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The early detection of procalcitonin (PCT) is crucial for diagnosing bacterial infections due to its high sensitivity and specificity. While colloidal gold colorimetric and immune-chemiluminescence methods are commonly employed in clinical detection, the former lacks sensitivity, and the latter faces challenges with a brief luminescence process and an elevated background. Here, we introduce a novel approach for the quantitative analysis of PCT using surface-enhanced Raman spectroscopy (SERS), leveraging the enhanced properties of metal nanoparticles. Simultaneously, we employed a magnetic nanoparticle coating and surface biofunctionalization modification to immobilize PCT-trapping antibodies, creating the required immune substrates. The resulting magnetic nanoparticles and antibody complexes, acting as carriers and recognition units, exhibited superparamagnetism and the specific recognition of biomarkers. Then, this complex efficiently underwent magnetic separation with an applied magnetic field, streamlining the cumbersome steps of traditional ELISA and significantly reducing the detection time. In conclusion, the exploration of immunomagnetic bead detection technology based on surface-enhanced Raman spectroscopy holds crucial practical significance for the sensitive detection of PCT. [ABSTRACT FROM AUTHOR]

The early detection of procalcitonin (PCT) is crucial for diagnosing bacterial infections due to its high sensitivity and specificity. While colloidal gold colorimetric and immune-chemiluminescence methods are commonly employed in clinical detection, the former lacks sensitivity, and the latter faces challenges with a brief luminescence process and an elevated background. Here, we introduce a novel approach for the quantitative analysis of PCT using surface-enhanced Raman spectroscopy (SERS), leveraging the enhanced properties of metal nanoparticles. Simultaneously, we employed a magnetic nanoparticle coating and surface biofunctionalization modification to immobilize PCT-trapping antibodies, creating the required immune substrates. The resulting magnetic nanoparticles and antibody complexes, acting as carriers and recognition units, exhibited superparamagnetism and the specific recognition of biomarkers. Then, this complex efficiently underwent magnetic separation with an applied magnetic field, streamlining the cumbersome steps of traditional ELISA and significantly reducing the detection time. In conclusion, the exploration of immunomagnetic bead detection technology based on surface-enhanced Raman spectroscopy holds crucial practical significance for the sensitive detection of PCT.

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In recent years, Raman spectroscopy has been used to study biological tissues. However, the analysis of experimental Raman spectra is still challenging, since the Raman spectra of most biological tissue components overlap significantly and it is difficult to separate individual components. New methods of analysis are needed that would allow for the decomposition of Raman spectra into components and the evaluation of their contribution. The aim of our work is to study the possibilities of the multivariate curve resolution alternating least squares (MCR-ALS) method for the analysis of skin tissues in vivo. We investigated the Raman spectra of human skin recorded using a portable conventional Raman spectroscopy setup. The MCR-ALS analysis was performed for the Raman spectra of normal skin, keratosis, basal cell carcinoma, malignant melanoma, and pigmented nevus. We obtained spectral profiles corresponding to the contribution of the optical system and skin components: melanin, proteins, lipids, water, etc. The obtained results show that the multivariate curve resolution alternating least squares analysis can provide new information on the biochemical profiles of skin tissues. Such information may be used in medical diagnostics to analyze Raman spectra with a low signal-to-noise ratio, as well as in various fields of science and industry for preprocessing Raman spectra to remove parasitic components. [ABSTRACT FROM AUTHOR]

Over the past decades, Raman spectroscopy has been proven to be a powerful tool for in situ detection in the deep sea. However, two important issues are usually presented for solid detection of Raman in the sea: (a) The implementation of accurate laser focusing using the manipulator of remotely operated vehicles is difficult; (b) it is challenging to recognise minerals by Raman only. In this study, a novel approach was presented to address these difficulties by introducing microimage into underwater Raman system to aid laser focusing and spectra analysis. The further evaluation results showed that, using 5× objective lens, the joint system could obtain the focused laser spot size of 290 μm on the focal plane for Raman detection and the spatial resolution of 2.2 μm for the microimaging. With the aid of microimaging, the Raman probe was successfully applied to the China Yellow Sea (36.129°N, 120.215°E) for in situ detection on the seafloor. Microimaging is a practical method of promoting the detection ability of underwater Raman spectroscopy, and biological applications would be another perspective in the future. [ABSTRACT FROM AUTHOR]

