关键词: 表面定向印迹, 磁性碳纳米管, 槲皮素, 识别

Abstract:

Flavonoids are one of the most important compounds， which have been successfully used in medicine in ancient times because of their unique antioxidant and anti-inflammatory effects. Quercetin is a polyphenol compound， which contains cis-diol structure and belongs to flavonol. It is found in a variety of foods， including vegetables and fruits， such as tea， cocoa powder， cranberries， kale， celery， cauliflower， lettuce， tomatoes and carrots. Quercetin has the ability of scavenging free radicals and binding transition metal ions so that it can inhibit and reduce oxidative stress and related damage. Quercetin also has a variety of biological activities， such as antioxidant， antiviral， anti-tumor and so on. In addition， quercetin shows the potential to treat and prevent a variety of diseases， such as cancer， osteoporosis， asthma， Alzheimer's disease， diabetes and skin diseases. Molecularly imprinted polymers（MIPs） are chemically synthesized receptors with pre-designed binding sites and rigidity to target molecules and have important applications in many fields， such as chemical sensing， separation， catalysis and disease diagnosis. Boric acid is an important functional monomer which can reversibly bind nucleosides， sugars， polysaccharides and glycoproteins to cis-diol compounds in covalent imprinting. In recent years， boric acid functional materials have attracted more and more attention. Considering the importance of selectivity and sensitivity to the efficiency of detection methods， a new imprinting strategy， called boric acid affinity surface oriented imprinting， was proposed by combining the covalent bin-ding of boric acid affinity with molecular imprinting technique. It is used to prepare high performance molecularly imprinted materials. This directed imprinting strategy is based on the interaction between the functional solid matrix and the template. In the process of template immobilization， the covalent interaction（boric acid affinity） is more stable than the non-covalent interaction， and the imprinting process can produce a more uniform distribution of binding sites. In addition， the interaction between boric acid ligands and cis-diol molecules is easily destroyed by acidic solution， which is beneficial to the removal of templates. Therefore， combined with the surface imprinting technique， the surface imprinting guided by boric acid affinity can almost completely remove the template molecules and provide more accessible binding sites for the target molecules. Using boric acid functionalized magnetic carbon nanotubes as reaction matrix， quercetin magnetic MIPs was prepared by a simple and green boronate affinity surface oriented imprinting method. It was also applied to the specific recognition of quercetin in ginkgo biloba extract powder. Transmission electron microscope， X-ray photoelectron spectroscopy， X-ray diffraction and vibrating sample magnetometer tests showed that the prepared MIPs had good morphology and crystal structure. A series of adsorption experiments showed that the MIPs had an ideal adsorption capacity（4.57 μg/mg）， a high selectivity（IF=8.44）and regeneration ability for quercetin. The adsorption experiments of the actual samples of Ginkgo biloba extract showed that the established method could achieve the expected detection effect of quercetin and could be used as an effective tool for specific identification of quercetin in traditional Chinese medicine.

Key words: Surface oriented imprinting, Magnetic carbon nanotube, Quercetin, Recognition