July 18, 2017 Credit: Wiley <\/p>\n
Traces of biomolecules such as DNA can be detected with a new \"dynamic\" technique based on the observation of association and dissociation events of gold nanoparticles. If the desired DNA sequence is present, it can reversibly bind two nanoparticles together. This can be detected in real time through a change in light scattering. As reported in the journal Angewandte Chemie, this method differentiates true signals from noise and can detect deviations of individual bases. <\/p>\n
Detecting and quantifying biomolecules at extremely small concentrations is increasingly important for applications such as early and precise diagnosis, monitoring cancer treatment, forensic investigations, and highly sensitive tests for biological weapons. The current method of choice is the polymerase chain reaction (PCR), which is based on the enzymatic replication of DNA. The disadvantage of this method is the false positives that may result from the tiniest amounts of impurity. <\/p>\n
Scientists working with Jwa-Min Nam at Seoul National University (South Korea) have now developed a new method for detecting extremely small amounts of DNAwithout replication, signal amplification, or false positive results. Their method is based on the detection of individual binding events. Because the binding partners continuously separate and then bind again, the number of detectable results is multiplied and unspecific signals are minimized. This associating and dissociating nanodimer analysis (ADNA) is based on the measurement of light scattering by gold nanoparticles using dark-field microscopy. <\/p>\n
The sample and two types of gold nanoparticles are placed onto a glass slide coated in a lipid double layer. One type of nanoparticle has binding sites on the surface that anchor to the lipid layer. The other type reversibly binds to the lipid layer, remaining mobile. Both nanoparticles have short single-stranded DNA segments that are complementary to two different sequences in the target DNA so that they can bind it. When a mobile nanoparticle comes very close to an immobilized one, the target DNA can bind them into a dimer. <\/p>\n
When two nanoparticles are bound, their vibrations (plasmons) are coupled. This changes the intensity and color of scattered light, which can be detected in real time. The dynamic analysis of dimers that dissociated during observation is the key to the clear differentiation between the presence and absence of the target DNA. The kinetics of the dissociation are significantly different for DNA that is a perfect match and DNA with a single altered base. <\/p>\n
Even in the presence of other DNA, such as in a sample of human blood serum, it was possible to selectively detect and reliably quantify ultra-low concentrations of the target DNA. Under the test conditions used, the detection limit was about 46 DNA copies. <\/p>\n
Explore further: Nanoparticles offer insights into interactions between single-stranded DNA and their binding proteins <\/p>\n
More information: Keunsuk Kim et al. Associating and Dissociating Nanodimer Analysis for Quantifying Ultrasmall Amounts of DNA, Angewandte Chemie International Edition (2017). DOI: 10.1002\/anie.201705330<\/p>\n
Double-stranded DNA must disentangle itself into single strands during replication or repair to allow functional molecules to bind and perform their various operations. Cellular proteins specifically bind to single-stranded ... <\/p>\n
(PhysOrg.com) -- Mention of arsenic poisoning usually brings to mind underhanded murder. However, the danger of arsenic poisoning from contaminated drinking water is far greater. Low concentrations of arsenic are found in ... <\/p>\n
The INM Leibniz Institute for New Materials has joined forces with a manufacturer of analytical equipment to reduce particles losses and avoid false negatives. <\/p>\n
Five years of hard work and a little \"cosmic luck\" led Rice University researchers to a new method to obtain structural details on molecules in biomembranes. <\/p>\n
Medical diagnostics is searching for substances capable of documenting early on whether a serious disease is developing or what its course will be. In many cases, the treacherous molecules are present only in trace amounts ... <\/p>\n
Infectious diseases such as malaria and syphilis can be diagnosed rapidly and reliably in the field by using a simple test developed by Canadian scientists. The test is based on the use of DNAzymes and gold nanoparticles. ... <\/p>\n
Material scientists and physicists from Heidelberg University (Germany) and the University of St Andrews (Scotland) have demonstrated electrical generation of hybrid light-matter particles, so-called exciton-polaritons, by ... <\/p>\n
Traces of biomolecules such as DNA can be detected with a new \"dynamic\" technique based on the observation of association and dissociation events of gold nanoparticles. If the desired DNA sequence is present, it can reversibly ... <\/p>\n
An exotic interaction between light and metal can be harnessed to make chemical reactions more sustainable, but the physics behind it has been widely debated in the field. <\/p>\n
A hypoallergenic electronic sensor can be worn on the skin continuously for a week without discomfort, and is so light and thin that users forget they even have it on, says a Japanese group of scientists. The elastic electrode ... <\/p>\n
A Rice University professor's method to \"upconvert\" light could make solar cells more efficient and disease-targeting nanoparticles more effective. <\/p>\n
Scientists from the Swiss Nanoscience Institute and the University of Basel have succeeded in coupling an extremely small quantum dot with 1,000 times larger trumpet-shaped nanowire. The movement of the nanowire can be detected ... <\/p>\n
Please sign in to add a comment. Registration is free, and takes less than a minute. Read more <\/p>\n
<\/p>\n
Link: July 18, 2017 Credit: Wiley Traces of biomolecules such as DNA can be detected with a new \"dynamic\" technique based on the observation of association and dissociation events of gold nanoparticles. If the desired DNA sequence is present, it can reversibly bind two nanoparticles together. This can be detected in real time through a change in light scattering. Continue reading
\nUltrasensitive DNA quantification by light scattering - Phys.Org<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"