Biofunctional magnetic nanoparticles as contrast agents for magnetic resonance imaging of pancreas cancer

We report on the fabrication and characterization of biofunctional magnetic nanoparticles as contrast agents for magnetic resonance imaging. The anti-cancer antigen 19-9 monoclonal antibody (a cancer-targeting antibody) was conjugated onto the magnetic contrast agents in an effort to detect pancreatic tumor. The structure, size, morphology and magnetic property of the biofunctional magnetic nanoparticles are characterized systematically by means of transmission electron microscopy and X-ray diffractometry. Furthermore, the interaction between the nanoparticles and pancreas cancers cells are investigated by atomic force microscope and transmission electron microscopy. Magnetic resonance imaging demonstrates that the conjugated nanoparticles can effectively target cancer cells both in vitro and in vivo, suggesting that they potentially can be used as contrast agents for magnetic resonance imaging of pancreas cancer.     

Specific hydrolysis of DNA by Ce~(4+) -ODN hybrid

The cerium complex bound to the derivative of oligoDNA has been synthesized successfully that can hydrolyze DNA with sequence-specificity. The synthesized derivative of oligoDNA, 5'-EDTA-P-10 mers ODN, was demonstrated by HPLC. The fluorescence spectrum of Tb3+ was detected after its interaction with the hybrid of 10-mers ODN and 26-mers ODN and the results show that the artificial endo-enzyme can recognize and combine firmly with the substrate DNA. The electrophorogram shows that the cerium-oligoDNA hybrid can specifically hydrolyze its substrate DNA and the cleavage site of this hydrolysis reaction is also discussed. This artificial nuclease can be widely used in molecular biology and genetic engineering as one kind of endo-enzyme.     

Biofunctional magnetic nanoparticles as a general agent to immobilize proteins contained in traditional Chinese medicines

Maghemite nanoparticles were synthesized by the coprecipitation method. Silica was coated to the maghemite nanoparticles and amino silane was modified to the surface of the silica magnetic nanoparticles. We use the biofunctional magnetic nanoparticles as a general agent to immobilize and separate the proteins in a broad range from different traditional Chinese medicines. The transmission electron microscopy results showed that the average diameter of the well-dispersed silica-coated nanoparticles was about 60 nm. The Fourier transform infrared spectrum indicated that the amino group had been successfully coupled to the surface of the maghemite particles. And the protein immobilization effect was characterized by the microplate reader. The characterization results proved that the synthesized functional magnetic nanoparticles could effectively immobilize and separate the proteins from traditional Chinese medicines.     

Chitosan-coated magnetic nanoparticles as carriers of 5-Fluorouracil: Preparation,characterization and cytotoxicity studies

The chitosan-coated magnetic nanoparticles (CS MNPs) were prepared as carriers of 5-Fluorouracil (CS–5-Fu MNPs) through a reverse microemulsion method. The characteristics of CS–5-Fu MNPs were determined by using transmission electron microscopy (TEM), FTIR spectroscopy and vibrating-sampling magnetometry (VSM). It was found that the synthesized CS–5-Fu MNPs were spherical in shape with an average size of 100 ± 20 nm, low aggregation and good magnetic responsivity. Meanwhile, the drug content and encapsulation rate of the nanoparticles was 16–23% and 60–92%, respectively. These CS–5-Fu MNPs also demonstrated sustained release of 5-Fu at 37 °C in different buffer solutions. The cytotoxicity of CS–5-Fu MNPs towards K562 cancer cells was investigated. The result showed that CS–5-Fu MNPs retained significant antitumor activities. Additionally, it was observed that the FITC-labeled CS–5-Fu MNPs could effectively enter into the SPCA-1 cancer cells and induced cell apoptosis.     

