Preration Of Interface Materials Based On Porous SiO₂ And Influence On The Aggregationand And Crystallization Of Protein

The three-dimensional information of protein structure is of particularly significance in protein engineering and rational drug design.X-ray single crystal diffraction analysis has been the most reliable technique to achieve the spatial structure of protein in recent years.However,acquisition of high quality crystals of proteins remains the bottleneck restrictionin this area.The introduction of specificinterface materials into theprotein solution in metastable zone could lower the free energy barrier to nucleation,allowing protein molecules to form ordered arrays gradually,which leads to high-quality crystals.Due to the structural diversity and complexity of proteins,there has been no proven methodology or techniqueto ensurethe acquisitionof high-quality crystals.Therefore,in this paper,the influence of interface hydrophobicity and hydrophilicity,as well as chirality on the aggregation and crystallization process of lysozyme protein were systematically studied in two parts,with the purpose of providing theoretical basis and new ideas for developing interface for inducing protein crystallization materials in the future.In the first part,six modified porous SiO₂ spheres(OH@SiO₂、Ph@SiO₂、C₆@SiO₂、C₁₈@SiO₂、F₁₇@SiO₂and NH₂@SiO₂)were designed and synthesized,with different interface hydrophobicity and hydrophilicity.Then,the influence of the hydrophilic and hydrophobic surfaces on the aggregation and crystallization process of lysozyme protein were monitoredby DLS and AFM techniques.The results demonstrated thatthe porous structures could facilitate the disaggregation of the disordered protein“clusters”and prevent them from hindering crystal growth.Furthermore,this process was enhanced by hydrophobic interface of the porous material,resulting in the monodisperse state of aggregation and subsequent crystallization in a relatively short time,while the hydrophilic surface had the opposite effect.Moreover,the SEM results exhibited that the hydrophobic surface could induce nucleating with higher rate,and also accelerate crystal growth rate by regulating the protein aggregation in solution,compared to the hydrophilic surface.In the second part,inspired by the interaction between biomacromolecules and chiral surfaces in nature,we prepared monolayer-modified and polymer-modified porous SiO₂spheres with D and L-phenylalanine.The characterization of these porous SiO₂ demonstrated that the material interface exhibited the same chirality as monomers,resulting in chiral interface materials.With the cooperation of stereochemistry configuration,hydrophobic interaction,electrostatic attraction,π-πstacking and H-bonding between protein molecules andthe chiral interface,as well as the“entrapping effect”of the pores on surface,the original disordered protein clusters disaggregated into“growth units”for protein crystallization quickly when contacting those porous SiO₂,thus the crystal growth on those interfaces were facilitated.Although both L and D-surface could promote protein crystallization,the former usually behaved better,perhaps resulting from the chiral preference of lysozymefor L enantiomer in the so-called chiral recognition mechanism.Moreover,due to the amplification of chiral effect from monolayers to polymers,the polymer-modified porous SiO₂ could facilitate cluster deaggregation and subsequent protein crystallization more,compared with their counterparts.