# Gold Nanoparticles and Nanorods in Nuclear Medicine: A Mini Review
## 3 In Vitro Evaluation of Radionuclides Delivered by AuNPs and AuNRs
Another important aspect of the AuNPs and AuNRs used in nuclear medicine and which need careful in vitro evaluation is their uptake inside the cell, because this key point may also depend on the cell type under consideration. In effect, the uptake of \({}^{198}\)AuNPs in HepG2 cells and in Madin-Darby canine kidney (MDCK) has shown a dose-dependent internalization in both cell lines, but with a different trend. Moreover, the uptake in HepG2 cells is higher compared to uptake in MDCK cells [129]. The uptake of \({}^{68}\)Ga-AuNPs with bombesin (BBN) and the Lys-urea-Glu motif (LUG), which binds the gastrin-releasing peptide receptor (GRPR) and the prostate-specific membrane antigen (PSMA) in PC3, A431, and LNCaP cells, is evaluated. Figure 8 shows these obtained results. [130]. Figure 7: In vitro single-photon emission computed tomography (SPECT) images of glioma C6 cells treated with (**a**) \({}^{131}\)I–Au polyethyleneimine-entrapped gold nanoparticles (PE–NPs) and (**b**) \({}^{131}\)I–Au. PENPs–chlorotoxin (CTX) for 4 h at the radioactive concentrations of 25 \(\upmu\)Ci/mL, 50 \(\upmu\)Ci/mL, 100 \(\upmu\)Ci/mL, 200 \(\upmu\)Ci/mL, and 400 \(\upmu\)Ci/mL, respectively, and (**c**) their relative SPECT signal intensities. Adapted with permission of [127]. The cellular in vitro uptake of \({}^{131}\)I-AuNRs conjugated with cyclic RGD (namely, a peptide targeting a cell adhesion molecule integrin \(\alpha_{\rm v}\beta_{3}\)) in B16F10 mouse malignant melanoma cells (positive for integrin \(\alpha_{\rm v}\beta_{3}\)) and MCF-7 human breast cancer cells (negative for integrin \(\alpha_{\rm v}\beta_{3}\)) has been studied. The result shows a strong uptake in the first ones compared to the last ones, and this confirms that the internalization occurs through receptor-mediated endocytosis [91]. Also, the uptake of AuNPs (\(\mathcal{O}=56.37\pm 3.04\) nm) and AuNRs (\(22.41\pm 1.01\) nm in diameter and \(56.12\pm 3.22\) nm in length) labeled with \({}^{125}\)I and with addition of \(\alpha_{\rm v}\beta_{3}\) integrin-targeted and cisplatin has been evaluated in H1299 cells. The results show a high cell uptake of the AuNRs with respect to AuNPs, indicating that the shape could influence the uptake into cells. Furthermore, the study shows a greater therapeutic efficacy of NRs compared to NPs assessed in terms of cell viability in vitro and the \(\gamma\)-H2 AX induction ex vivo, which is probably due to their rapid spread in the tumor interstitial [131]. The uptake of AuNPs labeled with \({}^{99m}\)Tc-TOC and conjugated to either Lys3-BBN, cyclo [Arg-Gly-Asp-D-Phe-Lys-(Cys)] (c[RGDfK(C)]) or thiol-mannose, in \(\alpha_{\rm v}\beta_{3}\) receptor-positive C6 glioma cancer cells, GRP-r-positive PC3 cancer cells, or mannose receptor-positive rat liver cells, has been evaluated in order to verify the specific target recognition. In all cases, the uptake of radiopharmaceutical \({}^{99m}\)Tc-AuNP conjugated with Lys3-BBN or c[RGDfK(C)] or mannose, has been significantly higher with respect to \({}^{99m}\)Tc-AuNP only [87].