of the conductivity of the sample is also shown for the 31 test frequencies and the different temperature values in the range between 293 K and 733 K. The DC conductivity of the Al0,2Ni0,3Zn0,5Fe2O4 as a function of temperature is also presented and the measurements confirm that the sample exhibits semiconductor behavior in accordance with the literature. Finally, the relative humidity, frequency and impedance map of the sample has been investigated in detail.

Amaryllidaceae alkaloids as agents with protective effects against oxidative neural cell injury

AimsDetermine a relationship between the neuroprotective activity and the antioxidant capacity of the Amaryllidaceae alkaloids in a model of Glu excitotoxicity in rat cortical neurons. Materials and methodsWas evaluated several alkaloidal fractions isolated from Amaryllidaceae species, a family known to contain neuroprotective alkaloids, in a model of Glu excitotoxicity in rat cortical neurons. In addition, several mechanisms of antioxidant activity were used, and a theoretical study of the antioxidants was performed. Key findingsThe results of this study suggest that a possible neuroprotective mode of action of the alkaloidal fractions of Eucharis bonplandii (Kunth) Traub bulbs, Eucharis caucana Meerow bulbs, and Clivia miniata Regel leaves, is through their antioxidant activity and ability to stabilize free radicals generated from an excitotoxic process mediated by Glu. The chemical structure characterization and antioxidant activity of the fractions suggest that the phenol and enol groups in the structures of the alkaloids are critical for the stabilization of ROS and RNS. Additionally, the pair of free electrons on the N is spatially close to a hydroxyl group, which benefits the cleavage of this group and, consequently, the stabilization of the generated O. SignificanceThe versatility of the structures of the studied Amaryllidaceae alkaloids suggests that they have potential as neuroprotective agents against an oxidative stimulus.

Study of the Physical and Structural Properties of Some Local Mineral Clays and Effect of Doping with Chromium Oxide

Chemical composition, physical properties and structural characterization of local natural mineral clays have been studied. The study approach is based on using X-ray diffraction and fluorescence, thermal gravimetric analysis, differential scanning calorimetry, infrared spectroscopy, instrumental and classical chemical analysis techniques. The results were compared with those obtained from acidically treated and chromium oxide doped clay samples. Four samples were prepared in order to be a more active and selective adsorbent materials. Soxhlet fractionating techniques were set for all the above types of adsorbents using four eluants gradually increased in polarity. The fractionation results showed significant variations in the fractions isolated according to their polarities as indicated by percentage results.

Molecular Structure Characterization by Isotopic Splitting in Nonlinear Ion Mobility Spectra.

Nearly all compounds comprise numerous isotopologues ensuing from stable natural isotopes for constituent elements. The consequent isotopic envelopes in mass spectra can reveal the ion stoichiometry but not geometry. We found those envelopes to split in differential ion mobility (FAIMS) spectra in a manner dependent on the ion geometry and buffer gas composition. The resulting multidimensional matrix of isotopic shifts is specific to isomers, providing a fundamentally new approach to the characterization of chemical structure. The physical origins of the effect remain to be clarified but likely ensue from the transposition of center of mass of the ion within its geometry frame affecting the partition of energy in above-thermal collisions between the translational and rotational degrees of freedom. The additivity of shifts, holding with no exception so far, may be the key to unraveling the foundations of observed behavior.

Superior flame retardancy and smoke suppression of epoxy-based composites with phosphorus/nitrogen co-doped graphene

Phosphorus and/or nitrogen doping is an effective method of improving the physical and chemical properties of reduced graphene oxide (rGO). In this work, phosphorus and nitrogen co-doped rGO (PN-rGO), synthesized using a scalable hydrothermal and microwave process, was used as an additive to improve the flame retardancy of epoxy resin (EP) for the first time. Chemical structure and morphology characterization confirmed that the nitrogen and phosphorus atoms were doped into the graphite lattice adopting pyrrolic-N, pyridinic-N, quaternary-N and pyrophosphate and metaphosphate forms. Doping increased the oxidization resistance of rGO and the thermal-oxidative stability of its composites’ char, while also improving the catalytic charring ability of polymer. Both effects resulted in the formation of a stable char protective layer during burning and to a significant improvement in flame retardation and smoke suppression in the final composites. The peak heat release rate (PHRR), total heat release (THR) and total smoke production (TSP) for the EP-based composite (containing 5 wt% PN-rGO) decreased by 30.9%, 29.3% and 51.3%, respectively, compared to neat EP. Our work has produced a promising graphene-based flame retardant additive for the mass production of high-performance composites, also expended the application of heteroatom-doped graphene.

