Synthesis And Performance Of Rare-Earth/Biological Hybrid Materials

The energy level structure and bonding ability of rare earth elements play an important role in the development of rare earth functional materials in the fields of luminescent materials,electric materials,magnetic materials and so on.Due to its unique coordination function,rare earth elements can coordinate with a variety of biological molecules,such as hydroxyl acids,amino acids,peptides,proteins,and DNA to form high-performance rare-earth biological hybrid materials with specific functions.Among them,small molecule chirality α-hydroxy acids have received extensive attention in the field of chemical synthesis.However,due to the existence of different chiral streuctures,α-hydroxyl acids generally show structure-guided chemical activity differences in material synthesis.Therefore,it is of great significance to identify and distinguish the chirality of hydroxyl acids prior to use.On the other hand,inspired by a variety of natural excellent mechanical structural proteins,protein-based high-performance biological fiber materials have been widely studied.Rational regulation of protein amino acid sequences,molecular weight,functional groups,secondary structures,and subsequent fiber spinning process is crucial to optimize the properties of protein hybrid fiber materials.Based on the above background,this paper mainly focuses on optimizing the synthesis and performance of rare-earth biological hybrid materials,which is carried out from the following four aspects:(1)Firstly,we successfully prepared three macrocyclic rare earth complexes YbDO3A(ala)3 with different numbers of chiral centers by chemical synthesis.Further,utilizing the lanthanide-induced shift(LIS)effect of rare earth element Yb,the efficient identification of four different commercial chiral α-hydroxy acids in an aqueous solution was achieved by hydrogen nuclear magnetic resonance(1H NMR)and chemical exchange saturation transfer(CEST)spectroscopy.We found that the chemical shift deviation between R-configuration and S-configuration α-hydroxy acids were substantially enhanced in 1H NMR and CEST NMR spectra,reaching 1540 and 20-40 ppm,respectively,which greatly improved the chiral discrimination sensitivity.This work solves the problems of small chemical shift deviation and low sensitivity for chiral recognition of α-hydroxy acids by NMR,and constructs an efficient platform for universal sensing and detection of chiral biomolecules.(2)In addition to the structural design and performance optimization of rareearth biological small molecule hybrid materials,we further studied the functional hybrid materials based on protein macromolecules.We prepared high-performance protein fibers based on spherical structural bovine serum albumin(BSA)by microfluidic spinning technology.We first designed a dual-channel microfluidic chip,which successfully induced the orderly arrangement of protein molecules via introducing dynamic covalent cross-linking of imines formed via aldehyde-amino condensation.The high shear inside chip channel further enhanced the tight packing of the cross-linked protein network,and achieved a significant improvement in the mechanical properties of the protein fiber material(toughness up to 143 MJ/m3).At the same time,we found that the post-stretching treatment was helpful to induce the formation of long-range ordered structures within fibers,and realize effective mechanical strength enhancement(up to 300 MPa),which is superior to those mechanical properties of recombinant spider silk and regenerated silkworm fibers.Therefore,this work opens a new avenue for the construction of high-performance biofibers based on commercial globular proteins.(3)We next employed molecular biology techniques for the precise construction and high-efficiency expression of supercharged elastin-like proteins(VPGKG,K protein)with different molecular weights.Driven by supramolecular interactions,the electrostatic assembly of K protein-DNA was realized,and the corresponding fibers exhibited a superior toughness of 203.6±16.0 MJ/m3.The dynamic imine bonds were further introduced to realize rapid fiber formation of structural proteins in the aqueous phase,avoiding possible destruction of protein domain by organic solvent during fiber spinning.These K-protein fibers performed a breaking strength of 440 MPa and toughness of 80 MJ/M3,which exceed many recombinant proteins and synthetic polymer fibers.In addition,the imine bond formed in the protein network endowed fibers with high-/low-temperature mechanical stability,self-recoverability,and humidity-triggered responses.In addition,various actuation behaviors of protein fibers have been realized,such as self-folding/extending,reciprocating stretching motion,and contraction motions.This work paves new strategies to modulate the mechanical properties of protein fibers by introducing supramolecular interactions and dynamic covalent bonds,and intrigue new inspirations for the design of protein fibers for high-tech applications.(4)Finally,we designed a fusion protein composed of resilin(VGSGGRPSDSYGAPGGGNP)and supercharged elastin(ELP,VPGKG).The unfolded high-performance chimeric protein was successfully constructed and highly efficient expressed in E.coli.Furthermore,the preparation of covalent and non-covalent bond-driven high-performance protein fibers was achieved,showing a breaking strength of～550 MPa and toughness of 250 MJ/m3,respectively.These mechanical performances outperform those of many polymer and artificial protein fibers.Further construction of biological patch realized the application of this mechanical functional protein fiber in rat hernia repair.Therefore,this work pioneers a strategy for the further development of high-performance protein fiber materials in the medical field.