New Age of Water

Protons in Quantum Jazz Concert

Multiple protons in water clusters caught quantum tunnelling in concert, resulting in superfast and accurately directed current flow; could this be happening in our body? Dr. Mae-Wan Ho

All together go!

Wang En-Ge and Jiang Ying at Peking University, Beijing, China and their colleagues caught 4 protons switching partners simultaneously in a cyclic water tetramer under a cryogenic scanning tunnelling microscope (STM). The tetramers were carefully constructed so they are chiral, i.e., with their hydrogen bonds all pointing in one direction, either clockwise, or anticlockwise. Each proton in this 4-membered ring is covalently bonded to an oxygen on the left (or right), and hydrogen-bonded to the oxygen on another water molecules on the right (or left) for the clockwise (anticlockwise) state. To convert between the clockwise and anticlockwise states the protons essentially change partners, from hydrogen bond to a covalent bond and from covalent to hydrogen bond, and they all have to do it at the same time.

In order to see this happening, the team constructed the water tetramers in the two different chiral directions on a NaCl film supported by gold at 5 K. The two chiral forms can be readily distinguished. Next, they attached a single Cl^- ion to the tip of the STM and tuned the Cl-proton electric coupling by carefully positioning the tip and moving it up and down to picometre precision (see Figure 1).  They found that when the coupling to the four protons in a tetramer is symmetric (equal) the probability of tunnelling is considerably enhanced, whereas asymmetric coupling inhibits tunnelling.

Figure 1   Tetramers switching states by coherent proton tunnelling (see text for details)

The switching dynamics of the tetramer chirality is monitored by recording the tunnelling current. The Cl-terminated tip is positioned slightly off the centre of a clockwise tetramer. With the tip far above the tetramer, no current flows, indicating no switching (Fig. 1 left). When the tip height is reduced by about 230 pm, the current increases suddenly by > 300 pA and two current levels are evident (Fig. 1 middle). By retracting the tip to the original position and rescanning, the chirality of the tetramer can be checked. The results unambiguously show that the lower and higher current levels correspond to the clockwise and the anticlockwise state (Fig. 1 right) of the tetramers respectively.

The proton transfer does not result from the excitation of the tunnelling electrons, nor is it driven by the applied electric field between the tip and the sample. Switching rates are only weakly dependent on temperature over the range of 5 to 20 K. Therefore the team attribute the interconversion to quantum tunnelling of protons (driven solely by quantum fluctuations, which do not disappear even at 0 K). Switching rates drop by at least two orders or magnitude when hydrogen is substituted by deuterium (isotope of hydrogen with double the atomic mass).

Proton tunnelling in the tetramer shows a distinct dependence on the tip height. As the tip approaches the tetramer, both switching rates exhibit an initial rise followed by a rapid drop. In addition, the two switching rates gradually deviate from each other as the tip is lowered, which implies that they may have different energies in the presence of the tip.

Theoretical calculations confirm quantum tunnelling

Ab initio (starting from first principles) quantum mechanical density function theory calculations (for the electronic structure of the many body system) show that the energy barrier to switching is lowest when the 4 protons hop in concert from the hydrogen-bond donor to the acceptor molecule. Any conceivable sequential or stepwise rearrangement of the protons would result in significantly higher energy barriers.

When a Cl-terminated tip is positioned above the centre of the tetramer, the reaction barrier is effectively suppressed both in height and width. The effective barrier height and width keeps decreasing until the tip height is reduced to about 3.5 Å. The calculated barrier height and width of the reaction exhibits a monotonic decrease when lowering the tip, which is not consistent with the experimental observation, in which further approach of the tip results in an apparently rapid increase of the barrier height and width (see above).

The most likely explanation is that quantum tunnelling involves a simultaneous inward displacement of the four oxygen atoms in the tetramer. In other words, proton tunnelling is most likely coupled to the internal breathing mode of the tetramer.

As the Cl ion at the tip approaches the tetramer, an attractive interaction between the proton and Cl facilitates proton transfer through the hydrogen bonds, and thus suppresses the tunnelling barrier. However, when the tip is too close to the tetramer, electrostatic repulsion between Cl^- and O^2- leads to considerable expansion of the tetramer, which rapidly increases the tunnelling barrier.

The switching rate decreases by almost one order of magnitude in just 0.5Å as the tip moves from the centre to the edge of the tetramer along two axes of symmetry, probably due to the collective nature of the proton tunnelling. When the tip is positioned near the centre of the tetramer, the four protons are equally coupled to the Cl anion and can be treated as a quantum quasiparticle, which moves in a completely correlated manner. However, slight deviations from the centre leads to asymmetric coupling, breaking the degeneracy (sameness) of the four hydrogen bonds and destroying the cooperativity of the four protons. 

The mechanism proposed Is similar to that suggested earlier for the concerted tunnelling of 6 protons within a chiral hexamer in ordinary ice at 50 K carried out by Christof Dreschsel-Grau and Dominik Marx at Rhur-University Bochum in Germany [2], in a similar quantum mechanical simulation. They found unexpectedly, that only a moderate contraction of the oxygen skeleton of the hexamer is sufficient to enable quasiparticle-like concerted tunnelling of all 6 protons.  Commenting on the new results from Beijing, Dreschsel-Grau and Marx speculate that the same can occur also in larger water clusters, or maybe chirality could be transferred between individual clusters, and that it might also occur at higher temperatures [3].  Let me take this speculation further in an interesting direction suggesting that such concerted proton transfers may well occur in our body.

