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Piezoelectric effect at molecular scales in collagen

PainSci » bibliography » Denning et al 2014
Tags: random, fascia, connective tissue, controversy, debunkery, etiology, pro, massage, manual therapy, treatment, modalities

PainSci commentary on Denning 2014: ?This page is one of thousands in the bibliography. It is not a general article: it is focused on a single scientific paper, and it may provide only just enough context for the summary to make sense. Links to other papers and more general information are provided wherever possible.

This paper (and Harnagea and Rivard) definitely qualifies as research showing that there is piezoelectric effect (PE) in fascia. But there’s a huge “but.” Context is everything.

This is about as basic as basic biology gets, a biologically trivial finding: a teensy little microscopic spark of PE when you would need a bonfire to get any biological significance out of it (never mind clinical significance). The researchers found PE effect at molecular scales, but nearly everything at that scale has a mess of interesting electromagnetic properties, and you can find PE all over the place. For instance, hair, some plastics, lots of minerals … nearly any molecularly regular structure will exhibit some PE. For it to be leveraged biologically for anything, it would have to be happening on a much larger scale, electrons would have to actually go somewhere, further than a few nanometres. PE at the scale investigated here is just a little molecular noise.

Their imaging technology and methodology is much more interesting than what they found with it. Really quite impressive tools they were using!

~ Paul Ingraham

original abstract Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.

Electromechanical coupling, a phenomenon present in collagenous materials, may influence cell-extracellular matrix interactions. Here, electromechanical coupling has been investigated via piezoresponse force microscopy in transparent and opaque membranes consisting of helical-like arrays of aligned type I collagen fibrils self-assembled from acidic solution. Using atomic force microscopy, the transparent membrane was determined to contain fibrils having an average diameter of 76 ± 14 nm, whereas the opaque membrane comprised fibrils with an average diameter of 391 ± 99 nm. As the acidity of the membranes must be neutralized before they can serve as cell culture substrates, the structure and piezoelectric properties of the membranes were measured under ambient conditions before and after the neutralization process. A crimp structure (1.59 ± 0.37 µm in width) perpendicular to the fibril alignment became apparent in the transparent membrane when the pH was adjusted from acidic (pH = 2.5) to neutral (pH = 7) conditions. In addition, a 1.35-fold increase was observed in the amplitude of the shear piezoelectricity of the transparent membrane. The structure and piezoelectric properties of the opaque membrane were not significantly affected by the neutralization process. The results highlight the presence of an additional translational order in the transparent membrane in the direction perpendicular to the fibril alignment. The piezoelectric response of both membrane types was found to be an order of magnitude lower than that of collagen fibrils in rat tail tendon. This reduced response is attributed to less-ordered molecular assembly than is present in D-periodic collagen fibrils, as evidenced by the absence of D-periodicity in the membranes.

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