Photorefractive gratings in DR1-doped hybrid sol–gel films

Photorefractive gratings have been obtained with 632.8 nm writing beams in organic–inorganic SiO₂-based films. The hybrid glass is prepared by a sol–gel technique, starting from organic Si precursors, and contains Disperse Red 1 (DR1), carbazole units and 2,4,7-trinitro-9-fluorenone (TNF). The photorefractive gain, which has been found unexpectedly even without poling field, has been determined through an asymmetric energy exchange by two-beam coupling measurements. The effects of the polarization of the writing beams and of a circularly polarized photoisomerizing radiation during the erasure of the grating have been interpreted in terms of an orientational contribution to the grating formation.     

A Retina‐Like Dual Band Organic Photosensor Array for Filter‐Free Near‐Infrared‐to‐Memory Operations

Human eyes use retina photoreceptor cells to absorb and distinguish photons from different wavelengths to construct an image. Mimicry of such a process and extension of its spectral response into the near‐infrared (NIR) is indispensable for night surveillance, retinal prosthetics, and medical imaging applications. Currently, NIR organic photosensors demand optical filters to reduce visible interference, thus making filter‐free and anti‐visible NIR imaging a challenging task. To solve this limitation, a filter‐free and conformal, retina‐inspired NIR organic photosensor is presented. Featuring an integration of photosensing and floating‐gate memory modules, the device possesses an acute color distinguishing capability. In general, the retina‐like photosensor transduces NIR (850 nm) into nonvolatile memory and acts as a dynamic photoswitch under green light (550 nm). In doing this, a filter‐free but color‐distinguishing photosensor is demonstrated that selectively converts NIR optical signals into nonvolatile memory.     

Active Targeting Using HER‐2‐Affibody‐Conjugated Nanoparticles Enabled Sensitive and Specific Imaging of Orthotopic HER‐2 Positive Ovarian Tumors

Despite advances in cancer diagnosis and treatment, ovarian cancer remains one of the most fatal cancer types. The development of targeted nanoparticle imaging probes and therapeutics offers promising approaches for early detection and effective treatment of ovarian cancer. In this study, HER‐2 targeted magnetic iron oxide nanoparticles (IONPs) are developed by conjugating a high affinity and small size HER‐2 affibody that is labeled with a unique near infrared dye (NIR‐830) to the nanoparticles. Using a clinically relevant orthotopic human ovarian tumor xenograft model, it is shown that HER‐2 targeted IONPs are selectively delivered into both primary and disseminated ovarian tumors, enabling non‐invasive optical and MR imaging of the tumors as small as 1 mm in the peritoneal cavity. It is determined that HER‐2 targeted delivery of the IONPs is essential for specific and sensitive imaging of the HER‐2 positive tumor since we are unable to detect the imaging signal in the tumors following systemic delivery of non‐targeted IONPs into the mice bearing HER‐2 positive SKOV3 tumors. Furthermore, imaging signals and the IONPs are not detected in HER‐2 low expressing OVCAR3 tumors after systemic delivery of HER‐2 targeted‐IONPs. Since HER‐2 is expressed in a high percentage of ovarian cancers, the HER‐2 targeted dual imaging modality IONPs have potential for the development of novel targeted imaging and therapeutic nanoparticles for ovarian cancer detection, targeted drug delivery, and image‐guided therapy and surgery.