Ce^4+水解切籽5'-AMP,3'-AMPA和CAMP的原位增强 拉曼光谱研究

首次用原位增强拉曼光谱技术研究了Ce^4+水解切断核苷酸的过程,实验表明在粗糙化的银表面可以得到5'---AMP,3'－AMP和CAMP明显增强的拉曼光谱,Ce^4+水解切断5'--AMP时在2895cm^-1和2950cm^-1处分别出现CH~2的动振峰;3'---AMP中原有CH~2振动峰,当它的磷酸酯键被Ce^4+水解切断时,这些峰则明显减弱,甚至消失,把Ce^4+水解切断CAMP过程的原位拉曼光谱与5'---SAMP同Ce^4+反应以后的拉曼光谱相比较,推测Ce^4+断裂CAMP和3'--AMP时,首先切断CAMP中的一个磷酸酯键,生成5'--AMP和3'---AMP随着反应的进行Ce^4+再逐渐断裂5'--AMP和3'---AMP的磷酸酯键,生成最终产物腺苷。     

Proof of Artés–Llibre–Valls's conjectures for the Higgins–Selkov and the Selkov systems

The aim of this paper is to prove Artés–Llibre–Valls's conjectures on the uniqueness of limit cycles for the Higgins–Selkov system and the Selkov system. In order to apply the limit cycle theory for Liénard systems, we change the Higgins–Selkov and the Selkov systems into Liénard systems first. Then, we present two theorems on the nonexistence of limit cycles of Liénard systems. At last, the conjectures can be proven by these theorems and some techniques applied for Liénard systems.     

Dynamical analysis of a Lotka-Volterra learning-process model

A Lotka-Volterra learning-process model was proposed by Monteiro and Notargiacomo in [{\it Commum. Nonlinear Sci. Numer. Simulat.} {\bf 47}(2017), 416-420] to approach learning process as an interplay between understanding and doubt. They studied the stability of the boundary equilibria and gave some numerical simulations but no further discussion for bifurcations. In this paper, we study the qualitative properties of the interior equilibria and a singular line segment completely. Moreover, we discuss their bifurcations such as transcritical, pitchfork, Hopf bifurcation on isolated equilibria and transcritical bifurcation without parameters on non-isolated equilibria. Finally, we also demonstrate these analytical theory by numerical simulations.     

Preparation of immunomagnetic nanoparticles and their application in the separation of mouse CD34 hematopoietic stem cells

The magnetic nanoparticles with a diameter of about 60 nm were synthesized by coprecipitation from ferrous and ferric iron solutions and coated with silica. Then the nanoparticles were modified with N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AEAPS) in order to immobilize anti-CD34⁺ monoclonal antibodies to the surface of modified magnetic particles. The results of transmission electron microscope (TEM) and Fourier transformed infrared (FT-IR) indicated that the nanoparticles were successfully prepared. Scanning electron microscope (SEM) photo confirmed that the mouse CD34⁺ cells (cells expressing CD34) were separated by the immunomagnetic nanoparticles. The viability of the separated cells was studied by hematopoietic colony-forming assay, the result of which showed that the target cells still had an ability of proliferation and differentiation. The application of the separated CD34⁺ cells was in testing the pharmacological effect of three samples isolated from enzyme-digested traditional Chinese medicine Colla corii asini.     

铕苯丙氨酸配合物与DNA相互作用的循环伏安法和紫外光谱法研究

运用循环伏安法和紫外光谱法研究了Ｅｕ（ｐｈｅ）３＾３＋与ＤＮＡ的相互作用。Ｅｕ（ｐｈｅ）３＾３＋与ＤＮＡ作用后，循环伏安曲线的峰电流密度减小，峰电位差稍有增中，扩散系数减小，紫外光谱的特征吸收峰呈明显的减色效应，这可能是Ｅｕ（ｐｈｅ）３＾３＋与ＤＮＡ因静电引力形成加合物以及Ｅｕ（ｐｈｅ）３＾３＋有很强的遮蔽负电荷 作用，促使碱基面与碱基面的进一步堆积所致。     

Specific hydrolysis of DNA by Ce<Superscript>4+</Superscript>-ODN hybrid

The cerium complex bound to the derivative of oligoDNA has been synthesized successfully that can hydrolyze DNA with sequence-specificity. The synthesized derivative of oligoDNA, 5′-EDTA-P-10 mers ODN, was demonstrated by HPLC. The fluorescence spectrum of Tb³⁺ was detected after its interaction with the hybrid of 10-mers ODN and 26-mers ODN and the results show that the artificial endo-enzyme can recognize and combine firmly with the substrate DNA. The electrophorogram shows that the cerium-oligoDNA hybrid can specifically hydrolyze its substrate DNA and the cleavage site of this hydrolysis reaction is also discussed. This artificial nuclease can be widely used in molecular biology and genetic engineering as one kind of endo-enzyme.