Development of a multifunctional active food packaging membrane based on electrospun polyvinyl alcohol/chitosan for preservation of fruits.

To mitigate environmental impacts in food preservation, the development of a multifunctional membrane for packaging is of importance. In this study, we have successfully fabricated a nanofibrous membrane using an eco-friendly electrospinning technique, comprising polyvinyl alcohol (PVA), chitosan (CS), and tannic acid (TA). The resulting nanofibrous membranes were crosslinked with glutaraldehyde (GA) and surface modified with ZnO. Our findings demonstrate that the crosslinking process enhances water resistance, reduces water vapor permeability, improves tensile strength (from 3 to 18 MPa), and enhances thermal stability (increasing decomposition temperature from 225 °C to 310 °C). Furthermore, the incorporation of TA and ZnO provides antioxidant properties to the membrane, effectively preventing food decomposition caused by UV-induced oxidation. Additionally, CS, TA, and ZnO synergistically exhibit a remarkable antibacterial effect with a bacteriostasis rate exceeding 99.9 %. The strawberry fresh-keeping experiment further confirms that our developed membrane significantly extends shelf life by up to 6 days. Moreover, cytotoxicity assays confirm the non-toxic nature of these membranes. The innovative significance of this study lies in proposing a robust GA-PVA/CS/TA@ZnO nanofibrous membrane with excellent mechanical properties, biocompatibility, and multiple functionalities including antibacterial, anti-ultraviolet, and anti-oxidation capabilities. It has tremendous potential for applications in active food packaging materials.

pH and NIR responsive polydopamine-doped dendritic silica carriers for pesticide delivery.

The stimuli-responsive pesticide delivery system provides a powerful strategy for enhancing the effective utilization of pesticides and reducing environmental pollution. Here, we prepared a new polydopamine doped dendritic silica (SiO2/PDA) nanocarriers for pesticide delivery. The SiO2/PDA nanocarriers present uniform spheres with an average diameter of 250 nm and carry center-radial inner pores. After loading dinotefuran (DNF) insecticide, polyethyleneimine (PEI) was used to cap the loaded-pesticide pores. The resulting SiO2/PDA@PEI displays high photothermal conversion effect (η = 35.1 %) and pH and near infrared (NIR) light-responsive release behavior. Meanwhile, the SiO2/PDA and SiO2/PDA@PEI carriers displayed high adhesion and wettability to leaves, and the photostability of DNF encapsulated in SiO2/PDA@PEI was improved by nearly 10 times greater than for free DNF. Importantly, the SiO2/PDA carriers possessed a benign biocompatibility on Escherichia coli (E. coli), seed and cells. Therefore, this work provides a promising approach to improve the utilization of pesticide.

Polydopamine-encapsulated cap-like mesoporous silica based delivery system for responsive pesticide release and high retention.

Nanopesticides formulation has been applied in modern agriculture, but the effective deposition of pesticides on plant surfaces is still a critical challenge. Here, we developed a cap-like mesoporous silica (C-mSiO2) carrier for pesticide delivery. The C-mSiO2 carriers with surface amino groups present uniform cap-like shape and have an mean diameter of 300 nm and width of 100 nm. This structure would reduce the rolling and bouncing of carriers on plant leaves, leading to improving the foliage deposition and retention. After loading dinotefuran (DIN), polydopamine (PDA) was used to encapsulate the pesticide (DIN@C-mSiO2@PDA). The C-mSiO2 carriers exhibit high drug loading efficiency (24.7%) and benign biocompatibility on bacteria and seed. Except for pH/NIR response release, the DIN@C-mSiO2@PDA exhibited excellent photostability under UV irradiation. Moreover, the insecticidal activity of DIN@C-mSiO2@PDA was comparable to that of pure DIN and DIN commercial suspension (CS-DIN). This carrier system has the potential for improving the foliage retention and utilization of pesticides.