Gel Diffusion AnalysisGel Diffusion Analysis

STEM ED/CHMSTEM ED/CHM

Nanotechnology 2011Nanotechnology 2011

Presented by Jennifer Welborn Presented by Jennifer Welborn

BackgroundBackground

The delivery of nanoscale medicines The delivery of nanoscale medicines to cells in the human body requires to cells in the human body requires diffusion through tissues, organs and diffusion through tissues, organs and cell membranescell membranes

This activity will explore the affect of This activity will explore the affect of particle size on diffusion ratesparticle size on diffusion rates

Understanding molecular diffusion Understanding molecular diffusion through human tissues is important through human tissues is important for designing effective drug delivery for designing effective drug delivery systems systems

IntroductionIntroduction

Measuring the diffusion of dyes in gelatin Measuring the diffusion of dyes in gelatin illustrates the transport of drugs in the illustrates the transport of drugs in the extra-vascular space extra-vascular space

Gelatin is a biological polymeric material Gelatin is a biological polymeric material with similar properties to the connective with similar properties to the connective extracellular matrix in tumor tissueextracellular matrix in tumor tissue

Dyes are similar in molecular weight and Dyes are similar in molecular weight and transport properties to transport properties to chemotherapeuticschemotherapeutics

Their concentration can be easily Their concentration can be easily determined simply by color intensitydetermined simply by color intensity

Analysis In The Classroom

Groups can share data – model for repeated trials- all data can be combined onto one data table

Provides for discussion of constants, outliers, statistical analysis ( basic– range, mean-- and advanced– standard deviation, etc.)

Visual measurement = actual distance dye diffused

Photo measurements can be used as is for comparison between dyes, or they can be used to calculate actual distance diffused

using a ratio- provides opportunity to discuss use of tools to improve reduce error in measurement.

Diffusion screen measurement X gel radius screen measurement = 32.5 mm

Gel radius = 32.5 mm

Image AnalysisImage Analysis

Method 1: Method 1: – Measure the dye diffusion distance each Measure the dye diffusion distance each

day using a ruler.day using a ruler.– Use graph paper to plot distance vs. timeUse graph paper to plot distance vs. time– The rate is the slope of the line. During The rate is the slope of the line. During

the relatively short diffusion time (as in the relatively short diffusion time (as in this lab), the relationship between this lab), the relationship between distance and time is somewhat linear. A distance and time is somewhat linear. A line of best fit may not have a y-intercept line of best fit may not have a y-intercept of 0 due to error. of 0 due to error.

Measurement by HandMeasurement by Hand

y = 0.2057x + 1.0715

0

2

4

6

8

10

12

14

16

18

0 20 40 60 80

Time

Dis

tan

ce

(m

m)

Image AnalysisImage Analysis Method 2: Group Pictures by Color in Method 2: Group Pictures by Color in

date/time orderdate/time order

– Create a data table (paper or Excel)Create a data table (paper or Excel)

6-1-0600 6-1-1800 6-2-0600 6-2-1800

Pick one color to startPick one color to start Load the first morning shotLoad the first morning shot

– Windows Photo Gallery or other image Windows Photo Gallery or other image programprogram

Using the magnifier, expand the Using the magnifier, expand the photophoto

Using a mm ruler, measure from the Using a mm ruler, measure from the edge of the gel disk to the inner most edge of the gel disk to the inner most edge of the diffusion for each color. edge of the diffusion for each color.

Enter diffusion distances for each Enter diffusion distances for each color and time period in the color and time period in the appropriate column of your data appropriate column of your data tabletable

When finished, your table might When finished, your table might look something like thislook something like this

Use the graphing wizard to complete the Use the graphing wizard to complete the project.project.

Image Analysis Method 31.Download ADI software from: http://www.umassk12.net/adi

2. Open one of your photos. Trim. Use the line tool and color along the line option to observe the change in RGB values along the line which illustrates the diffusion of the dye.

3. Repeat Step 2 with the other photos you took.

Directions for Using ADI

1. Open a picture using analyzing digital images software

2. Use the trim option available to reduce processing speed

4. Select Line tool under file options5. Clicking on blue and red squares under adjust can fine tune placement

of coordinate points. 6. Draw line. Note coordinates and color averages along line.

Calculate Mean Percentage of DiffusionFor the last time period measured and for each color

of dye, calculate and record the mean percentageof diffusion

Use: total distance traveled by dye in mm / 32.5 x 100 = ________%

Questions to considerQuestions to consider

Are the results expected? Are the results expected? Which dyes penetrated better?Which dyes penetrated better? Does that make sense? Does that make sense? Conversely, does fast diffusion mean Conversely, does fast diffusion mean

greater or poorer retention?greater or poorer retention? How could diffusion and retention be How could diffusion and retention be

optimized?optimized? Is this the intuitive result? Is this the intuitive result?