1,721,496 research outputs found
SERS on semiconductor substrates receives an electromagnetic boost
No full textBoosting electromagnetic enhancement in semiconductor substrates will be key to rendering surface-enhanced Raman scattering (SERS) a commercially viable technique. So far, doing so has been difficult, and detecting non-chemisorbing analytes, such as volatile organic compounds (VOCs), by using these materials had never been achieved. In this issue of Chem, Liu, Ye, Xiang, et al. have finallzed reached this milestone by synthesizing ZnO@ZIF-8 nanostructures
Gold-based SERS Tags for Biomedical Imaging
No full textThe use of SERS tags in biomedical imaging is described. SERS tags are a novel entity that has recently emerged in the SERS community, mainly spurred by the necessity of carrying out experiments in the biomedical and clinical fields, where the heterogeneity and constant evolution of the environment hamper the application of direct SERS sensing concepts. Direct sensing would in fact require the use of nanoparticles with bare metallic surfaces to allow for intense signal responses; however, the high salt contents typical of physiological conditions and issues such as fouling lead the nanoparticles to aggregate and precipitate out of solution, thus limiting reproducibility and quantitative target identification. As a consequence, the concept of indirect detection has gained importance, in which the SERS signal provided by the SERS tag indirectly provides identification and localization of the target. In this brief review, aimed both at the expert scientist and the novice, the anatomy of a SERS tag is first described, which includes the gold nanoparticle, Raman reporter molecules, a coating layer, and targeting moieties, and the concept of hot spot is explained. A brief overview of the most recent imaging applications in vitro, ex vivo, and in vivo is also provided, along with specific recommendations toward the synthesis of effective SERS tags that could find application in the biomedical field, and meet specific needs of the clinical community. Major emphasis is placed on the concept of multiplexing, which is perhaps the most important feature of SERS tags that could render their clinical application a reality
Noble Metal Nanoparticles as SERS Tags: Fundamentals and Biomedical Applications
No full textThe use of noble metal nanoparticles for the synthesis of SERS tags is described. Initially, the chapter briefly explores the fundamental aspects of SERS, including the definition of enhancement factor and hot spot. Then, a detailed description of the nanoparticles used as substrates is provided, with guidelines on the choice of their morphological and optical properties as guided by the prospective applications. After describing the concept of Raman reporter, surface coating and targeting moiety, the chapter delves into the topics of multiplexing and multimodal tags, which are recent developments of significant relevance in the biomedical field. Finally, a brief overview of the most recent in vitro, ex vivo and in vivo imaging application is given. The chapter concludes by a summary of the topics presented and offers a reflection on the future of the field
Gold Nanostars in Biology and Medicine: Understanding Physicochemical Properties to Broaden Applicability
No full textOver the past few years, gold nanostars have gained significant relevance in biology and medicine, in particular, in imaging and photothermal therapy, also owing to their biocompatibility. Furthermore, they have improved the sensitivity of diagnostic assays and have been integrated in lab-on-chip platforms for low-cost, field-deployable devices. However, despite their widespread use, they have not found applicability beyond the research laboratories. One of the main reasons for this limitation has been the almost exclusive focus, until recently, on applications alone and not on the understanding of the fundamental properties of these particles, which has hampered reproducibility, stability, and overall reliability. Recently, however, a resurgence in the fundamental research of gold nanostars has dramatically improved our understanding of their synthesis, functionalization, properties, and thus their applicability. In this Perspective, the literature exploring and improving our knowledge of the physicochemical properties of gold nanostars is critically presented and framed within the specific context of biological and clinical applications. Furthermore, on the basis of the most recently reported results, a path forward is proposed, aimed at enabling an effective integration of these particles in the clinic
Multiparametric Assessment of Gold Nanoparticle Cytotoxicity in Cancerous and Healthy Cells: The Role of Size, Shape, and Surface Chemistry
No full textIn recent years, we and others have become interested in evaluating the use of surface-enhanced Raman scattering (SERS) tags for early cancer detection and in designing new approaches to demonstrate the applicability of this spectroscopic technique in the clinic. SERS-based imaging in particular offers ultra sensitivity up to the single molecule, multiplexing
capability, and increased photostability and has been shown to outperform fluorescence. However, to employ SERS tags for early cancer detection, it is important to understand their interaction with cells and determine their cytotoxicity. We have been particularly interested for quite some time in determining if and how gold nanostars, which have been demonstrated as
outstanding SERS enhancing substrates, can be safely employed in living systems and translated to the clinic. In this study, we carried out a multiparametric in vitro study to look at the cytotoxicity and cellular uptake of gold nanoparticles on human glioblastoma and human dermal fibroblast cell lines. Cytotoxicity was evaluated by incubating cells with three different morphologies of AuNPs, namely nanospheres, nanorods, and nanostars, each having three different surface chemistries (cetyltrimethylammonium bromide (CTAB), poly(ethylene glycol) (PEG), and human serum albumin (HSA)). Our
results showed that the surface chemistry of the nanoparticles had predominant effects on cytotoxicity, and the morphology and size of the nanoparticles only slightly affected cell viability. CTAB-coated particles were found to be the most toxic to cells, and PEGylated nanostars were determined to be the least toxic. Caspase-3 assay and LDH assay revealed that cell death occurs via apoptosis for cancerous cells and via necrosis for healthy ones. Cellular uptake studies carried out via TEM showed that the particles retain their shape even at long incubation times, which may be beneficial for in vivo SERS-based disease detection. Overall, this study provides valuable information on gold-nanoparticle-induced cytotoxicity that can be leveraged for the development of safe and effective nanoparticle-based therapeutic and diagnostic systems
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