Hydrolysis-dominated catalytic system: Hydrogen-free hydrogenolysis of lignin from Pd-MoOx/TiO2.

Lignin is continuously investigated by various techniques for valorization due to its high content of oxygen-containing functional groups. Catalytic systems employing hydrolysis­hydrogenolysis, leveraging the synergistic effect of redox metal sites and acid sites, exhibit efficient degradation of lignin. The predominance of either hydrolysis or hydrogenolysis reactions hinges upon the relative activity of acid and metal sites, as well as the intensity of the reductive atmosphere. In this study, the Pd-MoOx/TiO2 catalyst was found to primarily catalyze hydrolysis in the lignin depolymerization process, attributed to the abundance of moderate acidic sites on Pd and the redox-assisted catalysis of MoOx under inert conditions. After subjecting the reaction to 240 °C for 30 h, a yield of 48.22 wt% of total phenolic monomers, with 5.90 wt% consisting of diphenols, was achieved. Investigation into the conversion of 4-propylguaiacol (4-PG), a major depolymerized monomer of corncob lignin, revealed the production of ketone intermediates, a phenomenon closely linked to the unique properties of MoOx. Dehydrogenation of the propyl is a key step in initiating the reaction, and 4-PG could be almost completely transformed, accompanied by an over 97 % of 4-propylcatechol selectivity. This distinctive system lays a new theoretical groundwork for the eco-friendly valorization of lignin.

Sustainable synthesis of lignin-derived carbon dots with visible pH response for Fe3+ detection and bioimaging.

Synthesis of lignin-based carbon dots (LCDs) with high quantum yield (QY), stable fluorescence properties and biocompatibility has been a challenge. Here, we propose an improved two-step strategy for producing high-quality LCDs from enzymatic hydrolysis lignin (EHL). The p-aminobenzenesulfonic acid used in the strategy not only provides nitrogen and sulfur elements, but also tailors the disordered three-dimensional structure of EHL. The successful co-doping of N and S elements favors the reduction of the optical energy bandgap (Eg), resulting in a high QY of 45.05% for LCDs. The LCDs exhibited superior selectivity and sensitivity for Fe3+ with a limit of detection (LOD) of 0.15 µM when Fe3+ concentration was 50-500 µM. In addition, LCDs demonstrated significant fluorescence in HepG2 cells and HepG2 cells loaded with LCDs at a concentration of 80 µg/mL showed good viability, suggesting that they are suitable for in vivo applications. The luminescent centers of LCDs change during pH regulation and thus show a special visual response to pH changes, making them have great potential for detecting metabolism in living cells. This work provides a novel and low-cost method for fabricating sustainable fluorescent probes for chemical sensing and bioimaging.

Research Progress of Chitosan-based Multifunctional Nanoparticles in Cancer Targeted Therapy.

Conventional tumor therapeutic modalities, such as radiotherapy, chemotherapy, and surgery, involve low tumor inhibition efficiency, non-targeted drug delivery, and side effects. The development of novel and practical nano-drug delivery systems (DDSs) for targeted tumor therapy has become particularly important. Among various bioactive nanoparticles, chitosan is considered a suitable candidate for drug delivery due to its non-toxicity, good biocompatibility, and biodegradability. The amino and hydroxyl groups of chitosan endow it with the diverse function of chemical modification, thereby improving its physical and biological properties to meet the requirements of advanced biomedical applications. Therefore, it is necessary to review the property and applications of chitosan-based materials in biomedicine. In this review, the characteristics of chitosan related to its applications are first introduced, and then the preparation and modification of chitosan-based nanoparticles, including the function tailoring of chitosan-modified nanoparticles, are demonstrated and discussed. Finally, the opportunities and challenges of chitosan-based nanomaterials in this emerging field are proposed from the perspective of the rational and systematic design for the biomedicine field.

Lignin-to-chemicals: Application of catalytic hydrogenolysis of lignin to produce phenols and terephthalic acid via metal-based catalysts.

Lignin is the only renewable aromatic material in nature and contains a large number of oxygen-containing functional groups. High-value and green utilization of "lignin-to-chemicals" can be realized via using lignin to produce fine chemicals such as phenols and carboxylic acids, which can not only reduce the waste of lignin in the process of lignocellulosic biomass treatment, but gradually make the substitution of traditional fossil fuels come true. The hydrogenolysis process under catalysis of metal catalyst has high product selectivity and less impurity, which is suitable for the production of same type or single fine chemicals. Hydrogenolysis of lignin via metal catalysts to produce lignin oil, and further modification of functional groups (e.g. methoxyl, alkyl and hydroxyl group) of depolymerized monomers in the bio-oil to yeild phenols and terephthalic acid are reviewed, and catalytic mechanisms are briefly summarized in this paper. Finally, the problems of lignin catalytic conversion existing currently are investigated, and the future development of this field is also prospected.

Preparation and catalytic performance of biomass-based solid acid catalyst from Pennisetum sinense for cellulose hydrolysis.

