Surface-enhanced Raman Scattering Nanoparticles Research Articles

Nucleic Acid Probes in Bio-Imaging and Diagnostics: Recent Advances in ODN-Based Fluorescent and Surface-Enhanced Raman Scattering Nanoparticle and Nanostructured Systems.

Raman nanoparticle probes are a potent class of optical labels for the interrogation of pathological and physiological processes in cells, bioassays, and tissues. Herein, we review the recent advancements in fluorescent and Raman imaging using oligodeoxyribonucleotide (ODN)-based nanoparticles and nanostructures, which show promise as effective tools for live-cell analysis. These nanodevices can be used to investigate a vast number of biological processes occurring at various levels, starting from those involving organelles, cells, tissues, and whole living organisms. ODN-based fluorescent and Raman probes have contributed to the achievement of significant advancements in the comprehension of the role played by specific analytes in pathological processes and have inaugurated new possibilities for diagnosing health conditions. The technological implications that have emerged from the studies herein described could open new avenues for innovative diagnostics aimed at identifying socially relevant diseases like cancer through the utilization of intracellular markers and/or guide surgical procedures based on fluorescent or Raman imaging. Particularly complex probe structures have been developed within the past five years, creating a versatile toolbox for live-cell analysis, with each tool possessing its own strengths and limitations for specific studies. Analyzing the literature reports in the field, we predict that the development of ODN-based fluorescent and Raman probes will continue in the near future, disclosing novel ideas on their application in therapeutic and diagnostic strategies.

Biomimetic Surface-Enhanced Raman Scattering Nanoparticles with Improved Dispersibility, Signal Brightness, and Tumor Targeting Functions.

The development of biocompatible and nontoxic surface-enhanced Raman scattering (SERS) nanoparticles is of considerable current interest because of their attractive biomedical applications such as ultrasensitive in vitro diagnostics, in vivo tumor imaging, and spectroscopy-guided cancer surgery. However, current SERS nanoparticles are prepared and stored in aqueous solution, have limited stability and dispersibility, and are not suitable for lyophilization and storage by freeze-drying or other means. Here, we report a simple but robust method to coat colloidal SERS nanoparticles by naturally derived biomimetic red blood cell membranes (RBCM), leading to a dramatic improvement in stability and dispersibility under freeze-thawing, lyophilization, heating, and physiological conditions. The results demonstrate that the lyophilized SERS nanoparticles in the solid form can be readily dissolved and dispersed in physiological buffer solutions. A surprising finding is that the RBCM-coated SERS particles are considerably brighter (by as much as 5-fold) than PEGylated SERS particles under similar experimental conditions. This additional enhancement is believed to arise from the hydrophobic nature of RBCM's hydrocarbon chains, which is known to reduce electronic dampening and boost electromagnetic field enhancement. A further advantage in using biomimetic membrane coatings is that the bilayer membrane structure allows nonvalent insertion of molecular ligands for tumor targeting. In particular, we show that cyclic-RGD, a tumor-targeting peptide, can be efficiently inserted into the membrane coatings of SERS nanoparticles for targeting the ανβ3 integrin receptors expressed on cancer cells. Thus, biomimetic RBCMs provide major advantages over traditional polyethylene glycols for preparing SERS nanoparticles with improved dispersibility, higher signal intensity, and more efficient biofunctionalization.

SERS-Based Ultrasensitive Lateral Flow Assay for Quantitative Sensing of Protein Biomarkers

The remarkable optical properties of surface-enhanced Raman scattering (SERS) has prompted the design and fabrication of SERS nanoparticles as biosensing and imaging labels. Among a variety of biosensing assay platforms within the growing point of care technology (POCT) field, lateral flow assay (LFA) has gained significant attention because of their simplicity, low cost, and user-friendly assay protocols. Herein, we show the development and performance benchmarking of SERS-based LFA for rapid and quantitative sensing of two important biomarkers: hCG and cTnT. The results suggest the feasibility of this platform for POCT applications.

