A Split CRISPR/Cas13b System for Conditional RNA Regulation and Editing.

The CRISPR/Cas13b system has been demonstrated as a robust tool for versatile RNA studies and relevant applications. New strategies enabling precise control of Cas13b/dCas13b activities and minimal interference with native RNA activities will further facilitate the understanding and regulation of RNA functions. Here, we engineered a split Cas13b system that can be conditionally activated and deactivated under the induction of abscisic acid (ABA), which achieved the downregulation of endogenous RNAs in dosage- and time-dependent manners. Furthermore, an ABA inducible split dCas13b system was generated to achieve temporally controlled deposition of m6A at specific sites on cellular RNAs through conditional assembly and disassembly of split dCas13b fusion proteins. We also showed that the activities of split Cas13b/dCas13b systems can be modulated by light via using a photoactivatable ABA derivative. Overall, these split Cas13b/dCas13b platforms expand the existing repertoire of the CRISPR and RNA regulation toolkit to achieve targeted manipulation of RNAs in native cellular environments with minimal functional disruption to these endogenous RNAs.

Correction: Tumor-targeting, enzyme-activated nanoparticles for simultaneous cancer diagnosis and photodynamic therapy.

Correction for 'Tumor-targeting, enzyme-activated nanoparticles for simultaneous cancer diagnosis and photodynamic therapy' by Huaxia Shi et al., J. Mater. Chem. B, 2016, 4, 113-120, https://doi.org/10.1039/C5TB02041G.

Inducible and reversible RNA N6-methyladenosine editing.

RNA modifications, including N6-methyladenosine (m6A), have been reported to regulate fundamental RNA processes and properties, and directly linked to various human diseases. Methods enabling temporal and transcript/locus-specific editing of specific RNA modifications are essential, but still limited, to dissect the dynamic and context-dependent functions of these epigenetic modifications. Here, we develop a chemically inducible and reversible RNA m6A modification editing platform integrating chemically induced proximity (CIP) and CRISPR methods. We show that m6A editing can be temporally controlled at specific sites of individual RNA transcripts by the addition or removal of the CIP inducer, abscisic acid (ABA), in the system. By incorporating a photo-caged ABA, a light-controlled version of m6A editing platform can be developed. We expect that this platform and strategy can be generally applied to edit other RNA modifications in addition to m6A.

Near-Infrared Light-Harvesting Fullerene-Based Nanoparticles for Promoted Synergetic Tumor Phototheranostics.

A synergetic phototheranostic system, combining diagnostic photo-imaging and phototherapies [such as photothermal therapy and photodynamic therapy (PDT)], shows great potential in today's tumor precise therapy. Herein, we fabricate near-infrared (NIR) light-harvesting fullerene-based nanoparticles (DAF NPs) for photoacoustic (PA) imaging-guided synergetic tumor photothermal and PDT. The fullerene derivatives (DAF) absorbing in the NIR region have been synthesized by conjugating NIR-absorbing antenna with fullerene. In addition, DAF NPs with good biocompatibility have been fabricated via a nanoprecipitation approach. The as-prepared DAF NPs can accumulate and generate PA signals around the tumor site 6 h post injection via enhanced permeability and retention effect in vivo. More importantly, the DAF NPs exhibit better reactive oxygen species and heat generation efficacy compared with fullerene and antenna nanoparticles (DA NPs), respectively. Further in vitro and in vivo studies demonstrate that DAF NPs can effectively inhibit tumor growth through synergetic photodynamic and photothermal therapies, which provides a new sight of photosensitizer design for enhanced cancer phototheranostics.

NIR-Absorbing water-soluble conjugated polymer dots for photoacoustic imaging-guided photothermal/photodynamic synergetic cancer therapy.

