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1.
Food Chem ; 367: 130505, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34343813

RESUMO

Di-n-butyl phthalate (DBP) as a plasticizer is widely used in food and chemical industries. It is harm to human health when it appeared in food and water. A novel near-infrared (NIR) fluorescence molecularly imprinted sensor based on CdTe quantum dots and zeolite imidazolate framework-67 was developed with a sol-gel polymerization method for rapid and sensitive determination of DBP in foodstuff rapidly (only in 1.5 min). The fluorescence imprinted sensor provided a rapid detection method for DBP in the linear response concentration range of 0.05-18.0 µM with a low detection limit of 1.6 nM. Compared with previous fluorescence imprinted sensor, it behaved faster response speed and lower detection limit for determination of DBP. The fluorescence imprinted sensor was used to detect DBP in real samples successfully with satisfied recoveries of 97.2-106.4%, suggesting a potential application in food analysis.


Assuntos
Compostos de Cádmio , Impressão Molecular , Pontos Quânticos , Zeolitas , Dibutilftalato , Humanos , Limite de Detecção , Telúrio
2.
Anal Chim Acta ; 1184: 338984, 2021 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-34625268

RESUMO

In this study, Zeolitic Imidazole Framework-8/cellulose aerogel (ZIF-8/CA) hybrid was successfully fabricated through a simple doping method and ZIF-8 acted as the major component for adsorption. In order to elucidate the adsorption mechanism deeply, molecular simulation was adopted to the expound the interaction modes between ZIF-8 and the fluoroquinolones (FQs). ZIF-8/CA was used as the adsorbent for semi-automated pipette tip solid phase extraction (PT-SPE). In combination with high performance liquid chromatography tandem fluorescence detector (HPLC-FLD), the established method was successfully employed to determine trace amount of FQs in water samples. Extraction parameters such as the content of ZIF-8, pH of sample solution, volume of sample, flow rate of sampling, type and volume of elution solvent were investigated. Under the optimized conditions, satisfactory linearity was achieved with the correlation coefficient (R2) ranging from 0.9954 to 0.9992. The limits of detection were in the range of 0.337-1.707 ng L-1. And the recoveries varied from 75.9% to 96.8% with RSD less than 8.0%. The established method was demonstrated to be sensitive, efficient and convenient.


Assuntos
Poluentes Químicos da Água , Zeolitas , Celulose , Fluoroquinolonas/análise , Imidazóis , Extração em Fase Sólida , Água , Poluentes Químicos da Água/análise
3.
Trop Anim Health Prod ; 53(5): 465, 2021 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-34546468

RESUMO

The current research was conducted to compare the effect of various buffers or alkalizers in Arabi lambs and find new and less expensive buffering resources. Forty-five Arabi lambs with an average weight of 29.37 ± 3.63 kg were used in a completely randomized design with five treatments and nine replicates. Treatments included 1 - control diet (no buffer); 2 - base diet + 0.75% sodium sesquicarbonate, 0.75% sodium bicarbonate; 3 - base diet + 2% zeolite; 4 - base diet + 1.5% sodium bicarbonate; and 5 - base diet + 1.5% sodium sesquicarbonate. Results showed that rumen pH increased and ammonia nitrogen concentration decreased in diets containing buffer in comparison to control diet (P < 0.05). Rumen concentration of acetate and acetate to propionate ratio showed reduction in experimental diets compared to control (P < 0.05). The concentration of propionate in control diet increased significantly compared to diets receiving buffer (P < 0.05). Using 1.5% sodium bicarbonate in the diet causes a significant increase in rumen protozoa population compared to the control group (P < 0.05). There was no significant difference in dry matter intake and growth performance of lambs. Generally, the effects of using 2% of zeolite were competitive with the effects of other buffers, and caused an increase in the rumen pH and concentration of the acetate. Therefore, the use of buffer in fattening lambs ration fed moderate concentrate diets is beneficial, and it is possible to use low-cost zeolite buffer in the ration of livestock as an alternative to sodium bicarbonate and/or sodium sesquicarbonate.


