engleski

Interaction of metallic nanoparticles with cysteine-rich proteins

Protein binding to nanoparticles (NPs) is one of the most important factors influencing biodistribution and biocompatibility of NPs, as well as pharmacokinetics and pharmacodynamics of nanodrugs [1-3]. Designing NPs to specifically adsorb certain proteins or to prevent adsorption of proteins is a potentially powerful tool in nanomedicine, which may enable delivery of NPs to specific locations in the body [1]. There have been numerous articles reviewing the importance of NPs interaction with plasma proteins, mainly albumin, apolipoproteins, fibrinogen and immunoglobulins [1-3, and references therein]. However, a deep understanding of how physicochemical properties of NPs affect their interaction with proteins is still missing. Particle surface properties, such as charge, hydrophobicity, and coating, are of particular interest for the elucidation of the nature of such nano-bio interfaces [1]. Among the most used and commercialized NPs, silver nanoparticles (AgNPs) take special place. Because Ag ion has high binding affinity for sulphur and thiols, Ag-thiol complexes can easily be formed in the biological environment [4]. Recently, sulfidation has been detected as an important environmental transformation of AgNPs [5]. Our study on cellular uptake of AgNPs in mammalian kidney cells has also showed that AgNPs interfere with cellular S-containing compounds such as metallothionein (MT) or glutathione (GSH) [6]. Moreover, our recent in vivo investigation showed significant change in MT level in liver and kidneys of Wistar rats exposed either chronically or acutely to different AgNPs [7]. Therefore, our investigation is focused on how the nature of the surface of AgNPs may control their interaction with cysteine-rich proteins. Our model system encompasses AgNPs with varying surface properties and MT, an important representative of cysteine-rich, metal-binding proteins. During investigation of biodistribution pattern of AgNPs in Wistar rats after acute exposure, we have observed that AgNPs with different surface coatings form differently shaped (i.e. cubic, triangular, hexagonal) agglomerates in different tissue fractions. Transmission electron microscopy (TEM) observation proved that these agglomerations consist of AgNPs bound to biomolecules. Employing the already developed method of size-exclusion chromatography (SEC) hyphenated to inductively coupled plasma mass spectrometry (ICPMS) [8], we have found Ag bound to different proteins depending on the type of tissue. Interaction of AgNPs with MT probably led to agglomerate structures eluted at retention times of bigger proteins. The isolation and identification of particle-associated proteins using nonperturbing methods that do not disrupt the protein–particle complex or induce additional protein binding is challenging. From a methodological point of view, coupling SEC to ICPMS looks promising to study NPs-protein interactions, with specific emphasis on the determination of the residence times of specific proteins on NPs. A comparison of chromatographic profiles of proteins eluting with and without NPs will allow the identification and exchange rates of NPs-protein interactions. Further development of the technique, using a wide range of column designs and other parameters, is expected to make the approach increasingly flexible and contribute significantly to our understanding of influence of NPs surface properties (charge and hydrophobicity) on the particle–protein corona using a model system of cysteine-rich proteins.

metallic nanoparticles; protein interaction; nanosafety

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