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Sat Oct 15, 2016, 02:36 PM

Get a haircut; save the world.

This post is a bit tongue in cheek, but I came across a fun paper today while leafing through the current issue one of my favorite scientific journals, ACS Sustainable Chemistry and Engineering.

(The current issue has a considerable focus on the chemistry of lignin, the "other" constituent in wood and straw besides cellulose, and in many ways, the more interesting and possibly more useful constituent for producing high value added - and carbon sequestering - chemicals in a sustainable world, not that we have any intention of creating a sustainable world.)

The paper in question is this one: Human Hair: A Suitable Platform for Catalytic Nanoparticles (Dian Deng⊥†, Mayakrishnan Gopiraman*‡, Seong Hun Kim§, Ill-Min Chung⊥‡, and Ick Soo Kim*†, ACS Sustainable Chem. Eng., 2016, 4 (10), pp 5409–5414)

One can access the full paper in a good university science library, but I'll put up a few excerpts of the paper here:

Human hair (HH) is a complex tissue that consists of proteins, lipids, water and pigments in which proteins of hard fibrous type known as keratin are largely present (67–88%).(1) Unlike other biomaterials, structural morphology of HH-tissue is highly unique and it is nearly impossible to mimic the structure. HH-derived biomaterials have been employed in biomedical applications.(2) Walter et al.(3) utilized HH fiber as a reactor/medium for the controlled synthesis of fluorescent Ag nanoparticles. PbS nanocrystals were also formed within the HH-matrix during blacking.(4) They found that the shape and distribution of nanoparticles are controllable. In spite of these advantages and availability, the HH is often considered as biowaste.(5) Proteins in HH are heteroatom (O, N and S) rich condensation polymers of amino acid. Chemical and physical integrity of the HH units are extremely good respectively due to the presence of cystine group (-s-s- bonds) and cortex.(6) In addition, the keratin of HH is one of the highly insoluble fibrous-proteins in most of the organic solvents.(1-6) Fiber structure and the presence of heteroatom are also interesting points to be noted. Considering its unique physical and chemical properties, we assumed that the human hair would be a suitable candidate for the immobilization of catalytic metal nanoparticles (NPs). Besides, we expected that HH would overcome the drawbacks of common supports (silica, alumina, carbon materials and polymers). In general, the catalyst support provides a platform for NPs to have a much larger number of active atoms on the surface.(7) Nanocellulose,(8) wool-keratine,(9) chitosan,(10) natural pumice,(11) mycelial,(12) Gram-negative bacteria and Gram-positive bacteria(13) are some of the green supports reported to date. However, most of the common supports are moderately expensive, difficult to prepare, toxic and environmentally nonfriendly. In addition, hydrophobic nature of the common supports (carbon nanomaterials including biomass-derived activated carbons) often limits metal–support interaction which leads the further growth and aggregation of NPs.(14, 15) To overcome this issue, additional surface modifications are necessary for the supports prior to the immobilization of NPs.(16) Moreover, to control the NPs size and morphology of catalysts, surfactants are often used.(17) Expensive and hazardous acid treatments (H2SO4/HNO3 or HCl) have been performed for carbon materials to make them suitable as supports for decoration of metal NPs.(18) Similarly, the surface of cellulose nanofiber was modified with anionic groups to obtain better morphology of NPs-supported cellulose catalysts.(19) Notably, obtaining better morphology of green catalysts at high metal loading is also a highly challenging task.(20, 21) Considerable effort has been devoted to develop green and sustainable protocols for the preparation of nanomaterials by R. S. Varma.(22, 23) According to Joo et al.,(24) a good support must have strong interaction with foreign elements and have strong influence on the morphology and better activity of the targeted composites. Noble metals including Au and Ag are generally inactive in the bulk form, whereas, the Au and Ag NPs with diameter of few nanometers are highly efficient. In addition, synergistic effects between metals (Au or Ag NPs and other foreign metals) may also improve the activity of Au and Ag NPs. We postulate that the polymetallic nature of HH would enhance the activity of Ag and Au NPs. To our delight, this is the first investigation on human hair-supported Au and Ag catalysts reported for organic transformations.

"To our delight..." (my bold).

This is what science should be, and occasionally is, "To our delight..."

The chemists here attach gold and silver nanoparticles to materials derived from human here, and conduct a reaction known as the "aza-michael reaction" which involves making nitrogen carbon bonds.

This may be esoteric, but, well, trust me, these kinds of reactions are very important in many areas of technology, including but not limited to, the synthesis of life saving drugs.

Why is this important, and how will it "save the world" (if in fact, the world can be saved, an ever more dubious proposition)?

For one thing, the world is running out of many critical materials, gold and silver among them. While these coinage metals are often valued for their exchange value, it turns out that they are also very critical for a wide range of technologies, including electronics, and, of course, catalysis. Non-chemists may not appreciate catalysis, but in thousands of ways, every day life is totally dependent on this chemistry. By supporting metals on supports like human hair, we can extend the lifetime of these supplies of critical metals far into the future, providing for future generations that we have robbed of so much already.

It's important.

If you think that the collection of human hair cannot be industrialized, you are wrong. Early in my career I was involved in work to manufacture the important AIDS drug Nelfinavir. One of the starting materials for one route to the industrial synthesis of this drug - hundreds of metric tons of the drug needed to by synthesized each year - was the amino acid cysteine. The world's largest source of cysteine, at least at that time - it goes back 20 years - was, in fact, human hair, sourced mostly in China.

The paper has a graphic, produced below, shows a triazol made with the hair based catalyst. Triazols and the related tetrazols are often utilized in medicinal chemistry, where they serve as mimetics for carboxylic acids while conferring several pharmacokinetic and absorption advantages over the carboxylic acids themselves.

Esoteric, I know, but fun, if only in a dorky kind of way. We need a little fun at least until we get rid of that awful orange cancerous growth on the body politic, Trump.

Have a nice weekend.

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Reply Get a haircut; save the world. (Original post)
NNadir Oct 2016 OP
Raster Oct 2016 #1

Response to NNadir (Original post)

Sat Oct 15, 2016, 02:53 PM

1. Haircuts are good, but please, can we get rid of all the fucking beards?

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