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The enduring puzzle of why biomolecules in living organisms exist predominantly in one of two mirror-image forms, known as homochirality, has intrigued scientists for centuries. Now, researchers from Empa and Forschungszentrum Jülich in Germany have uncovered compelling evidence suggesting that the interplay between electric and magnetic fields could be central to unraveling this phenomenon.
Homochirality, first observed by Louis Pasteur, has persisted as a scientific enigma, with luminaries like William Thomson (Lord Kelvin) and Nobel laureate Pierre Curie delving into its mysteries. Despite extensive study, a conclusive explanation has remained elusive due to the identical chemical stability and physico-chemical properties of both mirror-image forms, or enantiomers, of biomolecules.
However, recent research has indicated that electric and magnetic fields might play a crucial role in determining the prevalence of one enantiomer over the other. A team led by Karl-Heinz Ernst from Empa and collaborators at the Peter Grünberg Institute in Germany demonstrated this phenomenon in a study published in the journal Advanced Materials.
Their experiments involved coating a copper surface with tiny magnetic cobalt islands and depositing chiral molecules onto these surfaces. By manipulating the direction of the magnetic field in the cobalt islands, the researchers observed a distinct preference for one enantiomer of the molecules over the other, suggesting that the interplay between magnetism and electric fields influences molecular binding.
Furthermore, the researchers discovered that this preference emerges even before the molecules settle onto the cobalt islands. Molecular migration across the copper surface, driven by weak van der Waals forces, exhibited dependence on the magnetic field’s direction, shedding light on the intricate relationship between magnetism and molecular behavior.
In a related study published in the journal Small, the team uncovered another intriguing facet of this phenomenon. They found that electron transport through the molecules was influenced by both molecular chirality and the magnetization of the surface, a phenomenon termed chirality-induced spin selectivity (CISS effect). This effect, observed at the individual molecule level, adds another layer of complexity to the interplay between electric and magnetic fields in molecular interactions.
Despite these groundbreaking discoveries, Karl-Heinz Ernst cautions against expecting a complete solution to the enigma of homochirality. He acknowledges that while these findings provide valuable insights, they do not fully elucidate the origins of life’s handedness. Nonetheless, Ernst speculates that the unique combination of electric and magnetic fields on early Earth may have played a pivotal role in driving the accumulation of specific enantiomers during chemical reactions, laying the groundwork for life’s chirality as we know it.
As scientists continue to unravel the mysteries of homochirality, the role of electric and magnetic fields in shaping molecular behavior promises to remain a focal point of research, offering tantalizing clues to one of life’s enduring mysteries.
