Severity: Warning
Message: file_get_contents(https://...@gmail.com&api_key=61f08fa0b96a73de8c900d749fcb997acc09): Failed to open stream: HTTP request failed! HTTP/1.1 429 Too Many Requests
Filename: helpers/my_audit_helper.php
Line Number: 143
Backtrace:
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 143
Function: file_get_contents
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 209
Function: simplexml_load_file_from_url
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 994
Function: getPubMedXML
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 3134
Function: GetPubMedArticleOutput_2016
File: /var/www/html/application/controllers/Detail.php
Line: 574
Function: pubMedSearch_Global
File: /var/www/html/application/controllers/Detail.php
Line: 488
Function: pubMedGetRelatedKeyword
File: /var/www/html/index.php
Line: 316
Function: require_once
Cleaved, cation-derivatized Muscovite mica is utilized extensively in atomic force microscopy (AFM) imaging because of its flatness over large areas (millimeter cleavage planes with local root-mean-square roughness < 0.3 nm), ease of preparation, and ability to adsorb charged biomolecules such as DNA (work by Hansma and Laney, Guthold et al., and McMaster et al.). In particular, NiCl(2) treatment has become a common method for controlling DNA adsorption on mica substrates while retaining the mica's ultraflat surface (work by Pietrement et al.). While several studies have modeled the mica/metal ion/DNA system using macroscopic colloidal theory (DLVO, etc.; Pietrement et al., Sushko et al., Pastre et al., and Cheng et al.), nickel/mica's physicochemical properties have not been well characterized on the nanoscale. Efforts to manipulate and engineer DNA nanostructures would benefit greatly from a better understanding of the surface chemistry of nickel/mica. Here we present in situ nanometer- and attogram-scale measurements and thermodynamic simulation results that show that the surface chemistry of nickel-treated mica is more complex than generally appreciated by AFM practitioners because of metal-ion speciation effects present at neutral pH. We also show that, under certain preparations, nickel/mica allows in situ nanoscopic nucleotide sequence mapping within individual surface-adsorbed DNA molecules by permitting localized, controlled desorption of the double helix by soluble DNA binding enzymes. These results should aid efforts to precisely control the DNA/mica binding affinity, particularly at the physiological pH ranges required by enzymatic biochemistry (pH 7.0-8.5), and facilitate the development of more complex and useful biochemical manipulations of adsorbed DNA, such as single-molecule sequencing.
Download full-text PDF |
Source |
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3010388 | PMC |
http://dx.doi.org/10.1021/am100697z | DOI Listing |
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