Multinuclear NMR spectroscopy, photophysical, electrochemical and DNA-binding properties of fluorinated 1,8-naphthyridine-based boron heterocycles

This paper reports the results of the synthesis and structural elucidation by multinuclear NMR spectroscopy and single crystal X-ray diffraction of a new series of four examples of 1,1-difluoro-3-methyl-9-(aryl/heteroaryl)-7-(trifluoromethyl)-1H-[1,3,5,2]oxadiazaborinino[3,4-a][1,8]naphthyridin-11-ium-1-uides, which were obtained, at good yields (60–66%), from the reaction of 7-substituted N-(5-(trifluoromethyl)-1,8-naphthyridin-2-yl)acetamides — in which the 7-substituents are C6H5, 4-CH3C6H4, 4-FC6H4, and 2-Thienyl — with BF3·Et2O solution. One-dimensional multinuclear NMR spectroscopy (1H, 13C, 19F, and 11B) and two-dimensional 1H–15N HMBC are presented as powerful tools for an easy and secure NMR chemical shift assignments and structural characterization of fluorinated 1,8-naphthyridine-based boron complexes. Additionally, investigations of photophysical, electrochemical and DNA-binding properties were done.

The antioxidant, anti-inflammatory and antidiabetic activities of Sternbergia lutea ssp. lutea and Sternbergia lutea ssp. sicula

Determine a relationship between the neuroprotective activity and the antioxidant capacity of the Amaryllidaceae alkaloids in a model of Glu excitotoxicity in rat cortical neurons.Was evaluated several alkaloidal fractions isolated from Amaryllidaceae species, a family known to contain neuroprotective alkaloids, in a model of Glu excitotoxicity in rat cortical neurons. In addition, several mechanisms of antioxidant activity were used, and a theoretical study of the antioxidants was performed.The results of this study suggest that a possible neuroprotective mode of action of the alkaloidal fractions of Eucharis bonplandii (Kunth) Traub bulbs, Eucharis caucana Meerow bulbs, and Clivia miniata Regel leaves, is through their antioxidant activity and ability to stabilize free radicals generated from an excitotoxic process mediated by Glu. The chemical structure characterization and antioxidant activity of the fractions suggest that the phenol and enol groups in the structures of the alkaloids are critical for the stabilization of ROS and RNS. Additionally, the pair of free electrons on the N is spatially close to a hydroxyl group, which benefits the cleavage of this group and, consequently, the stabilization of the generated O.The versatility of the structures of the studied Amaryllidaceae alkaloids suggests that they have potential as neuroprotective agents against an oxidative stimulus.

Pyrolysis and flame retardant behavior of a novel compound with multiple phosphaphenanthrene groups in epoxy thermosets

A novel flame retardant compound (TDBA) with multiple phosphaphenanthrene groups was synthesized and confirmed by chemical structural and elemental characterization. Contrastive analysis on thermal decomposition behavior showed that the two kinds of bridge bonds linking phosphaphenanthrene groups in TDBA caused a wider decomposition temperature range, contributing to inhibiting combustion in relatively longer time. The application of TDBA in epoxy thermosets suggested that, TDBA capacitated the limited oxygen index of thermosets to surpass 35% and 4wt.% or more loadings of TDBA made 4,4′-diamino-diphenyl methane curing thermosets pass UL94 V-0 rating especially. During combustion, the incorporated TDBA induced the matrix to decompose earlier, reduced the fuels production, reduced burning intensity and inhibited the combustion reaction of fuels in gaseous phase, and promoted the charring behavior of thermosets in condensed phase. The pyrolysis of TDBA proceeded along two main directions, namely substituted phosphaphenanthrene and bisphenol-A. Through releasing massive phenolic derivatives, PO free radicals and other certain phosphorus-containing substances, TDBA is capable to exert free radical quenching effect in gaseous phase, and to promote charring behavior to form compact residue with barrier effect on heat and fuels transportation in condensed phase. This bi-phase joint action mode from TDBA endowed epoxy thermosets with excellent flame retardancy.

Partial pore blockage and polymer chain rigidification phenomena in PEO/ZIF-8 mixed matrix membranes synthesized by in situ polymerization

Abstract Nanostructured zeolitic imidazolate frameworks (ZIF-8) was incorporated into the mixture of poly (ethylene glycol) methyl ether acrylate (PEGMEA) and pentaerythritol triacrylate (PETA) to synthesize mixed matrix membranes (MMMs) by in situ polymerization for CO 2 /CH 4 separation. The solvent-free polymerization between PEGMEA and PETA was induced by UV light with 1-hydroxylcyclohexyl phenyl ketone as initiator. The chemical structural characterization was performed by Fourier transform infrared spectroscopy. The morphology was characterized by scanning electron microscope. The average chain-to-chain distance of the polymer chains in MMMs was investigated by X-ray diffraction. The thermal property was evaluated by differential scanning calorimetry. The CH 4 and CO 2 gas transport properties of MMMs are reported. The relationship between gas permeation–separation performances or physical properties and ZIF-8 loading is also discussed. However, the permeation–separation performance was not improved in Robeson upper bound plot compared with original polymer membrane as predicted. The significant partial pore blockage and polymer rigidification effect around the ZIFs confirmed by the increase in glass temperature and the decrease in the d -spacing, were mainly responsible for the failure in performance improvement, which offset the high diffusion induced by porous ZIF-8.