Raman spectroscopy is promising as a noninvasive tool for cancer diagnosis. A superficial Raman probe might improve the classification of bladder cancer, because information is gained solely from the diseased tissue and irrelevant information from deeper layers is omitted. We compared Raman measurements of a superficial to a nonsuperficial probe, in bladder cancer diagnosis. Two‐hundred sixteen Raman measurements and biopsies were taken in vivo from at least one suspicious and one unsuspicious bladder location in 104 patients. A Raman classification model was constructed based on histopathology, using a principal‐component fed linear‐discriminant‐analysis and leave‐one‐person‐out cross‐validation. The diagnostic ability measured in area under the receiver operating characteristics curve was 0.95 and 0.80, the sensitivity was 90% and 85% and the specificity was 87% and 88% for the superficial and the nonsuperficial probe, respectively. We found inflammation to be a confounder and additionally we found a gradual transition from benign to low‐grade to high‐grade urothelial carcinoma. Raman spectroscopy provides additional information to histopathology and the diagnostic value using a superficial probe. [ABSTRACT FROM AUTHOR]

Prevalent contamination of water by cadmium ion (Cd2+) brings environmental risk, which threatening to human health including renal dysfunction, reduced lung capacity, and some cancers. It calls for rapid, sensitive and selective protocol to analyze Cd2+ on field. In this work, specific Raman probe is rationally designed by gold nanoparticles (AuNPs) functionalized with tripeptide glutathione (GSH) and Rhodamine 6G (R6G) (denoted as R6G/GSH/AuNPs), which is explored for indirectly determining trace Cd2+ in river water. Based on chelating interaction between GSH and Cd2+ to form tetrahedral Cd(SG)4, which trends easy detachment from R6G/GSH/AuNPs. With increasing Cd2+ concentration, the Raman probe without protection of GSH happens due aggregation and Raman signal of R6G increases correspondingly. The R6G/GSH/AuNPs-based Raman detection of Cd2+ in river water shows rapidness, excellent sensitivity, selectivity and good repeatability. Limit of detection of 10 ppb with a widely linear range of 0.5–20 ppm could be achieved. It could be perspective that such Raman probe could be extended to be used for on-site monitoring trace Cd2+ in river water system.

In recent years, Raman spectroscopy has been used to study biological tissues. However, the analysis of experimental Raman spectra is still challenging, since the Raman spectra of most biological tissue components overlap significantly and it is difficult to separate individual components. New methods of analysis are needed that would allow for the decomposition of Raman spectra into components and the evaluation of their contribution. The aim of our work is to study the possibilities of the multivariate curve resolution alternating least squares (MCR-ALS) method for the analysis of skin tissues in vivo. We investigated the Raman spectra of human skin recorded using a portable conventional Raman spectroscopy setup. The MCR-ALS analysis was performed for the Raman spectra of normal skin, keratosis, basal cell carcinoma, malignant melanoma, and pigmented nevus. We obtained spectral profiles corresponding to the contribution of the optical system and skin components: melanin, proteins, lipids, water, etc. The obtained results show that the multivariate curve resolution alternating least squares analysis can provide new information on the biochemical profiles of skin tissues. Such information may be used in medical diagnostics to analyze Raman spectra with a low signal-to-noise ratio, as well as in various fields of science and industry for preprocessing Raman spectra to remove parasitic components.

