Ultrahigh magnetic resonance contrast switching with water gated polymer-silica nanoparticles

Very high T-1 magnetic resonance imaging (MRI) switches can be obtained with pH-responsive polymer-coated paramagnetic mesoporous silica nanoparticles (MSNs), as the local environment traverses the pK(a) of the polymer coat (Delta r(1) similar to 50 mM(-1) s(-1) at 1.5 T and Delta r(1) similar to 22 mM(-1) s(-1) at 3 T). We assign these characteristics to a strong peripheral hydration capping at the mesopores, impacting channel-confined water mobility such that outer sphere contributions to contrast are greatly enhanced.

Automated summary

High T-1 MRI switches can be obtained using pH-responsive polymer-coated paramagnetic mesoporous silica nanoparticles. The strong peripheral hydration capping at the mesopores enhances water mobility, leading to greatly enhanced outer sphere contributions to contrast.