In vivo antitumor efficacy study in A549 cells bearing xenograft tumor model after intranasal treatment of free DOX, GNP, and EGNP. (a) In vivo anti-tumor effects (b) lung tumor mass (c) body weight changes (d) survival rate of mice. Each data point was represented as mean ± sd (n = 4). ***p < 0.0001 is the statistical difference between EGNP and control. **p < 0.001 is the statistical difference between EGNP and GNP.