Monitoring the infection process of Rhizopus stolonifer on strawberry fruit during storage using films based on chitosan/polyvinyl alcohol/polyvinylpyrrolidone and plant extracts.

Different formulations based on nanoparticles of chitosan-plant extracts were evaluated to detect the infection process from the earliest stage of the fungus Rhizopus stolonifer on strawberry fruit during storage. Chitosan/polyvinyl alcohol (Ch/PVA) and chitosan/polyvinylpyrrolidone (Ch/PVP) films enriched with nanoparticles (NPs) of chitosan blended with plant extracts were prepared. They were placed inside a plastic package containing inoculated fruits and stored at 25 °C for 72 h. The thickness values of the films were in the range of 0.10 to 0.25 mm. All samples showed a maximum absorbance peak of about 300-320 nm; however, the Ch/PVP films enriched with NPs of chitosan and 10% of radish extract had an evident decrease in the optical absorbance as the fungal infection progressed. Additionally, as observed by scanning electron microscopy, the cross-section and surface morphology of films were not modified during storage, and the growth of R. stolonifer was evident after 48 h. Therefore, the Ch/PVP films enriched with chitosan NPs blended with 10% radish extract could be a reliable indicator of this fungus's growth.

Carbohydrate-based films containing pH-sensitive red barberry anthocyanins: Application as biodegradable smart food packaging materials.

A novel pH-sensitive colorimetric film was prepared based on immobilizing red barberry anthocyanins (RBAs) within composite chitin nanofiber (CNF) and methylcellulose (MC) matrices. The incorporation of CNFs and RBAs improved their mechanical properties, moisture resistance, and UV-vis screening properties. Moreover, the RBAs could be used as colorimetric indicators to detect food spoilage because they are sensitive to changes in pH and ammonia gas production. The RBA-halochromic indicator changed from reddish/crimson → pink → yellow with increasing pH, and from pink → yellow with increasing ammonia vapor concentration. Furthermore, the smart films possessed good antioxidant and antimicrobial activity owing to the presence of the RBAs and CNFs. Finally, the validity of the indicator to monitor the freshness/spoilage of a model food (fish) was demonstrated. Overall, this study shows that active/smart films can be assembled from food grade ingredients that can protect and monitor the freshness of products, like meat and fish.

Active and intelligent gellan gum-based packaging films for controlling anthocyanins release and monitoring food freshness.

Active and intelligent packaging films with multiple functions including antioxidant, antibacterial and colorimetric pH indicator properties were developed by incorporating Clitoria ternatea (CT) extract into gellan gum (G) film. G enhanced the stability of CT anthocyanins and allowed the anthocyanins to release from G film in a pH-responsive behavior. Heat-treated soy protein isolate (HSPI) was able to interact with G and CT anthocyanins through the formation of electrostatic forces and covalent bonds. G film blended with HSPI greatly reduced the swelling capacity of G/HSPI composite film and controlled the anthocyanins release at pH greater than 6.0. The physical and mechanical properties of G films such as hydrophobicity, water vapor permeability, swelling capacity and tensile strength were also significantly modified by addition of HSPI to G films. The smart films changed their color with the increase of total volatile basic nitrogen (TVBN) values during progressive spoilage of shrimp, revealing their potential application for monitoring seafood freshness.

3D printed intelligent scaffold prevents recurrence and distal metastasis of breast cancer.

Rationale: Tumors are commonly treated by resection, which usually leads to massive hemorrhage and tumor cell residues, thereby increasing the risk of local recurrence and distant metastasis. Methods: Herein, an intelligent 3D-printed poly(lactic-co-glycolic acid), gelatin, and chitosan scaffold loaded with anti-cancer drugs was prepared that showed hemostatic function and good pH sensitivity. Results: Following in situ implantation in wounds, the scaffolds absorbed hemorrhage and cell residues after surgery, and promoted wound healing. In an in vivo environment, the scaffold responded to the slightly acidic environment of the tumor to undergo sustained drug release to significantly inhibit the recurrence and growth of the tumor, and reduced drug toxicity, all without causing damage to healthy tissues and with good biocompatibility. Conclusions: The multifunctional intelligent scaffold represents an excellent treatment modality for breast cancer following resection, and provides great potential for efficient cancer therapy.

Biocompatible film sensors containing red radish extract for meat spoilage observation.

pH-sensitive films were developed based on biocompatible materials and natural pH sensitive dye. The films were successfully fabricated using starch/gelatin and red radish anthocyanin. The colors of films could be differentiated by naked eye within 5 min changing from orange to grey-purple at pH 2-12 and captured by a smartphone. The color parameters were evaluated by the Image J software. In addition, the color change of films was observed in ammonia gas atmosphere. The color stability of sensing films was evaluated and the results indicated that the films had great stability and were able to store more than two weeks. The results from intra-day and inter-day color response study showed good precision. Finally, the pH-sensitive films could be applied to real samples for real-time meat spoilage observation.

Using near-infrared enhanced thermozyme and scFv dual-conjugated Au nanorods for detection and targeted photothermal treatment of Alzheimer's disease.

Investigation of targeting inhibitors of Aß aggregation, heme-Aß peroxidase-like activity and efficient detectors of Aß aggregation, are of therapeutic value and diagnostics significance for the treatment of Alzheimer's disease (AD). Due to the complex pathogenesis of AD, theranostics treatment with multiple functions are necessary. Herein we constructed the NIR absorption property of gold nanorods (GNRs) loaded with single chain variable fragment (scFv) 12B4 and thermophilic acylpeptide hydrolase (APH) ST0779 as a smart theranostic complex (GNRs-APH-scFv, GAS), which possesses both rapid detection of Aß aggregates and NIR photothermal treatment that effectively disassembles Aß aggregates and inhibits Aß-mediated toxicity. Methods: We screened targeting anti-Aß scFv 12B4 and thermophilic acylpeptide hydrolase as amyloid-degrading enzyme, synthesized GAS gold nanorods complex. The GAS was evalued by Aß inhibition and disaggregation assays, Aß detection assays, Aß mediated toxicity assays in vitro. In vivo, delaying Aß-induced paralysis in AD model of Caenorhabditis elegans was also tested by GAS. Results: In vitro, GAS has a synergistic effect to inhibit and disassociate Aß aggregates, in addition to decrease heme-Aß peroxidase-like activity. In cultured cells, treatment with GAS reduces Aß-induced cytotoxicity, while also delaying Aß-mediated paralysis in CL4176 C.elegans model of AD. Furthermore, the photothermal effect of the GAS upon NIR laser irradiation not only helps disassociate the Aß aggregates but also boosts APH activity to clear Aß. The GAS, as a targeting detector and inhibitor, allows real-time detection of Aß aggregates. Conclusion: These results firstly highlight the combination of scFv, APH and nanoparticles to be theranostic AD drugs. Taken together, our strategy provides a new thought into the design of smart compounds for use as efficiently therapeutic and preventive agents against AD. Moreover, our design provides broad prospects of biomedical strategy for further theranostics application in those diseases caused by abnormal protein.