Literature/202212291648 optical methods for single molecule analysis

<ul> <li>Source: [<a class="litnote tooltip" href="/literature/@walt2013">@walt2013<span class="tooltiptext">Optical Methods for Single Molecule Detection and Analysis</span></a>]</li> <li>Tags: <a href="/tags/single-molecule">#single-molecule</a> <a href="/tags/analysis">#analysis</a> <a href="/tags/detection">#detection</a> </li> </ul> <p>The earliest method to get single-molecule data is to interrogate a very small volume. For example, if we consider a $1\mu m^3=1\,\textrm{fl}$ volume with only one molecule inside, we get a concentration of $100\, \textrm{nM}$. However, at a concentration of $1\ \textrm{fM}$, we have 600 molecules per $10^9$ femto-liter volumes. </p> <p>Therefore, flow-methods (like <a class="wikilink" href="/flow_cytometry/">Flow Cytometry</a>) operate a concentration regimes close to pico-molar: concentrated enough to detect a statistically significant number of molecules, and diluted enough to neglect coincidental detections (known as <a class="wikilink" href="/swarming/">swarming</a> in flow cytometers). </p> <p>Low concentrations are important, for example see: <a class="wikilink" href="/literature/202212291643_errors_in_amino_acid_sequences/">literature/202212291643 Errors in amino acid sequences</a>, <a class="wikilink" href="/why_pushing_sensitivity_of_assays/">why pushing sensitivity of assays</a>. </p> <ul> <li> <p>Many methods rely on pre-concentration steps, to limit the volume that must be scanned. Examples:</p> <ul> <li><a class="wikilink" href="/simoa/">Simoa</a></li> <li><a class="wikilink" href="/erenna/">Erenna</a></li> </ul> </li> <li> <p>Some methods are truly single-molecule sensitive:</p> <ul> <li><a class="wikilink" href="/zero-mode_waveguide/">Zero-mode waveguide</a></li> </ul> </li> </ul>