COLLOIDAL particles of metals and semiconductors have potentially useful optical, optoelectronic and material properties1–4 that derive from their small (nanoscopic) size. These properties might lead to applications including chemical sensors, spectro-scopic enhancers, quantum dot and nanostructure fabrication, and microimaging methods2–4. A great deal of control can now be exercised over the chemical composition, size and polydis-persity1,2 of colloidal particles, and many methods have been developed for assembling them into useful aggregates and materials. Here we describe a method for assembling colloidal gold nanoparticles rationally and reversibly into macroscopic aggregates. The method involves attaching to the surfaces of two batches of 13-nm gold particles non-complementary DNA oligo-nucleotides capped with thiol groups, which bind to gold. When we add to the solution an oligonucleotide duplex with 'sticky ends' that are complementary to the two grafted sequences, the nanoparticles self-assemble into aggregates. This assembly process can be reversed by thermal denaturation. This strategy should now make it possible to tailor the optical, electronic and structural properties of the colloidal aggregates by using the specificity of DNA interactions to direct the interactions between particles of different size and composition.

A DNA-based Method for Rationally Assembling Nanoparticles Into Macroscopic Materials

http://experimentationlab.berkeley.edu/sites/default/files/AFMImages/butt_AFM.pdf

Force measurements with the atomic force microscope: Technique, interpretation and applications

The large ribosomal subunit catalyzes peptide bond formation and binds initiation, termination, and elongation factors. We have determined the crystal structure of the large ribosomal subunit from Haloarcula marismortui at 2.4 angstrom resolution, and it includes 2833 of the subunit's 3045 nucleotides and 27 of its 31 proteins. The domains of its RNAs all have irregular shapes and fit together in the ribosome like the pieces of a three-dimensional jigsaw puzzle to form a large, monolithic structure. Proteins are abundant everywhere on its surface except in the active site where peptide bond formation occurs and where it contacts the small subunit. Most of the proteins stabilize the structure by interacting with several RNA domains, often using idiosyncratically folded extensions that reach into the subunit's interior.

https://science.sciencemag.org/content/sci/289/5481/905.full.pdf

The complete atomic structure of the large ribosomal subunit at 2.4 A resolution.

The DNA of telomeres--the terminal DNA-protein complexes of chromosomes--differs notably from other DNA sequences in both structure and function. Recent work has highlighted its remarkable mode of synthesis by the ribonucleoprotein reverse transcriptase, telomerase, as well as its ability to form unusual structures in vitro. Moreover, telomere synthesis by telomerase has been shown to be essential for telomere maintenance and long-term viability.

Structure and function of telomeres

Molecular self-assembly presents a `bottom-up' approach to the fabrication of objects specified with nanometre precision. DNA
 molecular structures and intermolecular interactions are particularly
 amenable to the design and synthesis of complex molecular objects. We
 report the design and observation of two-dimensional crystalline forms
 of DNA that self-assemble from synthetic DNA double-crossover
 molecules. Intermolecular interactions between the structural units are
 programmed by the design of `sticky ends' that associate according to
 Watson-Crick complementarity, enabling us to create specific periodic
 patterns on the nanometre scale. The patterned crystals have been
 visualized by atomic force microscopy.

https://issg.cs.duke.edu/courses/spring04/cps296.4/papers/WLWS98.pdf

Design and self-assembly of two-dimensional DNA crystals

A system for a trajectory and aiming guide for use with fluoroscopy is comprised of a ring holder is with a plurality of connecting arms, a radiolucent ring disk with an outer perimeter wall and a central axle on the bottom surface of the ring disk; a first rotatable disk located below the ring holder and comprised of a handle, a radiolucent disk ring with a central cutout to receive the central axle, the material of the disk comprising an embedded array of a plurality of radiopaque wires and an outer perimeter wall; a second rotatable disk located below the first rotatable disk and comprised of a handle, a radiolucent disk ring with a central cutout to receive the central axle, the material of the disk comprising an embedded array of a plurality of radiopaque wires and an outer perimeter wall; and a locking cap for the axle.

Trajectory and aiming guide for use with fluoroscopy

L'invention concerne l'interrogation de volumes d'echantillon extremement petits. L'invention concerne des sondes presentant sur leur surface une pluralite de domaines formant un reseau, en particulier un nanoreseau. L'invention concerne egalement des methodes de detection de molecules et d'evenements d'interaction moleculaire, de recuperation et d'analyse d'analytes, et d'administration de substances a des cellules ou a des tissus, au moyen de sondes de l'invention.

Methode et appareil pour une analyse moleculaire dans de petits volumes d'echantillon

The atomic force microscope (AFM) is proving to be a powerful tool for analysis of biological samples. We provide three examples of the application of AFM to the study of biological questions. First, polytene chromosomes from Drosophila are imaged and manipulated by the AFM. Second, the localization of calcium channels on the release face of a nerve terminal is described. Finally, analyses of a new form of DNA, the G-wire, is presented. These examples illustrate the wide variety of biological questions to which AFM can contribute.

https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=1003&context=zool_conf

Analyzing chromosomes, ion channels and novel nucleic acid structures by afm

ABSTRACT Introduction Reconstructing long bone defects following intercalary tumor resection presents an exciting challenge with a greater range of surgical solutions than more typical situations requiring arthroplasty. Segmental bone transport (distraction osteogenesis) is the least utilized option for intercalary reconstruction; however, it arguably provides patients with the most desirable result. Distraction osteogenesis can be used in the management of multiple skeletal conditions including deformity (congenital or acquired), or in the presence of bone defects (by trauma or planned surgical excision). Lack of broader adoption of transport is likely due to the highly technical demands and common complications of utilizing fine-wire fixators via the Ilizarov method. More recently, internal lengthening nails such as the PRECICE nail have been employed to facilitate distraction osteogenesis without the added complexity of external fixation. Areas covered This review will examine the literature on the indications, design, and safety of the PRECICE nail (NuVasive) for intercalary reconstruction after tumor resection. Expert opinion Bone transport using the PRECICE nail represents a viable alternative to Ilizarov distraction and has the benefit of avoiding the complications of an external fixator. For large defects, the PRECICE nail can be supplemented with a locking plate for additional stability and maintenance of limb length.

Use of the PRECICE nail for distraction osteogenesis after tumor resection

Hemangioblastoma, one of the characteristic tumors associated with Von Hippel-Lindau (VHL) disease, most often presents in the central nervous system (CNS) but can uncommonly arise in extraneuraxial, or previously referred to as peripheral, locations. Without the clinical context of known VHL disease, hemangioblastoma may not enter the differential for a soft tissue mass outside the CNS. Here, we present two patients with diagnostically challenging extraneuraxial hemangioblastoma to highlight the importance of considering this entity within the differential diagnosis of soft tissue neoplasms containing clear cells and delicate vasculature. We review the relevant diagnostic features, including a suggested immunohistochemical panel, along with the potential associated clinical implications of making this diagnosis. It is recommended that affected patients be offered genetic counseling to assess for underlying VHL disease.

Eric Henderson

Papers

Trajectory and aiming guide for use with fluoroscopy

Methode et appareil pour une analyse moleculaire dans de petits volumes d'echantillon

Analyzing chromosomes, ion channels and novel nucleic acid structures by afm

Use of the PRECICE nail for distraction osteogenesis after tumor resection

Extraneuraxial Hemangioblastoma: An Unusual Soft Tissue Neoplasm that Mimics More Common Entities but Carries Distinct Clinical Implications