Assuntos
Arabis , Zeolitas , Ração Animal/análise , Animais , Bicarbonatos , Fermentação , Rúmen/metabolismo , Ovinos , Bicarbonato de Sódio/metabolismo
4.
Biomater Sci ; 9(19): 6391-6402, 2021 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-34582540

RESUMO

In cancer immunotherapy, antibodies have acquired rapidly increasing attention due to their sustained immune effect by target specific delivery without any adverse effects. Among many recent strategies, controlled delivery of monoclonal antibodies, check point inhibitor storage and tumor-specific targeted delivery have enabled biodegradable immunotherapeutic delivery via translation of tailored nano-zeolitic imidazolate frameworks (ZIFs) with encapsulated biopharmaceuticals. In addition, a robust antitumor immunity was developed by anti-programmed death ligand-1 (anti-PD-L1) antibody delivery by ZIF-8 with polyethylene glycol (PEG) protection by forming a multiple immunoregulatory system. The unique biorecognition capability of antibodies, encapsulated in ZIFs, was recognized by using growth on different substrates, such as bioconjugates on gold nanorods, to transform them into plasmonic nanobiosensors with sensitivity of the refractive index profile of surface plasmons to track the conjugating antibody. Herein, we have discussed the mechanistic window of antibody delivery-based immunotherapy via the encapsulation of antibodies within ZIFs as an emerging tool for protecting biopharmaceuticals from the complex cellular microenvironment and hyperthermia to enable an antitumor immune response. To fully achieve the potential of antibodies upon ZIF encapsulation, more endeavors should be undertaken in the biodegradable engineering of ZIF-surfaces via forming cellular or polymeric layers to gain higher in vivo circulation time without inhibiting endocytosis by tumor cells. The possible future prognosis for achieving ZIF-protected biocompatible and biodegradable immunotherapeutic antibody delivery systems of therapeutic significance is discussed.


Assuntos
Produtos Biológicos , Neoplasias , Zeolitas , Humanos , Imunoterapia , Neoplasias/tratamento farmacológico , Polímeros , Microambiente Tumoral
5.
Molecules ; 26(17)2021 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-34500641

RESUMO

A novel diatomite-supported zeolitic imidazolate framework-8 sorbent (ZIF-8@Dt-COOH) was in situ fabricated and developed for solid-phase extraction of three benzodiazepines (triazolam, midazolam and diazepam) in urine followed by high-performance liquid chromatography. ZIF-8@Dt-COOH was easily prepared by coating ZIF-8 on the surface of Dt-COOH and characterized by Fourier transform infrared spectra, X-ray powder diffractometry and scanning electron microscopy. Compared with bare Dt-COOH, the extraction efficiency of ZIF-8@Dt-COOH for the target was significantly increased from 20.1-39.0% to 100%. Main extraction parameters, including ionic strength and pH of solution, loading volume, washing solution, elution solvent and elution volume, were optimized in detail. Under optimum conditions, the developed method gave linearity of three BZDs in 2-500 ng/mL (r ≥ 0.9995). Limits of detection (S/N = 3), and limits of quantification (S/N = 10) were 0.3-0.4 ng/mL and 1.0-1.3 ng/mL, respectively. In addition, the average recoveries at three spiked levels (5, 10 and 20 ng/mL) varied from 80.0% to 98.7%, with the intra-day and inter-day precisions of 1.4-5.2% and 1.5-8.2%, respectively. The proposed method provided an effective purification performance and gave the enrichment factors of 24.0-29.6. The proposed method was successfully employed for the accurate and sensitive determination of benzodiazepines in urine.


Assuntos
Benzodiazepinas/urina , Terra de Diatomáceas/química , Urina/química , Zeolitas/química , Cromatografia Líquida de Alta Pressão/métodos , Humanos , Limite de Detecção , Extração em Fase Sólida/métodos , Soluções/química , Solventes/química
6.
J Environ Manage ; 299: 113610, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34474254

RESUMO

The objective of this research is to synthesize hierarchical strontium loaded Y-zeolite and study its application for ironbark (IB) and plastic waste (PW) co-pyrolysis. Commercial parent Y-zeolite (Si/Al = 2.48) was modified via sequential dealumination-desilication using citric acid and NaOH. Further, strontium (8 wt %) was loaded into the modified Y-zeolite via wet and dry impregnation methods. The prepared catalyst was characterized by N2 adsorption-desorption isothermal, field emission scanning electron microscopy (FESEM) combined with energy dispersive x-ray spectroscopy (EDS), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and Thermogravimetric analyzer (TGA). After dealumination (treatment using 0.1 M of citric acid), the external surface area and Si/Al ratio increased from 53.5 to 147.4 m2/g and 2.48 to 5.36, respectively. However, the sequential desilication treatment reduced Si/Al ratio from 5.36 to 2.57. In addition, Y-zeolite enhanced the total aromatic percentage and reduced the acidic group in co-pyrolysis oil.