Proton currents for energy and intercommunication

Back in the late 1990s, my colleague David Knight and I first proposed that water aligned along collagen fibres support rapid jump conduction of protons, and could be the anatomical basis of the acupuncture meridians of traditional Chinese medicine, which are thought to provide a flow of qi (coherent energy) throughout the body [4]. Since then, the hypothesis looks increasingly promising, as water aligned in nanospace shows all the signs of quantum delocalization of protons and high proton conductivity, while nonlinear optical activity characteristic of birefringent crystals has been found associated with collagen fibres, more specifically, with water aligned in collagen fibres, and the same for proton conductivity (see [5]  Superconducting Quantum Coherent Water in Nanospace Confirmed, SiS 55, [6]). I have highlighted the importance of such aligned liquid crystalline water in cells and the extracellular matrix in my books [7] The Rainbow and the Worm, The Physics of Organisms  and [8] Living Rainbow H₂O (ISIS publications). But most researchers have yet to take those ideas on board.

The new findings described above now suggest that proton conduction through liquid crystalline water may be infinitely faster (in a time period during which a single proton can tunnel), more substantial, and precisely directed than previously thought. Though again, the researchers themselves appear unaware of these implications of their work. Let me update on what has been found in collagen recently.

The collagen fibre is liquid crystalline and chiral

Collagens, the most abundant proteins in vertebrates are composed of three polypeptide chains wound together in a right-handed triple-helix, and hence intrinsically chiral. Structural changes of collagen due to misfoldings of the triple helices are associated with severe diseases; while the 3D structure of collagen molecules in malignant tissues has been found differ significantly from that in normal tissues. Chiral changes are conventionally studied by optical circular dichroism (CD) spectroscopy, due to the unequal absorption of right and left plane-polarized light. However, the contrast in CD is typically less than 1 %. Second harmonic generation (SHG) is a nonlinear optical phenomenon in which a birefringent crystalline medium combines two photons to generate a new one with double the frequency (and energy). Collagen exhibits exceptionally strong SHG, as discovered more than 30 years ago, and has been used in imaging ever since. It has also been shown that chirality can give rise to different efficiency of SHG for left circularly polarized and right circularly polarized light, resulting in SHG-CD responses. These considerations prompted researchers at National Taiwan University in Taiwan and Tampere University of Technology in Finland to provide definitive evidence that the chirality of collagen can indeed give rise to strong SHG-CD responses, resulting in 100 % contrast with submicron resolution of individual collagen fibres in a laser scanning microscope [9].

The imaging was done on sliced ligament of a freshly slaughtered young pig ~10 mm thick sealed on the microscope slide with “abundant water”. The reason is simple. There is already evidence that the SHG signal depends almost entirely on the liquid crystalline water associated with the collagen fibres (see [6]). It is therefore highly likely that the CD signal also comes from the liquid crystalline water. This liquid crystalline water is most likely chiral based on its probable structure in the form of a nanotube 6 water molecules in diameter nested in each groove of the triple helix, as worked out by Gary Fullerton (now at University of Texas Health Science Center San Antonio) and colleagues [10] (see also [11] Collagen Water Structure Revealed, SiS 32).

Quantum tunnelling proton currents within the body would indeed enable “every single molecule to intercommunicate [instantaneously] with every other”, as they are all performing the most exquisite quantum jazz [7, 8] within the liquid crystalline medium.

Article first published 09/03/15

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References

1. Meng X, Guo J, Peng J, Wang Z, Shi J-R, Li X-Z, Wang E-G and Jiang Y. Direct visualization of concerted proton tunneling in a water nanocluster. Nature Physics 2015, published onling 16 February, DOI: 10.1038/NPHYS3225
2. Dreschsel-Grau C and Marx D. Quantum simulation of collective proton tunneling in hexagonal ice crystals. Phys Rev Letts 2014, 112, 148302 (5pp).
3. Dreschsel-Grau C and Marx D. Protons in concert. News & Views, Nature Physics 2015, 16 February 2015, Advance online publication | www.nature.com/naturephysics
4. Ho MW and Knight DP. The acupuncture system and the liquid crystalline collagen fibers of the connective tissues. Am J Chinese Medicine 1998, 26, 251-263.
5. Ho MW. Superconducting quantum coherent water in nanospace confirmed. Science in Society 55, 48-51, 2012.
6.  Ho MW. Super-conducting liquid crystalline water aligned with collagen fibres in the fascia as acupuncture meridians of traditional Chinese Medicine. Forum on Immunopathological Diseases and Therapeutics 2012, 2, 221-36.
7. Ho MW. The Rainbow and the Worm, the Physics of Organisms, World Scientific, 1^st ed. 1993; 2^nd ed. 1998; 3^rd edition, 2008.
8. Ho MW. Living Rainbow H2O, World Scientific and Imperial College Press, 2012.
9. Lee H, Huttunen M, Hsu K-J, Partanen M, Zhuo G-Y, Kauranen M and Chu S-W. Chiral imaging of collagen by second-harmonic generation circular dichroism. Optical Society America 2013, 4, DOI:10.1364/BOE.4.000909 | BIOMEDICAL OPTICS EXPRESS 909
10. Fullerton GD, Nes E, Amurao M, Rahal A, Krasnosselskaia L and Cameron I. An NMR method to characterize multiple water compartments on mammalian collagen. Cell Biol Int 2006, 30, 66-73.
11. Ho MW. Collagen water structure revealed. Science in Society 32, 15-16, 2006.