BLOCK 2 BIO1 Flashcards
What is meant by bioanalytical chemistry?
Development of analytical methodology to identify, quantify and understand the
role and structure of molecules in various biological samples
Development of tools that incorporate a biological component as part of the
detection principle - Bioassays and Biosensors
What is meant by a screening test (binary versus quantitative)?
Biosensing technologies for screening of samples in a
large sample population, i.e., for rapid and selective
detection of target compounds.
Binary readout
- Pregnant Yes or No
Quantitative readout
-Normal blood glucose level ca 4-6 mM
What is meant by false positive and false negative test, respectivvely?
False negative: A truly positive sample is not detected
False positive: A truly negative sample is detected as positive
Explain the difference between a bioassay and a biosensor
Bioassay:
A procedure for determining the concentration, purity, and/or biological
activity of a substance (e.g., vitamin, hormone, plant growth factor, antibiotic,
enzyme) by measuring its effect on an organism, tissue, cell, enzyme or
receptor preparation compared to a standard preparation
-An analytical method to determine concentration or potency of a substance by its effect on living cells, tissues, receptor, enzyme
Biosensor:
A self-contained integrated device providing quantitative and semi-quantitative
analytical information, composed of a biological recognition element (bioreceptor)
in direct spatial contact with a transduction element
- A bioassay, in which the biological component is
in close proximity to a physical transducer (e.g. electrode, optical probe), most often immobilised on the transducer surface
Give examples of different biological and artificial affinity molecules that can be used to develop biosensors.
Biological recognition:
-DNA/RNA
-Enzyme
-Antibody
Artificial recognition:
- Molecular imprinted polymers - MIPs - Chemically synthesized - Plastic antibodies
-Aptamers – Short single stranded synthetic nucleic acids (ssDNA or RNA) (or peptides)
How does a typical electrochemical glucose biosensor work?
How does a Lateral Flow Assay work?
In LFA, a liquid sample comprising the target analyte moves through test and control lines of paper strips under capillary force and makes contact with the capture probe immobilized on the membrane
How can you detect an ongoing Covid 19 infection respective a past covid 19 infection using a LFA ?
How can you immobilize (attach) biological affinity molecules on surfaces and what is most critical to consider for good functionality?
It is done by oriented covalent attachment, a covalenet reaction made with the surface, the enzyme and some molecule that gives common covalent bond to the surface and the enzyme
Avoid immobilizing via the active site of enzymes or the ligand binding site of anitbodies, nucleic acids, recpetors
Advantages:
Improved stability
Recyling/Regeneration
Possibility to stop the reaction
Disadvantages:
Lower affinity (anitbodies) or reaction rates (enzymes)
Cost for carrier and immboilisation reagents
What is the difference between compettive and non-competive immunoassay?
What is the difference between a signal ON versus a signal OFF nucleic acid biosensor?
Signal off:
The signal decreasses when target binds
Signal is ON to begin and goes OFF when target binds
Signal on:
The signal increases when target binds
Signal is OFF to begin and goes ON when target binds
Give examples of some different types of biosensors
Glucose
BIAcore
Pregnancy test
What type of information can be obtained from different types of biosensors?
Identification
Quantitative
Biological activity
-Mutations
-Genotoxicity
-Inhibtion/activation
-Agonist/Antagonist
-Metabolism
-Bioavailaility
Describe different analytical sensor/method performance criteria (sensitivity, specificity, linear range, limit of detection, accuracy and precision etc.).
Sensitivity:
1. Quantitative sensor - The slope of the calibration curve, i.e. the change in the measured quantity with concentration, e.g. uA/µM or Absorbance/µM.
- Binary sensor - The test’s ability to identify an individual with disease as positive. A highly sensitive test means that there are few false negative results, and thus fewer cases of disease are missed.
Accuracy:
Refers to how close a measuerment is to the ture or accepted value
Precision:
Refers to how close measurements of the same item are to each other,
i.e., how repeatable a measurement is.
Specificity:
1. Quantitative sensor: Ability to respond only to the analyte of interest in a mixture without any influence of other species
- Binary sensor: Ability to identify an individual who does not have a disease as negative. A highly specific test means that there are
few false positive results.
Limit of detection (LOD):
Quantitative sensor: The lowest quantity of analyte that generates a distinguishable response with respect to the signal of a blank – commonly 3 times the standard deviation of the blank.
Linearity:
Quantitative sensor: The range where the signal is linear with respect to the analyte concentration.
Dynamic range:
Quantitative sensor: The range where the detection output is varying with the analyte concentration
What does surface to volume ratio mean and how is it affected by miniaturization?
Surface to volume ratio is SAV refers to the amount of surface an object has relative to its size
Advantages
High SAV ratio:
- Faster mass transfer (shorter diffusion paths)
- Faster thermal transport (heating/
cooling)
- Faster analysis/faster separations
- Higher sample throughput
- Lower energy consumption
Drawbacks
High SAV ratio:
- Adsorption problems
- Protein denaturation
- Sensitivity
- Practical issues:
- Higher back-pressure
- Clogging and bubbles
-Difficulty in interfacing between macro <-> micro <-> nano
