Small quantities of nanometer-thin metal-organic layers effectively defend crimson blood cells throughout freezing and thawing, as a workforce of researchers writing within the journal Angewandte Chemie has found. The nanolayers, constructed from metal-organic frameworks primarily based on the steel hafnium, forestall ice crystal formation at very low concentrations. This efficient novel cryoprotection mode may very well be used to develop new and extra environment friendly cryoprotectants for the biosciences.

Picture Credit score: Angewandte Chemie

Cryoprotectants forestall ice crystals from forming when samples are frozen. Rising crystals can harm delicate cell membranes and cell elements and disrupt cell integrity. Some solvents or polymers make good cryoprotectants; they preserve ice crystal formation in examine by binding water molecules and disrupting their ordered meeting throughout ice formation.

Artificial chemistry has but extra tips up its sleeve for focusing on and influencing ice formation in a more practical means. Steel-organic frameworks (MOFs) are three-dimensional crystalline networks of steel ions linked by natural ligands. These ligands will be tailor-made to bind small molecules reminiscent of water, permitting the meeting of the water molecules into ice crystals to be very exactly tuned.

Wei Zhu from the South China College of Know-how in Guangzhou (China) and colleagues have now found that as MOFs primarily based on hafnium and natural ligands change into thinner, their means to bind and affect water molecules will increase, primarily as a result of extra ligand websites can be found. The workforce subsequently developed a technique for managed deconstruction of the three-dimensional metal-organic frameworks till solely two-dimensional skinny nanolayers stay.

To check the suitability of their hafnium-MOLs (MOL stands for metal-organic layer, to tell apart them from three-dimensional MOFs) as cryoprotectants, the workforce froze crimson blood cells, a sort of cell that must be saved in massive numbers for medical functions however is definitely destroyed by ice crystal formation. In comparison with the hydroxyethyl starch (HES), which is usually used as a cryoprotectant, hafnium MOLs confirmed wonderful cryoprotection at a minimal focus of lower than 0.1%, whereas the HES options are usually used at concentrations of as much as 30%.

Zhu and the workforce defined that the MOLs are so efficient as a result of the irregular two-dimensional construction of the ligands binding the water molecules prevents the formation of normal ice crystal nuclei. The workforce counsel that the dimensional discount of MOFs is an fascinating new perspective for acquiring extremely environment friendly cryoprotectants.