Staphylococcus aureus contamination in food supplements poses substantial challenges to public health and large-scale production but the sensitive detection in a timely manner remains a bottleneck. Drawing inspiration from the sea hedgehog, gold nanostars (AuNSs) were leveraged to design an ultrasensitive surface-enhanced Raman scattering (SERS) biosensor for the determination of Staphylococcus aureus in food supplements. Besides the surface enhancement furnished by the AuNSs, Raman reporter molecules and specific aptamers sequentially self-assembled onto these AuNSs to construct the "three-in-one" SERS biosensor probe for label-based quantitation of Staphylococcus aureus. Following incubation with contaminated health product samples, the gold nanostars@Raman reporter-aptamer specifically recognize and assemble around Staphylococcus aureus cells, forming a distinctive sea hedgehog structure. This unique configuration results in an amplified Raman signal at 1338 cm−1 and an enhancement factor of up to 6.71 × 107. The entire quantitative detection process can be completed within 30 min, boasting an exceptional limit of detection as low as 1.0 CFU mL−1. The method exhibits a broad working range for the determination of Staphylococcus aureus , with concentrations spanning 2.15 CFU mL−1 to 2.15 × 105 CFU mL−1. Furthermore, it demonstrates outstanding precision, with relative standard deviation values consistently below 5.0%. As a showcase to validate the practicality of the SERS method, we conducted tests on determining Staphylococcus aureus in a herbal food supplement, i.e., Ginkgo Biloba extract (GBE); the results align closely with those obtained through the conventional lysogeny broth agar plate method, pointing to the potential applicability in real-world scenarios. [ABSTRACT FROM AUTHOR]

Prevalent contamination of water by cadmium ion (Cd2+) brings environmental risk, which threatening to human health including renal dysfunction, reduced lung capacity, and some cancers. It calls for rapid, sensitive and selective protocol to analyze Cd2+ on field. In this work, specific Raman probe is rationally designed by gold nanoparticles (AuNPs) functionalized with tripeptide glutathione (GSH) and Rhodamine 6G (R6G) (denoted as R6G/GSH/AuNPs), which is explored for indirectly determining trace Cd2+ in river water. Based on chelating interaction between GSH and Cd2+ to form tetrahedral Cd(SG) 4, which trends easy detachment from R6G/GSH/AuNPs. With increasing Cd2+ concentration, the Raman probe without protection of GSH happens due aggregation and Raman signal of R6G increases correspondingly. The R6G/GSH/AuNPs-based Raman detection of Cd2+ in river water shows rapidness, excellent sensitivity, selectivity and good repeatability. Limit of detection of 10 ppb with a widely linear range of 0.5–20 ppm could be achieved. It could be perspective that such Raman probe could be extended to be used for on-site monitoring trace Cd2+ in river water system. [ABSTRACT FROM AUTHOR]

A bis‐triarylborane tetracation (4‐Ar2B‐3,5‐Me2C6H2)‐C≡C−C≡C‐(3,5‐Me2C6H2‐4‐BAr2 [Ar=(2,6‐Me2‐4‐NMe3‐C6H2)+] (24+) shows distinctly different behaviour in its fluorimetric response than that of our recently published bis‐triarylborane 5‐(4‐Ar2B‐3,5‐Me2C6H2)‐2,2′‐(C4H2S)2–5′‐(3,5‐Me2C6H2‐4‐BAr2) (34+). Single‐crystal X‐ray diffraction data on the neutral bis‐triarylborane precursor 2 N confirm its rod‐like dumbbell structure, which is shown to be important for DNA/RNA targeting and also for BSA protein binding. Fluorimetric titrations with DNA/RNA/BSA revealed the very strong affinity of 24+ and indicated the importance of the properties of the linker connecting the two triarylboranes. Using the butadiyne rather than a bithiophene linker resulted in an opposite emission effect (quenching vs. enhancement), and 24+ bound to BSA 100 times stronger than 34+. Moreover, 24+ interacted strongly with ss‐RNA, and circular dichroism (CD) results suggest ss‐RNA chain‐wrapping around the rod‐like bis‐triarylborane dumbbell structure like a thread around a spindle, a very unusual mode of binding of ss‐RNA with small molecules. Furthermore, 24+ yielded strong Raman/SERS signals, allowing DNA or protein detection at ca. 10 nm concentrations. The above observations, combined with low cytotoxicity, efficient human cell uptake and organelle‐selective accumulation make such compounds intriguing novel lead structures for bio‐oriented, dual fluorescence/Raman‐based applications. [ABSTRACT FROM AUTHOR]

