Lignin–carbohydrate complexes (LCCs) have shown antioxidant ability to scavenge the individual free radicals in vitro, while little work has been carried out to show if the LCCs can efficiently scavenge the intracellular and endogenous reactive oxygen species (ROS), which are the multiple radicals derived from the reduction of molecular oxygen during the metabolism process. In this work, carbohydrate-rich LCCs from bamboo (LCCs–B-B) and poplar (LCCs–B-P) were isolated according to the classical method, and their antioxidant activities were evaluated by scavenging intracellular ROS in RAW 264.7 cells in vitro and endogenous ROS in zebrafish in vivo. Results from composition analysis show that both LCC preparations possess similar contents of carbohydrate (52.2% and 51.2%) and lignin (44.1% and 47.8%). However, NMR analysis revealed that the LCCs–B-B contain 16.1/100C9 LCCs linkages, higher than that in LCCs–B-P (12.3/100C9). Antioxidant assays indicated that LCCs–B-B exhibited better antioxidant activities for scavenging the individual free radicals. At the cellular and animal model levels, LCCs–B-B also outperformed the performance of LCCs–B-P in scavenging the endogenous ROS in H2O2-stimulated RAW 264.7 cells in vitro and zebrafish in vivo, which may be due to its better ability to prevent the reduction of antioxidant enzyme activity (superoxide dismutase and glutathione peroxidase) in oxidative stress.

The carbon quantum dot (CQD), a fluorescent carbon nanoparticle, has attracted considerable interest due to its photoluminescent property and promising applications in cell imaging and bioimaging. In this work, biocompatible, photostable, and sustainably sourced CQDs were synthesized from byproducts derived from a biorefinery process using one-pot hydrothermal treatment. The main components of byproducts were the degradation products (autohydrolyzate) of biomass pretreated by autohydrolysis. The as-synthesized CQDs had a size distribution from 2.0–6.0 nm and had high percentage of sp2 and sp3 carbon groups. The CQDs showed blue-green fluorescence with a quantum yield of ~13%, and the fluorescence behaviors were found to be stable with strong resistance to photobleaching and temperature change. In addition, it is found that the as-synthesized CQDs could be used for imaging of cells and tumors, which show potential applications in bioimaging and related fields such as phototherapy and imaging.

No abstract

Cellulose nanofibrils (CNF) is considered as an inexhaustible precursor to produce antibacterial materials, such as antibacterial hydrogel, antibacterial paper, and antibacterial film. However, the poor antimicrobial property of neat CNF required it should be coupled with an antibacterial ingredient. Herein, biocompatible Au nanoclusters (AuNCs) were synthesized and added into the CNF dispersion to prepare a novel antibacterial film (AuNCs@CNF film). The effects of addition of AuNCs with different amount on the morphology and physicochemical properties of AuNCs@CNF films were characterized using atomic force microscopy (AFM), scanning electron microscopy (SEM), X-ray diffraction (XRD), FTIR (Fourier-transform infrared), light transmittance spectra, and thermogravimetric analysis (TGA). The results showed that AuNCs did not affect the nano-structural features of the CNF film and its basic structures, but could greatly increase the hydrophilicity, the flexibility and the thermal stability of CNF film, which might improve its application in antimicrobial wound-healing dressing. The prepared AuNCs@CNF films demonstrated high antibacterial properties toward Escherichia coli (E. coli) and Streptococcus mutans (S. mutans) both in vitro and in vivo, which can prohibit their growths and promote the healing of bacteria-infected wound, respectively. Thus, the prepared AuNCs@CNF film with great antibacterial properties could be applicable in biomedical field.

Lignin nano-particles (LNPs) exhibit properties that distinguish them from the production of other lignin-based materials. However, little research has been performed to investigate whether porous carbons produced from LNPs exhibit a performance superior to those derived from untreated lignin. In this study, lignin was fabricated into LNPs and used to prepare high-performance porous carbons with enhanced thermal conductivities compared to that of carbons from neat lignin. Two different preparation protocols were employed: direct pyrolysis and hydrothermal carbonization followed by pyrolysis. Carbons obtained from 100 to 300 nm LNPs possessed more graphene-like structures than carbons from unaltered lignin. In addition, carbons prepared using a combination of hydrothermal carbonization and pyrolysis exhibited higher specific surface areas (108.81-220.75 m 2 /g) and total pore volumes (0.098-0.166 cm 3 /g) than those prepared via direct pyrolysis. In addition, LNP-derived carbons exhibited superior thermal conductivities (0.45 W/mK) and thermal conductivity rates (0.51 • C/s). This work provides the useful finding that superior graphene-like porous carbons can be produced by transforming lignin into LNP and then hydrothermally carbonizing the resulting material prior to pyrolysis.