Self-assembly exploits a facile non-covalent way to couple structurally different building blocks for creating soft materials with synergetic novel properties and functions. Taking advantage of magneto-properties from magnetic surfactants as well as versatile functional ligand formed by carbon quantum dots with cysteine (cys-CQDs), the magnetic network materials were firstly constructed by using magnetic surfactants and cys-CQDs as self-assembly building blocks. Counterions of Br − , [GdCl 3 Br] − , [HoCl 3 Br] − in surfactants could control the morphology of magnetic network structures, and the concentration of magnetic surfactants manoeuvres a versatile scenario of self-assembly behavior. Self-assembly of cys-CQDs and CTAHo brought out a 10-fold increase in magnetic moment of CTAHo. The fluorescent property of carbon quantum dots firstly served as an effective indicator element to dissect the collective effect in self-assembly process. For the sake of capturing the target sequence-specific DNA molecules, in situ growth of Ag nanoparticles (AgNPs) upon the magnetic network structures was realized by synergetically electrostatic and coordinated interaction of carboxyl groups and Ag ions . The magnetic Ag self-assemblies anchored thiol-containing DNA, serving as a magnetic separation booster for the target sequence-specific DNA molecules under an applied magnetic field, which will bring light on designing magneto-functional self-assembly materials according to practical application requirements.
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.
A three-dimensional reduced graphene oxide porous aerogel with packaged TiO 2 nanoparticles was prepared by a simple one-step self-assembly in a water bath at a mild temperature. Herein, we overcame the aggregation of graphene layers by forming three-dimensional architecture, and utilized TiO 2 aggregates as blocks to make the composite surface uneven. The extended aromatic areas contribute to DNA adsorption by aromatic stacking and hydrophobic interaction. The obtained composite exhibited porous structure and was positively charged at a low pH. The composite exhibited a high capacity of 890.1 mg g −1 and an adsorption efficiency of 98.4% to DNA at pH 3, however, bovine serum albumin at the same concentration level was hardly adsorbed. The composite showed favorable selectivity to DNA against protein even designed in such a simple manner. The retained DNA could be stripped by using a 0.04 mol L −1 Britton–Robinson buffer at pH 10, giving rise to a recovery of 96.3%. The DNA was isolated from human whole blood to be used as templates for PCR amplification successfully. This illustrates that DNA with high purity and quality was obtained.
Ion exchange membrane adsorbers, an alternative to overcome the bottleneck of present deoxyribonucleic acid (DNA) solid-phase extraction material, still suffer from scarce binding capacity and uncontrollable recovery efficiency. Herein, inspired by mussel adhesion combined with in-situ coupling technique, a silane-modulated biomimetic amination strategy is proposed to construct an anion-exchange membrane adsorber for efficient DNA separation. The coupling of polyethyleneimine to the biomimetic interlayer formed by the co-coating of pyrogallol and 3-glycidoxypropyltrimethoxysilane onto polyethersulfone membranes provides high coverage of DNA-binding ligands for the resulting membrane adsorber. Furthermore, its surface charge properties are tailored by the tunable content of epoxy groups in the biomimetic interlayer, resulting in the pH-responsive reversible DNA binding capacity. Consequently, the resulting membrane adsorber exhibits unprecedented DNA adsorption capacity (396.2 mg g −1 ), which is renewable and requires no external binding agent. More importantly, this membrane adsorber in the form of spin columns achieves outstanding DNA recovery efficiency up to 88 %, which is 32 % improvement over commercial silica matrices. This research provides a new perspective on the design of novel ion exchange membrane adsorbers and holds promise for the low-loss, high-efficiency downstream separation and purification processes of biomacromolecules.
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