Preparation of Biocompatible Carboxymethyl Chitosan Nanoparticles for Delivery of Antibiotic Drug

Objective. To prepare biocompatible ciprofloxacin-loaded carboxymethyl chitosan nanoparticles (CCC NPs) and evaluate their cell specificity as well as antibacterial activity against Escherichia coli in vitro. Methods. CCC NPs were prepared by ionic cross-linking method and optimized by using Box-Behnken response surface method (BBRSM). Zeta potential, drug encapsulation, and release of the obtained nanoparticles in vitro were thoroughly investigated. Minimum inhibitory concentration (MIC) and killing profiles of free or ciprofloxacin-loaded nanoparticles against Escherichia coli were documented. The cytotoicity of blank nanoparticles and cellular uptake of CCC NPs were also investigated. Results. The obtained particles were monodisperse nanospheres with an average hydrated diameter of 151 ± 5.67 nm and surface of charge −22.9 ± 2.21 mV. The MICs of free ciprofloxacin and CCC NPs were 0.16 and 0.08 μg/mL, respectively. Blank nanoparticles showed no obvious cell inhibition within 24 h, and noticeable phagocytosis effect was observed in the presence of CCC NPs. Conclusion. This study shows that CCC NPs have stronger antibacterial activity against Escherichia coli than the free ciprofloxacin because they can easily be uptaken by cells. The obtained CCC NPs have promising prospect in drug delivery field

A Study of Phytoplankton Community Structure in Duobukuer Nature Reserve

In spring, summer, autumn 2015, we studied the seasonal variation of phytoplankton community structure in six rivers within Duobukuer Nature Reserve, and made preliminary evaluation of the water quality in Duobukuer Nature Reserve based on phytoplankton diversity. The results showed that a total of 7 phyla, 41 genera, 66 species and varieties of phytoplankton were identified in Duobukuer Nature Reserve; the annual species composition was dominated by diatom (59%) which also preponderated in dominant species (84.3%), biomass (68%) and abundance (75%), with no significant seasonal variation. Shannon-Wiener diversity index (H') and Pielou evenness index (J) were used to evaluate the water quality in 13 sampling points, and the results showed that the water quality was good in Duobukuer Nature Reserve, the sampling points 5, 6 and 12 presented β-pollution, and other sampling points were in an oligosaprobic-clean state

Phytoplankton functional groups response to environmental parameters in Muling River basin of northeast China

The present study was carried out in the biggest tributary of Ussuri River of boundary between China and Russia. The Muling River basin has undergone a long-term dredging works, and waterbody became seriously turbid. The succession of phytoplankton functional groups succession and environmental factors in the river were sampled in 2015. We totally identified 83 species, belonging to 17 functional groups which 5 were predominant, including group F, M, MP, P and Y. The seasonal succession of phytoplankton functional groups was M/P-F/MP/P-MP/P. Results of Spearman correlation analysis and canonical correspondence analysis (CCA) revealed that phytoplankton functional groups were mainly influenced by nutrient concentrations and light availability including total nitrogen (TN), ammonium nitrogen (NH4+–N), nitrate nitrogen (NO3−–N), N:P ratio (N:P), water depth (D) and transparency (SD) in the basin.The concept of functional feeding groups was used to classify and reveal the seasonal variation of phytoplankton functional groups in relation to environmental parameters. Phytoplankton species were grouped into 17 functional groups that vary significant spatially and seasonally. The pattern of phytoplankton functional groups seasonal successions decided by the five predominant functional groups. Total nitrogen, ammonium nitrogen, nitrate nitrogen, N:P ratio, water depth and transparency were the major factor influencing phytoplankton community in this basin