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Room temperature synthesis of Au NR@Ag2S and Au NR@Ag2S/CdS core-shells using a facile photochemical approach
摘要： In this work, Au nanorods with tunable longitudinal plasmon resonance were synthesized using hydroquinone as complimentary surfactant. Ag2S quantum dots (QDs) were grown directly on Au nanorods using the replacement of cetyltrimethylammonium bromide (CTAB) with 3-Mercaptopropionic acid (MPA) via a novel photochemical approach. X-ray diffraction revealed the presence of Au cubic structure as well as Ag2S monoclinic phase. Fourier-transform infrared spectroscopy, electrochemical impedance spectroscopy and cyclic voltamettery confirmed the successful substitution of CTAB with MPA as an appropriate capping agent for the growth of Ag2S and CdS quantum dots. UV-Vis spectroscopy demonstrated a red shift of plasmon resonance peak from 750 nm up to 835 nm indicating the increase of dielectric constant of surrounded Au nanorods due to the formation of Ag2S QDs as shell. Photoluminescence spectroscopy revealed near Infrared (NIR) emission of Au@Ag2S core-shells as an indication of controllable size of Ag2S during the growth time. Transmission electron microscopy (TEM) images clearly showed the formation of Ag2S QDs as shell around Au nanorods. To indicate the flexibility of current growth method, CdS QDs were also grown on Au@Ag2S core-shells only by addition of Cd precursor to as prepared Au@Ag2S colloidal solution and continuation of UV illumination. The clear and intense visible light emission of the sample together with the NIR emission of Ag2S and gradual red shift of plasmon resonance of Au nanorods with elapsing photochemical treatment time were the indication of successful growth of Ag2S/CdS on Au nanorods. TEM images clearly showed Au@Ag2S/CdS almond shape core-shells. This method has the simplest chemistry and the procedure is very simple, rapid (less than 2 h), energy efficient and scalable for large production of such core-shells.
关键词： Au nanorods,Metal-semiconductor core-shells,Ag2S QDs,Photoluminescence,Electroimpedance spectroscopy
更新于2025-09-23 15:22:29
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Facile Synthesis of Noncytotoxic PEGylated Dendrimer Encapsulated Silver Sulfide Quantum Dots for NIR-II Biological Imaging
摘要： Near-Infrared-II (NIR-II, 1000-1700 nm) bioimaging features high penetration depth and high spatio-temporal resolution compared to traditional fluorescence imaging, but the key is to develop stable and biocompatible NIR-II fluorophores suitable for in vivo applications. Silver sulfide quantum dots (Ag2S QDs) have been demonstrated excellent for in vivo NIR-II imaging with unique optical properties and decent biocompatibility, but they often require complex post modifications for in vivo applications. Herein we demonstrate a facile one-pot strategy to synthesize the PEGylated dendrimer-encapsulated Ag2S QDs useful for in vivo NIR-II imaging. Silver ions were first loaded into the core of acylthiourea-functionalized dendrimer (PEG-PATU) through the coordination between silver ions and acylthiourea groups, followed by the addition of sodium sulfide to form Ag2S QDs in situ. The resulting PEG-PATU Ag2S QDs hold excellent NIR-II fluorescence signal, and thus could be executed for high efficiency labelling and tracking of A549 cancer cells mobility in vivo and real time visualization of vast circulatory network of a mouse.
关键词： in vivo imaging,PEGylated dendrimer,one-pot synthesis,Ag2S QDs,NIR-II bioimaging
更新于2025-09-23 15:19:57