漆酶改性对再生植物纤维微观结构影响的机理研究

The strength properties of recycled plant fiber treated by laccase or laccase/mediator system are improved, resulting in the effective suppression of quality decay of recycled plant fiber. The mechanism of change of microstructure of recycled plant fiber during laccase modification is typically unknown, which is a research difficult in fiber modification. The modified experiment of laccase with L-tryptophan methyl ester hydrochloride will first carried out in this study. The variation of the activity, stability and structure of laccase will be studied. This project intends to explore the impact of laccase and laccase/mediator system treatment on physical and chemical properties of recycled plant fiber. The changing rule of nano-structure、pore size and pore size distribution of recycled plant fiber during laccase treatment will be explored. The effect of laccase and laccase/histidine system treatment on cell wall structure of fiber will be explained. Subsequently, predominant characteristics of laccase and laccase/histidine system treatment on fiber supramolecular structure and chemical structure of recycled plant fiber will be shown through studying changes of key factors, including different forming cellulose content, crystallinity, crystal size, fibril size, fibril aggregate size, hydrogen model and content. Overall, The mechanism of the effect of laccase modification on the microstructure of recycled plant fiber will be presented. It will be able to provide strong scientific evidences in recycled plant fiber modification via laccase.

漆酶及漆酶介体体系处理再生植物纤维可提高纤维强度性能，从而有效抑制其品质衰变。目前关于漆酶对再生植物纤维微观结构影响机理是纤维改性方面研究难点。本项目首先开展L-色氨酸甲酯盐酸盐与漆酶反应的改性实验，研究漆酶在不同反应条件下活性、稳定性及结构的变化规律；继而拟从改性漆酶及改性漆酶/组氨酸介体体系处理对再生植物纤维物理及化学性能的影响出发，探索处理前后纤维细胞壁孔径大小及其分布、纳米级结构的变化规律，诠释改性漆酶及改性漆酶/组氨酸介体体系处理对纤维细胞壁结构的影响。最后，通过研究处理前后纤维不同形态的纤维素含量、结晶度、晶面尺寸、基原纤尺寸及聚合基原纤尺寸、氢键模式及含量等关键因子的变化，得到改性漆酶及改性漆酶/组氨酸介体体系处理对纤维超分子结构和化学结构的影响特性，进而揭示漆酶生物处理对再生植物纤维微观结构影响的机理。本研究为改性漆酶用于再生植物纤维生物改性提供强有力的科学依据。

漆酶及漆酶介体体系处理再生植物纤维可提高纤维强度性能，从而有效抑制其品质衰变。本项目首先开展了改性剂（L-色氨酸甲酯盐酸盐（L-TEM）、L-苯丙氨酸甲酯盐酸盐（L-PME）、二氧化硫脲（TDO）、乙酸甲脒）与漆酶反应的改性实验，研究了漆酶在不同反应条件下活性、稳定性及结构的变化规律。与控制样相比，改性后漆酶活性和稳定性可提高209%和56.9%； L-PME改性漆酶的二级结构β-折叠含量和无规则卷曲都减少，α-螺旋含量增加，β-转角含量基本不变，改性后漆酶仍保持了未改性漆酶的紧密疏水结构。继而研究了改性漆酶及改性漆酶/介体体系处理对再生植物纤维物理、化学性能及纤维微观结构的影响。与加入相同量的未改性漆酶相比，加入L-PME改性漆酶OCC浆纤维所抄造纸页的抗张强度提高了12.2%。因此使用改性漆酶对OCC浆进行改性处理，不但可以提高纸页的物理强度性能，而且可以减少漆酶使用量。与对照样相比，未改性漆酶/组氨酸和改性漆酶/组氨酸处理后的OCC浆羧基含量分别增加了25%和31%。相比空白样，漆酶/组氨酸处理后OCC浆纤维结晶度和横截面积分别下降了6.7%和6.2%，分子间氢键O(6)H…O(3')含量增加了17.9%，而分子内氢键O(2)H…O(6) 和O(3)H…O(5)含量分别下降了57.4%和20.6%。与空白样相比，L-PME改性漆酶/组氨酸处理后OCC纤维结晶纤维素的相对比例下降了36.4%，而次晶纤维素的相对比例仅下降了1.2%。可知，漆酶/氨基酸处理对OCC纤维结晶纤维素影响较大。与空白样相比，L-PME改性漆酶/谷氨酸和L-PME改性漆酶/组氨酸体系生物处理后，纤维平均孔径分别增加36.3%和13.8%，BET比表面积分别增加27.4%和17.9%。本项目研究结果为改性漆酶用于再生植物纤维生物改性提供了强有力的科学依据。