Gold Nanoparticles in Bladder Cancer Applications: A Paradigm Shift from Diagnostic Tools to Integrated Theranostic Platforms.

Background: Bladder cancer, particularly non-muscle-invasive bladder cancer (NMIBC), poses significant clinical challenges due to its high recurrence rate. Traditional diagnostic approaches such as cystoscopy and urine cytology have limitations, including invasiveness and insufficient sensitivity. Gold nanoparticles (AuNPs) offer unique opportunities to address these challenges with their surface plasmon resonance effect, biocompatibility, and ease of functionalization. Methods: Through critical review of recent literature, this paper outlines the application principles, achievements, and mechanisms of AuNPs in bladder cancer, including in vitro diagnostics, multimodal molecular imaging, photothermal therapy, targeted drug delivery, radiotherapy sensitization, and tumor immune microenvironment remodeling. Main Findings: AuNPs are driving a paradigm shift in bladder cancer management. In diagnostics, AuNP-based biosensors enable ultra-sensitive detection of urinary biomarkers. In imaging, they serve as effective contrast agents for enhanced visualization. For therapy, AuNP-mediated photothermal therapy enables precise tumor ablation, and as drug carriers, they help overcome chemoresistance. Additionally, AuNPs demonstrate potential in remodeling the immunosuppressive microenvironment through modulation of signaling pathways and tumor-associated macrophages. Conclusion: Gold nanoparticles are transforming bladder cancer toward precision, minimally invasive, and personalized treatment models. However, it is important to acknowledge that most current findings remain in the preclinical stage, and significant translational barriers-particularly long-term biosafety and standardized production-must be addressed before widespread clinical adoption.