NIR-II Hydrogen-Bonded Organic Frameworks (HOFs) Used for Target-Specific Amyloid-ß Photooxygenation in an Alzheimer's Disease Model.

Phototherapy has emerged as a powerful approach for interrupting ß-amyloid (Aß) self-assembly. However, deeper tissue penetration and safer photosensitizers are urgent to be exploited for avoiding damaging nearby normal tissues and improving therapeutic effectiveness. A hydrogen-bonded organic framework (HOF)-based NIR-II photooxygenation catalyst is presented here to settle the abovementioned challenges. By encapsulating the pyridinium hemicyanine dye DSM with a large two-photon absorption (TPA) cross-section in NIR-II window into the porphyrin-based HOF, the resultant DSM@n-HOF-6 exhibits significant two-photon NIR-II-excited Fluorescence Resonance Energy Transfer (FRET) to generate singlet oxygen (1 O2 ) for Aß oxidation. Further, the target peptides of KLVFFAED (KD8) are covalently grafted on DSM@n-HOF-6 to enhance the blood-brain barrier (BBB) permeability and Aß selectivity. The HOF-based photooxygenation catalyst shows an outstanding inhibitory effect of Aß aggregation upon the NIR-II irradiation. Further in vivo studies demonstrate the obvious decrease of craniocerebral Aß plaques and recovery of memory deficits in triple-transgenic AD (3×Tg-AD) model mice.

Near-Infrared Activated Black Phosphorus as a Nontoxic Photo-Oxidant for Alzheimer's Amyloid-ß Peptide.

The inhibition of amyloid-ß (Aß) aggregation by photo-oxygenation has become an effective way of treating Alzheimer's disease (AD). New near-infrared (NIR) activated treatment agents, which not only possess high photo-oxygenation efficiency, but also show low biotoxicity, are urgently needed. Herein, for the first time, it is demonstrated that NIR activated black phosphorus (BP) could serve as an effective nontoxic photo-oxidant for amyloid-ß peptide in vitro and in vivo. The nanoplatform BP@BTA (BTA: one of thioflavin-T derivatives) possesses high affinity to the Aß peptide due to specific amyloid selectivity of BTA. Importantly, under NIR light, BP@BTA can significantly generate a high quantum yield of singlet oxygen (1 O2 ) to oxygenate Aß, thereby resulting in inhibiting the aggregation and attenuating Aß-induced cytotoxicity. In addition, BP could finally degrade into nontoxic phosphate, which guarantees the biosafety. Using transgenic Caenorhabditis elegans CL2006 as AD model, the results demonstrate that the 1 O2 -generation system could dramatically promote life-span extension of CL2006 strain by decreasing the neurotoxicity of Aß.