Silk Fibroin Improves the Biological Properties of Egg White-Based Bioink for the Bioprinting of Tissue Engineering Materials

Egg white (EW) is a common nutritious food with excellent heat gelation and biocompatibility, but its application in biomaterials is considerably limited. Silk fibroin (SF) is a protein-based fiber with both excellent mechanical properties and biocompatibility, and its application in biomaterials has attracted much attention. Here, the EW/SF composite scaffold was first synthesized with GMA-modified EW/SF composite bioink (G-EW/SF). When homogenized EW and SF were individually grafted with glycidyl methacrylate (GMA), the grafted EW (G-EW) and SF (G-SF) were mixed in different proportions and then added to I2959. The resulting G-EW/SF composite bioink could be bioprinted into various EW/SF composite scaffolds. Among them, the compressive modulus of EW/SF (50%) composite scaffolds incorporating 50% G-SF was significantly improved. It had a three-dimensional (3D) polypore structure with an average pore size of 61 μm and was mainly composed of β-sheet structures. Compared with the EW scaffold alone, the thermal decomposition temperature of the EW/SF scaffold was 10 °C higher, and the residual rate after 9 days of enzymatic hydrolysis had increased by about 18%. The scaffold prolonged the sustained release of insulin and promoted the adhesion, growth, and proliferation of the L-929 cells. Therefore, the EW/SF composite scaffolds with good cell proliferation ability and certain mechanical properties can be used in different applications including cells, drugs, and tissues. These results provide new prospects for the application of the EW protein to medical tissue engineering materials.

Recent Advances in Design and Application of Nanomaterials-Based Colorimetric Biosensors for Agri-food Safety Analysis

A colorimetric sensor detects an analyte by utilizing the optical properties of the sensor unit, such as absorption or reflection, to generate a structural color that serves as the output signal to detect an analyte. Detecting the refractive index of an analyte by recording the color change of the sensor structure on its surface has several advantages, including simple operation, low cost, suitability for onsite analysis, and real-time detection. Colorimetric sensors have drawn much attention owing to their rapidity, simplicity, high sensitivity and selectivity. This Review discusses the use of colorimetric sensors in the food industry, including their applications for detecting food contaminants. The Review also provides insight into the scope of future research in this area.

Evaluation of the Antioxidant Potential of Citrus medica from Different Geographical Regions and Characterization of Phenolic Constituents by LC-MS

The varying antioxidant potential of Citrus medica associated with different geographical regions makes the evaluation of C. medica for natural antioxidants essential. This work aimed to compare the antioxidant potential of the phenolic constituents from different geographical regions. The chemical compositions were characterized by ultra-high-performance liquid chromatography (UPLC) coupled with mass spectrometry (MS). A total of 67 compounds including 29 coumarin derivatives and 38 flavonoids were tentatively identified by UPLC-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS). To evaluate the quality of C. medica from seven different geographical regions, water and 80% methanol fractions were subjected to quantitative analysis. Antioxidant potentials were determined by 2,2-diphenyl-1-picrylhydrazyl, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), iron chelation, and reduction methods. The samples collected from Sichuan province showed the highest content of total phenolic compounds. Combined with antioxidant results, the sample from Sichuan province presented good antioxidant activity. This study also showed that total phenolic compounds significantly contributed to the antioxidant activities (2,2-azinobis(3-ethyl-benzothiazoline-6-sulphonic acid) and radical scavenging activity) of C. medica samples (p < 0.01). These results provided chemical information and potential antioxidant value for further research, providing ideal evidence for the quality evaluation and exploitation of the source.

Effect of Hydrogen Peroxide on the Soil Microbial Community Structure and Growth of Malus hupehensis Rehd. Seedlings under Replant Conditions

Apple replant disease (ARD) is common in apple production, which seriously affects the growth and development of apples. In this study, hydrogen peroxide with a bactericidal effect was used to treat the replanted soil, and the effects of different concentrations of hydrogen peroxide on replanted seedlings and soil microbiology were investigated in order to seek a green, clean way to control ARD. Five treatments were set up in this study: replanted soil (CK1), replanted soil with methyl bromide fumigation (CK2), replanted soil + 1.5% hydrogen peroxide (H1), replanted soil + 3.0% hydrogen peroxide (H2), and replanted soil + 4.5% hydrogen peroxide (H3). The results showed that hydrogen peroxide treatment improved replanted seedling growth and also inactivated a certain number of Fusarium, while the Bacillus, Mortierella, and Guehomyces also became more abundant in relative terms. The best results were obtained with replanted soil + 4.5% hydrogen peroxide (H3). Consequently, hydrogen peroxide applied to the soil can effectively prevent and control ARD.

Colorimetric Sensor Based on Ag-Fe NTs for H2S Sensing

Meat waste is widely associated with spoilage caused by microbial growth and metabolism. Volatile compounds produced by microbial growth such as volatile sulfides could directly indicate the freshness of meat during distribution and storage. Herein, silver-iron nanotriangles (Ag-Fe NTs) for hydrogen sulfide (H₂S) detection were developed via one-pot facile reflux reactions. The Ag-Fe NTs were integrated into food packaging systems for the rapid, real-time, and nondestructive detection of the freshness of chilled broiler poultry. The principle of color development is that an increase in the volatile sulfide content leads to a change in the absorption wavelength caused by the etching of the Ag-Fe NTs, resulting in a color change (yellow to brown). The minimum H₂S concentrations detected by the naked eye and UV-vis spectrophotometer were 4 and 2 mg/m³, respectively. This label is economical and practical and can monitor the spoilage of chilled broiler meat products in real-time.