Detection of Therapeutic Levels of Ionizing Radiation Using Plasmonic Nanosensor Gels

Abstract

Radiotherapy is a highly complex and efficient treatment modality for ablation of malignant tumors. Despite several technological advances, determination of the dose delivered to the tumor remains a challenge due to limitations of complex fabrication, cumbersome operation, and high costs associated with current dosimeters. Here, we describe fundamental studies and development of a novel gel-based colorimetric nanosensor for detecting therapeutic levels of X-rays (1-10 Gy) administered in clinical radiotherapy. Following exposure to X-rays, gold salts in the gel were converted to nanoparticles within the matrix, resulting in the formation of a maroon-colored plasmonic gel. Differences in color intensity of the gel following irradiation were used as a quantitative indicator of the radiation dose employed. The gelbased nanosensor was able to detect doses as low as 0.5 Gy, and demonstrated a linear detection range of 0 -3 Gy, which indicates its application in the fractionated radiotherapy regime. The gel was also able to successfully report therapeutic levels of radiation doses administered to anthropomorphic tissue phantoms. The range of detection, ease of fabrication, simplicity of colorimetric detection, and relatively lower costs indicate that this technology can be potentially translated to different radiotherapy applications in the clinic.

Hydrogel Nanosensors for Colorimetric Detection and Dosimetry in Proton Beam Radiotherapy

“…protons) results in the formation of free radicals upon hydrolysis (water splitting), which, in turn, reduce the encapsulated gold ions to gold nanoparticles within the matrix (Figure 2.3.1.). 12,19 Agarose gel Initially, gold exists as trivalent Au(III) ions along with the cationic surfactant molecules within the heated agarose solution. These Au(III) metal ions are then reduced to monovalent Au(I) ions using ascorbic acid as the reducing agent.…”

“…aliphatic surfactants) to engender the formation of plasmonic (gold and gold-silver) nanoparticles from their respective metal ion formulations. 12,[18][19][20] The formation of plasmonic nanoparticles in liquid or gel formulations is accompanied by a visible color change which is distinct from the original metal ion formulation, which is colorless. Here, we report, for the first time, a colorimetric approach for the rapid detection of therapeutic levels (0-3 Gy RBE ) of proton irradiation.…”

Protein‐facilitated gold nanoparticle formation as indicators of ionizing radiation

“…Additionally, other configurations for this protein‐based radiation sensor will bring improvements in the function and ease of use of this system. Previous work has shown that gold nanoparticle‐based sensors can be incorporated into a gel, which allows the system to be applied to the surface of the patient rather than in solution, and allows measurement of dose in 3D (S. Inamdar et al, ) (Karthik Pushpavanam et al, ). The protein‐based sensors described here should be able to be extended into the gel system as well through conjugation of the protein to the gel matrix.…”

“…Recently, a gold‐alanine nanocomposite has been evaluated as a radiation dosimeter but the requirement of a sophisticated readout technique like electron paramagnetic resonance has prevented its clinical translation (Guidelli, Ramos, Zaniquelli, Nicolucci, & Baffa, ). To mitigate these concerns, a colorimetric sensor based on the formation of gold nanoparticles as a response to therapeutic levels of ionizing radiation was demonstrated (Sahil Inamdar et al, ; Pushpavanam et al, ). The intensity of color was proportional to the intensity of irradiation and was used as a measure of ionizing radiation.…”

Determination of topographical radiation dose profiles using gel nanosensors

“…We recently developed a colorimetric sensor in which ionizing radiation engenders the formation of gold nanoparticles from its corresponding colorless salt precursors ( 20 ). Formulation of a gel-based nanosensor facilitates easier handling and application in clinical radiotherapy ( 21 , 22 ). Here, we demonstrate the colorimetric visualization and quantification of spatial dose distribution profiles using a gel nanosensor.…”