This study explores the in vivo targeting of semiconductor quantum dots (Qdots) using specific peptides to direct them to particular tissues and cells. Qdots are small, inorganic nanocrystals with unique luminescent properties, and their fluorescence can be tuned by altering their size or composition. The research demonstrates that Qdots coated with lung-targeting peptides accumulate in the lungs of mice after intravenous injection, while other peptides direct Qdots to blood vessels or lymphatic vessels in tumors. Adding polyethylene glycol (PEG) to the Qdot coating prevents nonselective accumulation in reticuloendothelial tissues. The study uses peptides that recognize molecular markers on blood vessels to target Qdots to specific vascular sites in mice. One peptide binds to membrane dipeptidase on lung endothelial cells, while two others preferentially bind to tumor blood vessels or lymphatic vessels and tumor cells. The results show that Qdots can be targeted in vivo with high specificity. The Qdots were synthesized and coated with peptides using a thiol-exchange reaction. The peptides were synthesized and purified, and the Qdots were then coated with thiolated peptides or PEG. The Qdots were then injected into mice, and their distribution was examined using fluorescence microscopy. The study shows that Qdots coated with specific peptides can target specific tissues and cells in vivo. The Qdots were found to accumulate in the lungs, tumors, and other tissues depending on the peptide used. The results suggest that Qdots can be used for in vivo imaging and drug delivery. The study also shows that PEG coating reduces nonspecific uptake by the reticuloendothelial system, increasing the circulation time of the Qdots. The study highlights the potential of Qdots as a tool for in vivo imaging and drug delivery. The results suggest that Qdots can be used to target specific tissues and cells in the body, which could have applications in cancer therapy and other medical treatments. The study also shows that Qdots can be used to deliver drugs to specific tissues, which could improve the effectiveness of treatments. The study concludes that the use of Qdots with specific peptides for in vivo targeting is a promising approach for medical applications.This study explores the in vivo targeting of semiconductor quantum dots (Qdots) using specific peptides to direct them to particular tissues and cells. Qdots are small, inorganic nanocrystals with unique luminescent properties, and their fluorescence can be tuned by altering their size or composition. The research demonstrates that Qdots coated with lung-targeting peptides accumulate in the lungs of mice after intravenous injection, while other peptides direct Qdots to blood vessels or lymphatic vessels in tumors. Adding polyethylene glycol (PEG) to the Qdot coating prevents nonselective accumulation in reticuloendothelial tissues. The study uses peptides that recognize molecular markers on blood vessels to target Qdots to specific vascular sites in mice. One peptide binds to membrane dipeptidase on lung endothelial cells, while two others preferentially bind to tumor blood vessels or lymphatic vessels and tumor cells. The results show that Qdots can be targeted in vivo with high specificity. The Qdots were synthesized and coated with peptides using a thiol-exchange reaction. The peptides were synthesized and purified, and the Qdots were then coated with thiolated peptides or PEG. The Qdots were then injected into mice, and their distribution was examined using fluorescence microscopy. The study shows that Qdots coated with specific peptides can target specific tissues and cells in vivo. The Qdots were found to accumulate in the lungs, tumors, and other tissues depending on the peptide used. The results suggest that Qdots can be used for in vivo imaging and drug delivery. The study also shows that PEG coating reduces nonspecific uptake by the reticuloendothelial system, increasing the circulation time of the Qdots. The study highlights the potential of Qdots as a tool for in vivo imaging and drug delivery. The results suggest that Qdots can be used to target specific tissues and cells in the body, which could have applications in cancer therapy and other medical treatments. The study also shows that Qdots can be used to deliver drugs to specific tissues, which could improve the effectiveness of treatments. The study concludes that the use of Qdots with specific peptides for in vivo targeting is a promising approach for medical applications.