The Bradford assay is one among many colorimetric assays used for protein quantification. It is based on a dye
named Coomassie brilliant blue. In an acidic solution, this dye is protonated and has a reddish or brownish color. In
the presence of protein, the dye disrupts the protein structure to expose the amino acid side chains. The sulfonic
acid group of the dye interacts with the positive amino groups of the protein to form a complex that has a blue
color. This blue solution can be measured in a spectrophotometer at 595 nm to calculate the concentration of the
protein. This assay is time-effective, easy to use, and extremely sensitive. The only drawback is that it is
dependent on the protein’s composition.
In vitro In vivo
De
fini
tio
n
“in glass” in Latin.
Study biological processes, reactions, or effects of
substances that occur outside the living organism,
in a controlled environment, such as a test tube or
petri dish.
“within the living” in Latin.
Test in complex biological systems, taking into
account immune response, systemic effects, and
interactions with other organs and tissues.
Ta
rg
et/
Ob
jec
t
- Object:
Cell-based testing, which means in vitro is used on
dead organisms’ cells or isolated cellular
components.
- Target:
Evaluate toxicity, metabolism, and interaction of
compounds with cells or biomolecules.
Develop new drugs, treatments, or therapies.
- Object:
In contrast to in vitro, in vivo is used on a
complete, living organism, such as plants,
laboratory animals, and human participants.
- Target:
Evaluate the overall biological response.
Investigate the long-term effects of treatments
on a living body.
Ad
va
nt
ag
es
They are fairly cost-effective as they require fewer
materials than in vivo studies.
They provide rapid results, facilitating faster
hypothesis testing and data collection.
The studied system is made simpler, allowing the
researcher to concentrate on specific components
and control variables more precisely.
In vivo studies capture interactions between
tissues, organs, and systems, providing insights
that are not possible in isolated in vitro models.
Therefore, the results are more accurate.
They are essential for understanding how drugs
behave within a living system. Scientists can
better evaluate the safety, toxicity, and efficacy
of a drug.
Di
sa
dv
an
ta
ge
s
The outcomes of these studies may not entirely or
accurately predict the effects on a whole organism.
The absence of systemic factors (like immune
responses) can lead to oversimplified conclusions.
The use of living animals can lead to many ethical
concerns, like causing the animal’s pain or
distress.
They take longer to arrive at the result and are
also more expensive.
It is more complicated to control all the variables
in these experiments.
Ex
a
m
ple
Polymerase chain reaction (PCR)
DNAs (or RNAs) are collected in a test tube, then
denatured, hybridized, and amplified, aiming to
increase the expression of a specific DNA sequence.
Protein purification
Proteins are isolated from living cells for
purification. These proteins are then used to
develop assays and diagnose disease.
Gamete intrafallopian transfer (GIFT)
A mixture of sperm and eggs is placed directly
into a woman's fallopian tubes using laparoscopy.
Oral drug delivery
The uptake of dosage by mouth for local action or
systemic absorption at any point along the
gastrointestinal tract.
