•Definition and concept of diffusion
•Concept of steady state diffusion and the laws involved
•Methods and procedures of conducting diffusion studies
•Applications of diffusion
• At the end of this lecture, student will be able to
– Explain the concept of diffusion
– Explain steady state and sink condition
– Explain the different laws involved in the process of
– Explain the different methods and procedures to conduct
the in vitro diffusion experiment
• Diffusion is defined as a process of mass transfer of
individual molecules of a substance from a region of higher concentration to a
region of lower concentration along a concentration gradient
• The process of diffusion occurs across a barrier
• Barrier is a
region or regions
that offers resistance
to the passage of materials
• The material that undergoes the transport is known as
diffusant or penetrant or permeant
• Diffusion is a process of migration of solute molecules
from a region of higher concentration to a region of lower concentration and is
brought by random molecular motion.
• Movement from one side of membrane to another side.
• Diffusion is a time dependent process.
• Movement is based on kinetic energy (speed), charge, and
mass of molecule
• It is defined as a process of mass transfer of individual
molecules of a substance brought about by random molecular motion and
associated with a driving force such as a concentration gradient.