Folic Acid-Conjugated Albumin-Stabilized Gold–Terbium Nanoparticles for SPCCT/MRI Imaging: An in vitro Cellular and Phantom Study

Yusuf O Ibrahim,1,2 Nabil Maalej,1,2 Aamir Younis Raja,1 Ahsanulhaq Qurashi,3,4 Mohamed Rahmani,5,6 Osama Abdullah,7 Fazila Sirajudeen,5 Rasha Nasser,8 Charalampos Pitsalidis,1,9 Mira Mousa6,101Department of Physics, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates; 2Functional Biomaterials Group, Khalifa University of Science and Technology, Abu Dhabi, Emirate of Abu Dhabi, United Arab Emirates; 3Department of Chemistry, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates; 4Center for Catalysis and Separations, Khalifa University, Abu Dhabi, United Arab Emirates; 5Department of Biological Sciences, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates; 6Center for Biotechnology, Khalifa University, Abu Dhabi, United Arab Emirates; 7Core Technology Platform Operations, New York University, Abu Dhabi, United Arab Emirates; 8Department of Biomedical Engineering and Biotechnology, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates; 9Advanced Research and Innovation Center (ARIC) Khalifa University, Abu Dhabi, United Arab Emirates; 10Department of Public Health and Epidemiology, Khalifa University, Abu Dhabi, United Arab EmiratesCorrespondence: Yusuf O Ibrahim; Nabil Maalej, Email [email protected]; [email protected]: Triple-negative breast cancer (TNBC) remains challenging to image because of its biological heterogeneity and the limitations of single-modality imaging. Multifunctional nanoparticles may provide complementary contrast for spectral photon-counting CT (SPCCT) and MRI, potentially improving multimodal tumor imaging.Methods: Folic acid-conjugated, albumin-stabilized gold-terbium nanoparticles (BSA@Au/Tb-FA) were synthesized and characterized using TEM, XRD, FTIR, XPS, and DLS. In vitro cellular uptake, cytotoxicity, and hemocompatibility were evaluated using MDA-MB-231 cells using confocal microscopy and flow cytometry. SPCCT and MRI performance were assessed in phantom models.Results: The BSA@Au/Tb-FA nanoparticles exhibited a spherical-like morphology, with a mean particle size of ~10.68 ± 1.69 nm (n = 55). Cell viability remained > 80% up to 250 μg/mL, with an IC50 of 352 μg/mL. The hemocompatibility was good, with hemolysis values below the ASTM safety threshold of 5% at 200 μg/mL. The materials demonstrated concentration-dependent cellular uptake at 25, 50, and 100 μg/mL, with BSA@Au/Tb-FA nanoparticles exhibiting higher uptake than the non-FA-conjugated nanoparticles, BSA@Au/Tb (p < 0.05). SPCCT showed an attenuation efficiency of 38.35 HU·mL·mg⁻1 for BSA@Au/Tb-FA, attributable to the strong X-ray attenuation of Au and Tb components near their K-edge energies. Material decomposition showed strong agreement between measured and experimental concentrations (R2 = 0.98). MRI phantom studies revealed relaxivity values of r1 = 1.42 mM⁻1s⁻1 and r2 = 13.82 mM⁻1s⁻1, indicating a dominant transverse relaxation effect and T2-weighted contrast capability.Conclusion: BSA@Au/Tb-FA exhibited favorable in vitro hemocompatibility and biocompatibility, with enhanced cellular uptake in MDA-MB-231 and complementary enhanced SPCCT/MRI contrast under phantom conditions, supporting its potential as a bimodal imaging agent. However, because cellular evaluation was limited to MDA-MB-231 cells without a receptor-blocking study, the enhanced uptake should not be interpreted as confirmed folate-receptor-mediated targeting. Further preclinical and in vivo studies are required to establish targeting specificity, safety, and imaging performance.Keywords: gold nanoparticles, spectral photon counting CT, magnetic resonance imaging, folate receptor, dual-mode imaging, triple-negative breast cancers