Tetrastigma hemsleyanum Diels et Gilg is a valuable medicinal herb, whose main bioactive constituents are flavonoids. Chilling sensitivity is the dominant environmental factor limiting growth and development of the plants. But the mechanisms of cold sensitivity in this plant are still unclear. Also, not enough information on genes involved in flavonoid biosynthesis in T. hemsleyanum is available to understand the mechanisms of its physiological and pharmaceutical effects. The electrolyte leakage, POD activity, soluble protein, and MDA content showed a linear sustained increase under cold stress. The critical period of cold damage in T. hemsleyanum was from 12 h to 48 h. Expression profiles revealed 18,104 differentially expressed genes (DEGs) among these critical time points. Most of the cold regulated DEGs were early-response genes. A total of 114 unigenes were assigned to the flavonoid biosynthetic pathway. Fourteen genes most likely to encode flavonoid biosynthetic enzymes were identified. Flavonols of T. hemsleyanum might play a crucial role in combating cold stress. Genes encoding PAL, 4CL, CHS, ANR, FLS, and LAR were significantly up-regulated by cold stress, which could result in a significant increase in crucial flavonols (catechin, epicatechin, rutin, and quercetin) in T. hemsleyanum. Overall, our results show that the expression of genes related to flavonol biosynthesis as well as flavonol content increased in T. hemsleyanum under cold stress. These findings provide valuable information regarding the transcriptome changes in response to cold stress and give a clue for identifying candidate genes as promising targets that could be used for improving cold tolerance via molecular breeding. The study also provides candidate genes involved in flavonoid biosynthesis and may be useful for clarifying the biosynthetic pathway of flavonoids in T. hemsleyanum.

In this study, porous scaffold materials based on polyvinyl alcohol (PVA) and gelatin (Gel) were successfully fabricated and characterized. The mechanism of the reaction, morphology, and crystallinity were investigated by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). In addition, thermogravimetric analysis (TGA) was performed together with differential scanning calorimetry (DSC) for examining the thermostability and phase transformation of the scaffolds. Degradation and swelling studies of PVA/Gel composite scaffold materials were performed in phosphate-buffered saline. Finally, the mechanical performances had been determined. According to the results, the polymer matrix that was formed by the combination of PVA and gelatin had better thermal stability. The synthesized composite scaffold was amorphous in nature. The addition of gelatin did not affect the fishbone-like microstructure of PVA, which ensures the excellent mechanical properties of the PVA scaffold. The denaturation temperature and elastic modulus of the PVA scaffold were improved by the gelatin addition, but the physical and chemical properties of the PVA scaffold were weakened when the gelatin content exceeded 10%. In addition, the PVA-10G sample has suitable degradability. Therefore, the PVA/Gel composite scaffold might potentially be applied in the field of tissue engineering that demands high strength.

The hydrogels based on gelatin cross-linked with chitosan (CS) and polyvinyl pyrrolidone (PVP) were synthesized using microwave and ultrasonic coupling technique in this study. This interpenetrating polymer network (IPN) hydrogels were cross-linked by glutaraldehyde and 1,2-Epoxy-4-vinylcyclohexane. The presence of function groups in the structure of hydrogel films were confirmed using Fourier transform infrared spectroscopy (FT-IR), thermal stability was measured by DSC, and the swelling behaviors were measured gravimetrically in distilled water at the temperature of 27°C. At last, the mechanical properties were tested. The results showed that the hydrogel prepared with microwave and ultrasonic exhibited the highest tensile strength (86.68MPa), comparing with the hydrogel prepared with traditional method and only microwave reactive field. The FT-IR and XRD results showed that the chemical reactions occurred between the NH2 of chitosan and the COOH of gelatin, and the introduction of ultrasound can improve the reaction rate. The hydrogel film gained in microwave and ultrasonic coupling field has the best combination properties. Therefore, the new microwave-ultrasonic coupling technique is the potential technology to prepare the new hydrogel due to less synthesis time.

A novel composite edible film was synthesized by grafting gelatin chain onto hydroxypropyl methyl cellulose (HPMC) in the presence of glycerol (used as a plasticizer) using a solution polymerization technique. The reaction was carried out in homogeneous aqueous medium. Thermal properties, chemical structure, crystallinity, surface morphology, and mechanical and hydrophilic performance changes of HPMC caused by the addition of gelatin were investigated by differential scanning calorimetry, thermogravimetric, Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, universal testing machine and water contact angle. The results shows that HPMC and gelatin are miscible and the hydrophobic property of the blending film can be enhanced with the introduction of the gelatin. Moreover, the HPMC/gelatin blend films are flexible, and exhibit excellent compatibility, good mechanical properties and also thermal stability, and could be promising candidates for food packaging materials.