The Effect Of Poly(carboxybetaine Methacrylate) Functioncalized With Peptide Inhibitor On Inhibiting Amyloid β Protein Aggregation

The aggregation and deposition of amyloidβprotein（Aβ）is considered to be the most important cause of Alzheimer’s disease（AD）.Therefore,the development of Aβaggregation inhibitors has been the main target for the treatment of AD.The peptide inhibitor LK7（Ac-LVFFARK-NH2）,which we designed previously,has inhibited the aggregation of Aβto a certain extent,but it was prone to self-aggregation,and its concentration required to inhibit Aβaggregation was high,and its water solubility was poor,which limits its development and application.In order to develop peptidic Aβaggregation inhibitors with practical application prospects,this study first crosslinked LK7 onto the superhydrophilic zwitterionic polymer pCBMA via EDC reaction,and obtained three different modification rates of LK7@pCBMA（8.58μmol/g,15.5μmol/g,51.3μmol/g）by adjusting the reaction conditions.Then we characterized their series of important physicochemical properties,and finally studied their effects on inhibiting Aβaggregation and the cytotoxicity induced by Aβaggregates.The results indicate that the micellar stability of the three LK7@pCBMAs was very strong,and their critical micelle concentration values were all around 10^-9 mol/L.As the modification rate increases,their zeta potentials gradually increase（more positive charges）,but their particle diameters gradually reduce.In addition,they all have excellent monodispersity and solubility.Compared with the control LK7,the inhibitory effect of the three LK7@pCBMA on Aβ₄₂ aggregation is significantly increased with the concentration,for example,LK7@pCB-2 with the best effect,its effective concentration is 4%of LK7.At the same time,they can change the aggregation pathway of Aβ₄₂,and prevent the transformation of Aβ₄₂ intoβ-sheet structure and aggregate into fibers.Furthermore,all three LK7@pCBMAs are able to significantly inhibit neurotoxicity induced by Aβ₄₂aggregates.For example,when the concentration of LK7@pCB-2 was 1μM,the cytotoxicity of Aβ₄₂ was almost completely suppressed（cell survival rate increased from 66%to 97%）.Through the study of aggregation kinetics,it is found that LK7@pCB-2 can significantly promote the nucleation of Aβ₄₀,thereby greatly shortening the lag phase.In particular,when LK7@pCB-2 concentrations were 1μM and 5μM,the aggregation of Aβ₄₀ was almost completely inhibited(the fluorescence value of Aβ₄₀ was reduced to 24.5%and 20.0%),while LK7 at the same concentration has no obvious effect on the aggregation of Aβ₄₀.The above results indicate that the cross-linking of peptide inhibitors on the zwitterionic polymer pCBMA can overcome the disadvantages of poor solubility and high effective concentration,and effectively improve the inhibition on Aβaggregation.Therefore,the LK7@pCBMA developed in this study has excellent application prospects.