Multifunctional PolySpermine-based Nanocapsules for Targeted Gene Delivery to Gastric Cancer Cells

In this study, multifunctional nanocapsules were developed and evaluated for targeted gene delivery to AGS gastric cancer cells. The design of the nanoparticles utilized hyperbranched polyspermine (HS) for efficient DNA condensation, polyethylene glycol (PEG) to increase nanoparticle stability and prolong circulation time via stealth properties, and dual-targeting ligands, i.e., folic acid and glucose, to improve selective binding and internalization by cancer cells. Folic acid targets folate receptors (FRα), while glucose binds glucose transporters (GLUTs), both of which are overexpressed in gastric cancer cells, thereby increasing uptake specificity. The synthesized ternary copolymers composed of polyspermine, PEG, folic acid, and glucose (PSPFG) were comprehensively characterized via multiple analytical techniques, including proton nuclear magnetic resonance (¹H-NMR), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and derivative thermogravimetric (DTG) analysis, to confirm their chemical structure and thermal stability. After complexation with DNA, the PSPFG/100 DNA nanocapsules were analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), which revealed uniform spherical nanoparticles with a nanoscale size. Dynamic light scattering (DLS) measurements confirmed a narrow size distribution, with an average particle size of 265 ± 18 nm. Biocompatibility assays using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay demonstrated significantly reduced cytotoxicity compared with the commonly used polyethylenimine (PEI) vector. Agarose gel electrophoresis revealed strong DNA binding, effective charge neutralization, and resistance to enzymatic degradation. Importantly, fluorescence microscopy and flow cytometry analyses demonstrated high transfection efficiency in AGS cells, with the optimized PSPFG50/DNA formulation achieving a transfection rate of 53.37%. These results collectively indicate that PSPFG-based nanocarriers exhibit favorable biocompatibility and enhanced gene delivery performance, addressing major limitations of traditional polycationic vectors. These findings suggest promising potential for the clinical translation of these spermine-derived nanocapsules in gastric cancer gene therapy.