For Raman hyperspectral detection and imaging in live cells, it is very desirable to create novel probes with strong and unique Raman vibrations in the biological silent region (1800-2800 cm -1 ). The use of molecular probes in Raman imaging is a relatively new technique in subcellular research; however, it is developing very rapidly. Compared with the label-free method, it allows for a more sensitive and selective visualization of organelles within a single cell. Biological systems are incredibly complex and heterogeneous. Directly visualizing biological structures and activities at the cellular and subcellular levels remains by far one of the most intuitive and powerful ways to study biological problems. Each organelle plays a specific and essential role in cellular processes, but importantly for cells to survive, mitochondrial function must be reliable. Motivated by earlier attempts and successes of biorthogonal chemical imaging, we develop a tool supporting Raman imaging of cells to track biochemical changes associated with mitochondrial function at the cellular level in an in vitro model. In this work, we present a newly synthesized highly sensitive RAR-BR Raman probe for the selective imaging of mitochondria in live endothelial cells.

A spatial heterodyne Raman spectrometer (SHRS), constructed using a modular optical cage and lens tube system, is described for use with a commercial silica and a custom single-crystal (SC) sapphire fiber Raman probe. The utility of these fiber-coupled SHRS chemical sensors is demonstrated using 532 nm laser excitation for acquiring Raman measurements of solid (sulfur) and liquid (cyclohexane) Raman standards as well as real-world, plastic-bonded explosives (PBX) comprising 1,3,5- triamino- 2,4,6- trinitrobenzene (TATB) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) energetic materials. The SHRS is a fixed grating-based dispersive interferometer equipped with an array detector. Each Raman spectrum was extracted from its corresponding fringe image (i.e., interferogram) using a Fourier transform method. Raman measurements were acquired with the SHRS Littrow wavelength set at the laser excitation wavelength over a spectral range of ∼1750 cm−1 with a spectral resolution of ∼8 cm−1 for sapphire and ∼10 cm−1 for silica fiber probes. The large aperture of the SHRS allows much larger fiber diameters to be used without degrading spectral resolution as demonstrated with the larger sapphire collection fiber diameter (330 μm) compared to the silica fiber (100 μm). Unlike the dual silica fiber Raman probe, the dual sapphire fiber Raman probe did not include filtering at the fiber probe tip nearest the sample. Even so, SC sapphire fiber probe measurements produced less background than silica fibers allowing Raman measurements as close as ∼85 cm−1 to the excitation laser. Despite the short lengths of sapphire fiber used to construct the sapphire probe, well-defined, sharp sapphire Raman bands at 420, 580, and 750 cm−1 were observed in the SHRS spectra of cyclohexane and the highly fluorescent HMX-based PBX. SHRS measurements of the latter produced low background interference in the extracted Raman spectrum because the broad band fluorescence (i.e., a direct current, or DC, component) does not contribute to the interferogram intensity (i.e., the alternating current, or AC, component). SHRS spectral resolution, throughput, and signal-to-noise ratio are also discussed along with the merits of using sapphire Raman bands as internal performance references and as internal wavelength calibration standards in Raman measurements. [ABSTRACT FROM AUTHOR]

As research progresses in the field of life sciences, there is an increased demand for new technologies that can allow us to study intact cells and tissues. The quantitative analysis and mathematical modeling of living things based on empirical data is useful for connecting molecular biology to new areas, such as computational biology. Raman spectroscopy is regarded as one of the possible methods by which we can observe living organisms in a noninvasive manner. This could improve the quality of research in the field of medicine and health and will largely contribute to society in the future. The present review introduces some techniques based on Raman spectroscopy and evaluates their applications in intact live samples. [ABSTRACT FROM AUTHOR]