Assuntos
Pirólise , Zeolitas , Catálise , Plásticos , Estrôncio
7.
J Environ Manage ; 299: 113590, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34474256

RESUMO

In this work, the removal of ammonia nitrogen and phenol by pulsed discharge plasma (PDP) and modified zeolite was investigated. The Fe-zeolite and Mn-zeolite catalysts were prepared by the impregnation method. Catalysts' morphology, specific surface area, and chemical bond structure were characterized. Based on the pollutants removal experiments, Fe-zeolite (0.01) in the PDP system had better catalytic oxidation of phenol and adsorption effect of ammonia nitrogen. The removal efficiency of the pollutants increased with the increase of discharge voltage and solution conductivity, but decreased with the increase of discharge distance. During the plasma discharge process, the pH value in the solution decreased, and the solution conductivity gradually increased. After PDP/Fe-zeolite system treatment, the toxicity of the wastewater was significantly reduced. This study provided a new treatment method for inorganic and organic pollutants treated by PDP.


Assuntos
Poluentes Químicos da Água , Zeolitas , Amônia , Nitrogênio , Fenol , Fenóis , Poluentes Químicos da Água/análise
8.
Phys Chem Chem Phys ; 23(36): 20541-20552, 2021 Sep 22.
Artigo em Inglês | MEDLINE | ID: mdl-34505580

RESUMO

In this study the absorption of glycine, α-alanine and ß-alanine amino acids into the pores of the synthetic zeolite Na-mordenite was investigated with the aim of: (i) evaluating the effectiveness of the MOR framework type in amino acid adsorption (via vapor and aqueous loading); (ii) understanding the host-guest and guest-guest interactions to possibly design a tailor made material and a loading procedure able to maximize the amino acid adsorption; (iii) studying the effect of pressure on the adsorbed amino acids such as, for instance, possible amino acid condensation. The structural characterization, carried out with the combination of diffractometric and infrared spectroscopy analyses, shows that MOR can adsorb amino acids, which are found both in protonated/deprotonated (possibly also generating zwitterions) form. Vapor loading is ineffective for α-alanine, while it is effective in ß-alanine and glycine adsorption, even if using different loading degrees. The shape and size of MOR channels make this zeolite suitable to accommodate a peptide. In a glycine loaded sample some molecules condensate to form cyclic dimers, while linear oligomers are detected only in a ß-alanine MOR hybrid. The sample loaded with α-L-alanine from aqueous solution does not show the presence of amide bond signals, indicating that the molecules are mostly hosted in zwitterionic form in Na-MOR channels. The application of external baric stimuli does not induce substantial modifications in the structure of the glycine loaded zeolite; this result may be explained by the low number of molecules hosted in the channels. The amino acid amount within the zeolite pores is the most important reactivity parameter and an increased loading could induce chemical modifications.


Assuntos
Silicatos de Alumínio/química , Aminoácidos/química , Zeolitas/química , Cápsulas , Estrutura Molecular
9.
Anal Chem ; 93(37): 12609-12616, 2021 09 21.
Artigo em Inglês | MEDLINE | ID: mdl-34498868

RESUMO

Hydrogen peroxide (H2O2) widely involves in intracellular and intercellular redox signaling pathways, playing a vital role in regulating various physiological events. Nevertheless, current analytical methods for the H2O2 assay are often hindered by relatively long response time, low sensitivity, or self-interference. Herein, a zeolitic imidazolate framework-8 (ZIF-8)-based surface-enhanced Raman scattering (SERS) sensor has been developed to detect H2O2 released from living cells by depositing ZIF-8 over SERS active gold nanoparticles (AuNPs) grafted with H2O2-responsive probe molecules, 2-mercaptohydroquinone. Combining the superior fingerprint identification of SERS and the highly efficient enrichment and selective response of H2O2 by ZIF, the ZIF-8-based SERS sensor exhibits a high anti-interference ability for H2O2 detection, with a limit of detection as low as 0.357 nM. Satisfyingly, owing to the enhanced catalytic activity derived from the successful integration of AuNPs and ZIF, the response time as short as 1 min can be obtained, demonstrating the effectiveness of the SERS sensor for rapid H2O2 detection. Furthermore, the developed SERS sensor enables real-time detection of H2O2 secreted from living cells under phorbol myristate acetate stimulation, as cells can be cultured on-chip. This study will pave the way toward the development of a metal-organic framework-based SERS platform for application in the fields of biosensing and early disease diagnosis associated with H2O2 secretion, thus exhibiting promising potential for future therapies.