Enrichment and ratiometric detection of circulating tumor cells using PSMA- and folate receptor-targeted magnetic and surface-enhanced Raman scattering nanoparticles.

The presence of circulating tumor cells (CTCs) in a patient's bloodstream is a hallmark of metastatic cancer. The detection and analysis of CTCs is a promising diagnostic and prognostic strategy as they may carry useful genetic information from their derived primary tumor, and the enumeration of CTCs in the bloodstream has been known to scale with disease progression. However, the detection of CTCs is a highly challenging task owing to their sparse numbers in a background of billions of background blood cells. To effectively utilize CTCs, there is a need for an assay that can detect CTCs with high specificity and can locally enrich CTCs from a liquid biopsy. We demonstrate a versatile methodology that addresses these needs by utilizing a combination of nanoparticles. Enrichment is achieved using targeted magnetic nanoparticles and high specificity detection is achieved using a ratiometric detection approach utilizing multiplexed targeted and non-targeted surface-enhanced Raman Scattering Nanoparticles (SERS-NPs). We demonstrate this approach with model prostate and cervical circulating tumor cells and show the ex vivo utility of our methodology for the detection of PSMA or folate receptor over-expressing CTCs. Our approach allows for the mitigation of interference caused by the non-specific uptake of nanoparticles by other cells present in the bloodstream and our results from magnetically trapped CTCs reveal over a 2000% increase in targeted SERS-NP signal over non-specifically bound SERS-NPs.

Surface-enhanced Raman nanoparticles for cancer theranostics

Raman spectroscopy is amplified by surface-enhanced Raman scattering nanoparticles (SERS-NPs), and Raman signal can be enhanced by SERS-NPs, which can achieve high-resolution imaging of tumors. Meanwhile, SERS-NPs have high molecular specificity and sensitivity, showing a good prospect of tumor diagnosis and treatment. The advantages of SERS-NPs and its application in tumor diagnosis and treatment, and related experimental studies are reviewed in this article. Key words: Spectrum analysis, Raman; Theranostic nanomedicine; Neoplasms; Trends

Quantitative Evaluation of Surface-Enhanced Raman Scattering Nanoparticles for Intracellular pH Sensing at a Single Particle Level.

Intracellular pH is one of the key factors for understanding various biological processes in biological cells. Plasmonic gold and silver nanoparticles (NPs) have been extensively studied for surface-enhanced Raman scattering (SERS) applications for pH sensing as a local pH probe in a living cell. However, the SERS performance of NPs depends on material, size, and shape, which can be controlled by chemical synthesis. Here, we synthesized 18 types of gold and silver NPs with different morphologies such as sphere, rod, flower, star, core/shell, hollow, octahedra, core/satellites, and chainlike aggregates, and quantitatively compared their SERS performance for pH sensing. The SERS intensity from the most commonly utilized SERS probe molecule ( para-mercaptobenzoic acid, p-MBA) for pH sensing was measured at the single nanoparticle level under the same measurement parameters such as low laser power (0.5 mW/μm2), short integration time (100 ms) at wavelengths of 405, 488, 532, 584, 676, and 785 nm. In our measurement, the Ag chain, Ag core/satellites, Ag@Au core/satellites, and Au core/satellites nanoassemblies showed efficient pH sensing at the single particle level. By using p-MBA-conjugated Au@Ag core/satellites, we performed time-lapse pH measurements during apoptosis of HeLa cells. These experimental results confirmed that the pH measurement using p-MBA-conjugated Au@Ag core/satellites can be applied for long-term measurements of intracellular pH during cellular events.

