Defects Can Increase the Melting Temperature of DNA-Nanoparticle Assemblies

DNA-gold nanoparticle assemblies have shown promise as an alternative technology to DNA microarrays for DNA detection and RNA profiling. Understanding the effect of DNA sequences on the melting temperature of the system is central to developing reliable detection technology. We studied the effects of DNA base-pairing defects, such as mismatches and deletions, on the melting temperature of DNA-nanoparticle assemblies. We found that, contrary to the general assumption that defects lower the melting temperature of DNA, some defects increase the melting temperature of DNA-linked nanoparticle assemblies. The effects of mismatches and deletions were found to depend on the specific base pair, the sequence, and the location of the defects. Our results demonstrate that the surface-bound DNA exhibit hybridization behavior different from that of free DNA. Such findings indicate that a detailed understanding of DNA-nanoparticle assembly phase behavior is required for quantitative interpretation of DNA-nanoparticle aggregation.Comment: 12 pages, 3 figure

Disorder in DNA-Linked Gold Nanoparticle Assemblies

We report experimental observations on the effect of disorder on the phase behavior of DNA-linked nanoparticle assemblies. Variation in DNA linker lengths results in different melting temperatures of the DNA-linked nanoparticle assemblies. We observed an unusual trend of a non-monotonic ``zigzag'' pattern in the melting temperature as a function of DNAlinker length. Linker DNA resulting in unequal DNA duplex lengths introduces disorder and lowers the melting temperature of the nanoparticle system. Comparison with free DNA thermodynamics shows that such an anomalous zigzag pattern does not exist for free DNA duplex melting, which suggests that the disorder introduced by unequal DNA duplex lengths results in this unusual collective behavior of DNA-linked nanoparticle assemblies.Comment: 4 pages, 4 figures, Phys.Rev.Lett. (2005), to appea

Laser modulation at the atomic level monthly report no. 8, 1 - 28 feb. 1965

Measurement of temperature dependence of energy levels involved in laser emissio

Laser modulation at the atomic level monthly report no. 7, 1-31 jan. 1965

Laser modulation at atomic level - yttrium- aluminum garnet emission and laser emission shift with homogeneous pulsed magnetic fiel

Discharge Patterns of Single Fibers in the Cat's Auditory Nerve

Discharge patterns of single fibers in cat auditory nerve in response to controlled acoustic stimul

The NASA-Ames Research Center stratospheric aerosol model. 2. Sensitivity studies and comparison with observatories

Sensitivity tests were performed on a one-dimensional, physical-chemical model of the unperturbed stratospheric aerosols, and model calculations were compared with observations. The tests and comparisons suggest that coagulation controls the particle number mixing ratio, although the number of condensation nuclei at the tropopause and the diffusion coefficient at high altitudes are also important. The sulfur gas source strength and the aerosol residence time are much more important than the supply of condensation nuclei in establishing mass and large particle concentrations. The particle size is also controlled mainly by gas supply and residence time. In situ observations of the aerosols and laboratory measurements of aerosols, parameters that can provide further information about the physics and chemistry of the stratosphere and the aerosols found there are provided

The NASA-AMES Research Center Stratospheric Aerosol Model. 1. Physical Processes and Computational Analogs

A time-dependent one-dimensional model of the stratospheric sulfate aerosol layer is presented. In constructing the model, a wide range of basic physical and chemical processes are incorporated in order to avoid predetermining or biasing the model predictions. The simulation, which extends from the surface to an altitude of 58 km, includes the troposphere as a source of gases and condensation nuclei and as a sink for aerosol droplets. The size distribution of aerosol particles is resolved into 25 categories with particle radii increasing geometrically from 0.01 to 2.56 microns such that particle volume doubles between categories

Research Notes : United States : Linkage of electrophoretic loci

In our studies of the inheritance of various electrophoretic variants, we have examined F2 segregation data from many crosses (see Gorman, 1983, for a listing). Many of these crosses were segregating for multiple loci, allowing linkage data to be collected. Table 1 represents a sunnnary of the linkage patterns we have observed between the listed electrophoretic loci (see Gorman and Kiang, 1978; Kiang, 1981; Gorman et al., 1983, concerning the establishment of these loci)

Research Notes: Amylase and acid phosphatase genotypes of Glycine max, Glycine soja and Neonotonia wightii

Three amylase loci, Am-1, Am-2 , and Am-3, have been identified by electrophoresis (Gorman and Kiang , 1978) . The activity of amylase at Am-1 and Am-2 is very weak, and that at Am-3 is much str onger. Based on heat lability and chemical reaction, Reiss (1978) concluded Am-1 and Am- 2 represent α - amylase and Am-3 β-amylase