Multimodal Gold Nanostars as SERS Tags for Optically-Driven Doxorubicin Release Study in Cancer Cells
TL;DR: In this paper, SERS active star-shaped nanoparticles were functionalized with doxorubicin molecules and covered with immuno-mimetic thiolated polyethylene glycol (PEG).
Abstract: Surface Enhanced Raman Scattering (SERS) active gold nanostars represent an opportunity in the field of bioimaging and drug delivery. The combination of gold surface chemical versatility with the possibility to tune the optical properties changing the nanoparticles shape constitutes a multimodal approach for the investigation of the behavior of these carriers inside living cells. In this work, SERS active star-shaped nanoparticles were functionalized with doxorubicin molecules and covered with immuno-mimetic thiolated polyethylene glycol (PEG). Doxorubicin-conjugate gold nanoparticles show an intense Raman enhancement, a good stability in physiological conditions, and a low cytotoxicity. The strong adsorption of the anticancer drug doxorubicin in close contact with the gold nanostars surface enables their use as SERS tag imaging probes in vivo. Upon laser irradiation of the nanoparticles, a strong SERS signal is generated by the doxorubicin molecules close to the nanostars surface, enabling the localization of the nanoparticles inside the cells. After long time irradiation, the SERS signal drops, indicating the thermally driven delivery of the drug inside the cell. Therefore, the combination of SERS and laser scanning confocal microscopy is a powerful technique for the real-time analysis of drug release in living cells.
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TL;DR: In this article , a simple and reproducible method for the fabrication of anisotropic silver nanostars (AgNS) that can be successfully used as highly efficient SERS substrates for different bioanalytes was reported.
Abstract: We report a very simple, rapid and reproducible method for the fabrication of anisotropic silver nanostars (AgNS) that can be successfully used as highly efficient SERS substrates for different bioanalytes, even in the case of a near-infra-red (NIR) excitation laser. The nanostars have been synthesized using the chemical reduction of Ag+ ions by trisodium citrate. This is the first research reporting the synthesis of AgNS using only trisodium citrate as a reducing and stabilizing agent. The key elements of this original synthesis procedure are rapid hydrothermal synthesis of silver nanostars followed by a cooling down procedure by immersion in a water bath. The synthesis was performed in a sealed bottom flask homogenously heated and brought to a boil in a microwave oven. After 60 s, the colloidal solution was cooled down to room temperature by immersion in a water bath at 35 °C. The as-synthesized AgNS were washed by centrifugation and used for SERS analysis of test molecules (methylene blue) as well as biological analytes: pharmaceutical compounds with various Raman cross sections (doxorubicin, atenolol & metoprolol), cell lysates and amino acids (methionine & cysteine). UV-Vis absorption spectroscopy, (Scanning) Transmission Electron Microscopy ((S)TEM) and Atomic Force Microscopy (AFM) have been employed for investigating nanostars’ physical properties.
4 citations
TL;DR: In the wake of a global, heightened interest towards biomarker and disease detection prompted by the SARS-CoV-2 pandemic, surface enhanced Raman spectroscopy (SERS) positions itself again at the forefront of biosensing innovation as discussed by the authors .
Abstract: In the wake of a global, heightened interest towards biomarker and disease detection prompted by the SARS-CoV-2 pandemic, surface enhanced Raman spectroscopy (SERS) positions itself again at the forefront of biosensing innovation. But is it ready to move from the laboratory to the clinic? This review presents the challenges associated with the application of SERS to the biomedical field, and thus, to the use of excitation sources in the near infrared, where biological windows allow for cell and through-tissue measurements. Two main tackling strategies will be discussed: (1) acting on the design of the enhancing substrate, which includes manipulation of nanoparticle shape, material, and supramolecular architecture, and (2) acting on the spectral collection set-up. A final perspective highlights the upcoming scientific and technological bets that need to be won in order for SERS to stably transition from benchtop to bedside.
3 citations
TL;DR: In this article , a facile method is presented to prepare nanoporous Ag nanoparticles-decorated Ag7O8NO3 micro-pyramids, which are fabricated through the chemical reduction of the electrodeposited Ag 7O8 NO3 micro pyramid using NaBH4.
Abstract: Porous noble metal nanomaterials can be employed to construct sensitive surface-enhanced Raman scattering (SERS) substrates, because the plasmonic nanopores and nanogaps of the porous materials can provide a larger number of hotspots, and can also serve as containers of analyte molecules. However, the fabrication processes of nanoporous noble metal are generally complicated. Here, a facile method is presented to prepare nanoporous Ag nanoparticles-decorated Ag7O8NO3 micro-pyramids, which are fabricated through the chemical reduction of the electrodeposited Ag7O8NO3 micro-pyramids using NaBH4. The Ag7O8NO3 micro-pyramids are fabricated by electrodeposition by using a simple aqueous solution of AgNO3 as electrolyte. Then, porous Ag-decorated Ag7O8NO3 micro-pyramids are achieved by the chemical reduction of the surface of the electrodeposited Ag7O8NO3 micro-pyramids with NaBH4. The high-density nanopores and nanogaps of the fabricated nanoporous Ag can provide plenty of hot spots for Raman enhancement. Additionally, the nanopores have an effective capacity to trap and enrich analytes. Using rhodamine 6G (R6G) as a probe molecule, the SERS performance of the fabricated SERS substrate has been investigated. It is found that a limit of detection (LOD) ~1.0 × 10−15 M can be achieved for R6G. Then, the SERS substrates are employed to detect dye molecule (crystal violet) and pesticide (thiram), and their LODs are calculated down to 9.6 × 10−13 M and 1.3 × 10−15 M, respectively. The enhancement factor of the fabricated SERS substrate is estimated to be as high as 5.6 × 108. Therefore, the nanoporous Ag-decorated Ag7O8NO3 micro-pyramids have shown promising application in the sensitive SERS detection of organic molecules.
