Effects Of Gold Nanomaterials On Protein Amyloid Fibrosis

Objective:To prepare gold nanoparticles with good homogeneity and dispersibility.Gold nanorods and gold nanoparticles with different physical and chemical properties were used to investigate the effect of them on the amyloid fibrosis of bovine serum albumin(BSA)and hen egg white lysozyme(HEWL).Methods:The AuNPs were prepared by classical Frens method.The physicochemical properties of AuNRs and AuNPs were characterized by UV-visible spectrophotometry,dynamic light scattering and Zeta potential analysis,transmission electron microscopy and inductively coupled plasma mass spectrometry.Their homogeneity and dispersibility were evaluated by above method.BSA and HEWL were used as research object of protein amyloid fibrosis.The formation of amyloid fibers were characterized by ThT fluorescence assay,synchrotron radiation circular dichroism(SRCD),atomic force microscopy(AFM)and SDS-PAGE gel electrophoresis.The effects of AuNRs and Au NPs on the kinetic growth curve,the changes of secondary structures and morphology,and molecular weight of amyloid fibers were investigated.Results:The results of TEM showed that AuNPs had good homogeneity and dispersibility.The average size of AuNPs was 18.48 ± 0.56 nm,its Zeta potential was-36.80 ± 0.44 mV,and its concentration was 155.82 ?g·mL-1.The size of AuNRs were 20 × 40 nm,20 × 60 nm,20 × 80 nm,their Zeta potential were 43.13 ± 1.16,39.83 ± 0.76,20.40 ± 1.11 mV,respectively.The average particle size of AuNRs-2,AuNRs-3,AuNRs-4,and AuNPs in aqueous solution were(1.63 ± 0.04)×(51.36 ± 0.75),(5.06 ± 0.06)×(82.73 ± 0.78),(5.47 ± 0.20)×(104.61 ± 6.5),34.29 ± 0.19,respectively.The BSA fibrosis kinetics curve followed exponential growth rule.The inhibitory effect of AuNRs on BSA fibrosis was significantly higher than that of AuNPs at the same concentration.In the process of fibrosis,the content of ?-helix structure decreased gradually and ?-strand structure increased gradually in the secondary structure of BSA.The addition of AuNRs and AuNPs inhibited the above process.BSA mature fibers morphology were interwined with each other to net-like structure.The fibers of AuNRs group with high concentration were shorter and dispersed,and fibers of AuNPs group were mostly aggragated to form larger amorphous aggregates.The results of SDS-PAGE showed that the large molecular weight fibers formed by BSA were significantly reduced in high concentration of AuNRs and AuNPs group.The HEWL fibrosis kinetics curve followed “s” type growth rule.The blue shift of the peak position of ?-helix was observed during the process of fibrosis,the addition of AuNRs and AuNPs would increase the degree of blue shift.The HEWL mature fibers were longer filamentous morphology.The HEWL of AuNRs and AuNPs group formed the protein amorphous aggregates and shorter filamentous fibers,respectively.Conclusion:BSA and HEWL could form amyloid fibers with good morphology,which had the typical properties of protein amyloid fibers.The AuNRs and AuNPs could inhibit the fibrosis of both,and had a concentration-dependent.At the same concentration,the inhibitory effect of AuNRs was greater than that of AuNPs.