One-Step Surface Immobilization of Protein A on Hydrogel Nanofibers by Core-Shell Electrospinning for Capturing Antibodies

Nanofibers (NFs) are potential candidates as filter materials for affinity separation owing to their high liquid permeability based on their high porosity. Multiple and complex processes were conventionally performed to immobilize proteins for modifying NF surfaces. A simple method must be developed to immobilize proteins without impairing their biological activity. Herein, we succeeded in fabricating NFs with a core of cellulose acetate and a shell of hydrophilic polyvinyl alcohol immobilized with staphylococcal recombinant protein A by a one-step process based on core-shell electrospinning. A total of 12.9 mg/cm3 of antibody was captured in the fiber shell through high affinity with protein A immobilized in an aqueous environment of the hydrogel. The maximum adsorption site and dissociation constant evaluated by the Langmuir model were 87.8 µg and 1.37 µmol/L, respectively. The fiber sheet withstood triplicate use. Thus, our NF exhibited high potential as a material for membrane chromatography.

In situ replacement of Cu-DEN: an approach for preparing a more noble metal nanocatalyst for catalytic use

The advantage of dendritic monodisperse macromolecules’ dual templating ability was useful in the formation of silica-supported copper nanoparticles Cu_n@SiO₂NPs.

Polyethylenimine-mediated synthetic insertion of gold nanoparticles into mesoporous silica nanoparticles for drug loading and biocatalysis

Mesoporous silica nanoparticles (MSNPs) have been used as an efficient and safe carrier for drug delivery and biocatalysis. The surface modification of MSNPs using suitable reagents may provide a robust framework in which two or more components can be incorporated to give multifunctional capabilities (e.g., synthesis of noble metal nanoparticles within mesoporous architecture along with loading of a bioactive molecule). In this study, the authors reported on a new synthetic route for the synthesis of gold nanoparticles (AuNPs) within (1) unmodified MSNPs and (2) 3-trihydroxysilylpropyl methylphosphonate-modified MSNPs. A cationic polymer, polyethylenimine (PEI), and formaldehyde were used to mediate synthetic incorporation of AuNPs within MSNPs. The AuNPs incorporated within the mesoporous matrix were characterized by transmission electron microscopy, energy dispersive x-ray analysis, and high-resolution scanning electron microscopy. PEI in the presence of formaldehyde enabled synthetic incorporation of AuNPs in both unmodified and modified MSNPs. The use of unmodified MSNPs was associated with an increase in the polycrystalline structure of the AuNPs within the MSNPs. The AuNPs within modified MSNPs showed better catalytic activity than those within unmodified MSNPs. MSNPs with an average size of 200 nm and with a pore size of 4-6 nm were used for synthetic insertion of AuNPs. It was found that the PEI coating enabled AuNPs synthesis within the mesopores in the presence of formaldehyde or tetrahydrofuran hydroperoxide at a temperature between 10 and 25 °C or at 60 °C in the absence of organic reducing agents. The as-made AuNP-inserted MSNPs exhibited enhanced catalytic activity. For example, these materials enabled rapid catalytic oxidation of the o-dianisidine substrate to produce a colored solution in proportion to the amount of H₂O₂ generated as a function of glucose oxidase-catalyzed oxidation of glucose; a linear concentration range from 80 to 800 μM and a detection limit as low as 80 μM were observed. The mesoscale pores of the as developed AuNP-inserted MSNPs were also used to entrap the hydrophobic drug paclitaxel. The results of this study indicate the potential use of the AuNP-inserted MSNPs in biocatalysis and drug delivery.

A new support material for IgG adsorption: Syntrichia papillosissima (Copp.) Loeske

In this presented work, Syntrichia papillosissima (Copp.) Loeske (S. papillosissima) was used as a natural phytosorbent for IgG purification. These moss species were collected for the natural habitat and prepared for IgG adsorption studies by cleaning, drying, and grinding to uniform size. Syntrichia papillosissima samples were characterized by using FTIR and SEM studies. Functional groups of S. papillosissima were identified by FTIR analysis, while surface characteristics were determined by SEM studies. A batch system was used for the adsorption of IgG onto S. papillosissima surface and physical conditions of the IgG adsorption medium were investigated by modifying the pH, IgG concentration and temperature. Maximum IgG adsorption onto S. papillosissima was found to be 68.01 mg/g moss by using pH 5.0 buffer system. Adsorption kinetic isotherms were also studied and it was found that, Langmuir adsorption model was appropriate for this adsorption study. Reusability profile of S. papillosissima was also investigated and IgG adsorption capacity did not decrease significantly after 5 reuse studies. Results indicated that S. papillosissima species have the capacity to be used as biosorbent for IgG purification, with its low cost, natural and biodegradable structure.