Assuntos
Técnicas Biossensoriais , Nanopartículas Metálicas , Zeolitas , Ouro , Peróxido de Hidrogênio , Análise Espectral Raman
10.
J Hazard Mater ; 416: 125888, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492826

RESUMO

Fabrication of simple and efficient adsorbents is greatly vital to satisfy the requirements of removal of tellurium in wastewater treatment, yet remains challenging. Here, a facile and cost-effective strategy to develop ZIF-L coated self-crosslinking cellulose membrane (ZIF-L/SC membrane) for tellurium adsorption was presented. In-situ vertical growth of ZIF-L nanoplates with functional properties on membrane substrate is an available strategy, effectively remedying deficiency of pure nanosized sorbent in agglomeration problem and unhandy recovery. The SC membrane formed by strong hydrogen bonding among cellulose fibers is an excellent substrate, due to the favorable mechanical strength and abundant hydroxyl groups. The as-prepared ZIF-L/SC membrane shows advantageous morphology of large contact surface, fine thermal stability and eligible mechanical strength. The adsorption performance and possible mechanism of ZIF-L/SC membrane for Te (IV) were investigated by diverse characterization methods, showing admirable adsorption effect. Furthermore, the ZIF-L/SC membrane has excellent antibacterial properties, thus it is expected to deal with membrane fouling caused by microorganism breeding. Therefore, the bifunctional ZIF-L/SC membrane with excellent antibacterial activity is anticipated to be a promising candidate for efficient tellurium adsorbents, and simultaneously have potential in various fields in the future.


Assuntos
Zeolitas , Adsorção , Antibacterianos/farmacologia , Celulose , Telúrio
11.
J Hazard Mater ; 416: 125925, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492857

RESUMO

SSZ-13 zeolite was successfully synthesized from coal bottom ash (CBA) upon hydrothermal treatment for selective sorption of Alizarin Red S (ARS) dye. The characterization of CBA, and SSZ-13 were performed using BET, SEM, FTIR, XRF, and XRD techniques. The optimal fusion ratio (CBA: NaOH) was identified as 1:3, resulting zeolite SSZ-13 with a specific surface area of 206.6 m2/g, compared to raw CBA (7.81 m2/g). The kinetics, isotherms, and thermodynamics of the ARS adsorption onto the SSZ-13, and CBA were assessed under various conditions. The results indicated that the adsorption phenomenon is optimal under acidic medium (pH = 2 for CBA, pH = 3 for SSZ-13); at ambient room temperature of 298 K; adsorbent dosage of 0.03 g, contact time of 120 min. Further, the equilibrium data fitted well to Langmuir isotherm (qe = 210.75 mg/g), following pseudo-second-order kinetics. Moreover, the chemisorption phenomenon is clearly described using Elovich kinetic model. Various thermodynamic parameters signifies the adsorption phenomenon is spontaneous, and endothermic in nature. Finally, regeneration studies revealed the sensitivity of SSZ-13 zeolite towards 0.1 M NaOH/EtOH eluent in recovery and the possibility of reuse to five successive adsorption/desorption cycles. Thus, hydrothermal treatment of CBA has potential in producing zeolites suitable to adsorption.


