A facile approach to prepare silica hybrid, spin-crossover water-soluble nanoparticles as potential candidates for thermally responsive MRI agents

Abstract

A reverse micelle method was used for the synthesis of water soluble silica hybrid, spin-crossover (SCO) nanoparticles (NPs). MRI experiments provided thermally responsive T2 values indicating their potential usage as...

Observation of two-step spin transition in iron(ii) 4-amino-1,2,4-triazole based spin crossover nanoparticles

“…1 It is therefore of utmost importance to correlate the SCO properties as a function of the size of SCO nanoparticles. Although there has been extensive research study for the case of 1D coordination polymers (CPs) of [Fe(Htrz)(trz) 2 ]BF 4 · x H 2 O 2–13 less attention is paid to the 1D CP of [Fe(NH 2 trz) 3 ](anion) 2 · x H 2 O. Conclusions have been drawn from studies in [Fe(NH 2 trz) 3 ] Br 2 ·3H 2 O, according to which NPs with dimensions 30–50 nm present considerably reduced thermal hysteresis width to values close to 2 K and critical temperatures T 1 = 312 K, T 2 = 310 K. 14–16 For macroscopic or micrometric particles the upper limit of T 1 value was found to be 320 K with thermal width of 15 K. 14–16 For the above mentioned NPs (will be referenced as NPL ) a reverse micellar method was followed using the non-ionic surfactant Lauropal playing the role of surfactant and oil.…”

Stimuli-responsive spin crossover nanoparticles for drug delivery and DNA-binding studies

“…In terms of a “bio-smart” hybrid nanomaterial, we present a direct coupling method for the drug loading of ( S )-naproxen (NAP) on the already synthesized Fe II SCO doped NPs with formula [Fe(Htrz) 2 (trz) 0.7 (NH 2 trz) 0.3 ](BF 4 ) 1.3 @SiO 2 ( 1 ). 33 NPs 1 were chosen among their counterparts 31 as they exhibit the optimum SCO and MRI properties both in their solid state and aqueous dispersions. The effective functionalization of their surface with NH 2 groups ( AmNPs 1 ) was confirmed by an estimated mean ζ -potential with a positive value greater than 30.0 mV.…”

“…Their spherical shape and reduced size (25 nm) also made these NPs good candidates for drug loading. 33 1 H NMR and IR spectra were recorded in order to confirm the formation of the covalent amide bond while UV-vis and drug release studies were performed for the estimation of drug loading. DNA- and albumin-binding were also examined by targeting a detailed investigation of the interaction of loaded nanoparticles with calf-thymus (CT) DNA and serum albumins.…”

“…The structure and detailed composition of AmNPs 1 are discussed in ref. 33, while the synthesis and characterization of the loaded AmNPs with S -naproxen ( 1@NAP ) are shown in Fig. S1†.…”

Bistable Spin‐Crossover Nanoparticles for Molecular Electronics

“…[Fe(Rtrz) 3 ](X) involves the coverage of SCO NPs with a silica shell. [44][45][46] The silica shell chemically stabilizes the SCO core by efficiently preventing iron oxidation in water, permitting its use as an MRI contrast agent, [47] or as an anchoring point to decorate NPs used as sensors. [46,48,49] Still, to be integrated in devices it is important to minimize the silica shell to a few nm, given its highly insulating character.…”