Surface-Enhanced Raman Scattering Nanoparticles for Multiplexed Imaging of Bladder Cancer Tissue Permeability and Molecular Phenotype

Bladder cancer has the highest recurrence rate of all cancers due in part to inadequate transurethral resection. Inadequate resection is caused by the inability of cystoscopes to detect invisible lesions during the resection procedure. To improve detection and resection of nonmuscle invasive bladder cancer, we quantified the ability of a surface-enhanced Raman nanoparticle and endoscope system to classify bladder tissue as normal or cancerous. Both antibody-based (active) and tissue permeability-based (passive) targeting mechanisms were evaluated by topically applying nanoparticles to ex vivo human bladder tissue samples. Multiplexed molecular imaging of CD47 and Carbonic Anhydrase 9 tumor proteins gave a receiver operating characteristic area under the curve (ROC AUC of 0.93 (0.75, 1.00). Furthermore, passively targeted nanoparticles enabled tissue classification with an ROC AUC of 0.93 (0.73, 1.00). Passively targeted nanoparticles penetrated 5-fold deeper and bound to tumor tissue at 3.3-fold higher concentrations in cancer compared to normal bladder urothelium, suggesting the existence of an enhanced surface permeability and retention effect in human bladder cancer.

Screen-Printed Electrodes As EC-SERS Active Surfaces for Quantitative Raman Spectroelectrochemical Detection of Biologically-Related Species

Surface-Enhanced Raman Scattering (SERS) is a very interesting technique for the detection of analytes at ultra-low concentrations. In recent years, it has been applied to the detection of species with biological or medical interest [1]. However, one of the key issues of SERS-based assays is the low reproducibility between different substrates and measurements due to the low control of hot spots and the strong influence of the surface features on the SERS activity. Therefore, there is a strong scientific interest for increasing the applicability of SERS assays for quantitative studies with reproducible and simple methods. Electrochemically roughened electrodes have been widely employed for SERS-based assays. Recently, we have demonstrated that the utilization of screen-printed electrodes with in situ dynamic simultaneous roughening and detection could improve the precision of these assays [2]. Furthermore, the dynamic and in situ electrogeneration of SERS substrates allows to obtain a strongly active metallic surface for increasing detection sensitivity. Screen-printed electrodes due to their versatility, precise mass-fabrication, disposability and low-cost could be promising SERS substrates. In this work, the evaluation of electrochemical SERS (EC-SERS) for the detection of biologically-related species at very low concentrations is performed using metallic screen-printed electrodes. Several species with a possible biological interest were tested such as Ruthenium-bipyridine, Naratriptan or Nicotinamide. Ruthenium-bipyridine is a very interesting molecule because it is the most common detection label in electrochemiluminescence bioassays due to its exceptional performance and sensitivity. Naratriptan is a pharmaceutical active ingredient used for the treatment of migraine headaches in human beings. Nicotinamide is an essential B-vitamin necessary to support the function of many biological enzymes. EC-SERS using screen-printed electrodes allows the detection of these species at very low concentrations. [1] L.A. Lane, X. Qian, S. Nie, “SERS Nanoparticles in Medicine: From Label-Free Detection to Spectroscopic Tagging”, Chem. Rev. 115 (2015), 10489-10529. [2] D. Martín-Yerga, A. Pérez-Junquera, M.B. González-García, J.V. Perales, A. Heras, A. Colina, D. Hernández-Santos, P. Fanjul-Bolado, “Quantitative Raman Spectroelectrochemistry using silver screen-printed electrodes”, Electrochim. Acta 264 (2018), 183-190.

Nanoparticles for live cell microscopy: A surface-enhanced Raman scattering perspective

Surface enhanced Raman scattering (SERS) nanoparticles are an attractive alternative to fluorescent probes for biological labeling because of their photostability and multiplexing capabilities. However, nanoparticle size, shape, and surface properties are known to affect nanoparticle-cell interactions. Other issues such as the formation of a protein corona and antibody multivalency interfere with the labeling properties of nanoparticle-antibody conjugates. Hence, it is important to consider these aspects in order to validate such conjugates for live cell imaging applications. Using SERS nanoparticles that target HER2 and CD44 in breast cancer cells, we demonstrate labeling of fixed cells with high specificity that correlates well with fluorescent labels. However, when labeling live cells to monitor surface biomarker expression and dynamics, the nanoparticles are rapidly uptaken by the cells and become compartmentalized into different cellular regions. This behavior is in stark contrast to that of fluorescent antibody conjugates. This study highlights the impact of nanoparticle internalization and trafficking on the ability to use SERS nanoparticle-antibody conjugates to monitor cell dynamics.

