Study On The Optical Properties And Biophotonics Applications Of Phosphorene And Antimonene

The development of two-dimensional(2D)materials represented by graphene is in the ascendant in the field of life science.Phosphorene(BP)and antimonene(AM)are both emerging mono-elemental two-dimensional materials.Due to their unique physicochemical properties,BP and AM have attracted more and more attention and become research hotspots in the fields of materials,optoelectronics,devices,energy and life science.Targeting at the problems existing in the optical therapy and diagnosis of tumors,and based on the analysis of the synthesis methods and optical properties of BP and AM,this thesis have focused on several important issues in life sciences of BP and AM,and the following works regarding BP and AM have been done:1.Development of near infrared(NIR)-responsive photothermal therapy and;2.NIR-responsive controlled release of drugs;3.X-ray induced sensitization for cancer treatments;4.and the visible light based surface plasmon resonance(SPR)biosensor for cancer markers diagnosis.The main contents of this thesis are as follows:1.Black Phosphorus/rGO(BP/rGO)hybrids for NIR)-responsive photothermal therapy.BP has been proved to be an excellent photothermal agent(PTA),while BP is expensive in price and readily degraded in the atmosphere,detrimental to its further application.It may provide an effective strategy to solve the instability problem of BP by forming chemical bonds to preoccupy the lone pair electrons of BP.Therefore,by using ultrasonic-assisted stripping and annealing processes,orthorhombic phase black phosphorus was prepared using inexpensive red phosphorus(RP)as raw material and BP/rGO hybrid was synthesized.Stability of BP/rGO hybrid in ambient conditions was greatly improved due to the formation of phosphorus-carbon(P-C)covalent bond between BP and rGO.the BP/rGO hybrid exhibited good biocompatibility,high NIR extinction coefficient(21.96 Lg^-1cm^-1)and photothermal conversion efficiency(57.79%).The improvement of photothermal performance may be due to the lattice mismatch defects of P and C.Studies at the cellular and nude mouse levels showed that BP/r GO exhibited excellent NIR-induced photothermal ablation of tumors with little toxic and side effects.This work not only provides a novel idea for the synthesis of BP crystal and BP/rGO hybrid,but also proposes a new BP based PTA.2.BP@hydrogel intelligent NIR light-controlled drug release system.There are still many challenges in the delivery methods in cancer therapy.Tumor treatment urgently needs a one-time injection and controlled release of drugs as an effective treatment strategy to improve the treatment effect and alleviate the pain of patients.NIR-responsive hydrogels are an ideal platform for controlled drug release due to their minimal invasiveness and potential for controlled release;black phosphorus nanosheets(BPNSs)possess comprehensive advantages such as high photothermal conversion efficiency and excellent biodegradability.Therefore,a BP@hydrogel drug delivery platform was constructed based on BPNSs and low melting point agarose.The BP@hydrogel is injected into the tumor site and becomes solid due to a phase transition caused by the lower body temperature.Under irradiation of NIR laser,BP@hydrogel experienced the controlled softening and melting state,and achieved the controlled light-triggered drug(DOX)release and hydrogel degradation.More importantly,the drug release rate can be precisely regulated by internal parameters(such as agarosine,BP and drug concentration)and external parameters(such as NIR light power,irradiation time),which is conducive to maintaining effective blood drug concentration in the clinical application of anticancer therapy.In particular,the toxicity of BP@hydrogels to all types of cells is minimal,and both hydrogels and BPNSs are degradable after treatment,which makes them promising for clinical conversion.This work proposes a unique concept of targeted cancer treatment that triggers the controlled release of anticancer drugs based on NIR excitation of the BP@hydrogel structure.3.Two-dimensional antimonene for X-ray radiosensitizer.Current radiosensitizers are constrained by low clearance rate or multi-step reaction during preparation.Because of its intrinsic properties such as high atomic number(High Z),could be quickly cleared by the kidney,simple and reliable synthesis,etc.,antimonene is expected to become an ideal X-ray radiosensitizer.Antimony has been used as medicine for centuries and pentavalent antimony is still a first-line remedy for leishmaniasis.These unique properties of antimonene or antimony agent inspire us to expand the application of antimonene to X-ray radiosensitizer and cancer treatment,but the mechanism of radiacatalytic enhancement of ROS is still unclear.In this work,we designed and synthesized antimonene quantum dots(AMQDs)and nanosheets(AMNSs)with radiosensitizing effect as a new generation of radiosensitizing agents,and tried to explore the mechanism of radiosensitizing.We first successfully prepare AMQDs and AMNSs,which were coated with amphiphilic PLGA to obtain antimony nanoparticles(AMNPs@PLGA)with good biocompatibility.It was found that X-ray irradiation can induce the oxidation of AMNPs to form heterojunction AMNPs/Sb₂O_x(x=2and/or 5).In contrast,AMQDs with smaller size and larger specific surface area produce more trivalent antimony(Sb(III))and ROS than AMNSs,which would promote the apoptosis of tumor cells.A charge-separation model of Sb/Sb₂O_x heterostructure radiaocatalysis was proposed to reveal underling mechanism of the enhanced production of ROS.It is found that the model satisfies the Z-Scheme phtocatalysts.Under X-ray excitation,the excited electrons in Sb₂O₃ conduction band(CB)quickly recombined with the excited holes in Sb valence band(VB),increasing the opportunity of energy transfer between the excited electrons in Sb CB and the surrounding ³O_2,thereby increasing the yield of ¹O₂.This work expands the application of antimonene as a next-generation radiotherapy sensitizer and provides new ideas for understanding the process of radiation-catalyzed ROS enhancement by heterostructure.4.Ultrasensitive detection of miRNA with an antimonene-based SPR biosensor.SPR technology has many advantages such as non-destructive,label-free,high reproducibility,low cost,etc.,but advanced materials with large adsorption are urgently needed to improve detection performance.Compared with graphene,antimonene has stronger interaction with single-stranded DNA or RNA,and is more suitable for detecting single-stranded DNA and RNA.But the interaction between DNA and antimonene and its application in optical sensing are still unclear.Based on this,we have developed an antimonene-based SPR biosensor using a layer-by-layer assembly process for specifically label-free detection of clinically relevant biomarkers,such as miRNA-21 and miRNA-155.The detection limit(LOD)can reach 10 aM.The proposed biosensor is the first reported method of clinically relevant nucleic acid detection based on two-dimensional antimony materials.