## 4 Applications
### Other Applications  
Bacterial infections are prevalent health issues worldwide, necessitating materials with antibacterial properties to mitigate infection risks. The production of non-biodegradable materials has contributed to environmental pollution, underscoring the need for innovative, biodegradable, and biocompatible antimicrobial materials for applications such as food packaging and biomedical devices [314]. [PERSON] et al. utilized a surface Fe\({}_{3}\)O\({}_{4}\) embedded PLA-PEG blend via a solution casting method to develop a nanocomposite [315]. This nanocomposite inhibited the growth of _Candida albicans_, a eukaryotic opportunistic pathogen harmful to human health, with antimicrobial activity increasing at higher MNP ratios. In a subsequent study, a direct green synthesis technique was employed to create an SMPNC incorporating AgNPs, which displayed significant antibacterial activity against both Gram-positive and Gram-negative bacteria [120]. [PERSON] and coworkers designed organic-inorganic hybrid PCL-TiO\({}_{2}\)/PLLA nanocomposites with antibacterial properties [126]. While PLLA exhibited no antibacterial activity, as indicated by the absence of inhibition zones, the PCL-TiO\({}_{2}\)/PLLA nanocomposites demonstrated significant antibacterial effects against _Bacillus subtilis_, _Bacillus licheniformis_, and molds, attributing the antibacterial role to uniformly distributed PCL-TiO\({}_{2}\) in the PLLA matrix (Figure 30a). Smart textiles have swiftly evolved due to consumer demands for high performance, functionality, and adaptability to both wearer physiology and environmental conditions. [PERSON] et al. engineered smart polyester fabric for sportswear with temperature and water/moisture responsive shape-memory performance [316]. The nanocomposite structure, comprising an SMPU matrix and hydrophilic nanowhiskers (CNWs), was applied to polyester fabric as a finishing treatment. The thermoregulation performance of the resultant composites was evaluated under varying temperatures and relative humidity conditions, demonstrating the textiles' ability to actively regulate temperature by adapting to dynamic environmental conditions of water vapor pressure and air permeability. [PERSON] et al. developed smart gloves using a \"swelling-ultrasonicating\" and one-step twisting procedure with shape-memory RGO/EVA composite [46]. The RGO/EVA composite yams were integrated into commercially available fabrics, such as silk fabrics and cotton gloves, using a simple sewing method (Figure 30b). This approach, particularly advantageous for practical applications, offers enhanced convenience over traditional flexible fiber sensors that rely on adhesive tapes, underscoring the potential of RGO/EVA composite yams in smart textiles, wearable devices, and artificial muscles. In a study by [PERSON] and colleagues, nanoclay reinforced polylactic acid/thermoplastic polyurethane was used to produce highly twisted yarn, introducing a key innovation for smart breathing textiles [59]. Recent research efforts have been directed towards developing rewritable paper to mitigate the environmental impact of the traditional pulp and paper industry, focusing on sustainable alternatives. [PERSON] and colleagues introduced an ink-free rewritable paper utilizing a core-shell NP-based photonic crystal, specifically ferroferric oxide-carbon (Fe\({}_{3}\)O\({}_{4}\)@C), combined with a bistable electroactive polymer (BSEP) [317]. This innovation allows forelectric field-induced switching of reflection colors, enabling the storage of vivid color images without ink and ensuring image stability for over a year under ambient conditions. Remarkably, the images on this rewritable paper can be overwritten up to 500 times without degradation, as demonstrated on a seven-segment numerical display (Figure 30c). [PERSON] and colleagues utilized stepwise emulsion polymerization to integrate monodisperse NPs into a poly(ethyleneerephthalate) (PET) film [318].