A real-time clinical endoscopic system for intraluminal, multiplexed imaging of surface-enhanced Raman scattering nanoparticles.

The detection of biomarker-targeting surface-enhanced Raman scattering (SERS) nanoparticles (NPs) in the human gastrointestinal tract has the potential to improve early cancer detection; however, a clinically relevant device with rapid Raman-imaging capability has not been described. Here we report the design and in vivo demonstration of a miniature, non-contact, opto-electro-mechanical Raman device as an accessory to clinical endoscopes that can provide multiplexed molecular data via a panel of SERS NPs. This device enables rapid circumferential scanning of topologically complex luminal surfaces of hollow organs (e.g., colon and esophagus) and produces quantitative images of the relative concentrations of SERS NPs that are present. Human and swine studies have demonstrated the speed and simplicity of this technique. This approach also offers unparalleled multiplexing capabilities by simultaneously detecting the unique spectral fingerprints of multiple SERS NPs. Therefore, this new screening strategy has the potential to improve diagnosis and to guide therapy by enabling sensitive quantitative molecular detection of small and otherwise hard-to-detect lesions in the context of white-light endoscopy.

Nanoparticle labels for pathogen detection through nucleic acid amplification tests

Magnetic nanoparticles and surface-enhanced Raman scattering (SERS) active nanoparticles were coated with short chain DNA tags. These were then used to identify a target bacterial DNA sequence. The tags function as primers in a standard PCR with the reverse primers and forward primers on the SERS nanoparticles and magnetic nanoparticles, respectively. During the PCR cycles, a composite nanostructure is formed that is both magnetically responsive and SERS active. After magnetic trapping, the intensity of the SERS signal can be related back to the concentration of the target DNA. A test assay was performed that showed a detection limit (based on the signal to noise ratio) of less than 3 zeptomole (41 pg/L). For comparison, a PCR assay based on the standard SYBR Green method was performed. This used the same primers and target DNA and had a detection limit of 10 attomoles (138 ng/L), 3,000 times less sensitive. The work documents the proof of principle study and shows for the first time the use of SERS-NP labels in the quantification of nucleic acid amplification tests and PCR.

Abstract 4829: Evaluation prognostic significance of circulating tumor cells (CTCs) using multiplexed gold nanoparticles in patients with head and neck cancer

Abstract Background: Detection, quantification, and molecular characterization of CTCs may aid physicians in optimizing treatment. However, current approaches for CTC detection, including CellSearch (FDA approved CTC detection method) rely on a single biomarker, whic may not be appropriate for heterogeneous tumors. Methods: We developeda multiplexed single-tube assay using two targeting Surface-Enhanced Raman scattering (SERS) nanoparticles for directdetection of CTCs in blood sample. The two SERS nanoparticles were distinguished with unique spectral signatures were targeted for simultaneous detection of the biomarkers epidermal growth factor receptor (EGFR) and epithelial cell adhesion molecule (EpCAM). The correlation of CTC level detected by two biomarkers with clinical characteristics was evaluated and compared. Results: CTCs were present in 60.9% of patients (39 of 64 patients) with a range of 5-1751 cells per ml of whole blood. CTC levels detected by EGFR-tag (CTC-EGFR) and EpCAM-tag (CTC-EpCAM) were strongly cross-correlated (P<0.001). CTC levels detected by both biomarkers correlated significantly with the presence of disease (P=0.005 and P<0.0001 for CTC-EGFR and CTC-EpCAM, respectively). In univariate analysis, CTC level detected by both biomarkers associated significantly with disease free survival (hazard ratio: 2.135; 95%CI: 1.028 to 4.435; P=0.042 for CTC-EGFR, and hazard ratio: 6.028; 95%CI: 2.294 to 12.84; P=0.0003 for CTC-EpCAM). In multivariate analysis, CTC level detected by EpCAM-tag but not by EGFR-tag was significant prognostic factor for disease free survival (hazard ratio: 6.771; 95%CI: 2.069 to 22.151; P=0.0016). Thus, the CTC level detected by EpCAM-tag has stronger association with disease free survival than that by EGFR-tag. Conclusions: We have developed two SERS nanoparticles, allowed the simultaneous detection of EGFR or EpCAM on CTCs from one blood sample. CTC levels detected by both biomarkers associated significantly with disease statue and disease free survival. CTC level detected by EpCAM-tag but not by EGFR-tag was significant prognostic factor for disease free survival. Our technique based on two biomarkers, compared with those relying on a single biomarker, may improve CTC assessment in clinical settings. (This research was supported by the National Cancer Institute awards 5 P50 CA128613 and U54CA119338-04). Citation Format: Xu Wang, Ximei Qian, Jonathan J. Beitler, Jun Zhang, Hyunseok Kang, Zhuo (Georgia) Chen, Kelly R. Magliocca, Xiaojing Wang, Zhengjia Chen, Shuming Nie, Dong M. Shin. Evaluation prognostic significance of circulating tumor cells (CTCs) using multiplexed gold nanoparticles in patients with head and neck cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4829. doi:10.1158/1538-7445.AM2014-4829

