Preparation of curcumin-loaded chitosan/polyvinyl alcohol intelligent active films for food packaging and freshness monitoring.

To fulfill the current need for intelligent active food packaging. This study incorporated the curcumin inclusion complexes (CUR-CD) into chitosan/polyvinyl alcohol polymer to develop a new intelligent active film. The structures of films were analyzed by Fourier-transform infrared (FT-IR), scanning electron microscope (SEM), and so on. The CP-Cur150 film displays exceptional mechanical properties, water vapor barrier, and UV blocking capabilities as demonstrated by physical analysis. The CP-Cur150 film exhibited free radical scavenging rates on 2,2-diazo-di-3-ethylbenzothiazolin-6-sulfonic (ABTS) (98 %) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) (87 %). Additionally, it showed inhibitory effects on Gram-positive bacteria (Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli), reducing live colony counts by approximately 2.7 and 1.3 Log10 CFU/mL, respectively. The films were used to monitor the shrimp's freshness in real time. With the spoilage of shrimp, the film exhibited clear color fluctuations, from light yellow to red. In addition, the evaluation of the impact of films on pork pH, total volatile basic nitrogen, and total bacterial counts demonstrated that the CP-Cur150 film displayed the most significant effectiveness in preserving freshness, thereby extending the shelf life of pork.

Sodium alginate/chitosan-based intelligent multifunctional bilayer film for shrimp freshness retention and monitoring.

Developing bifunctional innovative food packaging for maintaining and monitoring food freshness is crucial for food safety. Here, we prepared tannic acid cinnamaldehyde nanoemulsions through self-assembly and ionic cross-linking between the natural emulsifiers tannic acid and cinnamaldehyde, and were incorporated into chitosan as a protective outer layer. Sodium alginate anchored with alizarin was employed as the sensing inner layer. A pH-sensitive bilayer film integrating real-time monitoring and maintenance of food fresh food freshness was designed using layer-by-layer assembly (LBL) technology. The prepared bilayer film exhibited 100 % UV protection, >99 % antimicrobial effect, and 94.86 % and 97.91 % clearance rates for DPPH and ABTS free radicals, respectively. In addition, the bilayer film exhibited high biosafety and sensitive, reversible, and rapid response to pH/NH3. Shrimp preservation experiments showed that the smart bilayer film could effectively slow down the growth of microorganisms on the surface of shrimp, extend the freshness period of shrimp, and could monitor the freshness of shrimp in real-time through color changes. In conclusion, the prepared SL-CCT bilayer film has excellent potential for food preservation and freshness monitoring, providing a new perspective for design and development of multifunctional smart food packaging films.

[Progress in stimuli-responsive molecularly imprinted polymers for enrichment analysis of trace components in traditional Chinese medicine].

Molecularly imprinted polymers demonstrate outstanding performance in the research on trace ingredients because of their high selectivity. Stimuli-responsive molecularly imprinted polymers(STR-MIPs) with the introduction of different responsive groups on the basis of traditionally imprinted materials can undergo reversible transformations when exposed to external stimuli such as temperature, magnetism, pH or light. Such responsiveness, combined with the specific recognition, endows STR-MIPs with excellent perfor-mance in trace component studies. Traditional Chinese medicine(TCM) contains complex components with trace content, and thus STR-MIPs have broad application prospects in the enrichment analysis of trace components in TCM. This paper elaborates on the application of STR-MIPs in the enrichment analysis of trace components in TCM from the perspectives of different stimuli, summarized relevant research achievements in the recent five years to broaden the application fields of molecular imprinting, and proposed a few opi-nions about their future development.

Methylene Blue/Carbon Dots Composite with Photothermal and Photodynamic Properties: Synthesis, Characterization, and Antibacterial Application.

Photodynamic therapy and photothermal therapy provide new ways to combat antibiotic resistance. In this research, methylene blue (MB) as an effective photosensitizer was conjugated with carbon quantum dots (CQDs), the composite product not only possessed good antibacterial properties against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) due to excellent singlet oxygen (1 O2 ) production rate and light heat transfer performance, but also showed good biocompatibility. Combined with 808 nm and 660 nm laser irradiation, the minimum bactericidal concentration of CQDs-MB towards S. aureus and E. coli was 5 µm. Therefore, this study provides a potential candidate material based on CQDs for clinical applications.