Interstitial photodynamic therapy (I-PDT), which utilizes optical fibers to deliver light for photosensitizer excitation and the elimination of penetration depth limitation, is a promising modality in the treatment of deeply seated tumors or thick tumors. Currently, the excitation domain of the optical fiber is extremely limited, restricting PDT performance. Here, we designed and fabricated a biocompatible polymer optical fiber (POF) with a strongly scattering spherical end (SSSE) for I-PDT applications, achieving an increased excitation domain and consequently excellent in vitro and in vivo therapeutical outcomes. The POF, which was drawn using a simple thermal drawing method, was made of polylactic acid, ensuring its superior biocompatibility. The excitation domains of POFs with different ends, including flat, spherical, conical, and strongly scattering spherical ends, were analyzed and compared. The SSSE was achieved by introducing nanopores into a spherical end, and was further optimized to achieve a large excitation domain with an even intensity distribution. The optimized POF enabled outstanding therapeutic performance of I-PDT in in vitro cancer cell ablation and in vivo anticancer therapy. All of its notable optical features, including low transmission/bending loss, superior biocompatibility, and a large excitation domain with an even intensity distribution, endow the POF with great potential for clinical I-PDT applications.

We successfully electropolymerize homopolymer and copolymer from vinylbenzyltrimethylammonium chloride and divinylbenzene by cyclic voltammetry to form ultra-thin anion-conducting polymer films with significant anion conductance. The morphologies of electropolymerized polymers with different monomer compositions are analyzed by scanning electron microscopy and atomic force microscopy. In-situ electrochemical impedance spectroscopy is performed to track the electropolymerization process and film properties. High anion conductance of up to 2 mS is found in the electropolymerized thin films, suggesting that this technique can be suitable for making anion conducting electrodes for advanced electrochemical devices.