Alive attenuated Salmonella as a cargo shuttle for smart carrying of gold nanoparticles to tumour hypoxic regions.

In the present study, alive attenuated Salmonella typhi Ty21a was introduced as a vehicle for smart delivery of gold nanoparticles to the tumours' hypoxic regions. At the first step, the uptakes of gold nanoparticles with seven different decorations by S. typhi Ty21a was investigated using flow cytometry and inductively coupled plasma optical emission spectroscopy. The analyses demonstrated that folic acid functionalised gold nanoparticles (FA-GNPs) are the best candidates for producing the Golden Bacteria (GB). Subsequently, the GB and FA-GNPs efficacies for tumour targeting were investigated after intravenous injection to CT-26 tumour-bearing mice. The GB exhibited more GNPs delivery to the tumour in comparison with FA-GNPs. Moreover, GB injection causes more delivery of GNPs to the tumours' central regions in comparison with tumours' periphery. This trend is completely in reverse for FA-GNPs injected group. The ratios of peripheral to central regions' gold concentration of the tumours were 1.95 ± 0.13 and 0.61 ± 0.10 for FA-GNPs and GB groups, respectively. This observation demonstrates higher accumulation of gold nanoparticles in the centre of the tumour due to their active delivery by the S. typhi Ty21a to the deeps of tumours.