A new three-step photo-oxidative degradation mechanism of MAPbI3 is proposed. A strategy for protecting MAPbI3 by 2-(4-fluorophenyl)propan-2-amine modification is designed.

DNA für Nanogoldschmiede: DNA‐Origami‐Nanostrukturen (magenta) wurden als räumlich adressierbare Template zur Anordnung von Silber‐ und Goldnanopartikeln (gelbe bzw. rote Kugeln) in definierte diskrete Strukturen verwendet (siehe Beispiele mit entsprechenden TEM‐Bildern).

Many natural biological systems -such as biofilms, shells and skeletal tissues -are able to assemble multifunctional and environmentally responsive multiscale assemblies of living and nonliving components. Here, by using inducible genetic circuits and cellular communication circuits to regulate Escherichia coli curli amyloid production, we show that E. coli cells can organize selfassembling amyloid fibrils across multiple length scales, producing amyloid-based materials that are either externally controllable or undergo autonomous patterning. We also interfaced curli fibrils with inorganic materials, such as gold nanoparticles (AuNPs) and quantum dots (QDs), and used these capabilities to create an environmentally responsive biofilm-based electrical switch, produce gold nanowires and nanorods, co-localize AuNPs with CdTe/CdS QDs to modulate QD fluorescence lifetimes, and nucleate the formation of fluorescent ZnS QDs. This work lays a foundation for synthesizing, patterning, and controlling functional composite materials with engineered cells.Users may view, print, copy, and download text and data-mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use:http://www.nature.com/authors/editorial_policies/license.html#terms Additional information Supplementary information is available in the online version of the paper. Reprints and permissions information is available online at www.nature.com/reprints. Correspondence and requests for materials should be addressed to T.K.L. Competing financial interests HHS Public AccessAuthor manuscript Nat Mater. Author manuscript; available in PMC 2014 November 01. Published in final edited form as:Nat Mater. 2014 May ; 13(5): 515-523. doi:10.1038/nmat3912. Author Manuscript Author ManuscriptAuthor Manuscript Author ManuscriptNatural multicellular assemblies such as biofilms, shells, and skeletal tissues have distinctive characteristics that would be useful for materials production and patterning 1-9 . They can detect external signals and respond via remodelling, implement patterning across different length scales, and organize inorganic compounds to create organic-inorganic composites. In this work, such systems provide inspiration for the design of environmentally responsive systems that can integrate biotic and abiotic materials via hierarchical self-assembly. To achieve these capabilities, we engineered artificial gene circuits and self-assembling amyloid fibrils together with synthetic cellular consortia 10-16 and abiotic materials.Our model system is curli, an extracellular amyloid material produced by E. coli that forms fibrils based on the self-assembly of the secreted major curli subunit CsgA 17 . Secreted CsgA monomers are templated on CsgB, which is anchored to the cell surface, to form curli fibrils; moreover, CsgA secreted from one cell can interact with CsgB on other cells 17 . Using synthetic riboregulators 18 , we implemented inducible transcriptional and translational control over the expressi...

Fluorescent silver nanoclusters (AgNCs) of less than 2 nm in diameter have emerged as a new class of nanomaterials with potential for application in the nanosciences and nanotechnology.[1] A variety of methods have been demonstrated for the synthesis of fluorescent AgNCs, [2][3][4][5][6][7][8][9][10][11][12][13][14] among which the DNA-templated synthesis of AgNCs [13,15,16] is particularly attractive owing to the low toxicity, good biocompatibility, and unique optical properties of the AgNCs obtained. DNA nanostructures have also been envisioned as templates for metallization, for example, with gold or silver, to create nanowires with desired patterns or junctions for nanoelectronics.[17] However, site specificity and the uniform distribution of the metal NCs along the DNA templates remain a challenge, and these features are crucial for the homogeneity and efficiency of the subsequent metallization.Herein we describe a new DNA-based method for the synthesis of water-soluble fluorescent AgNCs with a narrow size distribution by use of the well-known Tollens reaction, which is commonly employed in carbohydrate chemistry to test for the aldehyde functionality in reducing sugars.[17f] We covalently incorporated a small number of sugar moieties into a DNA sequence at adjacent positions and hoped that they would enable the synthesis of AgNCs by the specific stoichiometry of the Tollens reaction: that is, one aldehyde sugar molecule can reduce two Ag + ions to Ag 0 2 . These Ag clusters could then act as nucleation sites for further Ag deposition under mild reductive conditions. Tethering of the sugar functional groups to DNA offers stabilization of the AgNCs synthesized, [15] and the DNA strands could serve as addressable points for further sequence-specific DNA hybridization. "DNA origami" [18] structures have become superior nanoscale scaffolds for the organization of various classes of functional materials.[19] Herein we demonstrate the sitespecific synthesis and in situ immobilization of AgNCs on a triangular DNA origami [18] scaffold (Figure 1). The addressability of DNA origami enables the site-specific synthesis and in situ incorporation of fluorescent AgNCs on the predefined DNA scaffolds with nanometer-scale spatial resolution.By a reported synthetic strategy, [20] we first synthesized the sugar(galactose)-modified DNA strands DNA1, DNA2, and DNA3, each of which contains 15 nucleotides and one, two, or three consecutive modified deoxyurinidine (dU m ) units, respectively; each dU m unit carries a sugar unit. Details of the synthesis and structural characterization of DNA1-DNA3 are given in the Supporting Information.The Tollens reagent, [Ag(NH 3 ) 2 + ], was first prepared by adding NH 4 OH (28 %) to a solution of AgNO 3 in 1 TAEMg 2+ buffer (40 mm tris(hydroxymethyl)aminomethane (Tris), 20 mm acetic acid, 2 mm ethylenediaminetetraacetic acid, and 12.5 mm Mg(OAc) 2 ) in the dark and then adding excess NH 4 OH to dissolve the precipitated AgOH. The Tollens reagent was filtered and then added to the sugarmodifie...