Injectable Mechanophore Nanoparticles for Deep-Tissue Mechanochemical Dynamic Therapy.

Photodynamic therapy (PDT) and sonodynamic therapy (SDT), using nonionizing light and ultrasound to generate reactive oxygen species, offer promising localized treatments for cancers. However, the effectiveness of PDT is hampered by inadequate tissue penetration, and SDT largely relies on pyrolysis and sonoluminescence, which may cause tissue injury and imprecise targeting. To address these issues, we have proposed a mechanochemical dynamic therapy (MDT) that uses free radicals generated from mechanophore-embedded polymers under mechanical stress to produce reactive oxygen species for cancer treatment. Yet, their application in vivo is constrained by the bulk form of the polymer and the need for high ultrasound intensities for activation. In this study, we developed injectable, nanoscale mechanophore particles with enhanced ultrasound sensitivity by leveraging a core-shell structure comprising silica nanoparticles (NPs) whose interfaces are linked to polymer brushes by an azo mechanophore moiety. Upon focused ultrasound (FUS) treatment, this injectable NP generates reactive oxygen species (ROS), demonstrating promising results in both an in vitro 4T1 cell model and an in vivo mouse model of orthotopic breast cancers. This research offers an alternative therapy technique, integrating force-responsive azo mechanophores and FUS under biocompatible conditions.

Using Protein Design and Directed Evolution to Monomerize a Bright Near-Infrared Fluorescent Protein.

The small ultrared fluorescent protein (smURFP) is a bright near-infrared (NIR) fluorescent protein (FP) that forms a dimer and binds its fluorescence chromophore, biliverdin, at its dimer interface. To engineer a monomeric NIR FP based on smURFP potentially more suitable for bioimaging, we employed protein design to extend the protein backbone with a new segment of two helices that shield the original dimer interface while covering the biliverdin binding pocket in place of the second chain in the original dimer. We experimentally characterized 13 designs and obtained a monomeric protein with a weak fluorescence. We enhanced the fluorescence of this designed protein through two rounds of directed evolution and obtained designed monomeric smURFP (DMsmURFP), a bright, stable, and monomeric NIR FP with a molecular weight of 19.6 kDa. We determined the crystal structures of DMsmURFP both in the apo state and in complex with biliverdin, which confirmed the designed structure. The use of DMsmURFP in in vivo imaging of mammalian systems was demonstrated. The backbone design-based strategy used here can also be applied to monomerize other naturally multimeric proteins with intersubunit functional sites.

Marine Actinomycetes-derived Natural Products.

Actinomycetes is an abundant resource for discovering a large number of lead compounds, which play an important role in microbial drug discovery. Compared to terrestrial microorganisms, marine actinomycetes have unique metabolic pathways because of their special living environment, which has the potential to produce a variety of bioactive substances. In this paper, secondary metabolites isolated from marine actinomycetes are reviewed (2013-2018), most of which exhibited cytotoxic, antibacterial, and antiviral biological activities.