Cloning, expression and function analysis of trehalose-6-phosphate synthase gene from Marsupenaeus japonicu.

Trehalose is an important disaccharide that plays an important role in extreme environmental conditions. Trehalose-6-phosphate synthase (TPS) gene is the key gene for trehalose synthesis in Marsupenaeus japonicus. In this study, a TPS gene was isolated and characterized from M. japonicus. The full-length cDNA of TPS gene of M. japonicus (MjTPS) was 3308 bp, encoding 844 amino acids. The protein of the deduced MjTPS contained a glycol_transf_20 domain and a trehalose_PPase domain. The mRNA expression level of MjTPS was the highest in hepatopancreas. The further analysis found that MjTPS gene expression was up-regulated in a short time under low-salinity and high-nitrite stress, indicating that MjTPS gene had certain resistance to low-salinity and high-nitrite stress. Compared with the control group, both the expression of MjTPS and the trehalose content significantly decreased from 3 h to 24 h after MjTPS gene interference,. After RNAi, the mortality of M. japonicus increased, the expression level of MjTPS and the synthesis of downstream products decreased under low-salinity and high-nitrite stress, and what's more, the expression of immune genes PMO25, ERP, CD, HSP90, HSP70, HSP60, HMC and CLEC2 were significantly changed, implying that MjTPS might be participated in the immune response of M. japonicus. In addition, MjTPS gene silencing could affect the expression of CHI1 and CHS, suggesting that MjTPS might be involved in molting behavior of M. japonicus. These results provide new information for further studying the function of trehalose-6-phosphate synthase in shrimp.

Fabrication and characterization of hollow starch nanoparticles by gelation process for drug delivery application.

Hollow nanoparticles (HNPs) have been widely regarded as controlled drug carriers owing to their advantages, such as high drug-loading efficiency and superior control over drug delivery and release. In this study, a facile and efficient strategy has been exploited for preparation of hollow starch nanoparticles (HSNPs) via a sacrificial hard-template process using gelled starch as the shell. These nanocapsules have been characterized through various techniques, including transmission electron microscopy, differential scanning calorimetry, X-ray diffraction, and Fourier transform infrared spectroscopy. The HSNPs have diameters ranging from 30nm to 300nm, with shell thickness of 5-10nm. X-ray diffraction analysis has revealed that HSNPs exhibit B+V type diffraction peaks with a relative crystallinity of 34.2%. Doxorubicin hydrochloride (DOX·HCl) was readily encased in the nanocarriers with a high loading efficiency (97.56%) and a high loading content (37.12%). In addition, no cytotoxicity for normal liver cells was found in HSNPs. However, DOX·HCl-loaded HSNPs exhibited clear cytotoxicity for liver hepatocellular cells. Thus, the hollow starch nanoparticles form a highly promising platform for cancer therapy.

Characterizations of Pickering emulsions stabilized by starch nanoparticles: Influence of starch variety and particle size.

Pickering emulsions were first successfully fabricated by different types and sizes of corn, tapioca, sweet potato, and waxy corn starch nanoparticles as stabilizers. Photography, optical microscopy, confocal laser scanning microscopy, and rheology measurements were used to characterize Pickering emulsions stabilized by various starch nanoparticles. The results showed that tapioca, sweet potato, and corn starch nanoparticles were appropriate for Pickering emulsion stabilization because the three nanoparticles have nearly neutral wettability (θow ∼90°). Confocal microscopy revealed that intact and thick nanoparticle shells coated the surface of oil droplets. The Pickering emulsions stabilized by sweet potato and corn starch nanoparticles with a diameter that ranged from 100 to 220nm had better stability than those with a diameter either less than 100nm or more than 220nm. These results suggested that starch nanoparticles could be used as promising particulate emulsifiers to fulfill the demands of Pickering emulsions with stable characteristics.

Preparation of Hollow Biopolymer Nanospheres Employing Starch Nanoparticle Templates for Enhancement of Phenolic Acid Antioxidant Activities.

Phenolic acids have been extensively studied because of their bioactive properties and disease prevention and control capacities. However, undesired odors and taste, low aqueous solubility, and thermal and ultraviolet (UV) light instability severely restrict their application. The aim of this work was to evaluate the enhancement in antioxidative activities of phenolic acids in hollow nanospheres and their stability in terms of their antioxidative activities under harsh conditions. For the first time, we have successfully fabricated hollow short linear glucan (SLG)@gum arabic (GA) nanospheres and hollow in situ SLG/GA hybrid nanospheres by removing the sacrificial starch nanoparticle templates through α-amylase treatment and Ostwald ripening. These two hollow nanospheres had a huge cavity area for the encapsulation of phenolic acids, and their loading capacities were >20%. Furthermore, they can be used as nanoreactors to immobilize phenolic acids, enhance their antioxidative activities, and improve their stability when exposed to high salt concentrations, UV light, or heat treatments.

Synthesis and study the properties of StNPs/gum nanoparticles for salvianolic acid B-oral delivery system.

To fabricate stable sized and shaped controlled release delivery systems for salvianolic acid B (Sal B), different food gums were individually added to short-chain glucan solution to prepare starch nanoparticles (StNPs)/gum nanocomposites by self-assembly, and Sal B was embedded in situ. The results showed that size of StNPs was reduced to ca. 45nm with the addition of chitosan and rosin, which decreased by over 50% than that of StNPs without the gum. The StNPs/guar gum nanocomposites had the largest size (109.2nm) among samples of StNPs with gums. The StNPs with chitosan and gum arabic exhibited an obvious core-shell structure. The loading capacities of Sal B in StNPs, StNPs/chitosan, and StNPs/gum arabic nanocomposites were 5.2, 8.26 and 8.08%, respectively. The in vitro release of Sal B from StNPs/gum nanocomposites were sustained and prolonged for over 12h, indicating that StNPs/gum nanocomposites are good candidates to control Sal B release.

The inhibition effect of starch nanoparticles on tyrosinase activity and its mechanism.

The objective of the current research was to investigate the effects of starch nanoparticles (SNPs) prepared from waxy maize, potato, normal corn, and tapioca starches on the activity of tyrosinase. As a main polyphenol oxidase, tyrosinase not only induces fruit and vegetable browning but also causes skin diseases by overproducing melanin. Herein, for the first time, we evaluated the inhibitory kinetics of SNPs on tyrosinase. It turned out that SNPs inhibited tyrosinase activity reversibly. The IC50 values of hollow nanoparticles, amylopectin nanoparticles, corn starch nanoparticles, and tapioca starch nanoparticles were 0.308, 0.669, 1.490, and 4.774 µM, respectively. Assay of fluorescence spectra demonstrated that SNPs quenched the tyrosinase intrinsic fluorescence. Moreover, binding constant and binding sites found that SNPs were bound to tyrosinase through van der Waals forces, hydrogen bonds, as well as electrostatic interactions. Analysis of circular dichroism indicated that the incorporation of SNPs into tyrosinase prompted conformational alteration of the enzyme. Furthermore, inhibition of browning by SNPs loading with l-dopa compound indicated that not only the tyrosinase activity was inhibited, but also SNPs decreased free dopa content by adsorption. This research on SNPs as potential inhibitors could give rise to advancement in the realm of anti-tyrosinase and have versatile applications in medicine, food, cosmetics, materials and drugs.