Preparation And Biomedical Applications Of Hybrids Of Black Phosphorus And Fullerene

As a new type of two-dimensional material similar to graphene,black phosphorus(BP)has attracted more and more interest due to its unique structure and properties.Each phosphorus atom of BP is connected covalently with neighboring three phosphorus atoms.This unique chemical structure promotes BP to have fascinating properties,such as high carrier mobility,bipolar transmission,adjusted bandgap with number of layers(0.3 eV for bulk and 2.0 eV for monolayer)and unique in-plane anisotropy,which result in having potential applications in filed effect transistor,optoelectronic devices,energy devices and biomedicine.However,due to the lone pairs of electrons on the phosphorus atoms,BP is easy to be oxidized and degraded when exposed to the air,which can affect its electronic properties and limit the practical application of BP.In particular,few-layer BP nanosheets(BPNSs)and BP quantum dots(BPQDs)are more prone to be oxidized.Therefore,enhancing the stability of BP is a top priority to realize its application.On the other hand,fullerene is a zero-dimensional(0D)material that is relatively stable to light,oxygen and water.Using fullerenes to covalently modify BPNSs not only enhances the ambient stability of BPNSs,but also brings new properties to hybrid materials.This dissertation takes the synthesis of BP and fullerene hybrid materials as the starting point,and focuses on exploring different chemical modification pathways to synthesize hybrid materials connected by different covalent methods and explores their ambient stability and applications in biomedicine,such as photodynamic therapy(PDT)and sonodynamic therapy(SDT).The main work includes the following three chapters.(1)We developed a new method to modify BP nanosheets via 4-azidobenzoic acid small molecules,and demonstrated that P=N double bonds were formed on the surface of BPNSs for the first time.The five-coordination chemically functionalized black phosphorus(abbreviated as f-BPNSs)greatly enhanced the ambient stability of BPNSs.To prove the successful formation of the P=N double bonds,basic structure characterization,such as Fourier transform infrared spectroscopy(FT-IR),X-ray photoelectron spectroscopy(XPS),solid-state nuclear magnetic resonance(NMR)were carried out.Then we tracked the stability of the modified material f-BPNSs through the UV/vis absorption characterization and found that the ambient stability of f-BPNSs had been increased by 12 times after 48h reaction.Based on theoretical calculations and experimental results,we also predicted the possible reaction mechanism.(2)On the basis of the previous work,we continued to explore the applications of the prepared hybrid of BP nanosheets and fullerene C60 materials and apply the hybrid to sonodynamic therapy(SDT)in biomedicine.Then BP nanosheets with carboxyl groups and fullerols with hydroxyl groups mixed together.Cyclohexylcarbodiimide(DCC)and 4-dimethylaminopyridine(DMAP)were added to the mixture as catalysts to prepare a hybrid materials of fullerene covalently grafting to the surface of BP via forming ester groups(abbreviated as C60-s-BP).We demonstrated that the hybrid material of BPNSs and C60(OH)n was connected by ester bonds.Then we prepared another hybrid nanomaterials(abbreviated as C60-e-BP)with fullerene C60 covalently grafting the edge of BP nanosheets by one-step mechanochemical ball-milling.We applied these different chemical functionalization of BP nanosheets to sonodynamic therapy(SDT).Based on experiment in vitro and in vivo,we found BA-s-BP samples had the best SDT efficiency.The tumor inhibition rate reached?61%after 15 days of treatment,which was much higher than that of the unmodified BP control sample.(3)We used a one-step mechanochemical ball-milling method to successfully covalently hybridize BPNSs with fullerene C60 to form the hybrid material(abbreviated as BP-C60),in which the C60 covalently grafting the edges of BPNSs.For the first time,the hybrid material BP-C60 was used as a new type of endocytic photosensitizer in the photodynamic therapy(PDT)application.Compared to the pristine unmodified BP nanosheets(abbreviated as BP-BM),BP-C60 not only enhanced the stability in the physiological environment,but also improved the PDT efficiency.In vivo,the cell inhibition rate of the BP-C60 hybrid(with high concentration of 140?g/ml)reached 65.6%with intravenous injection treatment,which was much higher than control group BP-BM.