SYBR Green Dye was the indicator used in this experiment. As it binds to DNA, it emits green light clearly when introduced to double-stranded DNA. However, when in the presence of single strands of DNA, RNA, or water, SYBR Green I glows significantly weaker or not at all.
Single-Drop Fluorimeter
A single-drop fluorimeter was the device used in this experiment. It measures the emission of light; in this experiment, it was used to determine the emission of green light from SYBR Green I. The value of the emission is related to the amount of the florescent or the amount of material being identified. If the amount of florescent is identical between samples, then the value of the light emission between samples shows the proportionality of the material being identified. In this pursuit, the amount of SYBR Green I was identical between samples, and the single-drop fluorimeter was utilized to determine the presence of double-stranded DNA (as SYBR Green I glows brightly in double-stranded DNA as compared to other substances).
How the Fluorescence Technique Works
Spectrofluorometer is extremely flexible, providing continuous ranges of excitation and emission wavelength. The light from an excitation source passes through a filter or monochromatic, and strikes the sample. A proportion of the incident light is absorbed by the sample, and some of the molecules in the sample fluoresce. The fluorescent light is released in all directions.
Procedure
Smart Phone Camera Settings
Type of Smartphone: Apple iPhone 5S
Flash: OFF
ISO setting: Auto
White Balance: Auto
Exposure: Auto
Saturation: Auto
Contrast: Auto
Calibration
The iPhone was placed in the cradle for support, allowing the camera to point directly at the slide at a right angle. The height of the fluorimeter was adjusted accordingly to allow for the best angle for the test.
Distance between the smart phone cradle and drop = 6.5 cm
Solutions Used for Calibration
Placing Samples onto the Fluorimeter
Step one consisted of setting up the camera in the cradle and aligning it at a certain length away from the light that shines on the drops of liquid on the slide.
The second step was making sure all the samples were properly mixed into the different solutions.
The third step was to place 80 micro liters on the slide with the rough hydrophobic side right in the middle of the beam or light.
Step four was making sure to cover the sample and that no light was coming in and reaching the solution so the camera could take the picture of the sample. Steps 1-4 were repeated until all solutions were completed.
Data Analysis
Representative Images of Samples
Sample with no DNA
Sample with DNA
Image J Values for All Samples
Original Calibration
Final DNA Concentration
RAWINTDEN of the Drop
RAWINTDEN of the Background
RAWINTDEN (drop) - RAWINTDEN (background)
0
345313
30224
315089
0
180564
6007
174557
0.25
491145
21842
469303
0.25
397249
24163
373086
0.5
422049
21030
401019
0.5
508450
20911
487539
1
600240
28758
571482
1
591941
31183
560758
2
630004
34042
595962
2
581118
28959
552159
5
667090
46900
620190
5
711795
34870
676925
Quick Calibration
Final DNA Concentration
RAWINTDEN of the Drop
5
959866
5
889122
2
408293
2
829977
1
356280
1
658943
PCR Product Sample Measurements
PCR Product TUBE LABEL
Volume of the DILUTED PCR Product solution (µL)
Volume of the SYBR GREEN I Dye solution (µL)
INTDENS VALUES BASED ON 3 SEPARATE DROP MEASUREMENTS
'
'
AVERAGE INTDENS VALUE
1A
80
80
256371
412299
165141
154247
2A
80
80
388143
377660
332221
366008
3A
80
80
238397
188553
437579
288176.333
1B
80
80
219121
484088
354011
352406.6667
2B
80
80
369201
331460
355380
352013.6667
3B
80
80
378003
335356
349226
354195
Fitting a Straight Line
This graph represents the relationship between concentration and RAWINTDEN.
Your positive control PCR result was 0.2306 μg/mL
Your negative control PCR result was -0.066416 μg/mL
Write-in each patient ID and give both a qualitative (what the images looked like) and a quantitative description (μg/mL) of what you observed
Patient 32298 : This patient did not produce a fluorescent light when the green dye solution was added to the slides. There was an average PCR product concentration of -0.11065 μg/mL.
Patient 26685 : This patient also did not produce a fluorescent light when the green dye solution was added to the slides. There was an average PCR product concentration of -0.04375 μg/mL.
Compare each patient's results to the positive control value and the negative control value. Draw a final conclusion for each patient (positive or negative) and explain why you made that conclusion.
Patient 32298 : After comparing the two controls, it can be concluded that Patient 32298 does not contain the DNA strand because the patient's PCR Concentration values were negative and close to that of the negative control value.
Patient 26685 : After comparing the two controls, it can be concluded that Patient 26685 also does not contain the DNA strand because this patient's PCR Concentration values were also negative and close to that of the negative control value.