"Theranostics" become increasingly significant in current personalized precision medicine. Herein, we developed a new NIR-absorbing photo-theranostic agent based on water-soluble diketopyrrolopyrrole (DPP) conjugated polymer (WSCP) dots. The WSCPs can be easily self-assembled into WSCP dots under ultrasonication only, instead of any other nano-technology. Compared to the monomers of WSCPs, WSCP dots have no fluorescence emission but produce photoacoustic (PA) signal detected upon laser irradiation due to the reduced energy loss from excited state. PA imaging in vivo indicated that WSCP dots can accumulate at tumor site within 4 h post-injection. More importantly, WSCP dots not only generate heat with a photothermal conversion efficiency of ∼54%, but also produce reactive oxygen species (ROS, QY ∼13%). Furthermore, in vitro and in vivo experiments confirmed effective inhibition of tumor growth by WSCP dots via synergetic photothermal/photodynamic therapy. All results indicate a great potential of WSCP dots as highly efficient theranostic agents in PA imaging-guided synergetic cancer treatment.

A Thienyl-Substituted Diketopyrrolopyrrole Derivative with Efficient Reactive Oxygen Species Generation for Photodynamic Therapy.

Reducing the energy gap of photosensitizer between singlet and triplet states (ΔEST ) can improve the efficiency of intersystem crossing, further enhancing the resulting generation of reactive oxygen species for photodynamic therapy. In this study, two photosensitizer chromophores-phenyl-substituted diketopyrrolopyrrole and thienyl-substituted diketopyrrolopyrrole (TDPP)-were synthesized. Theoretical calculations indicate that TDPP can greatly reduce the ΔEST (0.48 eV) relative to that of diketopyrrolopyrrole (0.66 eV). Experiments confirmed that TDPP generates reactive oxygen species more efficiently than diketopyrrolopyrrole. After conjugation of TDPP with methoxy poly(ethylene glycol)carboxyl (mPEG-COOH), the resulting TDPP-mPEG has excellent water solubility, biocompatibility and photostability. When it serves as photosensitizer for photodynamic therapy, in vitro and in vivo measurements indicate that TDPP-mPEG can effectively inhibit tumor growth and shows great potential for the treatment of cancer in the clinic.

Tumor-targeting, enzyme-activated nanoparticles for simultaneous cancer diagnosis and photodynamic therapy.

Specific targeting towards tumors and the on-site activation of photosensitizers to diagnose tumors and reduce side effects for patients are currently the main challenges for photodynamic therapy (PDT) in the clinic. Herein, uniform diiodostyryl bodipy conjugated hyaluronic acid nanoparticles (DBHA-NPs) were successfully synthesized. The evaluation of their PDT effect at both a cellular level and in animal models of tumor-bearing mice shows that the DBHA-NPs present a remarkable suppression of tumorous growth due to their specific targeting and enhanced permeability and retention (EPR) effect. More importantly, the enzyme-activated "self-assembly and disaggregation" behavior in tumors can lead to the on-site activation of DBHA-NPs, which can diagnose the tumor exactly and reduce the side effects for patients significantly. These findings confirm that DBHA-NPs have significant potential for photodynamically activated cancer theranostics in a clinical setting.

Free-standing electrochemical electrode based on Ni(OH)2/3D graphene foam for nonenzymatic glucose detection.

Three-dimensional graphene foam (3DGF) is a superior sensing material because of its high conductivity, large specific surface area and wide electrochemical potential windows. In this work, hexagonal Ni(OH)2 nanosheets are deposited on the surface of chemical vapor deposition-grown 3DGF through a facial hydrothermal process without any auxiliary reagents. The morphology and structure of the composite are characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM), Raman spectroscopy, and X-ray diffraction (XRD). Based on the Ni(OH)2/3DGF composite, a free-standing electrochemical electrode is fabricated. Being employed as a nonenzymatic glucose detection electrochemical electrode, it exhibits a high sensitivity (∼2.65 mA mM(-1) cm(-2)), low detection limit (0.34 µM) and excellent selectivity with a linear response from 1 µM to 1.17 mM. The excellent sensing properties of the Ni(OH)2/3DGF electrode may be attributed to the synergistic effect of the high electrocatalytic activity of Ni(OH)2 nanosheets and the high conductivity and large surface area of 3DGF.