Assuntos
Poluentes Químicos da Água , Zeolitas , Adsorção , Ânions , Antraquinonas , Carvão Mineral , Cinza de Carvão , Concentração de Íons de Hidrogênio , Cinética , Termodinâmica
12.
Anal Chim Acta ; 1181: 338901, 2021 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-34556209

RESUMO

In this work, we reported the preparation of the hollow zeolitic imidazolate framework-7 (ZIF-7) via etching ZIF-7 with tannic acid, and further fabricated the hollow ZIF-7 coated fiber for the solid phase microextraction (SPME) of the five volatile biomarkers (acetone, isopropanol, hexanal, hexanol and decanal) generated from breast cancer cell lines. The hollow structure not only endowed higher extraction performance for the SPME of analytes, but also improved the diffusion rate of the analytes inside the hollow ZIF-7. Under the optimal conditions, the hollow ZIF-7 coated fiber offered high extraction capacity (25-153 mg g-1) and enhancement factors (EFs, 2023-11250) for the five biomarkers, good linearity (R2 > 0.9918) of acetone and isopropanol (2.5-500 µg L-1) and hexanol, hexanal, and decanal (1.0-100 µg L-1), low limits of detection (S/N = 3) of 0.07-0.53 µg L-1 and the limit of quantifications (LOQs, S/N = 10) of 0.23-1.76 µg L-1. The precisions (RSDs, %) for intra-day (n = 6), inter-day (n = 5) and fiber-to-fiber (n = 6) were 2.8-7.5%, 4.3-8.5%, and 4.2-14.6%, respectively. The high EFs of the hollow ZIF-7 coated fiber for the five biomarkers resulted from the integrated effects of the large surface area, the unique porous structure, hydrophobic interaction, gate-opening effect, and enhanced properties after etching including faster mass transport, multiple active components, and more exposed active sites. The fabricated hollow ZIF-7 coated fiber lasted at least 140 cycles of extraction/desorption/aging without obvious decrease of extraction ability and no change of crystal structure. Finally, the hollow ZIF-7 coated fiber combined with GC-FID had been successfully used to detect the five biomarkers in the headspace gas of human breast cancer cell lines (MDA-MB-231) and normal mammary cell lines (CCD-1095Sk) with the recoveries of 84-105%. These results revealed the prospect of hollow MOFs as efficient adsorbents for sample pretreatment.


Assuntos
Neoplasias da Mama , Zeolitas , Biomarcadores , Linhagem Celular , Feminino , Humanos , Microextração em Fase Sólida , Aço Inoxidável
13.
Anal Chim Acta ; 1178: 338793, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34482863

RESUMO

Electroanalysis is an effective monitoring method for organic pollution in environmental samples. However, chemical fouling with the formation of non-conductive fouled films easily occurs on the surface of the electrode during organic pollution detection that would inactivate the electrode and affect the detecting sensitivity of organic pollution. In this work, we found that zeolitic imidazolate framework-8 (ZIF-8) electrode can achieve effective degradation of non-conductive fouled films under the light illumination during electrochemical detection of some typical organic pollution (sulfamethoxazole (SMX), Bisphenol A (BPA) and diclofenac sodium (DS)). Profiting from the charge transfer capability and photoelectric characteristics, ZIF-8 electrode exhibits a lower detection limitation for organic pollution detection and superior regeneration property. The nice detection and superior regenerated property are mainly due to non-selective superoxide radical (·O2-) and hydroxyl radicals (·OH) mediation produced by ZIF-8 electrode under light illumination that can mineralize anodic fouled products and resume surface reactive sites. Compared with the single electrochemical determination, photo-assisted electroanalysis provides a stable monitoring and a renewable pathway for practical applications.


Assuntos
Sulfametoxazol , Zeolitas , Antibacterianos , Eletrodos
14.
Mater Sci Eng C Mater Biol Appl ; 128: 112260, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34474819

RESUMO

Membranes with zeolites are encouraging for performing blood dialysis because zeolites can eliminate uremic toxins through molecular sieving. Although the addition of various pore-gen and adsorbent in the membrane can certainly impact the membrane production along with creatinine adsorption, however, it is not directed which pore-gen along with zeolite leads to better performance. The research was aimed at reducing the adsorption of protein-bound and uremic toxins by using mordenite zeolite as an adsorbent while polyethylene glycol and cellulose acetate as a pore generating agent. Membranes were cast by a phase-inversion technique which is cheap and easy to handle as compared to the electro-spinning technique. Through this strategy, the ability to adsorb creatinine and solute rejection percentage were measured and compared against the pristine PSU, when only PEG was used as a pore-modifier and when PEG along with CA was used as a pore-modifier along with a different concentration of zeolite. The experiments revealed that PEG membranes can give a better solute rejection percentage (93%) but with a low creatinine adsorption capacity that is 7654 µg/g and low bio-compatibility (PRT 392 s, HR 0.46%). However, PEG/CA membranes give maximum creatinine adsorption that is 9643 µg/g and also better bio-compatibility (PRT 490 s, HR 0.37%) but with a low BSA rejection (72%) as compared to the pristine PSU and PEG membranes. The present study finds that the concentration of mordenite zeolite affects the membrane performance because its entrapment and large pore size of the membrane decreases solute rejection but increases creatinine uptake level along with the better bio-compatibility.


