Plasma-enhanced Metal Nanosheets For Near-infrared Photoacoustic Imaging / Optical Therapy Of Tumors

Two-dimensional metal nanomaterials refer to ultra-thin metal nanomaterials with the size less than 100 nm.It has the advantages of high stability,large specific surface area,simple surface modification,adjustable LSPR,etc.It is gradually being used by researchers in the fields of catalysis,biosensing,biomedical imaging and therapy.Two-dimensional platinum-based nanomaterials can be used in photoacoustic imaging,photothermal therapy,and enhanced photodynamics due to their near-infrared(NIR-I and NIR-II)optical absorption and catalytic performance for the decomposition of hydrogen peroxide(H₂O₂),which are of great significance in tumor imaging and therapy as therapeutic agents.This article reported the application of two two-dimensional platinum-based nanomaterials(platinum-copper alloy nanoplates and platinum-silver alloy nanoplates)in NIR-II tumor imaging and optical therapy.The main works are as follows:1.Two-dimensional platinum-copper(Pt Cu)nanosheets with the average size of 6.5 nm were prepared by hydrothermal method,which were further modified with chlorin e6(Ce6)and folic acid(FA)to construct functionalized Pt Cu nanosheets(Pt Cu@Ce6-PEG-FA)for multifunctional tumor treatment.We firstly explored the photothermal and photoacoustic performance of Pt Cu nanosheets,and their ability to increase the photodynamic performance of Ce6 was also studied.The photoacoustic imaging and optical treatment of live tumors by Pt Cu@Ce6-PEG-FA were further investigated.The experimental results show that the Pt Cu nanosheets have a wide absorption from visible light to near infrared.They have excellent photothermal performance and strong photoacoustic signal under both NIR-I and NIR-II laser irradiation(photothermal conversion efficiencies at 808 nm and 1064 nm lasers are 20.43%and 32.7%,respectively).Meanwhile,Pt Cu nanosheets have excellent flexibility for surface modification and the catalytic ability for the decomposition of H₂O₂,which increase the photodynamic performance of Ce6 by 1.29 times in a hypoxic environment containing H₂O₂ under white light.The results of in vivo experiments show that the Pt Cu@Ce6-PEG-FA have excellent biocompatibility and can be well concentrated in the tumor site of mice.The tumor can be ablated through photothermal therapy guided by photoacoustic imaging under NIR-I and NIR-II lasers without endangering normal tissues.2.Two-dimensional platinum-silver(Pt Ag)nanosheets with the average size of 42.5 nm were prepared by hydrothermal method,which were further modified it with folic acid(FA)to construct functionalized Pt Ag nanosheets(Pt Ag-PEG-FA)for multifunctional tumor treatment.The photothermal and photoacoustic performance of Pt Ag nanosheets were explored.The photoacoustic imaging and photothermal treatment of live tumors by Pt Ag-PEG-FA were further investigated.The experimental results show that the Pt Ag nanosheets have a wide absorption from visible light to near-infrared light.They have excellent photothermal performance and strong photoacoustic signal under the NIR-I and NIR-II laser irradiation(photothermal conversion efficiencies at 785 nm and1064 nm lasers are 19.2%and 45.7%,respectively).The results of in vivo experiments show that the Pt Ag-PEG-FA nanosheets have good biocompatibility and very low biotoxicity,and can be well enriched in the tumor site of mice.The tumor can be efficiently ablated through photothermal therapy guided by photoacoustic imaging under NIR-I and NIR-II laser irradiation without endangering normal tissues.Since Ag has stronger plasmonic resonance effect than Cu,Pt Ag nanosheets have higher photothermal conversion efficiency and stronger photoacoustic signals under NIR-II laser irradiation compared to Pt Cu nanosheets.In summary,the two-dimensional platinum-based nanosheets has a broad-band light absorption in the near-infrared region(NIR-I and NIR-II),which endows them with excellent photothermal and photoacoustic properties.This kind of Pt-based two-dimensional alloy nanosheets can be used for photoacoustic imaging and photothermal therpy of mice tumors in NIR-I and NIR-II region.Furthermore,the Pt Cu nanosheets can effectively improve the photodynamic performance of Ce6by catalyzing the decomposition of hydrogen peroxide under white light.Such two-dimensional platinum-based nanosheets have shown great potential in tumor imaging and optical therapy.