With brain tumour incidence increasing, there is an urgent need for better diagnostic tools. Intraoperatively, brain tumours are diagnosed using a smear preparation reported by a neuropathologist. These have many limitations, including the time taken for the specimen to reach the pathology department and for results to be communicated to the surgeon. There is also a need to assist with resection rates and identifying infiltrative tumour edges intraoperatively to improve clearance. We present a novel study using a handheld Raman probe in conjunction with gold nanoparticles, to detect primary and metastatic brain tumours from fresh brain tissue sent for intraoperative smear diagnosis. Fresh brain tissue samples sent for intraoperative smear diagnosis were tested using the handheld Raman probe after application of gold nanoparticles. Derived Raman spectra were inputted into forward feature extraction algorithms to build a predictive model for sensitivity and specificity of outcome. These results demonstrate an ability to detect primary from metastatic tumours (especially for normal and low grade lesions), in which accuracy, sensitivity and specificity were respectively equal to 98.6%, 94.4% and 99.5% for normal brain tissue; 96.1%, 92.2% and 97.0% for low grade glial tumours; 90.3%, 89.7% and 90.6% for high grade glial tumours; 94.8%, 63.9% and 97.1% for meningiomas; 95.4%, 79.2% and 98.8% for metastases; and 99.6%, 88.9% and 100% for lymphoma, based on smear samples (κ = 0.87). Similar results were observed when compared to the final formalin-fixed paraffin embedded tissue diagnosis (κ = 0.85). Overall, our results have demonstrated the ability of Raman spectroscopy to match results provided by intraoperative smear diagnosis and raise the possibility of use intraoperatively to aid surgeons by providing faster diagnosis. Moving this technology into theatre will allow it to develop further and thus reach its potential in the clinical arena.

Functionalized graphene - metal nano-conjugates are used as Raman probes, in recent years, for trace level identification of materials having specific Raman active modes. In the present paper, model Raman probes were modeled through conjugation of Au and Ag clusters with functionalized graphene systems. In silico models of functionalized (5,5)-graphene sheets were designed at the density functional theory (DFT) level through attachments of epoxy, -OH and -NH(CH)SH/-CONH(CH)SH groups. Model Raman probes were designed through attachment of Au and Ag clusters to the functional sites. Full geometry optimizations followed by vibrational analysis were carried out to ensure that the designed Raman probes have acceptable geometric characteristics to attach Raman-active molecules to the metal site. Pyridine was used as a test system to investigate the functionality of such model Raman probes through attachment with the metal clusters. It was observed that the chemical effects due to such attachments increase the Raman intensities (RI) of specific Raman modes of pyridine (in-plane symmetric bending (1040 cm) and asymmetric stretch-bend (1634 cm)), which are too weak in the isolated molecule. Furthermore, the suggested in silico system could provide an important model for basic understanding of RI-enhancements of molecules through increase of the size of the metal clusters, as the observed enhancement was found to be dependent on the polarizability of the metal clusters attached to the molecule of interest. [ABSTRACT FROM AUTHOR]

Optical labels are needed for probing specific target molecules in complex biological systems. As a newly emerging category of tags for molecular imaging in live cells, the Raman label attracts much attention because of the rich information obtained from targeted and untargeted molecules by detecting molecular vibrations. Here, we list three types of Raman probes based on different mechanisms: Surface Enhanced Raman Scattering (SERS) probes, bioorthogonal Raman probes, and Resonance Raman (RR) probes. We review how these Raman probes work for detecting and imaging proteins, nucleic acids, lipids, and other biomolecules in vitro, within cells, or in vivo. We also summarize recent noteworthy studies, expound on the construction of every type of Raman probe and operating principle, sum up in tables typically targeting molecules for specific binding, and provide merits, drawbacks, and future prospects for the three Raman probes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Visualization of mitochondria and tracking of functional changes in live cells was shown. • Subcellular mitochondrial activity was tested using labeled and unlabeled Raman imaging, the latter improved sensitivity. • The MitoBADY Raman probe was used to detect subtle changes in mitochondrial membrane potential as an indicator of mitochondrial activity. • A semi-quantitative approach was used to estimate mitochondrial activity in live cells. The role of mitochondria goes beyond their capacity to create molecular fuel and includes e.g. the production of reactive oxygen species and the regulation of cell death. In endothelial cells, mitochondria have a significant impact on cellular function under both healthy and pathological conditions. Endothelial dysfunction contributes to the development of various lifestyle diseases and the key players in their pathogenesis are among others vascular inflammation and oxidative stress. The latter is very closely related to mitochondrial dysfunction; however, it is not straightforward. First, because mitochondria are small cellular structures, and second, it requires a sensitive method to follow the subtle biochemical changes. For this purpose, Raman microscopy (RM) was used here, which is considered a high-resolution method and can be applied in situ , usually as a non-labeled technique. In this work, we show that RM can not only locate mitochondria in the cell but also track their functional changes. Moreover, we test if labeling cells with Raman probes (Rp) can improve the specificity and sensitivity of RM (compared to conventional labeled techniques such as fluorescence, and the non-labeled Raman technique). MitoBADY Rp was used to detect changes in mitochondrial membrane potential as an indicator of mitochondrial activity, e.g. hyperpolarization or distortion of the proton gradient in the intermembrane space (depolarization). Thus, we show and compare RM, in the form of a label and non-labeled, to such a subtle cellular analysis. [ABSTRACT FROM AUTHOR]

