Water-Soluble and Degradable Gelatin/Polyaniline Assemblies with a High Photothermal Conversion Efficiency for pH-Switchable Precise Photothermal Therapy.

Photothermal therapy (PTT) is regarded as one of the potential techniques to replace surgery in the treatment of tumors. Polyaniline (PANI) shows better biocompatibility than inorganic reagents, which has been widely used in tumor photoacoustic (PA) imaging and PTT. However, the poor water solubility and nonspecific aggregation of PANI nanoparticles severely restricted their biomedical application. In addition, it is difficult to control the photothermal effect just on cancer cells. Herein, we develop tumor pH-responsive PANI-Gel/Cu assemblies, which can achieve targeted and precise ablation of tumors. Due to the high hydrophilicity of gelatin, the PANI-Gel/Cu assemblies show excellent dispersion in physiological solutions and long-term stability. By taking advantage of the self-doping effect between the carboxyl groups in gelatin and the imine part of the PANI skeleton, the photothermal characteristics of PANI-Gel/Cu assemblies can be promoted effectively by the acid tumor microenvironment, and the PA imaging of PANI-Gel/Cu assemblies can also be activated by tumor pH. Consequently, both the PTT enhancement and PA signal amplification can be triggered under a tumor microenvironment, and PANI-Gel/Cu assemblies can be targeted to cancer cells with the RGD sequences in their gelatin skeleton. In vivo imaging-guided PTT to A549 cancer shows precise treatment with little harm to normal cells, and PANI-Gel/Cu assemblies can disassemble into tiny particles (<15 nm) under laser irradiation. This work overcomes the intrinsic limitation of PANI materials, i.e., poor water solubility and nonspecific aggregation, meanwhile providing a pH-active PANI-based platform for precise and effective ablation of cancer.

[Effect of grass barrier-combined filter strips on the reduction of nitrogen and phosphorus concentration under concentrated flow of varying densities].

Vegetative barrier-combined filter strips are defined as grass barriers set up before filter strips. They could make concentrated water flow disperse, which exerts the function of grass barriers (i.e., existence of grass barriers improves the performance of filter strips in the purification of pollutants). In this regards, grass barriers are generally considered to be effective in the purification of pollutants when the density of concentrated flow is low, whereas little was known about this effect with an increasing density of concentrated flow. In this study, we constructed Miscanthus floridulus barrier before Vitex negundo filter strip with three densities of concentrated flow (low: one concentrated flow channel; middle: three channels; high: five channels). The aim of work was to identify the effect of M. floridulus combined V. negundo filter strips in reducing nitrogen and phosphorus concentration under three concentrated water flow levels. Our results showed that the combined filter strips had a higher performance in the reduction in the total N, NH(4+)-N, NO(3-)-N and total P compared to those in the V. negundo (P < 0.05), regardless of the water flow level. There was no significant difference in the reduction of total N, NH(4+)-N, NO(3-)-N and total P among three water flow levels (P > 0.05). We concluded that M. floridulus combined V. negundo filter strips could improve the reduction of nutrients, which couldn' t be influenced by varying density of concentrated flow level.

[Effects of nutritional condition on the competitive parameters of Prorocentrum donghaiense and Skeletonema costatum].

By the methods of pure culture and mixed culture in laboratory, this paper studied the effects of different substrate nitrogen and phosphorus concentrations on the population growth and interspecific competitive parameters of two kinds of microalgae, Skeletonema costatum and Prorocentrum donghaiens. With the increasing concentrations of substrate nitrogen and phosphorus, the maximum biomass of the two kinds of microalgae increased, and their specific growth rate was higher in pure culture than in mixed culture. In mixed culture, S. costatum was dominant at the beginning, while P. donghaiense became dominant later. The time period when this change happened was related to the nutritional conditions, and the inflection point for S. costatum and P. donghaiense was about 0-2.6 and 0.5-4.9 d, respectively. Under the test nutritional conditions, the competitive parameter of P. donghaiense to S. costatum (beta) was higher than that of S. costatum to P. donghaiense (alpha). When the substrate nitrogen and phosphorous concentrations were 128 micromol N x L(-1) and 32 micromol P x L(-1), the competitive capability of P. donghaiense was 3.8 times of that of S. costatum, presenting the most obvious difference.

Effect of dietary n-3 fatty acids on the composition of long- and very-long-chain polyenoic fatty acid in rat retina.

The effect of dietary supplementation with n-3 fatty acids, primarily docosahexaenoic acid (DHA) with high purity, on the fatty acid composition, especially very-long-chain fatty acids (VLCFA) longer than DHA, with four or six double bonds, in the rod outer segment (ROS) membranes of young Sprague-Dawley rats was investigated. After several weeks of feeding, diets high in n-3 fatty acids increased the DHA level significantly, while there were decreased levels of most n-6 fatty acids, such as arachidonic acid and 22:5n-6. Six kinds of VLCFA were detected by gas chromatography-mass spectrometry (GC-MS). Feeding a high n-3 fatty acid diet significantly increased the content of some n-3 VLCFAs such as 26:4n-3 and 30:4n-3 in ROS membranes, but not all detected n-3 VLCFAs. This study demonstrates that the dietary level of n-3 fatty acids not only affects the level of DHA, but also the levels of VLCFA in ROS membranes.

Effect of dietary DHA on DHA levels in retinal rod outer segments in young versus mature rats.

We compared the effect of direct supplementation with docosahexaenoic acid (DHA) on the fatty acid composition of the liver and the rod outer segment (ROS) membranes of the retina in young (five-week-old) and mature (one-year-old) rats. In young rats, a high content of DHA in the diet (9.7% of total energy) effectively increased the proportion of DHA in ROS membranes (41.8%), compared with the proportion observed in a linoleic acid (LA) diet group (control, 31.6%). The proportion of DHA was also significantly higher in the livers of young DHA-fed rats. These results show that direct supplementation with DHA is very effective in increasing DHA levels in the ROS membranes and livers of developing animals. In contrast, in mature rats there was no significant increase in the proportion of DHA in the ROS membranes, even after the highest dose (8.4% of total energy) of DHA, although the proportion of DHA was significantly higher in the livers of DHA-fed rats. The changes in fatty acid composition in the ROS membranes were different in young and mature rats fed high-DHA diets. Our findings indicate that mature rats maintain a constant level of DHA in the ROS membranes even after being directly supplemented with high doses of DHA.

Effect of docosahexaenoic acid and ascorbate on peroxidation of retinal membranes of ODS rats.

Mutant male osteogenic disorder Shionogi (ODS) rats, unable to synthesize ascorbic acid, were fed diets containing a high content of docosahexaenoic acid (DHA) and different amounts of ascorbic acid, to study the effect of DHA on peroxidative susceptibility of the retina and possible antioxidant action of ascorbic acid. ODS rats were fed from 7 weeks of age with diets containing high DHA (6.4% of total energy). A control group received a diet high in linoleic acid. The diets also contained varying amounts of ascorbic acid. Fatty acid compositions and phospholipid hydroperoxides in rod outer segment (ROS) membranes, and retinal ascorbic acid were analyzed. DHA in ROS membranes was significantly increased in rats fed high DHA, compared with the linoleic acid diet. Levels of phospholipid hydroperoxides in the DHA-fed rats were significantly higher than the linoleic acid-fed rats. Ascorbic acid supplementation did not suppress the phospholipid hydroperoxide levels after a high DHA diet, even when the supplement increased the content of retinal ascorbic acid. In conclusion, high DHA feeding induced a marked increase of phospholipid hydroperoxides in ROS membranes of ODS rats. Supplementation of ascorbic acid did not reverse this increase.