Solid phase extraction is an effective method for the separation and purification of nucleic acid molecules, which still suffers from high loss and low efficiency. Herein, a polyether sulfone membrane adsorber for deoxyribonucleic acid (DNA) separation and purification is constructed by combining vapor-induced phase separation (VIPS) technique and in-situ coupling reaction. More specifically, the slow phase separation during VIPS promotes the formation of reaction platform with loose bicontinuous structure, high porosity and surface segregation of poly (acrylic acid), which is subsequently highly aminated by in-situ coupling of polyethyleneimine. Significantly, the reversible binding of amine ligands to DNA is solely based on electrostatic interaction, which is regulated by medium pH, avoiding the requirement for additional binding agents as encountered by commercial silica matrices and dramatically reducing DNA loss. Consequently, the resulting membrane adsorber exhibits excellent DNA binding capacity of 293.3 mg·g −1 and improved dynamic DNA recovery efficiency of 85.2 %, far exceeding that of commercial silica matrices (55.5 %). This work provides a major breakthrough in the field of nucleic acid separation and purification, paving the way to construct next-generation solid phase extraction materials for biomacromolecules.
Rapid dispersive liquid-liquid microextraction (DLLME) based on the solidification of a switchable hydrophilicity solvent (SHS) was established for the preconcentration of pyrethroid pesticides from grain prior to determination using high‐performance liquid chromatography (HPLC) with photodiode array (PDA). Lauric acid was selected to be the switchable hydrophilicity solvent due to its conversion between hydrophobic and hydrophilic forms and solidification at low temperature, thereby avoiding a time-consuming centrifugation step. The results show that the optimal conditions for pyrethroid pesticides included 30 mmol/L lauric acid, hydrochloric acid as the hydrogen donor, a 1:1.8 stoichiometric ratio of sodium laurate and hydrochloric acid, an extraction temperature of 50 °C, an extraction time of 8 min, and a solidification time of 3 min. Under the optimal conditions, this approach provided a high enrichment factor (308.4 to 330.2), a short pretreatment period of less than 15 min, and sensitive detection limits from 5 to 20 ng/g suitable for the analysis of food. The method was employed for the determination of pyrethroid pesticides in grain. The recoveries were 84.3% to 115.7%, and the relative standard deviation was less than 9.9%.
Glutathione S-transferases (GSTs) are important type-II detoxification enzymes that protect DNA and proteins from damage and are often used as protein tags for the expression of fusion proteins. In the present work, octa-aminopropyl caged polyhedral oligomeric silsesquioxane (OA–POSS) was prepared via acid-catalyzed hydrolysis of 3-aminopropyltriethoxysilane and polymerized on the surface of graphene oxide (GO) through an amidation reaction. Glutathione (GSH) was then modified to GO–POSS through a Michael addition reaction to obtain a GSH-functionalized GO–POSS composite (GPG). The structure and characteristics of the as-prepared GPG composite were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), thermogravity analysis, and surface charge analysis. The specific binding interactions between glutathione and GST gave GPG favorable adsorption selectivity towards GST, and other proteins did not affect GST adsorption. The adsorption behavior of GST on the GPG composite conformed to the Langmuir isotherm model, and the adsorption capacity of GST was high up to 364.94 mg g−1under optimal conditions. The GPG-based solid-phase adsorption process was applied to the extraction of GST from a crude enzyme solution of pig liver, and high-purity GST was obtained via SDS-PAGE identification.Keywords:octa-aminopropyl caged polyhedral oligomeric silsesquioxane (OA–POSS);graphene oxide (GO);glutathione S-transferases (GST);adsorption;solid-phase extraction
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