Electrostatic Attractive Self-Delivery of siRNA and Light-Induced Self-Escape for Synergistic Gene Therapy.

Small interfering RNA (siRNA) holds immense promise for suppressing gene expression and treating various life-threatening diseases, including cancer. However, efficient delivery and lysosomal escape remain critical challenges that hinder the therapeutic effectiveness of siRNA. Herein, cationic photosensitizer (NB-Br) is grafted onto polo-like kinase 1 (PLK1) siRNA to form an amphiphilic siRNA-photosensitizer conjugate (siPLK1-NB), which can self-assemble into nanoparticles (siPLK1-NB NPs) via electrostatic attraction. Notably, siPLK1-NB NPs exhibit rapid and efficient cell endocytosis, as well as outstanding tumor-targeting property in multiple tumor-bearing mice models. When siPLK1-NB NPs are located inside tumor cell lysosomes, the generated reactive oxygen species (ROS) after photoactivation can disrupt the lysosome membrane structure and facilitate siRNA escape from lysosomes. Under light irradiation, siPLK1-NB NPs can downregulate PLK1 expression and induce photodynamic killing, effectively inhibiting tumor cell growth both in vitro and in vivo. Consequently, this study provides a novel design strategy for carrier-free siRNA delivery systems. As far as it is known, this is the first report of a carrier-free siRNA delivery system based on electrostatic attraction.

High Performance Polarization-Resolved Photodetectors Based on Intrinsically Stretchable Organic Semiconductors.

Polarization-sensitive photodetectors based on anisotropic semiconductors sense both the intensity and polarization state information without extra optical components. Here, a self-powered organic photodetector (OPD) composed of intrinsically stretchable polymer donor PNTB6-Cl and non-fullerene acceptor Y6 is reported. The PNTB6-Cl:Y6 photoactive film accommodates a remarkable 100% strain without fracture, exhibiting a high optical anisotropy of 1.8 after strain alignment. The resulting OPD not only shows an impressive faint-light detection capability (high spectral responsivity of 0.45 A W-1 and high specific detectivity of 1012 Jones), but also has a high anisotropic responsivity ratio of 1.42 under the illumination of parallel and traversed polarized light. To the best of the authors' knowledge, both the detector performance and polarization features are among the best-performing OPDs and polarization-sensitive photodetectors. As a proof-of-concept, polarization-sensitive OPDs are also utilized to set up a polarimetric imaging system and full-Stokes polarimeter. This work explores the potential of highly stretchable organic semiconductors for state-of-art polarization imaging and spectroscopy applications.