CEA-Functionalized Gold Nanoparticles for Oral Prophylaxis: An In Vivo Evaluation of Safety, Biodistribution, and Cytokine Expression in Healthy Mice

Background and Aim: Colorectal cancer remains a leading cause of cancer-related mortality, with growing interest in nanotechnology-driven immunotherapeutics. Gold nanoparticles (AuNPs) offer a promising platform due to their biocompatibility, functional versatility, and immunomodulatory potential. Carcinoembryonic antigens (CEAs), highly expressed in colorectal tumors, provide an ideal target for antigen-specific immune activation. The aim of this study is to evaluate the immunogenicity, biodistribution, and therapeutic efficacy of a CEA-functionalized gold nanoparticle (CEA-AuNP) construct in a mouse model of colorectal cancer following oral administration via a customized capsular delivery system. Methods: A 30-day oral administration study was performed in BALB/c mice (n = 30), who received increasing doses of CEA-AuNPs (5–50 mg/kg/day). Histological, hyperspectral imaging, and ELISA-based cytokine analyses were conducted to assess organ integrity, nanoparticle accumulation, and immune modulation. Results: CEA-AuNPs demonstrated a favorable safety profile and dose-dependent accumulation in reticuloendothelial tissues, particularly the spleen and liver. Cytokine profiling revealed enhanced IL-10 responses in the spleen, indicating anti-inflammatory immune modulation, with localized pro-inflammatory signals observed in hepatic tissue at higher doses. No signs of systemic toxicity or significant off-target effects were detected. Conclusions: The oral administration of CEA-AuNPs in healthy mice induced tissue-specific immune responses and exhibited a dose-dependent biodistribution pattern. These results support the further development of CEA-AuNPs as a nanovaccine platform for colorectal cancer immunoprophylaxis.