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    Hydrolytic degradation of poly(lactic acid): Population balance modelling for simulating molecular weight distribution
    (2025-04-01)
    Limsukon, Wanwarang
    ;
    Rubino, Maria
    ;
    Rabnawaz, Muhammad
    ;
    Lim, Loong Tak
    ;
    Sakkaplangkul, Puttha
    Poly (lactic acid) (PLA) is one of the most promising biobased and biodegradable polymers able to replace several fossil-based plastics for packaging and other applications. However, PLA is susceptible to hydrolytic degradation, impacting its overall service performance and end-of-life. The molecular weight distribution (MWD) is a critical parameter that provides insights during hydrolytic degradation. In this study, we introduced a population balance model, utilizing the high-order moment-conserving method of classes, to describe the MWD during the hydrolytic degradation of amorphous PLA film at 45 °C and 65 °C and expanded to 85 °C. The phenomenological model provided hydrolysis constants that clarified noncatalytic and autocatalytic reaction mechanisms and information on specific chain scission of a particular length. Our predictions demonstrate a promising alignment in weight location and distribution shape with the experimental MWDs observed throughout the hydrolytic process of PLA. One notable advantage is the MWD simulation, conducted over an extended time frame. Furthermore, this predictive capability extends to forecasting the lifetime of PLA films at various temperatures within the tested range, thereby fostering insights into PLA hydrolysis applicable to real-life scenarios and supporting environmentally conscious degradation practices.
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    Sulphation and hydrolysis improvements of bioactivities, and immuno-modulatory properties of edible amanita hemibapha subspecies javanica (Corner and bas) mucilage polysaccharide as a potential in personalized functional foods
    (2021-10-01)
    Surayot, Utoomporn
    ;
    Wangtueai, Sutee
    ;
    You, Sangguan
    ;
    Techapun, Charin
    ;
    Phimolsiripol, Yuthana
    In this study, the mucilage polysaccharide (MP) from Amanita hemibapha subspecies javanica was prepared by hot water extraction and ethanol precipitation and then fractionated using anion-exchange chromatography equipped with a DEAE Sepharose fast flow column. The most immune-enhancing polysaccharide fraction 2 (MPF2) was subjected to a structural modification such as hydrolysis or over-sulphation. The sulphate and molecular weight (Mw) of over-sulphated (OS1-3) and hydrolysed (HS1-3) derivatives of MPF2 differed between 9.85% and 14.2% and 32.8 and 88.1 × 10<sup>3</sup> g/mol, respectively. Further, the immune-enhancing properties of MPF2 and its derivatives were tested on RAW264.7 and NK cells through various in vitro assays. Interestingly, a low molecular weight of HS1-3 significantly increased the nitric oxide (NO) production (p < 0.05) more than MPF2, indicating that Mw is a major factor in RAW264.7 cell stimulation. In addition, RAW264.7 cells produced various cytokines by up-regulating mRNA expression levels and the activation of nuclear factor kappa-B (NF-κB) and mitogen-activated protein kinase (MAPK) pathways. On the other hand, OS1-3-treated natural killer (NK) cells induced cytotoxicity in HepG2 cells through the expression of IFN-γ, Grandzyme-B, perforin, NKp30, and FasL. These results demonstrated that sulphate derivatives play an important role in NK cell activation. Further, this study also explores how polysaccharide binds to RAW264.7 and NK cells. MPF2 and HS3 may activate RAW264.7 cells via binding to TLR4 receptors, and OS2 could be activated through the CR3 signalling pathways.
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    Comparative study on liquefaction behaviors of xylan hemicellulose as treated by different hydrothermal methods
    (2020-02-01)
    Phaiboonsilpa, Natthanon
    ;
    Champreda, Verawat
    ;
    Laosiripojana, Navadol
    Liquefaction behaviors of xylan were studied as treated by six different hydrothermal methods. As a comparative study, a xylan sample isolated from corn core was subjected to hot-compressed water, hot-compressed 0.01 and 0.1wt% H<inf>2</inf>O<inf>2</inf> solutions under pressurization of N<inf>2</inf> or CO<inf>2</inf> at 110–250 °C for 0 min in 10-ml batch-type reactor. Not only xylose and xylo-oligosaccharides, but also arabinose, glucose, and acetic acid were recovered as hydrolyzed products. In addition, decomposition compounds, i.e. furans and organic acids were found. The highest xylose yield could be attained at 210 °C in all the studied hydrothermal methods, except for only 0.1wt% H<inf>2</inf>O<inf>2</inf> solution under pressurization of CO<inf>2</inf>. By this strongly oxidative condition, where peroxy carbonic acid was formed in situ, the temperature that xylose could be highly recovered was at 190 °C. The highest xylose yield of 61.62wt% was obtained by 0.01wt% H<inf>2</inf>O<inf>2</inf> solution under pressurization of N<inf>2</inf>. Formation of furan compounds showed a preference to the treatments with pressurized CO<inf>2</inf>, while organic acids had a better recovery when N<inf>2</inf> was applied. Different results in the production of various liquefied products could be attributed to the degree of hydrolysis and oxidation reactions which altered under the different hydrothermal methods.