As a kind of lignocellulosic biomass, Pennisetum sinense (P. sinense) is commonly used as animal feed, fertilizer or papermaking raw materials. Based on the high carbon content and renewability of P. sinense, we explored the possibility and feasibility of using it as catalyst matrix. The catalyst was produced by sulfonation of char obtained from the carbonization of P. sinense at 550 °C. The structure of the catalyst was characterized by SEM, BET, XRD, FT-IR, XPS and TGA, and its catalytic performance for the hydrolysis of cellulose was investigated in detail. The highest acidity of the catalyst was 3.79 mmol/g and the maximum glucose yield of 59.92% was achieved under optimized conditions. The catalyst also showed a promising reusability. The glucose yield was 53.01% after 5 cycles and as high as 55.92% when using the regenerated catalyst.

Comparison of the neurotoxicity associated with cobalt nanoparticles and cobalt chloride in Wistar rats.

Cobalt nanoparticles (CoNPs) have been widely used in industry given their physical, chemical and magnetic properties; however, CoNPs may cause neurological symptoms and diseases in human, yet their mechanisms of toxicity remain unknown. Here, we used male Wistar rats to investigate differences in the toxic effects associated with CoNPs and CoCl2. Upon exposure to CoCl2, and 96 nm or 123 nm CoNPs at the same concentration, the Co2+ content in CoCl2 group was significantly higher than that in either the CoNPs groups in brain tissues and blood, but lower in liver. Significant neural damage was observed in both hippocampus and cortex of the temporal lobe. Increase malondialdehyde (MDA) content and CASPASE 9 protein level were associated both with CoCl2 and CoNPs treatments, consistent with lipid perioxidation and apoptosis. Heme oxygenase-1 and (NF-E2) p45-related factor-2 protein levels were elevated in response to 96 nm CoNPs exposure. In PC12 cells, NRF2 downregulation led to reduced cell viability and increased apoptotic rate. In conclusion, both CoNPs and CoCl2 cause adverse neural effects, with nanoparticles showing greater neurotoxic potency. In addition, NRF2 protects neural cells from damage induced by CoCl2 and CoNPs by activating downstream antioxidant responses.

Efficient adsorption of methylene blue and lead ions in aqueous solutions by 5-sulfosalicylic acid modified lignin.

As a kind of biomass that exists widely in plants, lignin shows much diversity as a functional material. In order to improve the adsorption ability, lignin was chemically modified by 5-sulfosalicylic acid and then used to adsorb methylene blue (MB) and Pb2+ from aqueous solutions. The results showed that the 5-sulfosalicylic acid modified lignin exhibited a high adsorption ability for dyes or heavy metals. The maximum adsorption capacity of the adsorbent approached 83.2 mg/g for MB and 39.3 mg/g for Pb2+ with the adsorbent dosage of 5 g/L at pH 5.85 or 5.35 (corresponding to MB or Pb2+, respectively), initial adsorbate concentration of 200 mg/L, temperature of 318 K and contact time of 12 h. The adsorption kinetics and isotherm studies indicated that both the adsorption of MB and Pb2+ onto SSAL followed the pseudo-second-order model and Langmuir isotherm model. It means that the adsorption process fits the model of mono-layer adsorption and it was mainly chemical process and accompanied with surface adsorption. The proposed SSAL is low-cost, eco-friendly and highly efficient therefore a promising material for adsorptive removal of MB and Pb2+ from wastewater.

Liquefaction of lignin by polyethyleneglycol and glycerol.

Enzymatic hydrolysis lignin (EHL), isolated from the enzymatic hydrolysis residues of the biomass, was liquefied using the mixed solvents of polyethyleneglycol (PEG) and glycerol at the temperature of 130-170°C with sulfuric acid as a catalyst. The influences of liquefaction parameters, such as the molecular weight of PEG, mass ratio of sulfuric acid to EHL, liquefaction temperature and time, and mass ratio of liquid (liquefying cosolvent) to solid (EHL) on the residue content and hydroxyl number were discussed. The FT-IR spectrum result showed that the liquefaction product of EHL was polyether polyol. The hydroxyl number of the liquefaction product was 80-120 mgKOH/g higher than that of PEG.

Preparation and characterization of phenol-formaldehyde adhesives modified with enzymatic hydrolysis lignin.

Phenol-formaldehyde (PF) adhesives modified with enzymatic hydrolysis lignin (EHL) were synthesized by a one-step process. The phenol component of the PF adhesives was partially substituted by EHL extracted from the residues of cornstalks used to produce bio-ethanol. The EHL-PF adhesives were used to prepare plywoods by hot-pressing. The pH value, viscosity, solid content, free phenol content, free formaldehyde content and brominable substance content of EHL-PF resins were investigated. The bonding strengths of the plywoods were determined, and the influences of the replacement percentage of phenol by EHL (a) and the NaOH content (b) on the properties of the adhesives were investigated. The results showed that the performance of the modified adhesives and the plywoods glued with them almost met the Chinese National Standard (GB/T 14732-2006) for first grade plywood when 20 wt% of the phenol was replaced by EHL.