Trotz der bekannten Vorteile der Raman-Spektroskopie, wie bspw. eine höhere chemische Selektivität gegenüber Messmethoden im nahen Infrarot (NIR) oder die im Vergleich zum mittleren Infrarotbereich (MIR) niedrigen Matrixeinflüsse des Wassermoleküls, ist diese optische Messtechnik in der Online-Prozessanalysentechnik nicht weit verbreitet. Ein wesentliches Problem besteht in einem oftmals kostenintensiven Nachrüsten einer Messstelle durch den Einbau sogenannter Immersionssonden in eine produktführende Rohrleitung oder einen Behälter. Eine praktikable Alternative stellt das hier entwickelte neuartige Sondensystem dar, welches eine Strahlführung über Linsen mit relativ großen Durchmessern beinhaltet, da dieses an vorhandene Schauglasarmaturen angekoppelt werden kann. Mit diesem robusten Sondenaufbau sind Brennweiten weit über 25 mm möglich, welche Echtzeit-Messungen von außerhalb der produktführenden Leitungen durch optische Schaugläser gestatten. Die dadurch entstehenden Messoptionen werden exemplarisch am Nachweis von Ethanol durch Schaugläser unterschiedlicher Dicken sowie bei einer quantitativen Echtzeit-Verfolgung eines Propylencarbonat-Wasser-Gemisches durch eine Schauglasarmatur (Nenndruck PN 16, Nennweite DN 50) im Technikumsmaßstab untersucht. Die vorgestellte Raman-Sonde hat durch einfache Adaption an bereits vorhandene Armaturen industrieller Anlagen das Potential einer preiswerten und kontaktlosen Inline-Messlösung mit hoher Standzeit in der Prozessanalysentechnik (PAT). Raman spectroscopy features some significant advantages against existing spectroscopic techniques. Amongst them are higher chemical sensitivities compared to NIR and a relatively low detection range for water molecules, in contrast to MIR spectroscopy. In process installations, compared to all spectroscopic techniques Raman plays only a minor role. Main challenges for process integration are long-term stability of the available measurement systems, high installation costs of so-called immersion probes and the addition of measurement points to existing plant layouts in piping and vessels. After the implementation of probes, a technical clearance that consists of an acceptance and pressure test has to be carried out by external certification authorities. A practical alternative is demonstrated by a robust probe concept, which enables beam propagation through large aperture optics. Therefore, focal lengths exceeding 25 mm allow real-time measurement of samples from the outside of piping filled with analytes through optical windows in production plants. The potential of this new measurement option is tested exemplarily by the detection of ethanol through optical windows of various thicknesses. A quantitative real-time monitoring of a mixture of propylene carbonate in water through an inspection glass PN 16 was tested in a pilot plant scale. The presented Raman probe has a high potential for the use in industrial plants, as it allows a simple, cost-efficient and contact-free adaption to existing measurement points in process analytic technology and features a long service life. [ABSTRACT FROM AUTHOR]

