Functionalization of multiwalled carbon nanotubes by microwave irradiation for lysozyme attachment: comparison of covalent and adsorption methods by kinetics of thermal inactivation

Abstract

Proteins suffer changes in their tertiary structure when they are immobilized, and enzymatic activity is affected due to the low biocompatibility of some supporting materials. In this work immobilization of lysozyme on carbon nanotubes previously functionalized by microwave irradiation was studied. The effectiveness of the microwave-assisted acid treatment of carbon nanotubes was evaluated by XPS, TEM, Raman and FTIR spectroscopy. The carboxylic modification of nanotube surfaces by this fast, simple and feasible method allowed the physical adsorption and covalent linking of active lysozyme onto the carbonaceous material. Thermal inactivation kinetics, thermodynamic parameters and storage stability were studied for adsorbed and covalent enzyme complexes. A major stability was found for lysozyme immobilized by the covalent method, the activation energy for inactivation of the enzyme was higher for the covalent method and it was stable after 50 d of storage at 4 °C. The current study highlights the effect of protein immobilization method on the biotechnological potential of nanostructured biocatalysts.

Studies on the Doping Mechanism of Conjugated Thienothiophene Polymer/MWCNT Hybrids for Thermoelectric Application

“…The incorporation of MWCNT led to the formation of 𝜋-𝜋* bonds due to the sp 2 carbon atoms of MWCNT. [60] A similar peak appears in the OH2 hybrid and the other characteristic peaks of PBDTTT-C-T, as shown in Figure 6b. However, in doped-OH1, an additional C-Cl bond was observed at ≈286.46 eV, confirming the presence of the CTC coordination site.…”

Highly Exfoliated and Functionalized Single-Walled Carbon Nanotubes as Fast-Charging, High-Capacity Cathodes for Rechargeable Lithium-Ion Batteries

“…% for B-SWCNT. The prepared samples show five separate peaks corresponding to sp 2 carbon (284.3 eV), sp 3 carbon (285.5 eV), C–O (286.5 eV), CO (287.5 eV), and COOH (289.5 eV) (Figure d–f). − The deconvolution of the C 1s XPS spectra indicate that the concentration of C–O group significantly decreased by 16.0% after hydrogen thermal reduction at 150 °C, whereas the concentrations of CO and COOH changed insignificantly (Figure e and Table S3). Meanwhile, the peak intensities for sp 3 , C–O, and CO groups decreased in the XPS spectra when B-SWCNTs were annealed at a reduction temperature of 400 °C (B-SWCNTs-TA400, Figure f and Table S3).…”

[MoS4]2–-Intercalated NiCo-Layered Double Hydroxide Nanospikes: An Efficiently Synergized Material for Urine To Direct H2 Generation

“…First of all, adventitious carbon signals of all the controlled samples were comparatively analyzed. Figure S4a illustrates that as compared to CO 3 -LDH, there is no additional higher binding energy carbonate (292.3 eV) signal 42 both in case of NO 3 -LDH and MoS 4 -LDH. This indicates the success of our anion intercalation process, which is further elaborated by analyzing XPS spectra in N 1s region (Figure S4b).…”