Adsorption solutions tested in experiment.

<p>Adsorption of DNA on silica was tested in six different adsorption solutions. Solutions at pH 3, 5.2, and 8 were buffered with 225 mM sodium formate, sodium acetate, and Tris-Cl respectively.</p

Lost DNA following incubation with silica.

<p>Plots show amount of DNA not adsorbed to silica after 1 hour of incubation for each adsorption solution. Solutions tested were pH 3 (circles), 5.2 (triangles), and 8(squares), and solutions D, E, and F also contained 5 M GuSCN. Note that DNA loss for 2.5, 25, and 250 pg/mL are not shown for adsorption solution D, since the signal from those values for unadsorbed DNA fell below that of the no DNA control. (n = 3).</p

Schematic of general protocol.

<p>Silica, adsorption solution, and DNA were combined in a microcentrifuge tube. This solution was incubated for 1 hour in an agitated state to promote mixing. The silica particles and any DNA adsorbed onto them were separated from solution using a filter. The supernatant was analyzed to determine the ‘Lost DNA’ (DNA amount not adsorbed after incubation). The particles were subsequently washed with 70% ethanol and dried. The elution buffer was then added and incubated for 5 min before it was also collected to determine the ‘Recovered DNA’ (DNA amount eluted from the silica surface.</p

Colorimetric Detection of Azidothymidine Using an Alkyne-Modified Dextran Substrate

Monitoring the adherence of patients taking highly active antiretroviral therapy (HAART) is a key step in treating an HIV infection, especially in resource-limited settings in the developing world. For most regimens, when patients are not at least 95% adherent to their drug schedule, there is a loss of effectiveness in treatment resulting in increases in health care costs, increases in the rate of transmission, and reduction of positive patient outcomes. Currently, subjective methods such as pill counting, electronic drug monitoring, and patient self-reporting are the only ways clinicians can track adherence and intervene in cases of noncompliance. We address this issue by developing a dipstick-based point-of-care azide–alkyne click chemistry assay with colorimetric read-out that directly tests for the presence of one common HAART drug in patient urine. An alkyne-modified dextran was synthesized and characterized by NMR and then used to colorimetrically report the presence of azidothymidine, an azide-containing HAART drug, in urine samples. The assay is specific to azide-containing molecules that are not naturally present in the urine and is sensitive to physiologically relevant urine concentrations as low as 750 uM. This point-of-care device is a strong alternative in resource-limited settings over current direct measurement techniques that are expensive and require trained users such as HPLC

Schematic of qPCR data analysis.

<p>Relative fluorescence (ΔRn) was recorded at each PCR cycle for samples and standards of known DNA amounts. A ΔRn threshold value was chosen (green line) in the linear region to determine a Ct value. The Ct value is plotted vs. the amount of input DNA and fit with a regression line. This line was used to back-calculate the initial amount of DNA in an unknown sample by plotting sample on the line with its Ct value.</p

Elution of DNA from silica using varying elution buffers.

<p>Amount of recovered DNA using five different elution buffers. Samples were eluted after 1 μg DNA was incubated with silica in adsorption solution D (5 M GUSCN pH 3). (n = 3).</p

Demographic Characteristics of Study Participants.

<p>Demographic Characteristics of Study Participants.</p

Bivariate Analysis of understanding why POC could be useful.

<p>Bivariate Analysis of understanding why POC could be useful.</p

Multivariate Analysis of understanding why POC could be useful.

<p>Multivariate Analysis of understanding why POC could be useful.</p

Knowledge of and Interest in Using POC Technology.

<p>Knowledge of and Interest in Using POC Technology.</p