| Photostability is a very important index in the study of medicine properties and drug quality control,which involves the light-substance interaction.Many drugs are unstable under light,and a series of photophysical and photochemical reactions will occur,which will affect medicine performance and drug quality.Drugs are easily exposed to various light conditions during the whole process from production,packaging,distribution,storage to sale on the shelf.Therefore,it is of great significance to study the photostability of medicine/drug for drug performance regulation and drug storage.With the development of nanotechnology,the study of nanoscale light-matter interaction has been further developed,but the real-time study on the photophysicochemical reaction process of small drug molecules is still in the initial stage.Therefore,nano optics was introduced in this paper to explore the photostability of small organic molecules to provide new ideas for the photostability regulation of small organic drug molecules and drug quality control.At present,the photostability of drugs was usually evaluated by measuring the small molecules of drugs by chromatography,spectroscopy,mass spectrometry,etc.Studying the photostability of drugs at a finer level,such as single particle,was largely unexplored.Studies at the single-particle level were usually based on the unique localized surface plasmon resonance（LSPR）phenomenon of metal nanoparticles.LSPR is determined by the material,shape and size of nanoparticles,electron density,refractive index of the environment,and the coupling between particles.Therefore,the optical behavior of organic small molecules on the surface of isomeric nanoparticles can be studied by using the changes of optical signals,which provides new ideas for exploring the photostability of small drug molecules.Based on this,the interaction between plasmonic nanoparticles and small molecules was studied by dark-field microscopy（DFM）technology with the help of plasmonic metal nanoprobes.This paper explored the physical and chemical properties of small molecules under specific conditions and monitored the dynamic reaction process in real time.The study of light-matter interaction between nanoparticles and drug-related small molecules provided a new approach to the optical properties of drug.The details are summarised as follows:1.Plasmon of gold nanoparticle-induced solidification deposition of safranine T.In this chapter,safranine T（ST）,the main component of saffron,was selected as the research object,through the DFM imaging technology combined with LSPR scattering spectroscopy and the co-location technology of DFM image and SEM image,the solidification deposition of ST on gold nanosphere（Au NSs）coated with sodium citrate and the growth of core-shell structure were monitored in situ at the single-particle level,and the photostability of ST on the surface of plasmons was explored.It was found that the surface of Au NSs coated with sodium citrate interacted with small positively charged molecules ST dissolved in water by electrostatic attraction.Then,the plasmon-induced the solidification of ST and finally formed the hybrid nanoparticles with the gold core organic small molecule shell under illumination.The contrastive analysis of metal nanoparticles with the different charge properties proved that electrostatic attraction played a very important role in the deposition process of ST.Further,the decisive role of plasmons in this process was proved by the interaction between nonmetallic Si O2nanoparticles and ST.The deposition and solidification of ST on the surface of Au NSs was a photophysical process,indicating that the photochemical properties of ST were relatively stable,while electrostatic attraction and plasmons can affect the photophysical properties of ST.Finally,the photophysical process was applied.2.Electron transfer imaging analysis in Cu Ag Janus nanoparticle for the catalytic hydrolysis of ammonia borane.In order to further clarify the mechanism of illumination,the photochemical properties of ammonia borane（AB）on the surface of Cu Ag Janus nanoparticles（JNPs）were investigated.As a new therapeutic strategy,gas-assisted therapy has been widely concerned,among which hydrogen has been used in the treatment of various diseases due to its high safety.The plasmon generated by the interaction between light and Cu Ag JNPs promoted the production of hot electrons and induced the hydrolysis reaction of AB to produce hydrogen.In the DFM,the optical properties of LSPR in the process of photocatalytic reaction were promoted by Cu Ag JNPs in the process of AB hydrolysis to produce hydrogen,and the microscopic mechanism of AB photochemical reaction was explored.The scattering peaks of Cu Ag JNPs were bimodal,which could provide the scattering information of Cu and Ag respectively.Therefore,according to the continuous LSPR scattering spectra and the microscopic electron counting theory,the relative electron density and electron loss rate of Cu region and Ag region in a single Cu Ag JNP during AB hydrolysis reaction were calculated,and the electron transfer path of Cu Ag JNPs catalyzed AB hydrolysis process was obtained.It provided a new idea for the further photocontrolled treatment of hydrogen and the design of an efficient AB hydrolysis catalyst.In summary,this paper focused on the interaction between light,metal nanoparticles,and small molecules,and used the scattered signals of plasmon to monitor the photophysical and photochemical processes induced by plasmon in real time at the single-particle level.Metal nanoparticles not only played the role of plasmon-promoting reaction but also were spectral probes for the study in propertyof small organic molecules.Further exploring the mechanism of plasmon inducing the solidification deposition of small molecules ST and the hydrolysis of AB was of great significance for the study of the light concentration of plasmon and the effect of photogenerated electrons on the physicochemical properties of organic small molecules and exploring the photostability of drug-related small molecules. |
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