Abstract Many studies describe the advantages of using hydrophobic particles on lipase immobilisation. However, many of these works neglect the effect of other variables of the supports, such as specific area and porosity, on the biocatalyst performance, and do not evaluate the influence of the hydrophobicity level of the particles on the biocatalysts’ activity as a single variable. Thus, the focus of the present work was to evaluate the effect of the hydrophobicity degree of polymeric particles on the biocatalysts’ activities, mitigating the influence of other variables. The study was divided into two steps. Firstly, distinct particles, exhibiting different composition and hydrophobicity levels, were used for the immobilization of a commercial lipase B from Candida antarctica (CAL-B). Then, distinct core-shell polymeric particles presenting different functional compounds on the surface were produced, using as comonomers styrene, divinylbenzene, 1-octene, vinylbenzoate and cardanol. Such particles were subsequently used for CAL-B immobilisation and the performance of the biocatalysts was evaluated on hydrolysis (using p-nitrophenyl laurate, as substrate) and esterification (using ethanol and oleic acid, as substrate) reactions. Based on the screening step, it was observed that for non-porous particles the correlation coefficients between the hydrophobicity level of the supports and the biocatalysts performance, for both hydrolysis and esterification reactions, were very low (0.32 and 0.45, respectively). It highlights that there was no significant correlation between these variables and that, probably, the chemical composition of the polymeric chains affects more significantly the biocatalyst performance. Then, analysing the subsequent stage, it was observed that small changes in the surface composition of the core-shell particles result in significant changes on the textural properties of the supports (specific area ranging from 1.2 m2.g−1 to 18.3 m2.g−1; and contact angles ranging from 71° (hydrophilic particles) to 92° (hydrophobic supports) when polymer films were put in contact with water). Such particles were also employed on CAL-B immobilization and it was noticed that higher correlation coefficients were achieved for hydrolysis (ρ = 0.53) and esterification (ρ = 0.74) reactions. Therefore, it is shown that the hydrophobicity degree of such supports starts to affect more effectively the biocatalysts performance when other textural features of the supports become more significant, such as specific area and porosity.

中文翻译：

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聚合物颗粒疏水度对脂肪酶固定化和生物催化剂性能的影响

摘要 许多研究描述了使用疏水性颗粒固定脂肪酶的优势。然而，这些工作中的许多工作忽略了载体的其他变量，例如比表面积和孔隙率，对生物催化剂性能的影响，并且没有将颗粒的疏水性水平对生物催化剂活性的影响作为单一变量进行评估。 . 因此，目前工作的重点是评估聚合物颗粒的疏水度对生物催化剂活性的影响，减轻其他变量的影响。研究分为两个步骤。首先，表现出不同组成和疏水性水平的不同颗粒用于固定来自南极念珠菌 (CAL-B) 的商业脂肪酶 B。然后，使用苯乙烯、二乙烯基苯、1-辛烯、苯甲酸乙烯酯和腰果酚作为共聚单体，制备了在表面上呈现不同功能化合物的不同核壳聚合物颗粒。随后将此类颗粒用于 CAL-B 固定，并通过水解（使用对硝基苯基月桂酸酯作为底物）和酯化（使用乙醇和油酸作为底物）反应评估生物催化剂的性能。基于筛选步骤，观察到对于无孔颗粒，对于水解和酯化反应，载体的疏水性水平与生物催化剂性能之间的相关系数非常低（分别为 0.32 和 0.45）。它强调了这些变量之间没有显着相关性，并且可能，聚合物链的化学组成对生物催化剂性能的影响更为显着。然后，分析后续阶段，观察到核壳颗粒表面组成的微小变化会导致载体的质地特性发生显着变化（比面积从 1.2 m2.g-1 到 18.3 m2.g -1；当聚合物薄膜与水接触时，接触角范围从 71°（亲水性颗粒）到 92°（疏水性载体）。此类颗粒也用于 CAL-B 固定，并注意到水解 (ρ = 0.53) 和酯化 (ρ = 0.74) 反应实现了更高的相关系数。所以，