Assuntos
Ultrafiltração , Zeolitas , Adsorção , Sinais (Psicologia) , Membranas Artificiais , Diálise Renal
15.
Biomed Res Int ; 2021: 5529368, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34368350

RESUMO

The aim of this study was to evaluate the biocompatibility and osteogenic potential of a Zeolite Socony Mobil-5 (ZSM-5) coating on a Ti-24 Nb-4 Zr-7.9 Sn (Ti-2448) surface. ZSM-5-modified Ti-2448 (ZSM-5/Ti-2448) and Ti-2448 (control) groups were employed. The physical and chemical properties of the two types of samples were evaluated by scanning electron microscopy, Fourier-transform infrared spectroscopy, nitrogen adsorption/desorption, and contact angle methods. The surface of the ZSM-5/Ti-2448 was rougher than that of the original Ti-2448, while the contact angle of the ZSM-5/Ti-2448 was smaller than that of Ti-2448. In addition, the ZSM-5/Ti-2448 largely increased the specific surface area and introduced silanol groups. A bone-like apatite layer could be formed on the surface of ZSM-5/Ti-2448 after 14 days of incubation in a simulated body fluid. ZSM-5/Ti-2448 was not cytotoxic. The number and alkaline phosphatase (ALP) activity of osteoblasts on ZSM-5/Ti-2448 were significantly higher than those on Ti-2448 surfaces, obtained in vitro using 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide and ALP activity assays. Few inflammatory cells were observed around ZSM-5/Ti-2448 after insertion into the femurs of Japanese white rabbits after 4, 12, and 26 weeks through hematoxylin-eosin staining. The average gray scale of transforming growth factor-ß1 (TGF-ß1) on ZSM-5/Ti-2448 peaked earlier than that on Ti-2448, according to immunohistochemical staining. These results indicate that ZSM-5/Ti-2448 has a good biocompatibility and improved early osteogenic potential compared to a noncoated Ti-2448.


Assuntos
Ligas/farmacologia , Materiais Revestidos Biocompatíveis/farmacologia , Osteogênese/efeitos dos fármacos , Zeolitas/farmacologia , Fosfatase Alcalina/metabolismo , Animais , Biomineralização/efeitos dos fármacos , Morte Celular/efeitos dos fármacos , Diferenciação Celular/efeitos dos fármacos , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Implantes Experimentais , Masculino , Camundongos , Coelhos , Propriedades de Superfície , Fator de Crescimento Transformador beta/metabolismo
16.
Bioresour Technol ; 341: 125812, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34455254

RESUMO

In this study, the suitability of zeolite as a possible medium for ammonium adsorption, desorption and recovery from wastewater was investigated. Specifically, batch adsorption and desorption studies with solutions enriched in NH4+ were conducted employing zeolite to evaluate how the chemical treatment and contact time affect adsorption and desorption. Several experimental tests were carried out considering both untreated and treated zeolite. Untreated and HCl-Na treated zeolite adsorbed up to 11.8 mg NH4+ g-1 and showed the highest efficiency in recovering NH4+ from aqueous solution. Regardless of pre-treatment, treatments with NaCl resulted in higher and faster adsorption of NH4+ than treatments with CaCl2 and MgCl2.


