Synthesis Of Noble Metal(Au?Ag) Nanomaterials And Their Applications In Bioimaging

Nanomaterials have been developed since 1980 s.With the continuous improvement of scientific and technological,they have made great progress in the fields of medicine.Among all the nanomaterials,noble metal(Au?Ag)nanomaterials have the characteristics of large surface area,tunable emission and strong signal output.These characteristics make them have excellent physical,chemical and optical properties,so they are widely used in biosensing,bioimaging,disease diagnosis,and drug delivery system.Fluorescent nanoparticles help to improve the spatial and temporal resolution of biological imaging.Advanced microscopy technology requires extremely bright fluorescent nanoparticles,which exhibit stable emission,used for single particle tracking,or flickering(switching)for super-resolution imaging.This paper mainly introduces the synthesis of gold and silver nanoparticles around 2 nm,the preparation of gold nanocomposite silk fibroin film.Fluorescence analysis and other methods were used to study the temperature sensing of gold nanomaterials,the stability of fluorescent dye-coated silver nanoparticles and their application in imaging.The details are as follows:1.Synthesis of gold nanoparticles with different emission wavelengths.Based on thereported 2 nm spherical luminous Au NPs,a one-pot synthesis method was used to synthesize 800nm single emitting GS-Au NPs using reduced glutathione(GSH)as a ligand.The whole reactionwas kept at the same concentration and reaction time.By adjusting the temperature,GS-Au NPswere synthesized at 610 nm single emitting,800 nm single emitting and double emitting(610 and800 nm),respectively.High resolution transmission electron microscope(HR-TEM),fluorescencespectroscopy,ultraviolet-visible spectrophotometer(UV)and circular dichroism(CD)were usedto characterize the morphology and performance of GS-Au NPs.The size of the GS-Au NPs isabout 2 nm,and there is no obvious absorption in the UV–vis absorption spectrum in thewavelength range of 200-800 nm.Double-emitting GS-Au NPs have a p H response in the range ofp H=5-9;800 nm single-emitting GS-Au NPs have a good temperature response in the range of 10-60 °C,and the fluorescence intensity at 800 nm is linear with temperature.At the same time,thetemperature response is reversible.2.Synthesize GS-Au NPs silk fibroin film(Au NPs-SFF)and study the temperaturecharacteristics of Au NPs-SFF in vivo and in vitro.Previous studies have found that silk fibroinfilms have good compatibility and biodegradability in vivo.Combined with the abovetemperature-responsive GS-Au NPs,an implantable temperature sensor Au NPs-SFF has beenconstructed to achieve a non-contact monitoring.Au NPs-SFF exhibits excellent toughness andtransparency.Within the range of 10-60 °C,Au NPs-SFF has good temperature response,and arealso reversible.Then,Au NPs-SFF was implanted into Balb/c mice,and no obvious biological toxicity was observed.In vivo imaging and biodistribution indicate that this composite films can be used as an implantable temperature sensor.3.Rhodamine modified silver nanoparticles(TG-Ag NPs)stability studies and in vivo imaging studies.Based on the existing 2 nm kidney-clearing GS-Ag NPs synthesized with GSH as ligand,we synthesized the TG-Ag NPs by coating the dye molecule NHS-TAMRA on the GSAg NPs through the EDC-NHS coupling reaction.TG-Ag NPs were stable at p H=7 and 9 under room temperature and dark conditions.After 83 days,no particle aggregation occurred.TGAg NPs can remain stable even after 120 days.After injection into mice,the retention time of TGAg NPs in the body is longer than that of fluorescent dyes.When the mice wake up,TG-Ag NPs are excreted in urine,and the intensity of fluorescence imaging in vivo is reduced.These results indicate that TG-Ag NPs are expected to be used for tumor diagnosis and treatment due to their superior stability,biocompatibility and processability.