CEA-Functionalized Gold Nanoparticles as a Nanovaccine Platform: In Vitro Evaluation of Cytocompatibility, Cellular Uptake, and Antigen Processing

Background: and aim. The efficacy of cancer vaccines depends on the development of safe and effective delivery systems that can improve antigen stability, facilitate targeted uptake by immune cells, and promote efficient intracellular processing. Gold nanopar-ticles offer an attractive platform due to their biocompatibility, stability, and modifiable surfaces. Functionalizing gold nanoparticles with tumor-associated antigens such as car-cinoembryonic antigen (CEA) peptides may enhance antigen presentation and stimulate immune activation. This study aimed to evaluate the cytocompatibility, cellular inter-nalization, and antigen-processing capabilities of CEA-functionalized gold nanoparticles (CEA-AuNPs) as a potential nanovaccine candidate in vitro. Materials and Methods. CEA peptides were conjugated to gold nanoparticles and characterized using UV-VIS spec-troscopy and dynamic light scattering to confirm functionalization and assess particle size distribution. In vitro assays were performed on macrophage cell cultures to evaluate cytotoxicity (via viability and caspase-3 expression), nanoparticle uptake (by reflectance microscopy), and antigen processing (via fluorescence intensity analysis). Results. Spectral analysis confirmed successful functionalization, with a broadened absorbance plateau between 510–700 nm and a size increase from 20 nm (bare AuNPs) to ~80 nm (CEA-AuNPs). Viability assays demonstrated cytologyc viability above 85% at all tested concentrations. Caspase-3 activity, suggested controlled apoptotic signaling in response to the nanoconstruct. Reflective imaging and fluorescence microscopy confirmed efficient cellular uptake, localized predominantly in the perinuclear region, and enhanced pro-teasomal activity in macrophages treated with the CCEA-AuNPs, indicating effective antigen processing. Discussion. Functionalization of gold nanoparticles with a CEA peptide resulted in stable, biocompatible nanostructures capable of efficient uptake by antigen-presenting cells. Enhanced intracellular processing, evidenced by increased ubiquitin-proteasome pathway activity, highlights the immunogenic potential of the construct. Low cytotoxicity supports its suitability for further preclinical development. Conclusion CEA-functionalized gold nanoparticles exhibit high cytocompatibility, tar-geted cellular uptake, and promote intracellular antigen processing—highlighting their promise as a nanovaccine platform in cancer immunotherapy. These results support further preclinical evaluation toward translational application.