Human serum albumin as protecting agent of silver nanoparticles: role of the protein conformation and amine groups in the nanoparticle stabilization

• Published in: Journal of nanoparticle research : an interdisciplinary forum for nanoscale science and technology 2013, Vol.15 (1), p.1, Article 1374
• Main Authors: Alarcon, Emilio I., Bueno-Alejo, Carlos J., Noel, Christopher W., Stamplecoskie, Kevin G., Pacioni, Natalia L., Poblete, Horacio, Scaiano, J. C.
• Format: Article
• Language: English
• Subjects: Applied sciences; Characterization and Evaluation of Materials; Chemistry and Materials Science; Collective excitations (including excitons, polarons, plasmons and other charge-density excitations); Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronics; Exact sciences and technology; Growth from solutions; Inorganic Chemistry; Ions; Lasers; Light sources; Materials Science; Methods of crystal growth; physics of crystal growth; Nanocrystalline materials; Nanoparticles; Nanoscale materials and structures: fabrication and characterization; Nanotechnology; Optical Devices; Optics; Optoelectronic devices; Photochemicals; Photonics; Physical Chemistry; Physics; Protein denaturation; Research Paper; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Silver; Sodium chloride; Surface and interface electron states
• ISSN: 1388-0764; 1572-896X
• DOI: 10.1007/s11051-012-1374-7

Thermally denatured human serum albumin interacts with ~3.0 nm spherical AgNP enhancing the fluorescence of Trp-214 at large protein/nanoparticle ratios. However, using native HSA, no changes in the emission were observed. The observation is likely due to differences between native and denatured protein packing resulting from protein corona formation. We have also found that NH 2 blocking of the protein strongly affects the ability of the protein to protect AgNP from different salts/ions such as NaCl, PBS, Hank’s buffer, Tris–HCl, MES, and DMEM. Additionally, AgNP can be readily prepared in aqueous solutions by a photochemical approach employing HSA as an in situ protecting agent. The role of the protein in this case is beyond that of protecting agent; thus, Ag + ions and I-2959 complexation within the protein structure also affects the efficiency of AgNP formation. Blocking NH 2 in HSA modified the AgNP growth profile, surface plasmon band shape, and long-term stability suggesting that amine groups are directly involved in the formation and post-stabilization of AgNP. In particular, AgNP size and shape are extensively influenced by NH 2 blocking, leading primarily to cubes and plates with sizes around 5–15 nm; in contrast, spherical monodisperse 4.0 nm AgNP are observed for native HSA. The nanoparticles prepared by this protocol are non-toxic in primary cells and have remarkable antibacterial properties. Finally, surface plasmon excitation of native HSA@AgNP promoted loss of protein conformation in just 5 min, suggesting that plasmon heating causes protein denaturation using continuous light sources such as commercial LED.