4 research outputs found
Detection of Iron in Nanoclustered Cytochrome C Proteins Using Nitrogen-Vacancy Magnetic Relaxometry
Nitrogen-vacancy (NV) magnetometry offers an alternative tool to detect iron
levels in neurons and cells with a favorable combination of magnetic
sensitivity and spatial resolution. Here we employ NV-T1 relaxometry to detect
Fe in cytochrome C (Cyt-C) nanoclusters. Cyt-C is a water-soluble protein that
contains a single heme group and plays a vital role in the electron transport
chain of mitochondria. Under ambient conditions, the heme group remains in the
Fe+3 paramagnetic state. We perform NV-T1 relaxometry on a functionalized
diamond chip and vary the concentration of Cyt-C from 6 uM to 54 uM, resulting
in a decrease of T1 from 1.2 ms to 150 us, respectively. This reduction is
attributed to spin-noise originating from the Fe spins present within the
Cyt-C. We perform relaxometry imaging of Cyt-C proteins on a nanostructured
diamond chip by varying the density of adsorbed iron from 1.44 x 10^6 to 1.7 x
10^7 per um^2
Nitrogen-vacancy magnetometry of individual Fe-triazole spin crossover nanorods
[Fe(Htrz)2(trz)](BF4) (Fe-triazole) spin crossover molecules show thermal, electrical, and optical switching between high spin (HS) and low spin (LS) states, making them promising candidates for molecular spintronics. The LS and HS transitions originate from the electronic configurations of Fe(II) and are considered to be diamagnetic and paramagnetic respectively. The Fe(II) LS state has six paired electrons in the ground states with no interaction with the magnetic field and a diamagnetic behavior is usually observed. While the bulk magnetic properties of Fe-triazole compounds are widely studied by standard magnetometry techniques their magnetic properties at the individual level are missing. Here we use nitrogen vacancy (NV) based magnetometry to study the magnetic properties of the Fe-triazole LS state of nanoparticle clusters and individual nanorods of size varying from 20 to 1000 nm. Scanning electron microscopy (SEM) and Raman spectroscopy are performed to determine the size of the nanoparticles/nanorods and to confirm their respective spin states. The magnetic field patterns produced by the nanoparticles/nanorods are imaged by NV magnetic microscopy as a function of applied magnetic field (up to 350 mT) and correlated with SEM and Raman. We found that in most of the nanorods the LS state is slightly paramagnetic, possibly originating from the surface oxidation and/or the greater Fe(III) presence along the nanorods’ edges. NV measurements on the Fe-triazole LS state nanoparticle clusters revealed both diamagnetic and paramagnetic behavior. Our results highlight the potential of NV quantum sensors to study the magnetic properties of spin crossover molecules and molecular magnets