title: Generation of polypeptide-templated gold nanoparticles using ionizing radiation.
abstract: Ionizing radiation, including γ rays and X-rays, are high-energy electromagnetic radiation with diverse applications in nuclear energy, astrophysics, and medicine. In this work, we describe the use of ionizing radiation and cysteine-containing elastin-like polypeptides (C(n)ELPs, where n = 2 or 12 cysteines in the polypeptide sequence) for the generation of gold nanoparticles. In the presence of C(n)ELPs, ionizing radiation doses higher than 175 Gy resulted in the formation of maroon-colored gold nanoparticle dispersions, with maximal absorbance at 520 nm, from colorless metal salts. Visible color changes were not observed in any of the control systems, indicating that ionizing radiation, gold salt solution, and C(n)ELPs were all required for nanoparticle formation. The hydrodynamic diameters of nanoparticles, determined using dynamic light scattering, were in the range of 80-150 nm, while TEM imaging indicated the formation of gold cores 10-20 nm in diameter. Interestingly, C2ELPs formed 1-2 nm diameter gold nanoparticles in the absence of radiation. Our results describe a facile method of nanoparticle formation in which nanoparticle size can be tailored based on radiation dose and C(n)ELP type. Further improvements in these polypeptide-based systems can lead to colorimetric detection of ionizing radiation in a variety of applications.
authors.affiliation: School of Biological and Health Systems Engineering, Arizona State University, Tempe, Arizona 85287, United States.
authors.forename: Candace Rae
authors.initials: CR
authors.lastname: Walker
authors.forename: Karthik
authors.initials: K
authors.lastname: Pushpavanam
authors.forename: Divya Geetha
authors.initials: DG
authors.lastname: Nair
authors.forename: Thrimoorthy
authors.initials: T
authors.lastname: Potta
authors.forename: Caesario
authors.initials: C
authors.lastname: Sutiyoso
authors.forename: Vikram D
authors.initials: VD
authors.lastname: Kodibagkar
authors.forename: Stephen
authors.initials: S
authors.lastname: Sapareto
authors.forename: John
authors.initials: J
authors.lastname: Chang
authors.forename: Kaushal
authors.initials: K
authors.lastname: Rege
mesh_terms: D019840:2-Propanol / Q000737:chemistry; D000096:Acetone / Q000737:chemistry; D005720:Gamma Rays; D006046:Gold / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry*; D011839:Radiation, Ionizing; D013499:Surface Properties; D014965:X-Rays
chemical_list: D010455:Peptides; D000096:Acetone; D006046:Gold; D019840:2-Propanol