Synthesis of core/shell gold/albumin nanoparticles by crosslinking radio-induced for theranostic applications

BEATRIZ PATRICIO CARVALHO; CONSTANZA Y. FLORES; MARIANO GRASSELLI; GILBERTO WEISMULLER

La Plata

Workshop; Imaging Techniques for Biotechnology and Biomedical Applications -Workshop-; 2016

Facultad de Ciencias Exactas UNLP

Synthesis of core/shell gold/albumin nanoparticles by crosslinking radio-induced for theranostic applicationsConstanza Y. Flores1, Beatriz Patricio Carvalho2, Estefania Achilli1, Gilberto Weismuller2, Mariano Grasselli1 1Laboratorio de Materiales Biotecnológicos, UNQ-IMBICE, Roque Sáenz Peña 352, Bernal, Bs. As., Argentina2Laboratório de Física Biológica, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rua Hélio de Almeida 75-Rio de Janeiro, Brazil constanzaflores@hotmail.comFunctionalization of gold nanoparticles (AuNPs) with different molecules has been provided to targeting, stability and biocompatibility in vivo and vitro. There is a wide range of molecules available that may also act as therapeutic agents (e.g., proteins, RNA, DNA, peptides and antibodies) or to reduce NPs? immunogenicity (e.g., PEG and BSA). In last years, AuNPs have proved to be useful in therapy, imaging and delivery applications (Boisselier et al., 2009; Ghosh et al., 2007; Janib et al., 2010). Besides, the gold is also presented as the isotope 198Au that are used as material for NPs preparation to generate radioactive nanomaterials, which can emit beta and gamma rays by imaging therapy. Those characteristics will allow generating nanomaterials as platform for therapy and diagnoses, or combination of both, called theranostic nanomaterials. Recently, our working group described the formation of BSA NPs from radiation-induced crosslinking with 60Co gamma rays in an ethanol solution of Albumin (Soto Espinosa et al., 2012). It is important to note that the size of the NPs obtained depends essentially on the initial concentration of solvent added. These NPs retain a large percentage dimensional structure of proteins that comprise it. The aim of this work is to prepare and characterize AuNPs coated with human serum albumin (HSA) and bovine serum albumin (BSA) multilayers by a novel radiation-induced crosslinkg method without any agent. These core/shell NPs are capable to maintain the functional properties of proteins and optical properties of AuNPs. We proposed a method that consists in the addition of AuNPs in the reaction media of radiosynthesis without any agent crosslinking (e.g glutaldehide). The core/shell Au/Albumins NPs are performed in two steps. First, AuNPs were prepared by chemical reduction of Au salt in aqueous medium. Then, AuNPs were pre-treated with albumin solution in different concentrations to perform extensive shell of protein and followed by cold ethanol to induce the aggregation. The water/ethanol suspension containing Alb and AuNPs were irradiated at 10 kGy dose under oxygen free atmosphere (PISI ? CNEA).The Au/Alb NPs were prepared with different concentrations of albumin (0, 5, 10, 20 and 30 mg/mL protein).The nanostructures were characterized by UV-visible and infrared spectroscopy, transmission electron microscopy (TEM), dynamic light scattering (DLS) and atomic force microscopy (AFM). In the UV-visible spectrum of NPs prepared was showed surface plasmon peak at about 534 nm, demonstrating the presence of AuNPs. When compared to the spectrum of naked AuNPs, a slight shift of the wavelength was observed and slight increase in the intensity absorbance demonstrated the presence of albumin. By DLS, it was found a new peak with an average diameter of about 60 nm. Moreover, TEM images showed that the NPs have spherical shape and the presence of a low-density halo around the metal core, confirming the presence of albumin. In the FT-IR spectrum Au/Alb NPs, was not found loss of the secondary protein structure in the presence of Au. Subsequently, the stability of Au/Alb NPs in different buffers and cell media were assessed. These NPs were stable at different conditions. AFM images were obtained by Peak Force QNM microscopy. This technique were provide high-resolution mapping of mechanical properties as adhesion, modulus, deformation and dissipation. AFM images of topography were showed spherical shape and size similar than to obtained in DLS (Figure 1a). Futhermore, we were capable to obtain several mapping of mechanical properties of nanostructures (Figure 1 b, c and d). Those maps show that materials are presented heterogenic surfaces. In conclusion, Au/Albumin NPs have been prepared by a novel cross-linking technique, besides characterized by several spectroscopic and microscopy techniques. In addition, NPs showed a core / shell composition with low aggregation.