Ferritin is a spherical metalloprotein, capable of storing and releasing iron in a controllable way. It is composed of a protein shell of about 12 nm and within its cavity, iron is stored in a... Show moreFerritin is a spherical metalloprotein, capable of storing and releasing iron in a controllable way. It is composed of a protein shell of about 12 nm and within its cavity, iron is stored in a mineral form. The ferritin core resembles an iron-based nanoparticle that is isolated from the environment by the ferritin shell, which makes ferritin an attractive element to be used in the fabrication of bioelectronic devices. Another intriguing aspect of ferritin is its potential relation to neurodegenerative diseases, such as Alzheimer’s and Parkinson’s. The relation is not yet well understood, but the studies indicate that dysfunctional ferritin appears to play an important role. This dissertation aims to characterize ferritin electrically and magnetically. First, the electrical properties of single ferritin are explored to understand the charge transport through ferritin, and additionally, the first ferritin single-electron transistor is obtained. Second, the magnetic properties of multiple ferritin particles are studied by electron paramagnetic resonance, which supplies information about the ferritin core. A model of the electron-spin structure of the ferritin core is proposed and extended to the ferritin signal from post-mortem brain tissues. Show less
Labra Muñoz, J.A.; Konstantinović, Z.; Balcells, L.; Pomar, A.; Zant, H.S.J van der; Dulić, D. 2019
We report on the fabrication and measurements of platinum-self-aligned nanogap devices containing cubed iron (core)/iron oxide (shell) nanoparticles (NPs) with two average different sizes (13 and... Show moreWe report on the fabrication and measurements of platinum-self-aligned nanogap devices containing cubed iron (core)/iron oxide (shell) nanoparticles (NPs) with two average different sizes (13 and 17 nm). The nanoparticles are deposited by means of a cluster gun technique. Their trapping across the nanogap is demonstrated by comparing the current vs voltage characteristics (I-Vs) before and after the deposition. At low temperature, the I-Vs can be well fitted to the Korotkov and Nazarov Coulomb blockade model, which captures the coexistence of single-electron tunneling and tunnel barrier suppression upon a bias voltage increase. The measurements thus show that Coulomb-blockaded devices can be made with a nanoparticle cluster source, which extends the existing possibilities to fabricate such devices to those in which it is very challenging to reduce the usual NP agglomeration given by a solution method. Show less
Stefani, D.; Perrin, M.; Gutiérrez-Cerón, C.; Aragonès, A.C.; Labra Muñoz, J.A.; Carrasco, R.D.C; ... ; Hill, J.P. 2018
A conformationally flexible calix[4]pyrrole possessing a conjugated electronic structure (an N‐substituted oxoporphyrinogen (OxP) related to porphyrin) was used to investigate the influence of... Show moreA conformationally flexible calix[4]pyrrole possessing a conjugated electronic structure (an N‐substituted oxoporphyrinogen (OxP) related to porphyrin) was used to investigate the influence of mechanical stretching on the single‐molecule conductance of these molecules using the mechanically‐controlled break junction (MCBJ) technique. The results show that the molecule can be immobilized in a single‐molecule break junction configuration, giving rise to different behaviours. These include step‐like features in the conductance vs. displacement traces as well as conductance traces that exhibit a slower decay (‘downhill’ traces) than measured for direct tunneling. The latter class of traces can be associated with the mechanical manipulation (i. e., stretching) of the molecule with inter‐electrode distances as long as 2 nm. Density functional theory (DFT) calculations reveal that OxP molecules are stable under stretching in the length regime studied. Show less
Stefani, D.; Gutiérrez-Cerón, C.A.; Aravena, D.; Labra Muñoz, J.A.; Suarez, C.; Lui, S.; ... ; Dulić, D. 2017
