Synthesis and Characterization of 5-Aminolevulinic Acid-Loaded Fibrous Nanosilica for Enhanced Detection of HT-29 Colorectal Cancer Cells

Accurate delineation of tumor margins remains a clinical challenge in colorectal cancer surgery. To address this, we developed a novel nanosystem by loading 5-aminolevulinic acid (5-ALA) onto amine-functionalized dendritic fibrous nanosilica (ALA@KCC-1-NH₂) for enhanced photodynamic diagnosis. The synthesized nanoparticles exhibited uniform spherical morphology (average diameter: 455 ± 30 nm), high surface area (352 m²/g for KCC-1), and mesoporous architecture. After functionalization and drug loading, the final formulation retained structural integrity with a drug loading content of 15.3 wt% and encapsulation efficiency of 85.6%. In vitro release studies revealed a pH-responsive profile, with minimal release (<20%) at pH 7.4 and accelerated release (>70%) at pH 5.5 over 24 hours. Cytotoxicity assays confirmed excellent biocompatibility of the blank carrier and significant light-induced cytotoxicity from ALA@KCC-1-NH₂, with an IC₅₀ of 0.45 mM under irradiation—three times lower than that of free 5-ALA (1.38 mM). Confocal microscopy demonstrated a 4.5-fold increase in intracellular protoporphyrin IX fluorescence in HT-29 colorectal cancer cells treated with ALA@KCC-1-NH₂ compared to free 5-ALA. These results indicate that the fibrous nanosilica carrier significantly enhances 5-ALA uptake and fluorescence signal generation, offering a promising strategy for improved intraoperative tumor visualization. The ALA@KCC-1-NH₂ platform thus holds strong potential for advancing fluorescence-guided surgery in colorectal cancer management. Given the ∼455 ± 30 nm particle diameter, the envisioned translational route is topical/endoscopic or intraluminal application (spray/instillation) rather than intravenous delivery.