Plasmonic surface of flexible multilayered nanofibers possesses special superiority for the surface-enhanced Raman scattering (SERS) sensing of molecules and microbial cells. However, the fabrication of flexible plasmonic nanofibers with high sensitivity and reproducibility is difficult. Herein, we report a smart strategy for fabricating flexible plasmonic fibers, in which compact and homogeneous gold nanoparticles (Au NPs) are in-situ grown on the high-curvature surface of multilayered fibers of electrospun polyvinylidene fluoride (PVDF). Firstly, the surface of PVDF fibers is changed electrically, and Au seeds are deposited on the surface of PVDF fibers using electrostatic driving force. Secondly, a stable AuI₄⁻ complex is formed employing coordination between I⁻ and AuCl₄⁻ ions, which could decrease the reduction potential of AuCl₄⁻ and restrain the self-nucleation, and then the reduction reaction of AuI₄⁻ is initiated by introducing PVDF@Au seeds to pull down the barrier of potential energy. Finally, in-situ growth of AuNPs is generated on the high-curvature surface of PVDF nanofibers, and large-scale hotspots are generated by adjacent AuNPs coupling in the three-dimensional (3D) space of multilayered fibers. Membrane of PVDF@Au nanofibers also realizes the sensitive detection of thiram molecules (low limit of detection of 0.1 nM) and good reproducibility (relative standard deviation of 10.6%). Meanwhile, due to the multilayered construction of PVDF@Au nanofibers, a valid SERS signal on 3D surface of bacteria could be generated. 3D distribution of hotspots on multilayered PVDF@Au nanofibers gives a clear advantage for SERS sensing of organic molecules and microbial cells.

This research explores the synthesis of carboxymethyl cellulose (CMC) for the development of a cost-effective bioplastic film that can serve as a sustainable alternative to synthetic plastic. Replacing plastic packaging with CMC-based films offers a solution for mitigating environmental pollution, although the inherent hydrophilicity and low mechanical strength of CMC present significant challenges. To address these limitations, zinc oxide nanoparticles (ZnO NPs) were employed as a biocompatible and non-toxic reinforcement filler to improve CMC’s properties. A solution casting method which incorporated varying concentrations of ZnO NPs (0%, 5%, 10%, 15%, 20%, and 25%) into the CMC matrix allowed for the preparation of composite bioplastic films, the physicochemical properties of which were analyzed using scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. The results revealed that the ZnO NPs were well-integrated into the CMC matrix, thereby improving the film’s crystallinity, with a significant shift from amorphousness to the crystalline phase. The uniform dispersion of ZnO NPs and the development of hydrogen bonding between ZnO and the CMC matrix resulted in enhanced mechanical properties, with the film CZ₂₀ exhibiting the greatest tensile strength—15.12 ± 1.28 MPa. This film (CZ₂₀) was primarily discussed and compared with the control film in additional comparison graphs. Thermal stability, assessed via thermogravimetric analysis, improved with an increasing percentage of ZnO Nps, while a substantial decrease in water vapor permeability and oil permeability coefficients was observed. In addition, such water-related properties as water contact angle, moisture content, and moisture absorption were also markedly improved. Furthermore, biodegradability studies demonstrated that the films decomposed by 71.43% to 100% within 7 days under ambient conditions when buried in soil. Thus, CMC-based eco-friendly composite films have the clear potential to become viable replacements for conventional plastics in the packaging industry.