Cellulose nanofiber/molybdenum disulfide aerogels for ultrahigh photothermal effect

Study on synergistic mechanism of molybdenum disulfide/sodium carboxymethyl cellulose composite nanofiber mats for photothermal/photodynamic antibacterial treatment

Innovative antibacterial therapies using nanomaterials, such as photothermal (PTT) and photodynamic (PDT) treatments, have been developed for treating wound infections. However, creating secure wound dressings with these therapies faces challenges. The primary focus of this study is to prepare an antibacterial nanofiber dressing that effectively incorporates stable loads of functional nanoparticles and demonstrates an efficient synergistic effect between PTT and PDT. Herein, a composite nanofiber mat was fabricated, integrating spherical molybdenum disulfide (MoS2) nanoparticles. MoS2 was deposited onto polylactic acid (PLA) nanofiber mats using vacuum filtration, which was further stabilized by sodium carboxymethyl cellulose (CMC) adhesion and glutaraldehyde (GA) cross-linking. The composite nanofibers demonstrated synergistic antibacterial effects under NIR light irradiation, and the underlying mechanism was explored. They induce bacterial membrane permeability, protein leakage, and intracellular reactive oxygen species (ROS) elevation, ultimately leading to >95 % antibacterial activity against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), which is higher than that of single thermotherapy (almost no antibacterial activity) or ROS therapy (about 80 %). In addition, the composite nanofiber mats exhibited promotion effects on infected wound healing in vivo. This study demonstrates the great prospects of composite nanofiber dressings in clinical treatment of bacterial-infected wounds.

Re-Designing Cellulosic Core-Shell Composite Fibers for Advanced Photothermal and Thermal-Regulating Performance

Flexible fibers and textiles featuring photothermal conversion and storage capacities are ideal platforms for solar-energy utilization and wearable thermal management. Other than using fossil-fuel-based synthetic fibers, re-designing natural fibers with nanotechnology is a sustainable but challenging option. Herein, advanced core-shell structure fibers based on plant-based nanocelluloses are obtained using a facile co-axial wet-spinning process, which has superior photothermal and thermal-regulating performances. Besides serving as the continuous matrix, nanocelluloses also have two other important roles: dispersing agent when exfoliating molybdenum disulfide (MoS2), and stabilizer for phase change materials (PCM) in the form of Pickering emulsion. Consequently, the shell layer contains well-oriented nanocelluloses and MoS2, and the core layer contains a high content of PCM in a leak-proof encapsulated manner. Such a hierarchical cellulosic supportive structure leads to high mechanical strength (139 MPa), favorable flexibility, and large latent heat (92.0 J g-1), surpassing most previous studies. Furthermore, the corresponding woven cloth demonstrates satisfactory thermal-regulating performance, high solar-thermal conversion and storage efficiency (78.4-84.3%), and excellent long-term performance. In all, this work paves a new way to build advanced structures by assembling nanoparticles and polymers for functional composite fibers in advanced solar-energy-related applications.

Chitosan/copper sulfide nanoparticles (CS/CuSNPs) hybrid fibers with improved mechanical and photo-thermal conversion properties via tuning CuSNPs' morphological structures

Conventional textiles are inadequate for maintaining warmth in extremely cold conditions. Therefore, the development of photo-thermal fibers for personal thermal management textiles has emerged as an urgent need. Herein, novel chitosan/copper sulfide nanoparticles (CS/CuSNPs) hybrid fibers with photo-thermal function were fabricated successfully. Significantly, our study demonstrated that the tensile and photo-thermal conversation properties of the CS/CuSNPs hybrid fibers could be effectively regulated by altering the CuSNPs` morphological structures. Compared with other CuSNPs (tube-like, sphere-like, and flower-like), the plate-like CuSNPs with smooth surfaces and uniform nanometer size played a significant role by scattering incident light in the fibers as a secondary light source for CuSNPs absorbance. Thus, under IR light irradiation at a power density of 1.0 W/cm2, the surface temperature of CS/0.1 wt% plate-like CuSNPs hybrid fibers sharply increased by 27.6 °C, which was more than 4 times of the pure CS fibers. And the breaking strength and initial modulus of CS/0.1 wt% plate-like CuSNPs hybrid fibers increased by more than 18.37 and 6.88 % compared with the nascent CS fibers. This study develops a novel and effective strategy to tune the photo-thermal and tensile properties of CS hybrid fibers without incorporating more content or additives.

Collaboration of two-star nanomaterials: The applications of nanocellulose-based metal organic frameworks composites

Nanocellulose, as the star nanomaterial in carbohydrate polymers, has excellent mechanical properties, biodegradability, and easy chemical modification. However, further practical applications of nanocellulose are limited by their inadequate functionalization. Metal-organic frameworks (MOFs), as the star nanomaterial in functional polymers, have a large surface area, high porosity, and adjustable structure. The collaboration of nanocellulose and MOFs is a desirable strategy to make composites especially interesting for multifunctional and multi-field applications. What sparks will be produced by the collaboration of two-star nanomaterials? In this review article, we highlight an up-to-date overview of nanocellulose-based MOFs composites. The sewage treatment, gas separation, energy storage, and biomedical applications are mainly summarized. Finally, the challenges and research trends of nanocellulose-based MOFs composites are prospected. We hope this review may provide a valuable reference for the development and applications of carbohydrate polymer composites soon.

Biological Thermal Performance of Organic and Inorganic Aerogels as Patches for Photothermal Therapy

Aerogels are materials with unique properties, among which are low density and thermal conductivity. They are also known for their exquisite biocompatibility and biodegradability. All these features make them attractive for biomedical applications, such as their potential use in photothermal therapy (PTT). This technique is, yet, still associated with undesirable effects on surrounding tissues which emphasizes the need to minimize the exposure of healthy regions. One way to do so relies on the use of materials able to block the radiation and the heat generated. Aerogels might be potentially useful for this purpose by acting as insulators. Silica- and pectin-based aerogels are reported as the best inorganic and organic thermal insulators, respectively; thus, the aim of this work relies on assessing the possibility of using these materials as light and thermal insulators and delimiters for PTT. Silica- and pectin-based aerogels were prepared and fully characterized. The thermal protection efficacy of the aerogels when irradiated with a near-infrared laser was assessed using phantoms and ex vivo grafts. Lastly, safety was assessed in human volunteers. Both types presented good textural properties and safe profiles. Moreover, thermal activation unveils the better performance of silica-based aerogels, confirming the potential of this material for PTT.