Flexible inorganic composite nanofibers with carboxyl modification for controllable drug delivery and enhanced optical monitoring functionality

Nanofibers with controllable drug release and sensitive monitoring properties for drug delivery can regulate the drug release rate and obtain the real-time information between drug release amount and therapeutic effect, which are of great importance in clinical applications. Herein, we introduce a reoxidation method to prepare flexibility-enhanced inorganic nanofibers that does not need traditional high temperature calcination. Compared with traditional calcination methods, stronger upconversion luminescence is obtained via this method. More interestingly, higher drug loading capacity and slower drug releasing rate are obtained after nanofibers are modified with carboxyl. The main mechanism is ascribed to the ionic interaction between DNR molecules and carboxyl group verified by FTIR. Further experimental results show that controllable drug release can be achieved not only via this carboxyl modification, but also the change of pH. Moreover, thanks to nanofibers prepared by this reoxidation method possessing stronger luminescence, they exhibit more sensitive monitoring properties especially for monitoring trace drug release such as 1% which cannot be well monitored by nanofibers prepared by traditional calcination methods.