Synthesis and its biological activity of carboxymethyl hemicellulose p-hydroxybenzoate (P-CMHC).

Hemicellulose extracted from ecalyptus APMP pulping waste liquor and undergoes etherification modification to produce carboxymethyl hemicellulose (CMHC). Subsequently, CMHC undergoes esterification reaction with p-hydroxybenzoic acid to synthesize a novel polysaccharide-based preservative known as carboxymethyl hemicellulose p-hydroxybenzoate (P-CMHC). The synthesis conditions of P-CMHC were optimized using the response surface methodology, resulting in an optimal esterification condition that achieved a degree of substitution of 0.232. P-CMHC exhibits excellent antioxidant activity, including 2,2-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radical scavenging activities. Additionally, it demonstrates favorable hygroscopic and moisturizing properties. Thiazole blue (MTT) experiments evaluating cell proliferation rate indicate that P-CMHC possesses negligible cytotoxicity, making it a promising, safe, and healthy preservative. Consequently, it can be considered as a new material for applications in the fields of biomedicine, food, and cosmetics.

Carboxymethylation modification, characterization, antioxidant activity and anti-UVC ability of Sargassum fusiforme polysaccharide.

Taking the degree of substitution (DS) as the index, the carboxymethylation conditions of Sargassum fusiforme polysaccharide (SFP) were studied. According to the single factor experiment results, the optimum experimental conditions were obtained: sodium hydroxide concentration, 15% (20 mL); alkalization temperature, 50 °C; dosage of chloroacetic acid 1.5 g; etherification time, 2 h, and the Carboxymethyl Sargassum fusiforme polysaccharide (CSFP) with the highest DS (0.635) was obtained. And then, the physicochemical properties, structural information and bioactivity of SFP and CSFP were characterized. The SFP and CSFP were composed of four monosaccharides, with a small amount of protein, and their molecular weights to 780.2 kDa and 386.3 kDa respectively. The results of FTIR and NMR showed that the carboxymethyl was successfully grafted onto the C-4 and C-6 of sugar chain. The results of anti UVC experiment showed that SFP and CSFP had a certain negative effect on cell activity, and the degree of damage caused by UVC radiation was weakened, and the anti UVC performance of CSFP was better than that of SFP.

Carboxymethylation of polysaccharide isolated from Alkaline Peroxide Mechanical Pulping (APMP) waste liquor and its bioactivity.

In recent years, the biological activity of polysaccharides and their derivatives has been widely studied. However, in addition to the natural polysaccharides directly extracted from plants and animals, there are rich polysaccharides in the pulping waste liquor that have not been fully utilized. The extracted polysaccharide from eucalyptus Alkaline Peroxide Mechanical Pulping (APMP) waste liquor was used as a raw material. For the production of carboxymethyl polysaccharide, the effects of temperature (T), the amount of alkali (NaOH) and the amount of etherifying agent (ClCH2COOH) on the degree of substitution (DS) were investigated, the optimal preparation conditions are: reaction time 2 h, temperature 75 °C, and the molar ratio of polysaccharide, NaOH and ClCH2COOH is 1:1:2, the highest DS is 1.47; FT-IR, NMR and GPC were used to characterize the structure and Molecular weight, the results show that the polysaccharide of APMP waste liquor is rich in xylan, and it was proved that the carboxymethyl substitution was successful and the positions of the substituent group were determined. The characterization and biological activity research of xylan polysaccharide (XP) and carboxymethyl xylan polysaccharide (CMXP), such as antioxidation, moisture absorption/retention, bacteriostatic action and cytotoxicity were discussed. CMXP shows better effects compared with XP.

Synthesis and characterization of temperature/pH dual sensitive hemicellulose-based hydrogels from eucalyptus APMP waste liquor.

In this investigation, a variety of innovative temperature/pH-sensitive hydrogels consisting of hemicellulose (extracted from APMP waste liquor) and acrylic acid/acrylamide monomers were synthesized via free radical polymerization for water retention agents and controlled release. The results showed that the hydrogel polymer was chemically cross-linked and entangled to form a three-dimensional network structure, and the monomer successfully grafted on the hemicellulose chain. The content of crosslinkers and monomers had obvious effects on the swelling ratio of hydrogel. The sensitivity of the hydrogel was determined according to the change of the swelling ratio of the hydrogel under different temperature and pH conditions, combined with the chemical structure analysis of the hydrogel, and explain its sensitivity mechanism. Finally, after 6 days at 25 °C and pH 6, the swelled hydrogel still retained 79.46 % of the moisture, which proved that it has high water retention ability.

Effects of γ-Ray Irradiation on the Radial Structure Heterogeneity in Polyacrylonitrile Fibers during Thermal Stabilization.

The radial structural heterogeneity of thermally-stabilized polyacrylonitrile (PAN) fiber is considered to be a limiting factor affecting the mechanical properties of the resulting carbon fibers. In this study, we demonstrate that a low-dose (60 kGy) γ-ray irradiation pretreatment can effectively mitigate the radial structural heterogeneity of PAN fibers after thermal stabilization. The characterization results indicate that low-dose γ-ray irradiation only affects the physical structure of PAN through decreasing its crystalline size and crystallinity, rather than inducing chemical cross-linking and/or intramolecular cyclization. It is proposed that an increased amorphous region in PAN fibers prompted by low-dose γ-ray irradiation can facilitate oxygen diffusion from skin to core during stabilization, which results in the increased structural homogeneity of stabilized PAN fibers.