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Study of the Optical Properties of Functionalized Gold Nanoparticles in Different Tissues and Their Correlation with the Temperature Increase

Mie theory explains the interaction of light with a gold nanoparticle (AuNP) through the absorption (abs), scattering (sca), and extinction (ext) cross sections. These parameters have been calculated in the case of AuNPs dispersed in homogeneous media, but not for specific tissues. The aim of this research was to theoretically obtain the optical cross sections (abs, sca, and ext) of functionalized AuNPs in liver and colon tissues through Mie theory and correlate them with the temperature increase observed experimentally in tissues containing AuNPs under plasmonic photothermal irradiation using a Nd-YAG laser ( = 532 nm). Calculations showed that abs represents 98.96 ± 0.03% of ext at 532 nm. The ext value for a functionalized AuNP in water was 365.66 nm2 (94% of the theoretical maximum value at 522.5 nm), 404.24 nm2 in colon (98% of the theoretical maximum value at 525 nm), and 442.39nm2 in liver (96% of the theoretical maximum value at 525 nm). Therefore, nanoparticles irradiated at 532nm are very close to their resonance value.These results correlated with the experimental irradiation of functionalized AuNPs in different tissues, where the average temperature increase showed the pattern liver > colon > water. The temperature increase observed (Δ up to 13∘C) is sufficient to produce cellular death.CATEDRAS-CONACYT-ININ-337 CONACYT-SEP-CB-2014-01-242443)

Theoretical and experimental characterization of emission and transmission spectra of Cerenkov radiation generated by 177Lu in tissue

Cerenkov radiation (CR) is the emission of UV-vis light generated by the de-excitation of the molecules in the medium, after being polarized by an excited particle traveling faster than the speed of light. When β particles travel through tissue with energies greater than 219 keV, CR occurs. Tissues possess a spectral optical window of 600 to 1100 nm. The CR within this range can be useful for quantitative preclinical studies using optical imaging and for the in-vivo evaluation of 177Lu-radiopharmaceuticals (β-particle emitters). The objective of our research was to determine the experimental emission light spectrum of 177Lu-CR and evaluate its transmission properties in tissue as well as the feasibility to applying CR imaging in the preclinical studies of 177Lu-radiopharmaceuticals. The theoretical and experimental characterizations of the emission and transmission spectra of 177Lu-CR in tissue, in the vis-NIR region (350 to 900 nm), were performed using Monte Carlo simulation and UV-vis spectroscopy. Mice 177Lu-CR images were acquired using a charge-coupled detector camera and were quantitatively analyzed. The results demonstrated good agreement between the theoretical and the experimental 177Lu-CR emission spectra. Preclinical CR imaging demonstrated that the biokinetics of 177Lu-radiopharmaceuticals in the main organs of mice can be acquiredThis study was supported by the Mexican National Council of Science and Technology (CONACYT) through the CATEDRAS-CONACYT-ININ-337 and CONACYT-SEP-CB- 2016-286753 projects. It was carried out as part of the activities of the “Laboratorio Nacional de Investigación y Desarrollo de Radiofármacos, CONACyT (LANIDER-CONACYT)” and the Red-Biofotónica, CONACYT. The financial support of the SIEA-UAEMex through the Grant No 4348/2017/CI is also acknowledged

Fluorescent, Plasmonic, and Radiotherapeutic Properties of the 177Lu–Dendrimer-AuNP–Folate–Bombesin Nanoprobe Located Inside Cancer Cells

The integration of fluorescence and plasmonic properties into one molecule is of importance in developing multifunctional imaging and therapy nanoprobes. The aim of this research was to evaluate the fluorescent properties and the plasmonic–photothermal, therapeutic, and radiotherapeutic potential of 177Lu–dendrimer conjugated to folate and bombesin with gold nanoparticles in the dendritic cavity (177Lu–DenAuNP–folate–bombesin) when it is internalized in T47D breast cancer cells. The intense near-Infrared (NIR) fluorescence emitted at 825 nm from the conjugate inside cells corroborated the usefulness of DenAuNP–folate–bombesin for optical imaging. After laser irradiation, the presence of the nanosystem in cells caused a significant increase in the temperature of the medium (46.8oC, compared to 39.1oC without DenAuNP–folate–bombesin, P < 0.05), resulting in a significant decrease in cell viability (down to 16.51% + 1.52%) due to the 177Lu–DenAuNP–folate–bombesin plasmonic properties. After treatment with 177Lu–DenAuNP–folate–bombesin, the T47D cell viability decreased 90% because of the radiation-absorbed dose (63.16 + 4.20 Gy) delivered inside the cells. The 177Lu–DenAuNP–folate–bombesin nanoprobe internalized in cancer cells exhibited properties suitable for optical imaging, plasmonic–photothermal therapy, and targeted radiotherapy.CONACYT-SEP-CB-2014-01-24244

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