Fig. 4

Distribution and accumulation of polystyrene nanoparticles in the kidney. Spectral images of adult mouse kidney sections 5 min (a, c) and 4 days (b, d) after injection of PS-COOH (a, b) or PS_PEG (c, d) nanoparticles through the tail vein. a′–d′: spectrum profiles of ROIs in the corresponding images. The spectrum of each ROI is marked with the same color as it is delineated in the microscopic image. Green curves represent particle fluorescence (positive controls); red curve represents tissue autofluorescence (negative control). Scale bars 50 µm