Time filter

Source Type

Harbin, China

Northeast Forestry University , located in Harbin, Heilongjiang Province, is an institution of higher education and research under jurisdiction of the Ministry of Education of the People's Republic of China, serve as the largest forestry university in China and a key university within the scope of national "211 Project". Wikipedia.

Oligomycin-A (Oli-A), an anticancer drug, was loaded to the folate (FA)-conjugated chitosan as a tumor-targeted drug delivery system for the purpose of overcoming the nonspecific targeting characteristics and the hydrophobicity of the compound. The two-level factorial design (2-LFD) was applied to modeling the preparation process, which was composed of five independent variables, namely FA-conjugated chitosan (FA-CS) concentration, Oli-A concentration, sodium tripolyphosphate (TPP) concentration, the mass ratio of FA-CS to TPP, and crosslinking time. The mean particle size (MPS) and the drug loading rate (DLR) of the resulting Oli-loaded FA-CS nanoparticles (FA-Oli-CSNPs) were used as response variables. The interactive effects of the five independent variables on the response variables were studied. The characteristics of the nanoparticles, such as amount of FA conjugation, drug entrapment rate (DER), DLR, surface morphology, and release kinetics properties in vitro were investigated. The FA-Oli-CSNPs with MPS of 182.6 nm, DER of 17.3%, DLR of 58.5%, and zeta potential (ZP) of 24.6 mV were obtained under optimum conditions. The amount of FA conjugation was 45.9 mg/g chitosan. The FA-Oli-CSNPs showed sustained-release characteristics for 576 hours in vitro. The results indicated that FA-Oli-CSNPs obtained as a targeted drug delivery system could be effective in the therapy of leukemia in the future. Source

Zhou Q.-M.,Northeast Forestry University
Nonlinear Analysis: Real World Applications | Year: 2015

In the present paper, in view of the variational approach, we discuss the nonlinear eigenvalue problems for p(x)-Laplacian-like operators, originated from a capillary phenomenon. Under some suitable conditions, we prove the existence of nontrivial solutions of the system for every parameter λ>0. © 2014 Elsevier Ltd. All rights reserved. Source

Northeast Forestry University | Date: 2015-01-16

The present invention disclosed N-acetyl amino acid ester derivatives of betulin and the preparation method thereof, the method comprising the steps that in the presence of an alkaline substance, a catalyst and a racemization-inhibitor, the carboxyl group of N-acetyl amino acid is activated by a coupling agent; and then the activated N-acetyl amino acid is reacted with betulin via esterification reaction to obtain the N-acetyl amino acid ester derivative of betulin. The present invention provided a simple synthesis method to synthesize the N-acetyl amino acid ester derivatives of betulin by using betulin as a precursor compound and modifying the molecular structure of betulin. Such structural modification of betulin significantly enhances the anti-tumor activity of the betulin derivatives and therefore has important values.

Ren X.,Northeast Forestry University | Chen L.,Northeast Forestry University
Biosensors and Bioelectronics | Year: 2014

A newly designed molecularly imprinted polymer (MIP) material was fabricated and successfully utilized as recognition element to develop a quantum dots (QDs) based MIP-coated composite for selective recognition of the template cyphenothrin. The MIP-coated QDs were characterized by fluorescence spectrophotometer, Fourier transform infrared spectroscopy, transmission electron microscope, dynamic light scattering and X-ray powder diffraction. The fluorescence of the coated QDs is quenched on loading the MIP with cyphenothrin, and the effect is much stronger for the MIP than for the non-imprinted polymer, which indicates the MIP could as a recognition template composite. This method can detect down to 9.0nmolL-1 of cyphenothrin in water, and a linear relationship has been obtained covering the concentration range of 0.1-80.0μmolL-1. The method has been used in the determination of cyphenothrin in water samples and gave recoveries in the range from 88.5% to 97.1% with relative standard deviations in the range of 3.1-6.2%. The present study provides a new and general strategy to fabricate inorganic-organic MIP-coated QDs with highly selective recognition ability in aqueous media and is desirable for chemical probe application. © 2014 Elsevier B.V. Source

Ma G.,Northeast Forestry University | Chen L.,Northeast Forestry University
Journal of Chromatography A | Year: 2014

The sensitive and efficient magnetic molecularly imprinted polymers (MMIPs) were successfully synthesized using carbon nanotubes as matrix and Fe3O4 particles as magnetic ingredient. Tetraethyl orthosilicate was used as modification material of the carbon nanotubes. Cyhalothrin, methacrylic acid and ethylene glycol dimethacrylate were used as template molecule, functional monomer and cross-linker, respectively. Azo-isobutyronitrile and polyvinylpyrrolidone were used as initiator and dispersant, respectively. The MMIPs were used for the separation of pyrethroids including beta-cyfluthrin, cyhalothrin, cyphenothrin and permethrin in fruit samples followed by high performance liquid chromatography analysis. The polymers were characterized with Fourier transform infrared spectrometry, Brunauer-Emmett-Teller method, transmission electron microscopy and a physical property measurement system. The isothermal absorption experiment, kinetics absorption experiment and selectivity of MMIPs were studied in detail. Scatchard analysis revealed that two kinds of different binding sites existed in MMIPs. The maximum adsorption capacities of two binding sites were 65.21 and 189.83mgg-1, and dissociation constants were 7.11 and 30.40μgmL-1, respectively. The kinetic property of MMIPs was well fitted to the second-order equation. The selectivity experiment indicated that MMIPs had higher selectivity toward cyhalothrin and its structural analogs than reference compound. The feasibility of detecting pyrethroids from real samples was testified in spiked fruit samples with different concentrations (0.025, 0.25 and 2.5mgkg-1). The LODs of beta-cyfluthrin, cyhalothrin, cyphenothrin and permethrin were 0.0072, 0.0035, 0.0062 and 0.0068mgkg-1, respectively. Precisions of intra-day and inter-day ranging from 2.6% to 4.3% and 4.2% to 5.6% were obtained, respectively. This method was applied to determine pyrethroids in different fruit samples including apple, pear, orange, grape and peach, and satisfied recoveries (82.4-101.7%) were obtained. © 2013 Elsevier B.V. Source

Discover hidden collaborations