Guiding brain tumor resection using surface-enhanced Raman scattering nanoparticles and a hand-held Raman scanner.

The current difficulty in visualizing the true extent of malignant brain tumors during surgical resection represents one of the major reasons for the poor prognosis of brain tumor patients. Here, we evaluated the ability of a hand-held Raman scanner, guided by surface-enhanced Raman scattering (SERS) nanoparticles, to identify the microscopic tumor extent in a genetically engineered RCAS/tv-a glioblastoma mouse model. In a simulated intraoperative scenario, we tested both a static Raman imaging device and a mobile, hand-held Raman scanner. We show that SERS image-guided resection is more accurate than resection using white light visualization alone. Both methods complemented each other, and correlation with histology showed that SERS nanoparticles accurately outlined the extent of the tumors. Importantly, the hand-held Raman probe not only allowed near real-time scanning, but also detected additional microscopic foci of cancer in the resection bed that were not seen on static SERS images and would otherwise have been missed. This technology has a strong potential for clinical translation because it uses inert gold–silica SERS nanoparticles and a hand-held Raman scanner that can guide brain tumor resection in the operating room.

Abstract 1460: Quantification of circulating tumor cells using multiplexed Surface-Enhanced Raman Scattering Nanoparticles.

Abstract Background: Detection, quantification, and molecular characterization of CTCs may aid physicians in treatment decision making and optimizing. However, the major challenge in the detection and characterization of CTCs is the lack of a highly specific and sensitive assay to isolate and identify the rare population of CTCs in complex blood samples. Moreover, current approaches for CTC detection including CellSearch (FDA approved CTC detection method) which primarily relays on single biomarker are suboptimal because of tumor heterogeneity. Here we develop a multiplexed single-tube assay for directly detection of CTCs in blood sample using two targeted Surface-Enhanced Raman scattering (SERS) nanoparticles. Methods: SERS nanoparticles (60 nm) were prepared by spectral encoding with a Raman reporter molecule (QSY or BHQ) and then stabilized and protected by low molecular weight polyethylene glycols (PEGs). A targeting ligand, epidermal growth factor (EGF) peptide or epithelial cell adhesion molecule (EpCAM) antibody, was covalently conjugated to PEG layer of SERS nanoparticle. The functionalized EGF- or EpCAM- SERS nanoparticle was able to identify CTCs in the peripheral blood with high specificity and affinity. Results: We collected and examined fresh blood samples from 20 SCCHN patients with various histologies and successfully detected positive SERS signals that were greater than background in 9 of 12 (75%) of patients. This technique was demonstrated to be capable of identifying rare CTCs by two biomarkers simultaneously, with a range of 5-720 cells per ml of whole blood. Blood samples from 3 normal controls did not show any CTCs. In one patient who had 0 count of CTC detected by EGFR-targeting SERS tag showed 170 CTCs/ml of blood detected by EpCAM-targeting SERS tags. Conclusion: Special design of the two SERS nanoparticles, distinguished with unique spectral signatures and bio-conjugation of EGF or EpCAM antibody as targeting molecule, allowed simultaneous detection of epidermal growth factor receptor (EGFR) or EpCAM on CTCs in one blood sample. Our technique based on two biomarkers rather than those relayed on single biomarker may improve CTC assessment in clinical settings. (This research was supported by the National Cancer Institute award 5 P50 CA128613 and U54CA119338-04). Citation Format: Xu Wang, Ximei Qian, Jonathan J. Beitler, Zhuo (Georgia) Chen, Fadlo R. Khuri, Melinda M. Lewis, Hyung J. Shin, Shuming Nie, Dong M. Shin. Quantification of circulating tumor cells using multiplexed Surface-Enhanced Raman Scattering Nanoparticles. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1460. doi:10.1158/1538-7445.AM2013-1460

