Adsorption of Lysozyme over Mesoporous Molecular Sieves MCM-41 and SBA-15:  Influence of pH and Aluminum Incorporation

Abstract

The adsorption of lysozyme on the mesoporous molecular sieves MCM-41 and SBA-15 from buffered solutions with different pH values has been studied as a model protein adsorption system. The amount adsorbed depends on the solution pH as well as on the pore volume and the composition of the adsorbent. The adsorption isotherms at pH 6.5 to 10.5 fitted the Langmuir model (type L isotherm), while the isotherms recorded at pH 12 are of the S type. The maximum amount adsorbed was observed for AlSBA-15 at pH 9.6 and amounted to 47.2 µmol/g (580 mg/g). The stability of SBA-15 toward to the buffer solution is higher for SBA-15 as compared to MCM-41, which is probably a consequence of the higher wall thickness of the former material. Diffuse reflectance Fourier transform infrared spectra of the adsorbed lysozyme confirm that the adsorption of the enzyme did not result in denaturation of Lz.

Fabrication and textural characterization of nanoporous carbon electrodes embedded with CuO nanoparticles for supercapacitors

“…Tetraethyl orthosilicate, sucrose and triblock copolymer poly(ethylene glycol)-block-poly(propylene glycol)-blockpoly(ethylene glycol) (Pluronic P123, molecular weight = 5800, EO 20 PO 70 EO 20 ) were obtained from Aldrich. Copper(II) nitrate trihydrate was purchased from Wako.…”

“…Nanoporous materials have attracted significant attention owing to their interesting textural parameters [16][17][18][19][20][21][22][23][24][25][26][27][28][29], which make them an excellent support for the fabrication of nanoparticles. Several reports on the fabrication of transition-metal-oxide-supported nanoporous materials are available in the literature [30][31][32][33][34][35].…”

New mesoporous silica/carbon composites byin situtransformation of silica template in carbon/silica nanocomposite

“…The XRD patterns exhibit primarily a very intense (1 0 0) diffraction peak centred at 2 ¼ 2.22 and 2.47 for A-MCM-41/HCMSC and C-MCM-41/ HCMSC, respectively, along with weaker (1 1 0) and (2 0 0) reflections characteristic of a 2-D hexagonal structure [26]. In the case of the C-MCM-41/HCMSC composite, the XRD peak intensity increased due to absence of CTABr in the mesoporee, and the XRD diffraction peaks are found to slightly shift to higher 2 values probably due to silica framework shrinkage, which is common during the calcination process at high temperature [27], compared with A-MCM-41/ HCMSC. Figure 3 shows the TEM images for HCMSC and C-MCM-41/HCMSC composite, respectively.…”

New families of mesoporous materials

“…Figs. 12C and D show adsorption isotherms of lysozyme [186] and cytochrome c [187] onto SBA-15 at various pH conditions, respectively. The maximum adsorption capability of lysozyme to SBA-15 was obtained at pH 10.5 that are very close to the isoelectric point of lysozyme and the most efficient adsorption of cytochrome c similarly occurred at around pH 9.6, close to the isoelectric point of cytochrome c. At near the isoelectric point of the protein, electric repulsion between the protein molecules are significantly suppressed, which may allow proteins to pack densely in confined spaces.…”

“…Adsorption of proteins to mesoporous materials, especially to mesoporous silica, has been rapidly paid attentions [169][170][171][172][173][174][175][176][177][178][179][180][181][182][183][184][185]. As shown below, Vinu et al provide systematic researches on protein adsorption onto mesoporous materials [96,[186][187][188][189][190][191][192][193][194][195][196]. Typical results of adsorption of hen egg white lysozyme and horse heart cytochrome c are shown in Fig.…”