Biomod/2011/HKBU/NBgamers:Results: Difference between revisions

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<tr> <td bgcolor="#232323" align="center"> <h3 align="center" style="color:white; font-size:20px;" >Results</h3> </td> </tr>

<h3>Content</h3> <ol>

 <li><a href="#Intensity Optimization">Intensity Optimization</a></li>
 <li><a href="#Calibration">Calibration</a></li>
 <li><a href="#Multiplex Detection">Multiplex Detection</a></li>

</ol> <br />

<h3><a name="Intensity Optimization">Intensity Optimization</a></h3> <p> In our project, each individual fibril is labeled by quantum dots (QD). The intensity of the output fluorescence signal from the QDs determines the ability of indentifying the fibrils. Therefore, maximizing the QD fluorescence signal intensity is one of our tasks. There are several factors influencing the output intensity: </p> <ol>

 <li>The ratio between the free Aβ monomers and biotinylated Aβ monomers.</li>
 <p>Imagining you put the free Aβ monomers and the biotinylated Aβ monomers into buffers to let them self-assemble into fibrils. If we choose a large proportion of free Aβ monomers, we may get a relatively long length distribution of fibrils. But since QD labeled streptavidin only "sits" on biotinylated Aβ monomers, there may not be enough seats for them to sit on. Therefore, in this case, the average intensity on each fibril may be low.</p>
 <li>The dilution factor of fibrils.</li>
 <p>After you assembled the fibrils, don't rush to let the QD labeled streptavidin sit on the seats. If there are a huge amount of fibrils, even though the number of seats on each fibril is sufficiently large, there may not be enough QDs to fully occupy them and hence result in a low average intensity on each fibril. On the contary, if we first dilute the buffer of fibrils, QDs may be able to fully occupy each of the fibrils and hence result in a high average intensity on each fibril.</p>

</ol> <p> The bar chart below shows the measured output intensity from the QDs under different conditions: </p> <p align="center"> <a href="http://openwetware.org/images/6/6a/Intensity_Optimization.png"> <img src="http://openwetware.org/images/6/6a/Intensity_Optimization.png" width="454.5" height="373.5" alt="Intensity measurement (Clikc to enlarge.)" title="Intensity measurement (Clikc to enlarge.)"> </a> </p> <p> The result of the intensity optimization gives us a suggestion: A condition with 20% biotin ratio and 50X dilution factor should be a good choice. </p> <br />

<h3><a name="Calibration">Calibration</a></h3> <p> We believe that, the fluorescence intensity emitted from YOYO will be proportional to the DNA target concentration: The more the targets are, the stronger the signal will be! Therefore, we performed calibration with a set of target concentration. The experiment result is shown in the figure below: </p> <p align="center"> <a href="http://openwetware.org/images/a/ae/NBgamers_calibration.png" alt="Calibration (Click to enlarge.)" title="Calibration (Click to enlarge.)"> <img src="http://openwetware.org/images/a/ae/NBgamers_calibration.png" width="415" height="292"> </a> </p> <p> We observed that, in the region of low target concentration (down to pM), there is a linear relationship between the fluorescence intensity from YOYO and the DNA target concentration. This result is very desirable. Because it indicates our nanosensor does not only sense the presence of the target, but also gives an accurate measurement on the amount of the target! </p> <br />

<h3><a name="Multiplex Detection">Multiplex Detection</a></h3> <p> There is another advantage of our nanosensor: Multiplex Detection, which means our sensor can detect multiple targets at the same time. To realize this idea, we use highly flourescent quantum dots. Quantum dots of different emission wavelengths are labeled on the streptavidin. We use them to distinguish different probes. </p> <p align="center"> <a href="http://openwetware.org/images/4/48/NBgamers_QD_Label.png" alt="QD Labeling (Click to enlarge.)" title="QD Labeling (Click to enlarge.)"> <img src="http://openwetware.org/images/4/48/NBgamers_QD_Label.png" width="462" height="203"> </a> </p> <p> The images below show the fluorescence signal from QD 565 nm and QD 625 nm. They are indicating the locations of two different probes. </p> <p align="center"> <a href="http://openwetware.org/images/5/57/NBgamers_QD565_QD625.png" alt="QD565_QD625 (Click to enlarge.)" title="QD565_QD625 (Click to enlarge.)"> <img src="http://openwetware.org/images/5/57/NBgamers_QD565_QD625.png" width="476" height="260"> </a> </p> <p> If one compare the fluorescence signal from quantum dots and the signal from YOYO in the same field of view, one can notice that: The image of YOYO shows the signal coming from all kinds of probes, but it does not tell which kind of probe the signal comes from. Now, with the aid of quantum dots, one can easliy distinguish different probes and indentify the location of corresponding nanosensors. </p> <p align="center"> <a href="http://openwetware.org/images/6/62/NBgamers_QD_YOYO.png" alt="QD_YOYO (Click to enlarge.)" title="QD_YOYO (Click to enlarge.)"> <img src="http://openwetware.org/images/6/62/NBgamers_QD_YOYO.png" width="476" height="260"> </a> </p> <br />

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Biomod/2011/HKBU/NBgamers:Results: Difference between revisions

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