2 citations
TL;DR: In this paper , a dual target recognition probe (DRP) based on the nonlinear hybridization chain reaction (HCR) was used for the simultaneous detection of microRNAs (miRNAs) and microRNA-21 (miR-21) using three-dimensional multi-hotspot DNA dendrimers.
1 citations
References
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TL;DR: In this paper, the optical constants for the noble metals (copper, silver, and gold) from reflection and transmission measurements on vacuum-evaporated thin films at room temperature, in the spectral range 0.5-6.5 eV.
Abstract: The optical constants $n$ and $k$ were obtained for the noble metals (copper, silver, and gold) from reflection and transmission measurements on vacuum-evaporated thin films at room temperature, in the spectral range 0.5-6.5 eV. The film-thickness range was 185-500 \AA{}. Three optical measurements were inverted to obtain the film thickness $d$ as well as $n$ and $k$. The estimated error in $d$ was \ifmmode\pm\else\textpm\fi{} 2 \AA{}, and that in $n$, $k$ was less than 0.02 over most of the spectral range. The results in the film-thickness range 250-500 \AA{} were independent of thickness, and were unchanged after vacuum annealing or aging in air. The free-electron optical effective masses and relaxation times derived from the results in the near infrared agree satisfactorily with previous values. The interband contribution to the imaginary part of the dielectric constant was obtained by subtracting the free-electron contribution. Some recent theoretical calculations are compared with the results for copper and gold. In addition, some other recent experiments are critically compared with our results.
17,509 citations
TL;DR: The fundamental theory of Surface-Enhanced Raman Scattering and the development of Multifunctional Nanoplatforms, a next generation of SERS tags, are studied.
Abstract: CONTENTS 1. Introduction 1.1. Fundamental Theory of Surface-Enhanced Raman Scattering 1.2. Optical Properties of SERS Tags 2. Synthesis of SERS Tags 2.1. Noble Metal Nanosubstrates 2.1.1. Single Particle-Based SERS Substrates 2.1.2. Nanoparticle Cluster-Based Substrates 2.2. Raman Reporter Molecules 2.2.1. Selection Principles and Reporter Types 2.2.2. Self-Assembled Monolayer Coverage Strategy 2.3. Surface Coating for Protection 2.3.1. Biomolecule Coating 2.3.2. Polymer Coating 2.3.3. Liposome Coating 2.3.4. Silica Coating 2.4. Attachment of Targeting Molecules 3. Bioanalysis Applications 3.1. Ionic and Molecular Detection 3.2. Pathogen Detection 3.3. Live-Cell Imaging 3.3.1. Cancer Marker Detection 3.3.2. Intercellular Microenvironment Sensing 3.4. Tissue SERS Imaging 3.5. In Vivo SERS Imaging 4. Challenges and Perspectives 4.1. Reproducible Signal of SERS Tags 4.1.1. Precisely Controlled Hot Spots for Nanosubstrates 4.1.2. Calibration of SERS Intensities and Enhancements 4.2. Improving Multiplexing Capability 4.3. Reduced Size for Subcellular Imaging 4.4. Development of Multifunctional Nanoplatforms 4.4.1. Magnetic SERS Dots 4.4.2. Multimodal Imaging Dots 4.4.3. SERS Tag-Based Therapeutic Systems 4.5. Biocompatibility 5. Conclusions and Remarks
1,108 citations
TL;DR: With doxorubicin hydrochloride loaded, Au@SiO(2)-DOX show two light-mediated therapeutic modes: low power density laser-triggered drug release for chemotherapy, and high powerdensity laser-induced hyperthermia, which suggest the potential for in-vivo applications.
Abstract: X. Wu, C. Chen, and co-workers develop mesoporous silica-coated gold nanorods (Au@ SiO2) as a versatile platform for imaging, chemotherapeutics, and hyperthermia. The Au@ SiO2 thus keeps both the unique functions of mesoporous silica nanoparticles and gold nanorods, and also provides a new functionality: lightcontrolled drug release. With integrated functions, such multifunctional theranostic systems are critical to optimize therapeutic efficacy and to improve safety of therapeutic regimes. They will provide more opportunities for on-demand therapy, paving the way to personalized medicine.
869 citations
TL;DR: This analysis demonstrates that the plasmon hybridization picture can be combined with numerical approaches to interpret the physical origin of the plasmons of highly complex nanostructures.
Abstract: Using the finite-difference time-domain method, we show that the plasmons of a nanostar result from hybridization of plasmons of the core and tips of the nanoparticle. The nanostar core serves as a nanoscale antenna, dramatically increasing the excitation cross section and the electromagnetic field enhancements of the tip plasmons. Our analysis demonstrates that the plasmon hybridization picture can be combined with numerical approaches to interpret the physical origin of the plasmons of highly complex nanostructures.
820 citations
TL;DR: An overview of the current state of research in utilizing gold nanomaterials for PA imaging of cancer, atherosclerotic plaques, brain function and image-guided therapy is provided.
455 citations