biosensors lecture 10

bioreceptors

what is an Enzyme

a protein molecule that acts as a biological catalyst

how does an Enzyme bind

• always binds to a specific substrate molecule

• the enzyme-substrate binding is highly specific to shape (lock-and-key mechanism)

glucose

simple sugar that is an important energy source in living organisms

glucose oxidase (Gox)

an enzyme used to capture and detect the glucose molecule in a glucose sensor

what is an Antibody (IgG)

protein molecule created by the immune system

when/how is an antibody created

when a foreign molecule invades the body, the immune system recognizes and creates an antibody molecule that is a perfect fit to the foreign molecule (lock-and-key mechanism)

mechanism of antibody production

lock-and-key mechanism

immunoglobin G (IgG)

most common form on antibody

Y shape

What are nucleic acids

specific sequences of deoxyribonucleic acid (DNA) or ribonucleic acid (RNA) can be used bioreceptors.

4 bases of nucleic acids

Adenine

Thymine

Guanine

Cytosine

bases that bind together

A to T

C to G

how is the specificity of the nucleic acid bioreceptor enhanced

by increasing the length of the DNA/RNA sequence

what is the nucleic acid bioreceptor powerful in identifying

different species of viruses and bacteria

3 important cells in the immune response

B cell

T cell

Natural Killer cell

B cell

a type of lymphocyte ( a white blood cell) that produces antibodies to fight against foreign molecules

T cell

a subset of lymphocytes that can recognize and fight against foreign molecules by itself

• can be used as a bioreceptor

Natural Killer Cell

a type of lymphocyte that can contain viral infections while the adaptive immune response is generating antigen-specific cytotoxic T cells

3 types of transducers for biosensors

optical transducers

electrochemical transducers

mechanical transducers

most common type of optical transducer

fluorescent dye

types of optical transducers

fluorescent dye

gold nanoparticles

surface plasmon resonance

optical ring resonator

optical fiber

optical cavity

types of electrochemical transducers

potentiometry (voltage)

amperometry (current)

conductometry (conductance/resistance)

impedimetric (impedance)

types of mechanical transducers

quartz crystal microbalance

microcantilever

piezoelectric

surface acoustic waves

4 categories of bioreceptors

1. enzymes

2. antibodies

3. nucleic acids (DNA/RNA)

4. cell or tissue