A short-term of starvation improved the antioxidant activity and quality of African catfish (Clarias gariepinus).

Clarias gariepinus is an important freshwater fish with high economic value and breeding potential in China. It is a fast-growing and adaptable catfish, but the main problems facing the current market are its low price and poor taste, although starvation is a good solution to these problems. In this study, the effects of starvation on the physiology, biochemistry, and muscle quality of C. gariepinus were investigated. The results showed that compared with the control group, the weight gain rate and specific growth rate of the starvation group were significantly different. Body weight, visceral weight, condition factor, viscerosomatic index, hepatosomatic index, and viscera fat index all decreased, while visceral weight and hepatosomatic index decreased significantly after starvation for 30 days. The hardness and crude protein of muscle increased significantly and crude lipid decreased significantly. Taste-enhancing amino acids increased slightly, and fatty acids increased significantly. Compared with the control group, starvation led to changes in antioxidant defense parameters. The level of malondialdehyde (MDA) in liver increased significantly; the activities of superoxide dismutase (SOD) increased in serum after 30 days; the activities of glutathione peroxidase (GSH-Px) increased considerably in the serum and liver after 15 days; the activities of alanine aminotransferase (ALT) increased considerably in the serum and liver after 30 days. The in-depth study of changes in physiological, biochemical, and nutritional components of fish under starvation is helpful to understand the ecological strategy of fish to adapt to starvation and of great guiding significance for fishery resource management and aquaculture production.

Dual cross-linked starch hydrogel for eugenol encapsulation and the formation of hydrogen bonds on textural hydrogel.

Physical and chemical cross-linked hydrogels combining N, N'-Methylenebisacrylamide (MBA)-grafted starch (MBAS) and sorbitol were successfully prepared and encapsulated with eugenol in this work. The dense porous structure with diameter of 10-15 µm and strong skeleton after restructuring inside the hydrogel was confirmed by SEM. The band shifts between 3258 cm-1 and 3264 cm-1 clarified the presence of a large number of hydrogen bonds in physical and chemical cross-linked hydrogels. The robust structure of the hydrogel was confirmed by mechanical and thermal property measurements. Molecular docking techniques were used to help understand the bridging pattern between three raw materials and to assess the advantageous conformation, which demonstrate sorbitol is beneficial to improve the characteristics of textural hydrogel by the formation of hydrogen bonds, creating a denser network, structural recombination and new intermolecular hydrogen bonds between starch and sorbitol afforded considerably junction zones. Compared to ordinary starch-based hydrogels, eugenol-loaded starch-sorbitol hydrogels (ESSG) exhibited a more attractive internal structure, swelling properties, viscoelasticity. Moreover, the ESSG showed excellent antimicrobial activity for typical undesired microorganisms in foods.

Green preparation of 3D micronetwork eugenol-encapsuled porous starch for improving the performance of starch-based antibacterial film.

In order to find a non-enzymatically treated alternative wall material with effective encapsulation properties, and to reduce the use of conventional non-biodegradable plastics, a novel 3D-micronetwork porous starch (3D-MPS) was created via a modified sacrificial template method to encapsulate eugenol (3D-EMPS) and used to incorporate with TiO2-starch film, for significantly improving the performance of starch-based antibacterial film. At the template SiO2 nanoparticles concentration of 0.1 %, the 3D-MPS exhibited anticipated alveolate structure with internal aperture of approximately 10 µm confirmed by SEM. With addition of 3D-EMPS, higher tensile strength (29.70 Mpa) and water barrier property (924 g/cm2·24 h) of the composite film was obtained. Moreover, molecular docking technique was used to model the intermolecular forces, which showed that the major forces maintaining the internal bonding of the composite film were hydrogen bonding and the interaction between eugenol and 3D-MPS skeleton in 3D-EMPS. Meanwhile, the composite film demonstrated the expected eugenol retardation and antimicrobial capacity against S. aureus, E. coli, and B. subtilis. Finally, the composite films were used for evaluating the feasibility in the actual food, which largely extended its shelf life compared to the negative control. This high-performance film revealed their potential for packaging materials application.

Developments in molecular docking technologies for application of polysaccharide-based materials: A review.

With the increasing pollution of the planet, the search for natural multifunctional alternatives to petroleum-based plastics has assumed to be a great important proposition. Polysaccharides, an inexhaustible natural resource with good biocompatibility as well as mechanical properties, are considered as an ideal alternative to petroleum-based materials. However, blind experimentation and development will inevitably lead to waste of raw materials and contamination of reagents. Therefore, researchers desire a technology which can assist in predicting and screening experimental materials at the higher level. Molecular docking simulations, an emerging computer technology that can effectively predict the structure of interactions between molecules and analyze the optimal conformation, are a common aid for materials and drug design. In this review, we describe the origins and development of molecular docking techniques, mainly performed an overview of various molecular docking software on their applications in the field of different polysaccharide materials.

Highly selective adsorption of Hg (II) from aqueous solution by three-dimensional porous N-doped starch-based carbon.

For the first time, N-doped carbon materials with 3D porous-layered skeleton structure was synthesized through a one-step co-pyrolysis method, which was fabricated by co-pyrolysis of natural corn starch and melamine using metal catalysts (Ni (II) and Mn (II)). The 3D-NC possessed a heterogeneously meso-macroporous surface with a hierarchically connected sheet structure inside. Batch adsorption experiments suggested that highly selective adsorption of Hg (II) by the 3D-NC could be completed within 90 min and had maximum adsorption capacities as high as 403.24 mg/g at 293 K, pH = 5. The adsorption mechanism for Hg (II) was carefully evaluated and followed the physical adsorption, electrostatic attraction, chelation, and ion exchange. Besides, thermodynamic study demonstrated that the Hg (II) adsorption procedure was spontaneous, endothermic, and randomness. More importantly, the 3D-NC could be regenerated and recovered well after adsorption-desorption cycles, showing a promising prospect in the remediation of Hg (II)-contaminated wastewater.

Modified Stranski-Krastanov Growth of Amino Acid Arrays toward Piezoelectric Energy Harvesting.

Biomolecule-based piezoelectric nanostructures emerged as a new class of energy-converse materials, and designing tailored piezoelectric amino acid arrays is essential to achieve efficient electrical-mechanical coupling and fulfill their application potential. However, the controlled growth of amino acid nanostructures is still challenging due to the limited understanding of their growth mechanism. Herein, we base on the Stranski-Krastanov (S-K) growth mode and propose a mechanism for the growth of ordered amino acid array structures via physical vapor deposition. The growth of vertical valine sheet arrays is examined by changing the substrate temperature, chamber pressure, and source-substrate distance, and a "layer-plus-sheet" growth process is revealed. The modified S-K growth mode is applied to fabricate other amino acid nanostructures like leucine and isoleucine. The growth mode not only explains the formation of uniform and controllable morphology of amino acid structures but also leads to the significant enhancement of their piezoelectric properties. The maximal effective piezoelectric constant of valine sheets is 11.4 pm V-1, which approaches its highest predicted value. The output voltage of the valine array-based nanogenerator is ∼4.6 times the output voltage of the valine powder-based nanogenerator. This work provides new insights into the growth mechanism of ordered piezoelectric amino acid arrays, making them promising candidates for applications in wearable or implantable electronic devices.