Ionizing radiation, including X-rays and gamma rays, is useful in several medical, defense, space, and agricultural applications. However, uncontrolled ionizing radiation can lead to large scale disasters and damage to human health. Given the necessity to balance potential deleterious effects and widespread application, it is important to develop novel radiation-sensing methods in order to ensure safety and prevent accidents. We have recently developed a novel nanobiosensing approach in which we employed proteins for templating the formation of metal nanoparticles from colorless metal salts. This change from colorless metal salts to colored dispersions of nanoparticles in water is a simple and visual indicator of ionizing radiation. In the proposed research, we will carry out a fundamental study on how different amino acids and small peptides mediate nanoparticle formation in the presence of different doses of ionizing radiation. Both, experimental and mathematical modeling approaches will be employed to study this behavior.
Our preliminary results indicated that polypeptides are capable of templating plasmonic metal nanoparticles from colorless metal salts in presence of ionizing radiation (X-Rays). In the proposed research, we will carry out an extensive investigation into how each of the 20 natural amino acids template bimetallic gold-silver nanoparticles upon exposure to different doses of ionizing radiation. We will then investigate dipeptides (?minimal peptides?), in which an amino acid with activity for templating the formation of plasmonic nanoparticles is juxtaposed with an amino acid that can bind and stabilize the templated nanoparticles. In addition, pentapeptides in which the binding and templating amino acids are separated by a tri-glycine linker will also be investigated. Mathematical modeling will be employed in order to investigate how different amino acids and peptides, together with experimental physicochemical conditions influence the formation kinetics of bimetallic nanoparticles. Water radiolysis, metal ion reduction, and nanoparticle formation will be modeled, and effects of pH, scavenging agents, and templating biomolecules will be investigated. Experimental and modeling studies will be employed for molecular engineering and developing sequence-property relationships for polypeptide-based colorimetric nanobiosensors for ionizing radiation.