Abstract LB-512: A novel rotational Raman imaging device for early cancer detection

Abstract A novel Raman imaging device that is capable of rotationally scanning hollow structures has been developed to be used in conjunction with tumor targeting Surface enhanced Raman scattering (SERS) nanoparticles. SERS nanoparticles can act as excellent contrast agents in that they offer ultra high sensitivity, and multiplexing capabilities due to the unique spectral signatures associated with them. One key advantage of multiplexing includes the ability to utilize several targeted SERS probes to target and localize a multitude of unique biomarkers associated with a specific disease, and effectively increasing cancer specificity. The device can potentially be used to distinguish a variety of tissues of interest in the colon such as: flat lesions, varying types of adenomas and carcinomas. There are also applications beyond the colon, such as the esophagus, stomach, oral cavity and bladder. In addition, multiplexing can allow for real-time functional imaging. A 45-degree scanning mirror, actuated with micro-motor, is used to perform circumferential scans of the lumen of the colon at a rate of 1 revolution per second and a spatial resolution or approximately 1.5 mm. The device is able to be used with currently available endoscopes by inserting it into the working channel of an endoscope. The use of many (36) multi-mode fibers is used to increase the flexibility of the fiber bundle so that it can be inserted and used in a fully articulating endoscope while still being able to collect a sufficient amount scattered Raman light. When in the circumferential scanning mode, American National Standards Institute (ANSI) regulations will allow us to increase the laser illumination power to about 580 mW at a scan rate of 60rpm, resulting in a detection limit of approximately 1 pM of SERS nanoparticles. One of the key features of our Raman device is that it has been designed for efficient use over a wide range of working distances. This is necessary to accommodate for imperfect centering of the device within the colon, as well as variable working distances due to folds and bends within the colon. These techniques could allow endoscopists to distinguish between normal and cancerous tissues instantly, as well as to identify flat lesions that are easily missed during conventional screening endoscopy. After a suspicious region has been identified, the rotating mirror can be held at a certain angle, and used to help guide biopsies or resection of tissues in real-time. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-512. doi:1538-7445.AM2012-LB-512

Abstract 4559: A novel rotational Raman imaging device for early cancer detection

