Magnetic nano applications in biomedicine Flashcards
Give five applications of magnetic nanoparticles
1)contrast agents for MRI 2) magnetic heating of nanoparticles during therapy (hyperthermia) 3) tissue engineering/repair 4) drug delivery 5) magnetofection (magnetically assisted gene transfection)
Is MRI safe?
hells yeah ,the safest imaging technique
Why are contrast agents required in MRI?
To increase the ability to distinguish between differences in soft tissues
What is magnetic hyperthermia?
An experimental tool in cancer therapy, uses mag nans to raise local temp in tumour which deactivates normal cellular processes (thermal ablation) resulting in necrosis. It increases therapeutic affects of other treatments. The surface of the nans can bechemically modified to enable target to a specific tissue eg with tumour specific antibodies
What is thermal ablation?
Deactivating normal cellular processes with a locally raised temperature
How are mag nans used to deliver drugs/genes?
It is for localisation of nans/drug at target site, prolonged drug release and targeting to specific cell receptors. Also magnetofection which is when magnetic particles associated w/vector DNA are transfected into cells by the influence of an external mag field
What is magnetofection?
When mag particles associated w/vector DNA are transfected into cells by the influence of an external mag field
Why do we need nanoscale superparamagnetic particles?
Because they need to be small enough for administration, must reside in vivo long enough to reach the target/avoid immunological reactions/toxicity/rapid excretion and capture by undesired tissues. The smaller/more neutral/more hydrophillic the particle surface, the longer its plasma 1/2 life - the particles are attracted to a a magnetic field but no remanence, and do not agglomerate after the removal of the field.
What increases a particles plasma 1/2 life?
Being smaller, neutral and hydrophillic
What 2 points must we consider when making/using mag nans?
Transport across physiological barriers (bbb, vascular capilliary endo, cell membranes) and they must be uniform in size/small enough/large magnetic susc/high colloidal stability/low toxicity and high biocompatibility
What is colloidal?
dispersed within a continuous medium in a manner that prevents them from being filtered easily or settled rapidly.
What 2 common stages do synthesis protocols have in common?
1) a short nucleation step 2) slower growth processes on the existing nuclei
Why do we use iron oxides?
They have useful magnetic properties and are potentially less toxic than metallic and they are easy to functionalise particle surfaces
What is SPIONS?
Superparamagnetic iron oxide nanoparticles
What are superparamagnetic iron oxide nans?
SPIONS
What is the main purpose of surface treatment of nans?
To prevent agglomeration and to generate multifunction
What are first gen nanoparticles?
Pure nanoparticles, Fe2O3 Fe304
What are 2nd gen nans?
Chem mod eg SiO2 coated Fe3O4
What are advanced gen nans?
further mods to functionalise eg ligand coated SiO2-Fe3O4 particles
How do we prevent nan agglomeration?
Environmental conditions affecting the stability of nan suspensions
How do we functionalise the particles?
1)chemically active nans can b coated w/bioactive components such as ligands and abs using knowledge of surface chem of the particle 2) these partcles can b trapped in nanobeads such as liposomes or biodegradable polymers which already have active components
