| Surface-enhanced Raman scattering spectroscopy(SERS)has catalyzed an upsurge of interest as an ultrasensitive analytical tool in fields of biosensing and biomedicine due to its fascinating merits of quick-response,narrow fingerprint signature,nondestructive sampling and single molecule sensitivity.In SERS,the rational design of a stable and uniform SERS-active substrate becomes one of the key issues for the improvement of SERS sensitivity and reproducibility,since the Raman enhancement is highly susceptible to the composition,size,and morphology of the substrate.Cancer as one of the momentous causes of mortality seriously threaten human health and life.For early cancer diagnosis and precision cancer therapy,Au-based nanomaterials were employed as the competent SERS-active substrates for rational fabrication of functionalized Raman nanotags and SERS sensing platforms.Furthermore,they were applied to distinguish cancer cells from normal cells and evaluate the therapeutic effects of cancers.In addition,they were used to construct a bifunctional theragnostic nanoplatform for SERS imaging-guided near-infrared photothermal therapy on cancer cells.The main contents are summarized as follows.1.Graphene Quantum Dots Wrapped Gold Nanoparticles with Integrated Enhancement Mechanisms as Sensitive and Homogeneous Substrates for Surface-Enhanced Raman SpectroscopyRational engineering of highly stable and Raman-active nanostructured substrates is still urgently in demand for achieving sensitive and reliable surface-enhanced Raman spectroscopy(SERS)analysis in solution phase.Herein,monodisperse N-doping graphene quantum dots wrapped Au nanoparticles(Au-NGQD NPs)were facilely prepared and further explored their applications as substrates in SERS-based detection and cellular imaging.The as-prepared Au-NGQD NPs exhibit superior long-term stability and biocompatibility,as well as large enhancement capability due to the integration of electromagnetic and chemical enhancements.The practical applicability of the Au-NGQD NPs was verified via the direct SERS tests of several kinds of aromatics in solution phase.Finite-difference time-domain(FDTD)simulations in combination with density functional theory(DFT)calculations were also successfully used to explain the enhancement mechanisms.Furthermore,the Au-NGQD NPs were conjugated with 4-nitrobenzenethiol(4-NBT,as reporter)and 4-mercaptophenylboronic acid(MPBA,as targeting element)to construct the MPBA/4-NBT@Au-NGQD probes,which could specifically recognize glycan over-expressed cancer cells through SERS imaging on cell surface.The prepared Au-NGQDs show great potential as superior SERS substrates in solution phase for on-site Raman detection.2.Aptamer-Conjugated Au Nanocage/SiO2 Core-Shell Bifunctional Nanoprobes with High Stability and Biocompatibility for Cellular SERS Imaging and Near-Infrared Photothermal TherapyThe combination of surface-enhanced Raman scattering(SERS)imaging technology with near-infrared(NIR)light-triggered photothermal therapy is of outmost importance to develop novel theranostic platforms.Herein,an aptamer-conjugated Au nanocage/SiO2(AuNC/SiO2/Apt)core-shell Raman nanoprobe has been rationally designed as the bifunctional theranostic platform to fulfill this task.In this theranostic system,the Raman-labelled Au nanocage(AuNC)was encapsulated into a bio-inert shell of SiO2,followed by conjugating aptamer AS1411 as the target-recognition moiety.AuNC served as the SERS-active and photothermal substrate due to its large free volume,built-in plasmon effect and NIR photothermal capacity,while the SiO2 coating endowed the nanoprobes with good stability and biocompatibility,as well as abundant anchoring sites for surface functionalization.Considering their prominent SERS and photothermal properties,the application potential of the AuNC/SiO2/Apt nanoprobes was investigated.The proposed nanoprobes could be applied to targeted detection and SERS imaging of nucleolin-overexpressing cancer cells(MCF-7 cells as the model)from normal cells,and also exhibited acceptable photothermal efficacy without systematic toxicity.This theranostic nanoplatform provided a possible opportunity for in situ diagnosis and noninvasive treatment of cancer cells by SERS imaging-guided photothermal therapy. |
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