Nanoencapsulation and release study of enzymes from Alkanivorax borkumensis in chitosan-tripolyphosphate formulation
The crude alkane hydroxylase and lipase enzymes from the hydrocarbonoclastic bacterium, Alcanivorax borkumensis were entrapped into chitosan nanoparticles (CSNPs) by ionotropic gelation method. For an optimal loading efficiency, enzyme-chitosan/tripolyphosphate (ENZ-CS/TPP) ratio was investigated. Fourier transform infrared spectra and morphology by scanning electron microscopy were used to explore and confirm alkane hydroxylase and lipase loaded into CSNPs. Seven consecutive ratios were investigated. Entrapment efficiency increased by increasing the ratio enzyme-chitosan/TPP. The optimal ratio with the best entrapment efficiency that was maintained for both alkane hydroxylase and lipase was 5:1. Particle size and zeta potential of the optimal ENZ-CSNPs was 473 nm and +21.8, respectively. Entrapment efficiency for alkane hydroxylase loaded CSNPs and lipase loaded CSNPs was 58.37% and 67.14%, respectively.
The immobilized alkane hydroxylase and lipase exhibited more than two folds increase in vitro half-life in comparison with the free enzymes maintaining around 70% of initial activity after 5 days. This study leads to a better understanding of how to prepare CSNPs, how to achieve high encapsulation efficiency and how to prolong the release of enzymes from CSNPs.
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