Nathaniel L. Rosi

Oligonucleotide-Modified Gold Nanoparticles for Intracellular Gene Regulation

We describe the use of gold nanoparticle-oligonucleotide complexes as intracellular gene regulation agents for the control of protein expression in cells. These oligonucleotide-modified nanoparticles have affinity constants for complementary nucleic acids that are higher than their unmodified oligonucleotide counterparts, are less susceptible to degradation by nuclease activity, exhibit greater than 99% cellular uptake, can introduce oligonucleotides at a higher effective concentration than conventional transfection agents, and are nontoxic to the cells under the conditions studied. By chemically tailoring the density of DNA bound to the surface of gold nanoparticles, we demonstrated a tunable gene knockdown.

High and Selective CO2 Uptake in a Cobalt Adeninate Metal−Organic Framework Exhibiting Pyrimidine- and Amino-Decorated Pores

The synthesis and structure of Co(2)(ad)(2)(CO(2)CH(3))(2) x 2 DMF x 0.5 H(2)O (bio-MOF-11) is described. Pyrimidine and amino groups of adeninate (ad) decorate the pores of the framework. The porosity of this material was studied, and its CO(2) and H(2) adsorption properties were evaluated. bio-MOF-11 exhibits a high heat of adsorption for CO(2) (approximately 45 kJ/mol), a high CO(2) capacity (approximately 6 mmol/g, 273 K), and exceptional selectivity for CO(2) over N(2) at 273 K (81:1) and 298 K (75:1).

Cation-Triggered Drug Release from a Porous Zinc−Adeninate Metal−Organic Framework

A porous anionic metal-organic framework, bio-MOF-1, constructed using adenine as a biomolecular building block is described. The porosity of this material is evaluated, its stability in biological buffers is studied, and its potential as a material for controlled drug release is investigated. Specifically, procainamide HCl is loaded into the pores of bio-MOF-1 using a simple cation exchange process. Exogenous cations from biological buffers are shown to affect the release of the adsorbed drug molecules.

Tuning MOF CO2 adsorption properties via cation exchange.

The pore volume and BET surface area of bio-MOF-1 (a), Zn(8)(ad)(4)(BPDC)(6)O.2Me(2)NH(2), is systematically modified via postsynthetic cation exchange with either tetramethylammonium, tetraethylammonium, or tetrabutylammonium cations to yield Zn(8)(ad)(4)(BPDC)(6)O.2Me(4)N (b), Zn(8)(ad)(4)(BPDC)(6)O.2Et(4)N (c), and Zn(8)(ad)(4)(BPDC)(6)O.2Bu(4)N (d), respectively. The impact that pore volume and BET surface area have on CO(2) capacity is evaluated, and it is found that materials with intermediate porosity (b and c) have the largest CO(2) capacities under the conditions studied.

Zinc-Adeninate Metal−Organic Framework for Aqueous Encapsulation and Sensitization of Near-infrared and Visible Emitting Lanthanide Cations

Luminescent metal-organic frameworks (MOFs), Ln(3+)@bio-MOF-1, were synthesized via postsynthetic cation exchange of bio-MOF-1 with Tb(3+), Sm(3+), Eu(3+), or Yb(3+), and their photophysical properties were studied. We demonstrate that bio-MOF-1 encapsulates and sensitizes visible and near-infrared emitting lanthanide cations in aqueous solution.

Total Structure and Electronic Properties of the Gold Nanocrystal Au36(SR)24

A golden opportunity: the total structure of a Au(36)(SR)(24) nanocluster reveals an unexpected face-centered-cubic tetrahedral Au(28) kernel (magenta). The protecting layer exhibits an intriguing combination of binding modes, consisting of four regular arch-like staples and the unprecedented appearance of twelve bridging thiolates (yellow). This unique protecting network and superatom electronic shell structure confer extreme stability and robustness.

Near-Infrared Luminescent Lanthanide MOF Barcodes

We demonstrate the conceptual advantage of using metal-organic frameworks (MOFs) for the creation of a polymetallic material that contains several different near-IR-emitting lanthanide cations and operates as a barcode material with unique luminescence properties. By choosing the ratio of lanthanide salts used during the synthesis, we can control the ratio of lanthanide cations present in the resulting material. We have demonstrated that the emission intensity of each of the different lanthanide cations is proportional to its amount in the MOF crystal, resulting in unique spectroscopic barcodes that depend on the lanthanide cation ratios and compositions.

Peptide‐Based Methods for the Preparation of Nanostructured Inorganic Materials

With their unique sequence-specific self-assembly and their substrate recognition properties, peptides play critical roles in controlling the biomineralization of inorganic nanostructures in natural systems and in directing the assembly of important soft matter. These attributes render them particularly useful molecules for the fabrication of new materials. Researchers from many scientific disciplines now use peptides to direct the synthesis of new inorganic nanostructures and the assembly of soft biomaterials. In this Review we describe the developments in this field and focus on the versatility of peptides and their ability to direct the composition and structure of new inorganic materials.

A new peptide-based method for the design and synthesis of nanoparticle superstructures: construction of highly ordered gold nanoparticle double helices.

Left-handed gold nanoparticle double helices were prepared using a new method that allows simultaneous synthesis and assembly of discrete nanoparticles. This method involves coupling the processes of peptide self-assembly of and peptide-based biomineralization of nanoparticles. In this study, AYSSGAPPMPPF (PEPAu), an oligopeptide with an affinity for gold surfaces, was modified with an aliphatic tail to generate C12-PEPAu. In the presence of buffers and gold salts, amphiphilic C12-PEPAu was used to both control the formation of monodisperse gold nanoparticles and simultaneously direct their assembly into left-handed gold nanoparticle double helices. The gold nanoparticle double helices are highly regular, spatially complex, and they exemplify the utility of this methodology for rationally controlling the topology of nanoparticle superstructures and the stereochemical organization of discrete nanoparticles within these structures.

Metal–biomolecule frameworks (MBioFs)

Biomolecules are the building blocks of life. Nature has evolved countless biomolecules that show promise for bridging metal ions. These molecules have emerged as an excellent source of biocompatible building blocks that can be used to design Metal-Biomolecule Frameworks (MBioFs). This feature article highlights the advances in the synthesis of this class of MOFs. Special emphasis is provided on the crystal structures of these materials, their miniaturization to the submicron length scale, and their new potential storage, catalytic, and biomedical applications.