Nanotechnology is having a significant impact in the drug delivery systems and diagnostic devices. As most of the nanosystems are intended to be administered in vivo, there is a need for stability models, which could simulate the biological environment. Instability issues could lead to particle aggregation and in turn could affect the release of the drug from the nanosystems and even lead to clogging of the systemic blood circulation leading to life-threatening situation. We have developed an ex vivo colloidal stability model for testing the stability of nanosystems over a period of 48h, which is the typical residence time of the nanoparticles in vivo. Tissue homogenates of rat spleen, brain, kidney, and liver were stabilized and optimized for the study; additionally, plasma and serum were used for the same. Poly (lactide-co-glycolic acid) nanoparticles were used as model nanosystem, and no significant change was found in the size and polydispersity index of the nanoparticles in the biological solutions. Moreover, no change in morphology was observed after 48h as observed by TEM microscopy. Hence, the developed model could prevent the failure of the developed nanosystem during clinical and preclinical application by serving as an initial checkpoint to study their interaction with the complex milieu.