Gold nanoparticles as biocompatible surface for lipase adsorption: Physical-chemical study of the "nano-bio" interface

As nanotechnology advances further, the developing of nanomaterials associated to biological components is increasing upward since the phenomena that occur in the “nano-bio” interface, are governed by driving forces of... [ view full abstract ]

As nanotechnology advances further, the developing of nanomaterials associated to biological components is increasing upward since the phenomena that occur in the “nano-bio” interface, are governed by driving forces of molecular and colloidal nature. The study of the interfacial interactions provides the understanding of the relationship between the materials structure. Also, the knowledge of their properties in different environments (for example, physiological media) is fundamental for the safe use of nanomaterials.
In this context, gold nanoparticles (AuNPs) are of great interest since they offer a biocompatible surface for proteins and enzymes. Also, associate to their enhanced stability and low toxicity, AuNPs are very attractive for biomedical and biotechnological applications. Structural changes in proteins caused by the interaction with diverse ligands can affect their catalytic properties. Therefore it is mandatory the investigation about the effect caused in the protein conformation and their properties due to the adsorption on the AuNPs surface.
Therefore, this work proposes the study of the interfacial interactions that occur in the adsorption of Candida antarctica type B (CALB) lipase on AuNPs surface and the impact in the catalytic activity. Two methodologies were analyzed: CALB added during the AuNPs synthesis (A-CALB/AuNP) and CALB added after the AuNPs synthesis (D-CALB/AuNP). In order to evidence this process, these systems were characterized by UV-Vis spectroscopy, transmission electron microscopy, zeta potential, dynamic light scattering, fluorescence spectrophotometry, circular dichroism and isothermal titration calorimetry. It was evidenced that changes in the conformation and catalytic properties of CALB depend on the AuNPs synthesis methodology. The main differences were attributed to the different sizes and shapes of the AuNPs obtained. Therefore, the presented work contributes to the understanding of surface interactions between CALB and AuNPs, providing useful information in the building-up of “nano-bio” interfaces.