25. Nanotechnologies in medicine 1: basic notions and terminology. Characteristics of nanomaterials. Nanoparticles and nanocapsules as drug carriers. Types of nanocarriers. Targeting and controlled release of drugs. Interaction with cells
Covers the size range and basic characteristics of nanomaterials, then compares the main types of nanocarriers in a table, from liposomes and polymeric particles to dendrimers and metal nanoparticles. It goes on to passive and active targeting, the triggers used for controlled drug release, how particles are cleared from the blood and enter cells, and closes with three examples of nanocarriers already in clinical use.
Topic 25 of 26 in the MU Sofia syllabus for Biophysics (Dental Medicine, Year 2). The free AceMed note covers it in 7 sections, about 285 words (3 min of reading), with 16 flashcards.
In this note
Introduction
Characteristics of nanomaterials
Types of nanocarriers
Targeting
Controlled release
Survival in the body and interaction with cells
Examples in use
Introduction
Nanotechnology uses structures of roughly 1 to 100 nm, the size range of proteins and viruses. In medicine, its best-known use is nanocarriers, which take a drug where it is needed and protect healthy tissue.
Characteristics of nanomaterials
Large surface area for their volume: this makes them reactive and able to carry a lot of drug.
New physical properties: at this scale, optical, magnetic and electrical properties can differ from those of the bulk material.
Small size: they can pass through some biological barriers and enter cells.
Adjustable surface: molecules can be attached to change how the particle behaves in the body.
Targeting
Passive targeting: tumor blood vessels are leaky and drainage is poor, so nanoparticles collect there. This is the enhanced permeability and retention effect.
Active targeting: ligands such as antibodies or folate are attached to the carrier, so it binds to receptors on the target cells.
Controlled release
A carrier should hold its drug during transport and release it at the target. Release can be triggered by:
Lower pH in tumors or inside endosomes
Enzymes found at the target
Outside signals, such as heat, light or a magnetic field
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