Preparation Of PEG Modified Molybdenum Oxide And Its Photothermal Ablation Ability To Hela Cells

With the improvement of medical methods and the continuous development techniques for nanomaterials,photothermal therapy technology,owing to its characters of minimal invasion,high efficiency,strong penetrating ability to biological tissues and less absorption by biological tissues,has received increasing attention from researchers in the biomedical field.In particular,molybdenum oxide(MoO_x)as an important photothermal material,could effectively absorb near-infrared laser and convert laser into heat energy to achieve ablation.Nevertheless,MoO_x generally exist some limitations in biomedical applications due to its poor biocompatibility and easy agglomeration.In order to meet the requirements of MoO_x as biomaterials,it is of significance to proceed the surface modification or grafting to improve its biocompatibility and stability,and obtain the photothermal materials with good photothermal performance.In this work,ammonium molybdate was selected as the original reagent,PEG was used as modifier and reducing agent and hydrochloric acid was the regulator of system p H to synthesize PEG-MoO_x particles through a hydrothermal process.Due to the reduction and stabilization of the ethoxy group of PEG,Mo(?)was partially reduced to low oxidation states of Mo(?)and Mo(?) species and coordinated with Mo to form a stable crown-like ether cavity structure.Charge-transfer transition of the valence states of Mo could cause localized surface plasmon resonance(LSPR)absorption of the PEG-MoO_x particles in the near infrared region to produce the photothermal effect.XRD,FT IR,SEM,XPS and other analytical techniques and methods were carried out to characterize the crystal phase,functional group structure,micromorphology,elemental composition and valence state of PEG-MoO_x particles,and the 808 nm laser was performed to measure its photothermal properties.The experimental results showed the PEG-MoO_x particles were successfully prepared with a particle size of around 270 nm,a spherical distribution and good dispersibility.Meanwhile,with the increase of PEG-MoO_x concentrations(0.05 mg/m L~0.4 mg/m L)within 10 min of near infrared laser irradiation,the temperature of the solution increased by10 ?~23 ?.PEG-MoO_x particles with different particle sizes were obtained by changing the conditions of the synthesis process including the p H value of the system,amount of PEG added and molecular weight of PEG.760 CRT UV-vis spectrophotometer was used to investigate the absorption range of PEG-MoO_x particles in the near-infrared region,and the photothermal conversion performanceof the particles synthesized under different conditions was examined to investigate the relationship between the size of particles and photothermal properties.The photostability of PEG-MoO_x particles during repeated on/off cycling irradiation was tested by the 808 nm laser,and colloidal stability after storage in solution for different time was examined using the UV-vis spectrophotometer.The experimental results showed that the highest point of the solution temperature after five cycles dropped by only 0.2 ? and the UV-vis-NIR absorption of solution after storage for one week decreased by less than 0.083,demonstrating that as-obtained PEG-MoO_x particles exhibited good photostability and colloidal stability,which were beneficial to its long-term repeated application.Hela cells were chosen as model cells and cytotoxicity of different concentrations of PEG-MoO_x particles was evaluated by using standard MTT assay.And the biocompatibility of MoO_x and PEG-MoO_x particles with Hela cells and photothermal ablation ability of PEG-MoO_x particles for Hela cells were investigated.In vitro cell experiments results showed that PEG-MoO_x particles exhibited low cytotoxicity for Hela cells even under the high tested concentrations(200 ?g/m L),the relative viability of Hela cells still remained over 86%.And the relative viability of cells treated with MoO_x particles was 68.13% under the same conditions,indicating the biocompatibility of molybdenum oxide was enhanced by the modification of PEG.Different concentrations of PEG-MoO_x and Hela cells were cultured in vitro,and PEG-MoO_x could efficiently ablate Hela cells under808 nm laser irradiation.With the increase of laser irradiation power densities or particles concentrations,the photothermal ablation ability of PEG-MoO_x particles was obviously enhanced.Therefore,PEG-MoO_x particles as promising photothermal conversion reagents exhibited potential in the field of disease treatment or other biomedical applications.