Immobilized Lipase on Gold Mesoflower (Au-MFs): As a Reusable and Efficient Biocatalyst

Enzymes are a kind of biocatalyst with high-performance under mild conditions. However, a free enzyme is difficult to separate from the reaction system, leading to low economic efficiency [1]. Nowadays, lipases are widely applied as biocatalysts to pharmaceuticals, cosmetic, textiles, and food industries. However, one of the main drawbacks for industrial application of lipases is their instability at high temperature and in strong polar organic solvents [2-4].Lipases (EC 3.1.1.3) have a great value as catalysts in organic synthesis. Chemists exploit their proprieties on a wide range of reactions using natural and synthetic substrates. Classifying lipases by chemical functional information, such as substrate selectivity, is particularly relevant to the practical application of enzymes, which is an important topic students will meet again in later courses.To date, a variety of materials have been explored as carriers or supports for immobilizing lipase, such as polymers, mesoporous and nanoscale materials, etc. In general, there are five strategies for realizing the immobilization of enzymes: adsorption, entrapment, ionic interaction, covalent binding, and cross-linking [5-10].One of the most economical immobilization methods is covalent attachment of an enzyme onto a support. The covalent binding is normally formed between functional groups of a support matrix and amino acid residues on the enzyme surface. There are a wide variety of methods for covalent immobilization of enzymes on different supports. Selection of a suitable technique depends on the relative importance of some factors such as selectivity, loading capacity, immobilization time and activity/stability of the resulting preparation.Gold mesoflowers (Au-MFs) are a new class of meso/nanoscale object developed recently. These mesoflowers (MFs) have unique and highly anisotropic morphology, and it is possible to synthesize them in high yield.Immobilized lipases are exploited in array of commercial biocatalysis applications, as fixed enzyme protocols have been demonstrated to yield high quality products at reduced processing costs with easy catalyst recovery.In this research we report simple, rapid and efficient covalent strategy for the site-specific immobilization of lipase onto Au-MF and its excellent catalytic activity in the hydrolysis of p-nitrophenylpalmitate (pNPP). The obtained biocatalyst was characterized by UV/Vis, Fourier-transform infrared spectra (FT-IR), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) and acceptable data and good results were obtained.

Keywords:

Biocatalyst , Enzyme immobilization , Gold mesoflower nanostructure , Reusability