Intravesical
instillation therapy is increasingly recognized as
one of the most common clinical treatment strategies for bladder cancer.
However, the antitumor efficacy of chemotherapy drugs is still limited
due to their rapid clearance by periodic urination. To circumvent
this issue, a drug-loaded thin film comprising the self-assembly of
tannic acid (TA) and ferric ions (Fe3+) was in situ fabricated
on the bladder wall in vivo. As expected, the TA@Fe film with adjustable
thickness could effectively prolong the residence time of anticancer
drugs in the bladder and realize sustained release of anticancer drugs.
Together with the antibacterial properties, the TA@Fe film enabled
improved chemotherapeutic efficacy. Moreover, the TA@Fe film caused
no adverse effects on bladder function, demonstrating the in vivo
biocompatibility. In addition, the T
2 contrast
effect of Fe3+ was employed to real-time monitor the disassembly
of the TA@Fe film and the ensuing drug release process by magnetic
resonance imaging. We believe that the TA@Fe-based drug delivery platform
with enhanced retention in the bladder would be of great potential
for treating various bladder diseases.