NIR light-activated upconversion POP nanofiber composite; an effective carrier for targeted photodynamic therapy and drug delivery

•New –COOH functionalized POP nanofiber TPDABA was developed via Schieff-based condensation reaction.•POP nanofiber composite UCNPs@TPDABA was synthesized and modified with folic acid for targeted therapy.•High amount of DOX was loaded into UCNPs@TPDABA@FA and shows anticancer effect in lung cancer cells.•Methylene Blue was loaded into UCNPs@TPDABA@FA for singlet oxygen generation upon NIR light excitation via FRET. Covalently linked porous organic polymers featuring a large surface area, low toxicity, and excellent stability is an emerging class of porous material that has drawn immense attention in the area of cancer therapy. However, the development of NIR light excitable nanoscale POP with available surface functional groups for active cancer cell targeting is still a great promise for chemotherapy and PDT. Herein, we have fabricated folic acid (FA) encapsulated upconversion nanoparticle embedded porous organic polymeric nanofiber (POP nanofiber) composite (UCNPs@TPDABA@FA) for cell imaging, targeted drug delivery, and photodynamic therapy. PEI-coated upconversion nanoparticle is attached with imine linked –COOH functionalized POP nanofiber in a single step to achieve highly porous composite UCNPs@TPDABA. Then functionalized folic acid has been attached with the composite which effectively targets cancer cell A549. The composite delivers the anticancer drug DOX and shows significant results for in-vitro lung cancer treatment. Besides the fluorescence imaging property, UCNPs serve as FRET donor to the photosensitizer methylene blue and then generates ROS upon photoexcitation. ROS generation is also detected in A549 cancer cells. So, the smart composite UCNPs@TPDABA@FA could open a new door in serving as an effective carrier for chemotherapeutic drug and PDT.