Adsorption Of Black Phosphorus Quantum Dots On Mucin Surface And Its Inhibition Of Insulin Aggregation

Due to its excellent photothermal properties,good biocompatibility and biodegradability,the application of black phosphorus quantum dots（BPQDs）nanomaterials in the field of biomedicine has attracted much attention.In this paper,BPQDs are selected as the research object.The adsorption and deposition behavior of BPQDs on the surface of mucin were studied to investigate its biological safety.And we also investigated the regulation of BPQDs on insulin amyloid fibrillation.The main research contents are shown as follows:（1）Adsorption Behavior of Black Phosphorus Quantum Dots on Mucin Surface:The interaction of BPQDs with proteins and their biological effects and potential risks are still unclear.Here,BPQDs of uniform size were prepared by liquid phase stripping,and the adsorption-deposition behavior of BPQDs on the surface of mucin was studied by surface plasmon resonance（SPR）sensing and quartz crystal microbalance with dissipation monitoring（QCM-D）.We found that BPQDs can be quickly adsorbed and released on the surface of mucin,and it is difficult to adhere closely to the surface of mucin.The p H value,ionic strength,and ionic valence also had significant effects on the adsorption behavior of BPQDs.In higher p H solutions,BPQDs and mucins are both negatively charged and cause electrostatic repulsion,reducing the amount of adsorption.The amount of adsorption also decreases with increasing ionic strength and valence(e.g.Na⁺,Mg²⁺,Al³⁺)due to charge screening.In addition,the surface modification of BPQDs with poly（ethylene glycol）-amine（PEG-NH₂）reduces the adsorption rate of the quantum dots but increases their adsorbed amount on the mucin surface.（2）Nontoxic Black Phosphorus Quantum Dots Inhibit Insulin Amyloid Fibrillation:Inhibiting amyloid aggregation or facilitating its disassembly are considered to be two major effective therapeutic strategies in diseases involving peptide or protein fibrillation such Alzheimer’s disease or diabetes.Using thioflavin-T（Th T）fluorescence,far-UV circular dichroism（CD）spectroscopy and atomic force microscopy（AFM）,we found BPQDs appear to have an exceptional capacity to inhibit insulin aggregation and to disassemble formed mature fibrils,even at an ultralow concentration（100 ng/m L）.The inhibition of fibrillation persists at all stages of insulin aggregation and increases PC12 cells survival when exposed to amyloid fibrils.Molecular dynamics（MD）simulations suggest that BPQDs are able to stabilize theα-helix structure of insulin and obliterate theβ-sheet structure to promote the fibril formation.