| 1. |
- Liu, Jinrong, 1995-, et al.
(författare)
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Ag-lignin hybrid nanoparticles for high-performance solar absorption in photothermal antibacterial chitosan films
- 2023
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Ingår i: iScience. - 2589-0042. ; 26:10
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Tidskriftsartikel (refereegranskat)abstract
- There is an urgent need for antimicrobial films based on sustainable resources and production methods. In this study, we present a bio-based nanocomposite film composed of chitosan (∼60 wt %), lignin nanoparticles (LNPs, ∼40 wt %), a small amount of glutaraldehyde (1.5 wt %), and a trace level of silver nanoparticles (AgNPs, 0.072 wt %). The uniform dispersion with LNPs prevented aggregation of metallic silver, resulting in small (diameter 3.3 nm) AgNPs. The nanocomposite film absorbs 89% of radiation across the entire solar spectrum and exhibits a remarkable photothermally triggered antibacterial effect, which is further enhanced by the dark color of lignin. Under simulated solar light illumination, the nanocomposite films demonstrated a significant reduction in viable Escherichia coli count compared to control scenarios. The potential applications of these nanocomposites extend to sunlight-activated antimicrobial films and coatings, addressing the growing demand for sustainable and effective antimicrobial materials.
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| 2. |
- Liu, Jinrong, 1995-, et al.
(författare)
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High-yield production of lignin photonic crystals with ethanol and water
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Structural colors in nature have inspired research into engineered photonic materials starting from renewable resources such as lignin extracted from wood and agricultural residues. A notable obstacle in developing lignin-based photonic crystals lies in the use of hazardous organic solvents, giving rise to safety and environmental concerns. Additionally, low product yields hinder scalable production of lignin photonics. Here, we report a highly efficient method for the fabrication of colloidal lignin particles of predicable size for producing photonic crystals using ethanol and water as the sole solvents. We achieved a 78% mass yield of photonic crystals starting from a crude soda lignin, resulting in vibrant colors spanning the entire visible spectrum. Controlling the particle size can be achieved by varying the dilution rate of a lignin ethanol solution with water, enabling the direct generation of colloidal crystals of preferred colors. The new method paves the way for large-scale development of lignin photonics.
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| 3. |
- Liu, Jinrong, 1995-
(författare)
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Lignin nanoparticles for photonic crystals and photothermal films
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The development of sustainable materials from biobased resources is essential due to environmental concerns posed by fossil-based materials. Lignin is a chemically complex biopolymer that exists in woody tissues of vascular plants. Lignin has many useful properties such as antioxidant activity, thermal stability, UV-absorbance, rigidity and so on. However, an inherent challenge of lignin relates to its complex molecular structures and poor solubility in water and common solvents. One strategy to utilize lignin is to fabricate lignin nanoparticles (LNP) that produce colloidally stable dispersions in water. This thesis aims to develop LNP-based materials which can be used in photonic crystals and photothermal films towards energy-efficient functional materials.The first part of the thesis focused on elucidation of the phenomena occurring during centrifugation-assisted assembly of LNP-photonic crystal (L-PC). L-PC with rainbow coloration or separate colors were produced by controlling the polydispersity index (PDI), particle size (150 to 240 nm), and assembly of LNPs. In a follow-up work, an improved method was developed to increase the yield of L-PCs. The effects of factors such as initial lignin concentration, and dilution time on the particle size and PDI of formed LNPs were studied. Empirical models were established to predict the size of LNPs and successfully used to control the resulting color of L-PCs. Moreover, the nanostructure of L-PCs was investigated. To harness lignin’s ability to absorb solar energy (light wavelength: 250–2500 nm), LNP-based composite films and coatings with photothermal performance were developed in the second part of the thesis. LNP-chitosan films and coatings were prepared and applied to indoor heat management. The LNPs content was adjusted from 10 to 40 wt%. By incorporating LNPs, the mechanical strength and photothermal properties of the films were improved compared to the pure chitosan film. Moreover, LNP-silver-chitosan (CC-Ag@LNP) films were prepared by using LNPs as a reducing agent. Silver ions were reduced on the surface of LNPs with UV-light assistance, and the hybrid nanoparticles were used to prepare films by casting. The CC-Ag@LNP films exhibited improved wet-strength and exhibited antibacterial performance against Escherichia coli (sterilization effect > 99.9%).Overall, this thesis contributes to both the fundamental insight in lignin aggregation to colloidal particles and showcases ways to control their assembly and incorporation into macroscopic materials with added functionality.
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| 4. |
- Liu, Jinrong, 1995-, et al.
(författare)
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Photonic crystals with rainbow colors by centrifugation-assisted assembly of colloidal lignin nanoparticles
- 2023
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Ingår i: Nature Communications. - 2041-1723. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- Photonic crystals are optical materials that are often fabricated by assembly of particles into periodically arranged structures. However, assembly of lignin nanoparticles has been limited due to lacking methods and incomplete understanding of the interparticle forces and packing mechanisms. Here we show a centrifugation-assisted fabrication of photonic crystals with rainbow structural colors emitted from the structure covering the entire visible spectrum. Our results show that centrifugation is crucial for the formation of lignin photonic crystals, because assembly of lignin nanoparticles without centrifugation assistance leads to the formation of stripe patterns rather than photonic crystals. We further prove that the functions of centrifugation are to classify lignin nanoparticles according to their particle size and produce monodispersed particle layers that display gradient colors from red to violet. The different layers of lignin nanoparticles were assembled in a way that created semi-closed packing structures, which gave rise to coherent scattering. The diameter of the lignin nanoparticles in each color layer is smaller than that predicted by a modified Bragg’s equation. In situ optical microscope images provided additional evidence on the importance of dynamic rearrangement of lignin nanoparticles during their assembly into semi-closed packing structures. The preparation of lignin nanoparticles combined with the methodology for their classification and assembly pave the way for sustainable photonic crystals.
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