To achieve a tunable molecular sieving in gel electrophoresis, novel hydrogels consisted of a poly(ethylene glycol) based crosslinker and ionic monomers were developed. The gels showed specific shrinking regarding ionic solutions by suppressing an ionic repulsion in the gels as our previous report. Additionally, the intermolecular interactions such as hydrophobic interaction and π-π stacking among the adsorbed solutes also affected the specific shrinking of the gels. These gels were evaluated in gel electrophoresis using several glucans and DNA base pairs to examine the possibility of the molecular sieving. The gel prepared without ionic monomers showed the various separations depending on the differences of crosslinking degree. Also, the gel prepared with acrylic acid provided the various separation patterns of glucans based on the molecular sieving by simply changing pH of the buffer solutions for electrophoresis.
We fabricated microfluidic dispensing devices, which can give the solution of different flow rates, successfully acquiring multivariate data on the adsorption capacity for protein imprinting hydrogels.
This paper demonstrates electric generation from sound to minimize and integrate microfluidic systems for point of care testing or in-situ analysis. In this work, 5.4 volts and 50 mW DC was generated from sound through an earphone cable, which is a versatile system and able to actuate small size and low power consumption devices like an electro osmotic pump.
A new stimulus-responsive drug delivery system using Fe3O4 nanoparticles coated with molecularly imprinted polymer (MIP) is reported. Magnetic thermal seeds (MTS) with their size controlled between 10 and 20 nm that could generate heat under an alternate current (AC) magnetic field were modified with a thermal-responsive MIP by grafting polymerization for effective release of an anticancer drug, methotrexate (MTX). The MIP-coated MTS showed the superparamagnetic property as well as the selective adsorption ability toward MTX, and 80% of MXT adsorbed on the MIP-coated MTS was stimulus released at 60 °C by cleaving hydrogen bonding in the recognition sites. Finally, the MTX release from the MTX-loaded MIP-coated MTS under an AC magnetic field within 10 min was successfully demonstrated.
To simplify a quantitative immobilization procedure of ligands with maintaining their activities, we developed an automated preparation method using an alginate hydrogel partially formed in a capillary. After a sodium alginate solution containing a ligand was injected into the capillary, a background solution containing Ca2+ was then introduced into the sodium alginate solution zone by applying an appropriate voltage for the hydrogelation, resulting in encapsulation of the ligand by the formed alginate hydrogel. According to the estimated binding capacity for biotin by the encapsulated avidin, the injected avidin was immobilized quantitatively by the formed hydrogel with keeping its affinity. When avidin (3.5–35.2 ng) was immobilized by the proposed method, the immobilization efficiency was estimated to be almost 100%. Furthermore, by using the prepared capillary, biotinylated fluorescein was specifically trapped and separated due to the affinity of the encapsulated avidin. By the change of pH of the background solution, the concentrated analytes could be easily eluted, resulting in 90% recovery with high reproducibility by using 1.18 fmol biotinylated sample.
Based on capillary zone electrophoresis (CZE), we validated a method of confirming the identity and purity of the separated charge variants of monoclonal antibodies (mAbs) and antibody-drug conjugates (ADCs). The validation includes the evaluation of the specificity, linearity, quantitation limit, precision (repeatability and intermediate precision), accuracy, range, and robustness. The method is applicable to the majority of mAbs and ADCs (with pI from 7 to 9 and a drug to antibody ratio up to 8), requiring no modification to the method conditions. The proposed CZE method showed reproducible separation profiles, while cation exchange chromatography (CEX) showed low reproducibility and deficient separation profiles due to an undesirable interaction between the separation column and the low molecular weight drugs combined in the ADCs. Since CZE is able to minimize this undesirable interaction during the separation, it proved to be a useful separation methodology for evaluating charge variants of ADCs. The validation of CZE for assessing ADCs was successfully demonstrated for the first time, and show that CZE is suitable for the separation method for detecting the charge heterogeneity of ADCs.
