A method for purifying nanoparticles using cationic modified monoliths and aqueous elution.

Nanoparticles are widely used in the medical field for diagnosis and therapy. In particular, the use of nanoparticles containing vaccines has spread rapidly; hence, ensuring nanoparticle safety and minimizing their side effects have become important concerns worldwide. In this study, we used three types (NH2, poly-Lys, and trimethylaminopropyl) of cationic modified silica monoliths with cylindrical structures, diameters of 4.2 mm, and heights of 1.5 mm. Doxil, an anticancer nanomedicine, and exosomes, as typical nanoparticles, were separated from model leaked drugs (e.g., doxorubicin and oligonucleotides) and proteins (e.g., albumin) coexisting in nanoparticle sample solutions using these monoliths. Each nanoparticle solution (200 µL) was applied to each monolith followed by centrifugation at 9,100 g for 1 min. The ionic concentration of the elution solution was increased stepwise to determine the concentration required to elute the nanoparticles from each monolith by centrifugation. The NH2- and poly-Lys-modified monoliths separated and purified nanoparticles from leaked drugs or proteins coexisting in nanoparticle sample solutions. The nanoparticles were separated from other substances by changing the pH and concentration of the aqueous Tris buffer used as the eluent. Doxil was eluted with 500-1,000 mM Tris buffer (pH 8) when using the NH2-modified monolith, and with 200-1,000 mM Tris buffer (pH 6) when using the poly-Lys-modified monolith. Exosome was obtained using 1,000 mM Tris buffer (pH 8) and the NH2-modified monolith. The recovery efficiencies (ratio of nanoparticle content in the most abundant fraction to that in the sample solution before purification) of Doxil and exosome were 64% and 55%, respectively. Because this method can purify nanoparticles using only low-speed centrifugation for a few minutes, we expect it will be used to improve nanoparticle safety.

Trimethylammonium modification of a polymer-coated monolith column for rapid and simultaneous analysis of nanomedicines.

Drug-containing nanoparticles (nanomedicine) are ideal targeted-drug-delivery systems. However, methods for the simultaneous analysis of the drug within the nanoparticle and free drug in a short time are rather limited. In this study, we developed a polymer-modified monolithic column with cationic groups (trimethylammonium) for the simultaneous analysis of the drug within the nanoparticle and the free drug. The use of the acrylamide group was determined as the optimum connecting group, and the optimum concentration of the modifier was 6%. The prepared column retained the drug within the nanoparticle by anion exchange, and its elution time was controlled by the ionic concentration (tris(hydroxymethyl)aminomethane, Tris) of the mobile phase. The separation of two typical nanomedicines was studied on the prepared column. For DOXIL and Abraxane, the drugs within the nanoparticle were well separated from the free drugs, on the developed column. The developed polymer-coated monolithic column with trimethylammonium modification is expected to enable the rapid analysis of various nanomedicines.

Threshold in stage-specific embryonic glycotypes uncovered by a full portrait of dynamic N-glycan expression during cell differentiation.

Although various glycoforms appear to participate independently in multiple molecular interactions in cellular adhesion that contribute to embryogenesis and organogenesis, a full portrait of the glycome diversity and the effect of the structural variations of cellular glycoforms on individual cell stages in proliferation and differentiation remain unclear. Here we describe a novel concept for the characterization of dynamic glycoform alteration during cell differentiation by means of "glycoblotting-based cellular glycomics," the only method allowing for rapid and quantitative glycan analysis. We demonstrated that processes of dynamic cellular differentiation of mouse embryonic carcinoma cells, P19CL6 and P19C6, and mouse embryonic stem cells into cardiomyocytes or neural cells can be monitored and characterized quantitatively by profiling entire N-glycan structures of total cell glycoproteins. Whole N-glycans enriched and identified by the glycoblotting method (67 glycans for P19CL6, 75 glycans for P19C6, and 72 glycans for embryonic stem cells) were profiled and bar-coded quantitatively with respect to the ratio of subgroups composed of characteristic glycoforms, namely glycotypes.