Publications by Lothar Helm | EPFL Graph Search

The Periodic Table and Kinetics?

Mendeleev in his first publication ordered the chemical elements following an apparent periodicity of properties such as atomic volume and valence. The reactivity of the elements was only studied systematically many years later. To illustrate the systemati ...

2019

MRI micelles self-assembled from synthetic gadolinium-based nano building blocks

Lothar Helm, Vassily Vorobiev

A synthetic nano building block endowed with amphiphilic properties and chelated gadoliniumis presented. Spontaneous self-assembly into small 12 nm corona-core stealth Gd-micelles with inherently high gadolinium loading occurs in water. Gd-Micelles are a n ...

Royal Society of Chemistry2019

Pharmacokinetics and biodistribution study of self-assembled Gd-micelles demonstrating blood-pool contrast enhancement for MRI

Lothar Helm, Yohan Van de Looij

Magnetic resonance angiography (MRA) requires the use of contrast agents (CAs) to enable accurate diagnosis. There are currently no CAs on the market with appropriate pharmacokinetic (PK) parameters, namely long persistence in the blood, that can be easily ...

2019

Self-Assembled Nanomicelles as MRI Blood-Pool Contrast Agent

Lothar Helm, Anne-Sophie Chauvin, Vassily Vorobiev

Gadolinium‐loaded nanomicelles show promise as future magnetic resonance imaging (MRI) contrast agents (CAs). Their increased size and high gadolinium (Gd) loading gives them an edge in proton relaxivity over smaller molecular Gd‐complexes. Their size and ...

2017

Carbazole as Linker for Dinuclear Gadolinium-Based MRI Contrast Agents

Lothar Helm, Bibimaryam Mousavi, Anne-Sophie Chauvin, Loïck Moriggi

Ligands able to complex two gadolinium ions have been synthesized and characterized in view of the ability of the complexes to increase the spin relaxation of water protons. All ligands are based on the heptadentate diethylenetriaminetetraacetic acid (DTTA ...

Wiley-V C H Verlag Gmbh2017

Water Exchange on [Ln(DO3A)(H2O)2] and [Ln(DTTA–Me)(H2O)2]− Studied by Variable Temperature, Pressure, and Magnetic Field NMR

Lothar Helm, Shima Karimi

Water exchange kinetics of [Ln(L)(H2O)2]x complexes (Ln = Pr, Nd, Dy, Tm, and Yb; L = DO3A and DTTA–Me) were studied by 17O NMR spectroscopy as a function of temperature, pressure, and frequency and by 1H nuclear magnetic relaxation dispersion. Water excha ...

American Chemical Society2016

In-Vivo Detection and Tracking of T Cells in Various Organs in a Melanoma Tumor Model by F-19-Fluorine MRS/MRI

Lothar Helm, Pascal Miéville, Olivier Michielin, Hikari Ananda Infinity Yoshihara

Background F-19-MRI and F-19-MRS can identify specific cell types after in-vitro or in-vivo F-19-labeling. Knowledge on the potential to track in-vitro F-19-labeled immune cells in tumor models by F-19-MRI/MRS is scarce. Aim To study F-19-based MR techniqu ...

Public Library of Science2016

Evaluation of Water Exchange Kinetics on [Ln(AAZTAPh–NO2)(H2O)q]x Complexes Using Proton Nuclear Magnetic Resonance

Lothar Helm, Shima Karimi

Water exchange kinetics on [Ln(AAZTAPh–NO2)(H2O)q]− (Ln = Gd3+, Dy3+, or Tm3+) were determined by 1H nuclear magnetic resonance (NMR) measurements. The number of inner-sphere water molecules was found to change from two to one when going from Dy3+ to Tm3+. ...

American Chemical Society2016

Complexation of [Gd(DTTA–Me)(H2O)2]− by Fluoride and Its Consequences to Water Exchange

Lothar Helm, Loïck Moriggi, Shima Karimi, Gail Ruth Hunter

The displacement of water molecule(s) from the inner coordination sphere of [Gd(DTTA–Me)(H2O)2]− (DTTA = ethylenetriamine-N,N,N″,N″-tetraacetate) by fluoride has been studied by multinuclear NMR relaxation (1H, 17O, 19F) and DFT calculations. Fluoride anio ...

American Chemical Society2016

Transient versus Static Electron Spin Relaxation in Mn2+ Complexes Relevant as MRI Contrast Agents

Lothar Helm

The zero,-field splitting (ZFS) parameters of the Mn(EDTA)(H2O).2H(2)O. and [Mn(MeNO(2)A)(H2O)].2H(2)O systems were estimated by using DFT and ab initio CASSCF/NEVPT2 calculations (EDTA = (ethane-1,2-41bis(azanetriy1))tetraatetate; MeNO2A = 2,2'-(7-m ...

American Chemical Society2016