Fig. 1. STAT3 expression is effectively silenced in vitro by siRNA-loaded SPNPs.

a Schematic of the jetting formulation for crosslinked, STAT3i-loaded, iRGD-conjugated, targeted albumin NPs (STAT3iSPNPs). b Particle size characterization and analysis was performed using scanning electron microscopy (SEM). Average particle diameter, 115 ± 23.4 nm. Scale bar 1 µm. c Particles undergo swelling in their hydrated state and further swell at reduced pH. Average diameters: pH 7.4, 220 ± 26.1 nm. pH 5.0, 396 ± 31.2 nm. d Representative confocal z-stack image of cells cultured in the presence of SPNPs (blue = nucleus, green = actin, yellow = lysosomes, red = SPNPs). Composite images of cells incubated with SPNPs (with and without iRGD) were collected from a single independent experiment to study intracellular particle fate. Scale bar = 30 µm. e, f Quantification of particle uptake and lysosome-particle colocalization. e Local release of iRGD from SPNPs increases particle uptake in GL26 glioma cells by greater than five-fold (***p < 0.0001). f Internalized SPNPs colocalize with lysosomes to a lesser extent than untargeted particles (*p = 0.0235). Data are presented as mean values ± s.d. (SPNPs n = 7, NPs n = 8, independent composite z-stack images; two-tailed unpaired t-test). g STAT3 siRNA-loaded SPNPs significantly reduce in vitro expression of target protein in GL26 glioma cells compared to untreated and empty particle control groups. Data are presented as mean values ± s.d. (SPNPs, n = 3; Lipofectamine + STAT3i, STAT3i SPNPs (25 and 2.5 µg mL⁻¹, n = 2 biological replicates). Representative bands obtained with the ProteinSimple Wes instrument for both STAT3 (siRNA target protein) and GAPDH (loading control) are displayed for each experimental group.