Assuntos
Compostos de Amônio , Poluentes Químicos da Água , Purificação da Água , Zeolitas , Adsorção , Águas Residuárias
18.
Anal Chem ; 93(36): 12257-12264, 2021 09 14.
Artigo em Inglês | MEDLINE | ID: mdl-34459201

RESUMO

Metal-organic frameworks (MOFs) can improve the stability and activity of enzymes under the MOF encapsulation. However, it remains a challenge to explore the effects of the MOF environment on enzymatic activity in a confined space. In this work, we immobilized the enzyme inside a glass nanopore to study the catalytic activity and stability of the enzyme in the MOF environment. Horseradish peroxidase (HRP) is encapsulated in zeolitic imidazolate framework-90 (ZIF-90) and zeolitic imidazolate framework-8 (ZIF-8), which are used as the catalytic platforms. The HRP can catalyze 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)diammonium salt (ABTS) molecules to generate ABTS+ ions, and the change of the transmembrane ion current will be monitored in real time. As the concentration of H2O2 increases, the amount of produced ABTS+ will increase; thus, the ionic current increases. The effects of the MOF structure on enzyme activity and stability are also investigated. The HRP encapsulated in the MOF and modified inside the nanopore provides a novel and unlabeled design for studying enzymatic catalysis in a confined environment, which should have extensive applications in chemical-/bio-sensing, electrocatalysis, and fundamental electrochemistry.


Assuntos
Nanoporos , Zeolitas , Catálise , Enzimas Imobilizadas , Peróxido de Hidrogênio
19.
Molecules ; 26(16)2021 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-34443467

RESUMO

Hierarchical crystals with short diffusion path, conventional microcrystals and nanocrystals of ZSM-5 zeolites were used for biodiesel production from waste frying oils and were assessed for their catalytic activity in regard to their pore structure and acidic properties. Produced zeolites were characterized using XRD, nitrogen adsorption-desorption, SEM, TEM, X-ray fluorescence, and FTIR. Pore size effect on molecular diffusion limitation was assessed by Thiele modulus calculations and turnover frequencies (TOF) were used to discuss the correlation between acidic character and catalytic performance of the zeolites. Owing to the enhanced accessibility and mass transfer of triglycerides and free fatty acids to the elemental active zeolitic structure, the catalytic performance of nanosponge and nanosheet hierarchical zeolites was the highest. A maximum yield of 48.29% was reached for the transesterification of waste frying oils (WFOs) using HZSM-5 nanosheets at 12:1 methanol to WFOs molar ratio, 180 °C, 10 wt % catalyst loading, and 4 h reaction time. Although HZSM-5 nanosponges achieved high conversions, these more hydrophilic zeolites did not function according to their entire acidic strength in comparison to HZSM-5 nanosheets. NSh-HZSM5 catalytic performance was still high after 4 consecutive cycles as a result of the zeolite regeneration.


Assuntos
Biocombustíveis , Óleos/química , Zeolitas/química , Catálise , Conservação dos Recursos Naturais/métodos , Fontes Geradoras de Energia , Esterificação , Ácidos Graxos não Esterificados/química , Metanol/química , Tempo de Reação , Eliminação de Resíduos/métodos , Temperatura , Triglicerídeos/química , Resíduos
20.
ACS Appl Mater Interfaces ; 13(33): 39719-39729, 2021 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-34392680

RESUMO

In this work, cucurbiturils (CBs), a class of macrocyclic supramolecules, were observed to have an interesting peroxidase-like activity, which is metal-free, substrate-specific, thermophilic, acidophilic, and insensitive to ionic strength. By coating CBs on enzyme-encapsulated zeolitic imidazolate framework-8 (ZIF-8), a composite nanozyme was constructed, which retains the catalytic ability of CBs and enzymes and makes them cascade. On addition of the substrate, i.e., the detection target, a highly efficient cascade catalysis can be launched in all the spatial directions to generate sensitive and visible signals. Convenient detection of glucose and cholesterol as models is thereby achieved. More importantly, we have also successfully constructed a composite nanozyme-based sensor array (6 × 8 wells) and thereby achieved simultaneous colorimetric analysis of multiple samples. The concept and successful practice of the construction of the unique core-shell supramolecule/biomolecule@nanomaterial architecture provide the possibility to fabricate next-generation multifunctional materials and create new applications by integrating their unique functions.


Assuntos
Hidrocarbonetos Aromáticos com Pontes/química , Imidazóis/química , Nanocompostos/química , Peroxidases/química , Zeolitas/química , Técnicas Biossensoriais , Hidrocarbonetos Aromáticos com Pontes/metabolismo , Catálise , Colorimetria , Corantes Fluorescentes/química , Glucose Oxidase/química , Glucose Oxidase/metabolismo , Peróxido de Hidrogênio/química , Imidazóis/metabolismo , Simulação de Acoplamento Molecular , Oxirredução , Peroxidases/metabolismo , Impressão Tridimensional
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