Research On Collagen Self-Assembly Monitoring Based On Nano-Gold And Quantum Dots

Self-assembly is the most important molecular behavior of natural collagen.Under suitable conditions,procollagen monomolecules with a complete triple-helical structure will first spontaneously assemble to form collagen microfibrils in a staggered manner through intermolecular forces,and the collagen microfibrils will further aggregate to form The collagen fibers with larger size are further assembled and bundled to form larger collagen fiber bundles.From nano-scale to macro-scale,this highly organized collagen fibril structure provides connective tissues(ligaments,tendons)with excellent mechanical properties,thermal stability and superior biological functions.Currently,collagen hydrogels and collagen fibers,as self-assembled products of collagen,have been widely used in the fields of biomedical tissue engineering materials,medical cosmetics,and food processing.Moreover,the self-assembled collagen gel or collagen fiber has highly ordered structural features,and has broad application prospects in targeted drug delivery,sustained release of growth factors,gene therapy,medical imaging,and tissue engineering.In addition,a large number of studies have confirmed that collagen fibers can be used as a scaffold,suitable for tissue regeneration,supporting the healing process,and maintaining good mechanical properties for the formation of new regenerated tissue.These studies confirm that self-assembly is the basis and prerequisite for the expansion of collagen applications.Therefore,it is extremely important to deeply explore the self-assembly molecular behavior of collagen.At present,the research on the molecular behavior of collagen self-assembly is generally based on higher concentration,and the research on the effect of low-concentration self-assembly behavior,such as the number of thin molecules,the interaction force between molecules,and the external environmental factors affecting its behavior Due to the lack of efficient,high-sensitivity,and simple analysis methods,in-depth research has not been carried out.At the same time,the occurrence of pancreatic cancer and cardiovascular diseases are all related to collagen fibrosis.Therefore,it is very important to construct a simple,effective and sensitive system for monitoring collagen self-assembly.In recent years,with the breakthrough of nanoscience and nanotechnology,scientists have aroused great interest in biomedicine by using the new characteristics of various nanomaterials.For example,gold nanoparticles and quantum dots are widely used in many fields including nanomedicine,catalysis and biosensing due to their unique optical,electrical and physical properties(depending on particle shape,size and distribution).However,these nanomaterials with unique optical properties have not been used to monitor collagen self-assembly.Based on this,we use its unique optical properties to construct an efficient and sensitive strategy for monitoring collagen self-assembly.The main research contents are as follows:(1)A new method of monitoring collagen self-assembly has been developed using gold nanoparticles(GNPs)as optical probes.We first prepared the GNPs modified with bovine Achilles tendon collagen(BATC),which showed the largest UV absorption peak at516 nm due to the presence of GNPs.After collagen self-assembly,the formation of the fibril network structure leads to the aggregation of GNPs,and the distance of GNPs becomes closer,resulting in an increase in the maximum absorbance and an increase in the absorbance ratio at 650 nm and 520 nm.In addition,control experiments proved that collagen self-assembly is a prerequisite for GNPs aggregation.On this basis,we further analyzed the mechanism of GNPs aggregation in the system.The results show that collagen and GNPs self-assemble as a whole and cause the aggregation of GNPs.(2)Developed a quantum dot(QDs)-based fluorescent sensing platform and applied it to monitor the self-assembly of collagen.Before collagen self-assembly,when Zn Cd Se/Zn S QDs were introduced into grass carp skin collagen(GCSC),we observed a strong fluorescence signal.After self-assembly,the formation of the collagen fiber network causes the aggregation of quantum dots,resulting in the quenching of the fluorescence of the quantum dots,and the fluorescence intensity is significantly reduced.In addition,the quenching efficiency is linearly related to the GCSC concentration in the range of 0.1-1mg/m L,and the detection limit is 0.06 mg/m L.Moreover,the proposed strategy has good specificity and wide applicability.The results showed that collagen and GNPs self-assembled as a whole and caused the aggregation of GNPs.(3)Developed a collaborative ultra-sensitive fluorescent sensing platform based on double quantum dots(QDs)and applied it to monitor the self-assembly of collagen.Before collagen self-assembly,when carboxyl-modified Zn Cd Se/Zn S QDs₅₂₅ and QDs₆₂₅were introduced into grass carp skin collagen(GCSC),we observed two strong fluorescence signals at 525 nm and 625 nm,which are due to the two quantum Caused by the simultaneous introduction of points.After self-assembly,the formation of the collagen fiber network causes the aggregation of quantum dots,which causes the fluorescence of the two quantum dots to be quenched at the same time,and the fluorescence intensity is significantly reduced.The quenching efficiency is linearly related to the GCSC concentration in the range of 0.1-0.5 mg/m L.Moreover,compared with the single quantum dot(QDs)strategy,the dual quantum dot fluorescence coupling strategy exhibits better linear correlation and lower detection limit.The linear equation is"quenching efficiency(%)=15.43+57.7 CGCSC(mg/m L)?(R²=0.999),the detection limit is 0.041 mg/m L.It is proved that the dual-quantum-dot dual-signal coordination strategy can simply and effectively monitor collagen self-assembly,and it exhibits superior sensitivity.