3.4b Biosensors And Chromatography

Question 1

How do biosensors work

Answer 1

1) a protein like an enzyme or antibody , or a single strand of DNA will be on a strip
- this is so a specific response (substrate , antigen , dna base ) can be generated

2) will react to its specific molecule and produce a reaction , like a colour

Question 2

How does a biosensor work with a transducer to produce a quantitative result ?

Answer 2

• a chemical change of energy will produce a change in electric current and based on this a result can be obtained
• monitors change in pH or current to give quantitative results
• for example blood glucose will cause machine in strip to produce a current

Question 3

Example of how a glucose biosensors works

Answer 3

Strip contains glucose oxidase and blue dye and peroxidase

1) if glucose is there glucose oxidase makes it hydrogen peroxide
2) then peroxidase converts hydrogen peroxide into water and oxygen
3) based on how much glucose is there will give more hydrogen peroxide and thus more water and that changes colour

Question 4

How does chromatography work
Main points
What does TLC chromatography consist of

Answer 4

• ratio of how far it travelled

TLC is a thin layer of silica on plastic inert strip.
- mobile phase goes up the same

1) ink on line so doesn’t dissolve in
2) bung on top so don’t evaporate, as soon as finish draw pencil line …

Question 5

Why TLC better / worse (3/1)

Answer 5

• gives more specific separation of points , better than paper, you can use it to compare two chemicals on same strip
• rigid and robust , you can use strong solvents thst dissolve other samples thst wouldn’t work in paper
• ## similar use warm temps that does it faster and gives better results thst doesn’t damage the plastic
• disadvantage is the cost is expensive