An Efficient Near-infrared Emissive Artificial Supramolecular Light-harvesting System For Imaging In The Golgi Apparatus

Supramolecular chemistry has developed rapidly in recent years and has become an important branch of chemistry.It is the study of the interaction between two or more molecules through non-covalent bonds,which has taken the advantages of simple construction method,easy reversible regulation,and self-repair.Over the decades,five generations of classical macrocycles have been developed as host molecules for supramolecular chemistry:crown ethers,cyclodextrins,calixarenes,cucurbiturils and pillarenes.Calixarenes,the third generation of macrocyclic host molecules,have attracted much attention because of their advantages such as adjustable cavities,easy derivatization,variable conformation,and good molecular complexation ability to form host and guest inclusion complexes with electrically neutral particles and charged ions.Photosynthesis is the process of converting the energy of natural light into chemical energy,which is the main form of external energy obtained by nature.Therefore,artificial simulation of photosynthesis is one of the hot topics in the field of chemistry and energy.The process of light-harvesting is the first and crucial step of photosynthesis,so the construction of artificial light-harvesting system is of great significance to the realization of artificial simulation of photosynthesis.On the other hand,the construction of artificial light-harvesting system mainly relies on the principle of F?rster Resonance Energy Transfer(FRET),which enables multiple fluorescent donor molecules to transfer energy to fluorescent acceptor molecules through FRET action,thus realizing the function of light-harvesting.The supramolecular self-assembly strategy is one of the effective means to construct the FRET system.Therefore,by introducing the donor molecule of FRET into the supramolecular self-assembly system,the artificial light-harvesting process can be achieved in the supramolecular assembly,and the advantages of good biocompatibility,reversible regulation,simple preparation,and adjustable donor proportion of the assembly can be achieved through the design of the assembly element.Moreover,NIR fluorescence not only has a small optical damage,but also can avoid the biological system's own fluorescence,and has a strong tissue penetration,suitable for application in biological imaging.In this paper,we designed and constructed an efficient supramolecular artificial light-harvesting system with near–infrared emission,developed a new energy receptor Nile Blue(Ni B),and applied the system to the targeting of Golgi.The full text is divided into three parts:The supramolecular assembly 1,8-NPS–SC4AD based on dodecyl sulfonated calix[4]arene was constructed.Due to hydrophobic interaction,SC4AD can induce aggregation induced emission enhancement(AIEE)of 1,8-NPS.The 1,8-NPS–SC4AD assembly was characterized by UV transmission,DLS,SEM,TEM and zeta potential.Next,based on the FRET principle,1,8-NPS–SC4AD–Ni B,an efficient supramolecular artificial light-harvesting system with near–infrared emission,was constructed because the fluorescence emission of 1,8-NPS–SC4AD overlaps with the ultraviolet absorption of Ni B.In PBS solution,the antenna effect is 33.1,the energy transfer efficiency(?_ET)is calculated60.8%,and the ratio of donor to acceptor is 250:1.In addition,a new light-harvesting system1,8-NPS–SDOBS–Ni B was constructed by using sodium dodecylbenzene sulfonate(SDOBS)instead of SC4AD,but its light-harvesting effect was not as good as that of1,8-NPS–SC4AD–Ni B.The development of new accepetor Ni B and new light-harvesting system can provide new ideas for the future research of supramolecular artificial light capture system and is expected to be applied to more research fields.We introduced 1,8-NPS–SC4AD–Ni B system into PC-3 cells to achieve light-harvesting effect and Golgi apparatus near–infrared imaging in living cells.Firstly,MTT method was used to determine that its effect on cell activity was almost negligible.Then we found that it can also achieve light-harvesting effect in living cells and can exist stably for a long time.However,1,8-NPS–SDOBS–Ni B disintegrates after entering cells due to the dispersion and high toxicity of the architecture.By co–staining 1,8-NPS–SC4AD–NIB with commercial dyes of Golgi apparatus,lysosomes and nuclei and analyzing its mechanism,it was confirmed that it could be targeted in Golgi apparatus.It provides the possibility to realize the light-harvesting effect in animal living cells.