We developed a highly sensitive surface-enhanced Raman scattering (SERS) technique for determining Fe 3+ ions via synthesis of inositol hexaphosphate (IP 6 ) capped silver nanoparticles (AgNPs). IP 6 (1.98 nm thickness) coated on the surface of AgNPs not only provided a protection layer to stabilize silver substrate but also specifically anchoring sites of phosphates to capture Fe 3+ ions from aqueous solution. Rhodamine 6G (R6G) was used as a Raman indicator in this case and the scattering intensity of R6G in Raman probe increased with adding Fe 3+ ions. A possible mechanism is that IP 6 bound with Fe 3+ narrowed the gap of neighboring AgNPs to produce plenty of SERS “hot spots”. Due to the controllable aggregation of IP 6 @R6G–AgNPs by Fe 3+ , it presents a widely linear range of 11.2–39.2 ppm for analyzing the Fe 3+ ions. This Raman-based method for detecting Fe 3+ showed a high selectivity in the presence of other metal ions in same solution involving Mg 2+ , Cu 2+ , Ca 2+ , Pb 2+ , Co 2+ , Na + , Zn 2+ , K + , Li + , Mn 2+ and Fe 2+ . Under optimal conditions, the limit of detection (LOD) for SERS testing Fe 3+ could be down to 0.28 ppm. As a practical application, the Raman assay for the determination of Fe 3+ in river water was carried out. [ABSTRACT FROM AUTHOR]

The objective of this study was to build and test an adjunct system to a colonoscope for in vivo measurement of Raman spectra from colon tissue for potentially improving the detection of early cancers. The novelty of this system was that low cost fibre optic probes were used, without the addition of expensive optical filters. Good quality in vivo Raman spectra were successfully obtained with a 1 s integration time in the high frequency (HF) range from normal tissue and polyps of patients during a colonoscopy. The polyps were subsequently removed, and their pathology determined. The acquired in vivo Raman spectra showed clear changes between tissue with normal and tubular adenoma pathology. Further clinical study with this low cost HF Raman probe is warranted to fully test its clinical utility. [ABSTRACT FROM AUTHOR]

Flow cytometry is an indispensable tool in biology and medicine for counting and analyzing cells in large heterogeneous populations. It identifies multiple characteristics of every single cell, typically via fluorescent probes that specifically bind to target molecules on the cell surface or within the cell. However, flow cytometry has a critical limitation: the color barrier. The number of chemical traits that can be simultaneously resolved is typically limited to several due to the spectral overlap between fluorescence signals from different fluorescent probes. Here, we present color-scalable flow cytometry based on coherent Raman flow cytometry with Raman tags to break the color barrier. This is made possible by combining a broadband Fourier-transform coherent anti-Stokes Raman scattering (FT-CARS) flow cytometer, resonance-enhanced cyanine-based Raman tags, and Raman-active dots (Rdots). Specifically, we synthesized 20 cyanine-based Raman tags whose Raman spectra are linearly independent in the fingerprint region (400 to 1,600 cm -1 ). For highly sensitive detection, we produced Rdots composed of 12 different Raman tags in polymer nanoparticles whose detection limit was as low as 12 nM for a short FT-CARS signal integration time of 420 µs. We performed multiplex flow cytometry of MCF-7 breast cancer cells stained by 12 different Rdots with a high classification accuracy of 98%. Moreover, we demonstrated a large-scale time-course analysis of endocytosis via the multiplex Raman flow cytometer. Our method can theoretically achieve flow cytometry of live cells with >140 colors based on a single excitation laser and a single detector without increasing instrument size, cost, or complexity., (© The Author(s) 2023. Published by Oxford University Press on behalf of the National Academy of Sciences.)

