{"title":"Thermodynamics and kinetic analysis of carbon nanofibers as nanozymes.","authors":"Maziar Bahreini, Monireh Movahedi, Maryam Peyvandi, Fereshteh Nematollahi, Hessam Sepasi Tehrani","doi":"10.2147/NSA.S208310","DOIUrl":null,"url":null,"abstract":"<p><strong>Purpose: </strong>Evaluation of structural features, thermodynamics and kinetic properties of carbon nanofibers (CNFs) as artificial nanoscale enzymes (nanozyme).</p><p><strong>Methods: </strong>Synthesis of CNFs was done using chemical vapor deposition, and transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM) and energy-dispersive x-ray spectroscopy (EDX) were used to provide information on the morphology, elemental monitoring and impurity assay of the CNFs. The thermal features of the CNFs were evaluated using differential thermal analysis (DTA), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) derivative and TGA. The calculated thermo-physical parameters were melting temperature (<i>Tm</i>), weight loss maximum temperature (<i>T<sub>max</sub></i> ) and enthalpy of fusion (Δ<i>H<sub>fusion</sub></i> ). Catalytic activity was assayed by a 4-aminoantypyrine (4-AAP)-H<sub>2</sub>O<sub>2</sub> coupled colorimetric system by UV-visible spectroscopy.</p><p><strong>Results: </strong>FE-SEM and TEM analysis demonstrated parallel graphitic layers and uniformity of atomic orientation and morphology. The EDX spectra approved carbon element as major signal and presence of partial Ti as impurities of CNFs during CVD process. The DTA thermogram showed the endothermic process had a maximum temperature of 82.27°C at -15.48 mV and that thermal decomposition occurred at about 200°C. The TGA-differential gravimetric analysis thermogram showed that <i>T<sub>max</sub></i> was 700°C. The DSC heat flow curve showed a melting temperature (Tm) of 254.52°C, Δ<i>H<sub>fusion</sub></i> of 3.84 J^.g<sup>-1</sup>, area under the curve of 58.58 mJ and <i>T<sub>e</sub></i> (onset) and <i>T<sub>f</sub></i> (end set) temperatures of 246.60°C and 285.67°C, respectively. The peroxidase activity of the CNFs obeyed the Michaelis-Menten equation with a double-reciprocal curve and the calculated <i>K<sub>m</sub>, K<sub>cat</sub></i> and <i>V<sub>max</sub></i> kinetic parameters.</p><p><strong>Conclusion: </strong>CNFs as peroxidase nanozymes are intrinsically strong and stable nanocatalysts under difficult thermal conditions. The peroxidase activity was demonstrated, making these CNFs candidates for analytical tools under extreme conditions.</p>","PeriodicalId":18881,"journal":{"name":"Nanotechnology, Science and Applications","volume":null,"pages":null},"PeriodicalIF":4.9000,"publicationDate":"2019-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2147/NSA.S208310","citationCount":"7","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Nanotechnology, Science and Applications","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.2147/NSA.S208310","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2019/1/1 0:00:00","PubModel":"eCollection","JCR":"Q2","JCRName":"NANOSCIENCE & NANOTECHNOLOGY","Score":null,"Total":0}
引用次数: 7
Abstract
Purpose: Evaluation of structural features, thermodynamics and kinetic properties of carbon nanofibers (CNFs) as artificial nanoscale enzymes (nanozyme).
Methods: Synthesis of CNFs was done using chemical vapor deposition, and transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM) and energy-dispersive x-ray spectroscopy (EDX) were used to provide information on the morphology, elemental monitoring and impurity assay of the CNFs. The thermal features of the CNFs were evaluated using differential thermal analysis (DTA), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) derivative and TGA. The calculated thermo-physical parameters were melting temperature (Tm), weight loss maximum temperature (Tmax ) and enthalpy of fusion (ΔHfusion ). Catalytic activity was assayed by a 4-aminoantypyrine (4-AAP)-H2O2 coupled colorimetric system by UV-visible spectroscopy.
Results: FE-SEM and TEM analysis demonstrated parallel graphitic layers and uniformity of atomic orientation and morphology. The EDX spectra approved carbon element as major signal and presence of partial Ti as impurities of CNFs during CVD process. The DTA thermogram showed the endothermic process had a maximum temperature of 82.27°C at -15.48 mV and that thermal decomposition occurred at about 200°C. The TGA-differential gravimetric analysis thermogram showed that Tmax was 700°C. The DSC heat flow curve showed a melting temperature (Tm) of 254.52°C, ΔHfusion of 3.84 J^.g-1, area under the curve of 58.58 mJ and Te (onset) and Tf (end set) temperatures of 246.60°C and 285.67°C, respectively. The peroxidase activity of the CNFs obeyed the Michaelis-Menten equation with a double-reciprocal curve and the calculated Km, Kcat and Vmax kinetic parameters.
Conclusion: CNFs as peroxidase nanozymes are intrinsically strong and stable nanocatalysts under difficult thermal conditions. The peroxidase activity was demonstrated, making these CNFs candidates for analytical tools under extreme conditions.
期刊介绍：
Nanotechnology, Science and Applications is an international, peer-reviewed, Open Access journal that focuses on the science of nanotechnology in a wide range of industrial and academic applications. The journal is characterized by the rapid reporting of reviews, original research, and application studies across all sectors, including engineering, optics, bio-medicine, cosmetics, textiles, resource sustainability and science. Applied research into nano-materials, particles, nano-structures and fabrication, diagnostics and analytics, drug delivery and toxicology constitute the primary direction of the journal.
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