biosensors and OTC Flashcards
what is a biosensor ?
an analytical device used for the detection of a chemical substance that combines a biological component with a physiochemical detector
examples - tests :
calibrators in labs blood glucose levels pregnancy tests blood tests urine tests pregnancy tests covid tests lateral flow tests
components of a biosensor :
the biological element
responsible for detecting the analyte and generating a response signal
components of a biosensor :
the transducer
the signal generated by the biological element is transformed into the detectable response
the transducer is the most critical component in any bio-sensing device
components of a biosensor :
the detector
amplifies and processes the signals before displaying it using an electronic display system
the detected reaction should be independent from physical parameters such as pH and temperature
this will allow analysis with minimal pretreatment of samples
components of a biosensor :
the receptor
must be highly specific for the purpose of analysis , stable under normal storage conditions and show a low variation between results
Requirements of an otc biosensor
the response should be accurate, precise , reproducible , linear and require minimal same pretreatment (dilution or concentration)
the complete biosensor should be cheap , small , portable and simple enough to be used by semi skilled operators
OTC kits
many OTC kits have a medical application
eg) pregnancy test kits
kits for measuring cholesterol levels in the blood
however there are other OTC tests available
eg) testing soil pH
measuring carbon monoxide levels in houses/car
exhausts
different testing kits available
ovulation production cholesterol chlamydia coeliac disease sperm quality blood glucose drug use HIV alcohol consumption bowel cancer
Natural Recognition - molecular recognition comes in several forms
ANTIBODY
ANTIGEN
antibody :
protein produced by organism to defend against invasion by foreign organisms or injury
target particular group of molecules on surface of target (normally a protein sequence known as an ‘epitope’ )
antigen
any molecule capable of stimulating antibody response
antibody- antigen response :
bound compounds formed
Monoclonal
targets a specific epitope so will have a single form
polyclonal
targets multiple- so ranges are formed
ovulation and pregnancy tests
lateral flow immunoassays
acts as a blotting paper
negative:
single band reacting to urine component causing a colour change
shows that test has been used correctly
positive :
2 bands
first is negative showing use
second band is an antibody targeting a specific antigen
a surge in this antigen is found in the top band and bottom band - bottom band indicates pregnancy
the antibody - antigen complex generates a colour change
ELISA
ENZYME LINKED IMMUNOASSAY
multiple methods
commonality in that they turn chemical interaction into optical signal
glucose biosensor (basic)
diabetes control and monitoring
measures glucose concentration
enzyme (glucose oxidase) controlled reaction between oxygen and glucose
detected changes through electrochemical means