Abstract A novel Raman imaging device that is capable of rotationally scanning hollow structures has been developed to be used in conjunction with tumor targeting Surface enhanced Raman scattering (SERS) nanoparticles. SERS nanoparticles can act as excellent contrast agents in that they offer ultra high sensitivity, and multiplexing capabilities due to the unique spectral signatures associated with them. One key advantage of multiplexing includes the ability to utilize several targeted SERS probes to target and localize a multitude of unique biomarkers associated with a specific disease, and effectively increasing cancer specificity. The device can potentially be used to distinguish a variety of tissues of interest in the colon such as: flat lesions, varying types of adenomas and carcinomas. There are also applications beyond the colon, such as the esophagus, stomach, oral cavity and bladder. In addition, multiplexing can allow for real-time functional imaging. A 45-degree scanning mirror, actuated with micromotor, is used to perform circumferential scans of the lumen of the colon at a rate of 1 revolution per second and a spatial resolution or approximately 1.5 mm. The device is able to be used with currently available endoscopes by inserting it into the working channel of an endoscope. The use of many (36) multi-mode fibers is used to increase the flexibility of the fiber bundle so that it can be inserted and used in a fully articulating endoscope while still being able to collect a sufficient amount scattered Raman light. When in the circumferential scanning mode, American National Standards Institute (ANSI) regulations will allow us to increase the laser illumination power to about 580 mW, resulting in a detection limit of approximately 1 pM of SERS nanoparticles. One of the key features of our Raman device is that it has been designed for efficient use over a wide range of working distances. This is necessary to accommodate for imperfect centering of the device within the colon, as well as variable working distances due to folds and bends within the colon. These techniques could allow endoscopists to distinguish between normal and cancerous tissues instantly, as well as to identify flat lesions that are easily missed during conventional screening endoscopy. After a suspicious region has been identified, the rotating mirror can be held at a certain angle, and used to help guide biopsies or resection of tissues in real-time. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4559. doi:1538-7445.AM2012-4559

Abstract 1155: Quantification of circulating tumor cells in peripheral blood using EGFR-targeting gold nanoparticles

Abstract Background: The prognostic significance of circulating tumor cells (CTCs) in patients with squamous cell carcinoma of the head and neck (HNSCC) is of great clinical interest. HNSCCs are overwhelmingly EGFR positive. Objective: Our goal was to pilot nanotechnology to identify CTCs in human xenograft mouse model as a prelude to clinical use. Methods: Surface-enhanced Raman Scattering (SERS)-gold nanocrystals (60 nm) were prepared by spectral encoding with a Raman reporter molecule and then stabilized and protected by low molecular weight polyethylene glycols (PEGs). Heterofunctional PEG was covalently conjugated to epidermal growth factor (EGF) peptide, a ligand that binds to EGFR with high specificity and affinity. To identify CTC in normal mouse blood, varying quantities of Tu212 cells were added into mice blood samples, then our nanoparticle was added to the sample and the presence of Tu212 cells were detected in vitro using laser excitation of the Raman reporters. Different types of cancer cells with variable EGFR expression were also examined in blood to confirm the specificity of the EGF-targeted SERS nanoparticles. Normal mouse blood served as the experimental control to account for non-specific binding. Results: The cellular uptake of the EGFR-targeting nanoparticle in high EGFR expression Tu212 cells was about 10-fold higher than that in low EGFR expression H460 cells in vitro, suggesting a specific EGFR targeting of the gold nanoparticle. Tu212 cells could be selectively labeled and quantified (5.6 × 104 nanoparticles/cell) at a concentration of approximately 10 cells per ml of normal mouse blood. Comparing the labeling of Tu212 cells by our nanoparticles with H460 cells in the mouse blood samples showed that the signal intensity in Tu212 cells was about 9-fold higher than that in H460 cells ((3750 ± 230 vs. 350 ± 120, respectively, p <0.05). These results indicated high sensitivity and specificity of using SERS-gold nanoparticles for detection of CTCs. Conclusion: We have demonstrated the ability to use targeted surface-enhanced Raman gold nanoparticles to quantify CTCs with EGFR expression (This research was supported by the National Cancer Institute award 5 P50 CA128613 and U54CA119338-04). Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1155.

SERS Nanoparticles: A New Optical Detection Modality for Cancer Diagnosis

Surface-enhanced Raman scattering (SERS) is an optical detection technique that offers advantages over traditional assay detection technologies, such as fluorescence and chemiluminescence. These advantages include sensitivity, high levels of multiplexing, robustness and ability to perform detection in blood and other biological matrices. Here, we report on the growing field of SERS-active nanoparticles as a novel method for detection, with special emphasis on their use in the field of oncology. We discuss examples of SERS-active nanoparticles used in an assay for PSA, BRCA1 and Her-2, along with examples of nucleic-acid detection. We present data on a novel homogeneous, single-tube, rapid assay for nucleic acid detection and show how it will benefit the oncology community.