A simple and reliable method based on surface-enhanced Raman scattering (SERS) with a portable Raman system is described for sensitive determination of trace levels of Rhodamine B (RB) in hot sauce samples. The sodium salt of phytic acid (IP 6 ) stabilized Au@Ag core–shell bimetallic nanoparticles are constructed and used as SERS substrate, yielding high Raman enhancement of RB. The limit of detection for RB in water is 5 nM (2 ppb), which is below China Exit and Entry Inspection and Quarantine Bureau’s tolerance level of 5 ppb. Also, the proposed easy assay of IP 6 –Au@Ag NPs combining with portable Raman system could be applied for on-site monitoring RB in hot sauce. [ABSTRACT FROM AUTHOR]

Abstract: The rapid sensing for melamine in milk products has been developed with a portable Raman system based on the facile synthesis of tri-sodium citrate and dodecasodium of phytic acid (IP6) dual-functionalized gold nanoparticles modified filter paper, shortly named IP6-TC@Au NPs test paper. The tri-sodium citrate improved the sensitivity of Raman probe and the later kept the shelf stability. The limit of detection for melamine in water is 5μM (0.63ppm) and it is 10μM (1.26ppm) for testing real milk sample, which is well below the FDA's tolerance level of 2.5ppm in milk. The proposed easy assay of IP6-TC@Au NPs test paper combining with portable Raman system could be applied for on-site monitoring melamine in milk products. [Copyright &y& Elsevier]

Summary: Light interacts with tissue in a number of ways including, elastic and inelastic scattering, reflection and absorption, leading to fluorescence and phosphorescence. These interactions can be used to measure abnormal changes in tissue. Initial optical biopsy systems have potential to be used as an adjunct to current investigative techniques to improve the targeting of blind biopsy. Future prospects with molecular-specific techniques may enable objective optical detection providing a real-time, highly sensitive and specific measurement of the histological state of the tissue. Raman spectroscopy has the potential to identify markers associated with malignant change and could be used as diagnostic tool for the early detection of precancerous and cancerous lesions in vivo. The clinical requirements for an objective, non-invasive, real-time probe for the accurate and repeatable measurement of pathological state of the tissue are overwhelming. This paper discusses some of the recent advances in the field. [Copyright &y& Elsevier]

In recent years, Raman spectroscopy has shown substantive promise in diagnosing bladder cancer, especially due to its exquisite molecular specificity. The ability to reduce false detection rates in comparison to existing diagnostic tools such as photodynamic diagnosis makes Raman spectroscopy particularly attractive as a complementary diagnostic tool for real-time guidance of transurethral resection of bladder tumor (TURBT). Nevertheless, the state-of-the-art high-volume Raman spectroscopic probes have not reached the expected levels of specificity thereby impeding their clinical translation. To address this issue, we propose the use of a confocal Raman probe for bladder cancer diagnosis that can boost the specificity of the diagnostic algorithm based on its suppression of the out-of-focus non-analyte-specific signals emanating from the neighboring normal tissue. In this article, we engineer and apply such a probe, having depth of field of approximately 280 μm, for Raman spectral acquisition from ex vivo normal and cancerous TURBT samples. Using this clinical dataset, a diagnostic algorithm based on principal component analysis and logistic regression is developed. We demonstrate that this approach results in comparable sensitivity but significantly higher specificity in relation to high-volume Raman spectral data. The application of only two principal components is sufficient for the discrimination of the samples underlining the robustness of the algorithm. Further, no discordance between replicate spectra is observed emphasizing the reproducible nature of the current diagnostic assessment. The high levels of sensitivity and specificity achieved in this proof-of-concept study opens substantive avenues for application of a confocal Raman probe during endoscopic procedures related to diagnosis and treatment of bladder cancer. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Existing approaches for early-stage bladder tumor diagnosis largely depend on invasive and time-consuming procedures, resulting in hospitalization, bleeding, bladder perforation, infection and other health risks for the patient. The reduction of current risk factors, while maintaining or even improving the diagnostic precision, is an underlying factor in clinical instrumentation research. For example, for clinic surveillance of patients with a history of noninvasive bladder tumors real-time tumor diagnosis can enable immediate laser-based removal of tumors using flexible cystoscopes in the outpatient clinic. Therefore, novel diagnostic modalities are required that can provide real-time in vivo tumor diagnosis. Raman spectroscopy provides biochemical information of tissue samples ex vivo and in vivo and without the need for complicated sample preparation and staining procedures. For the past decade there has been a rise in applications to diagnose and characterize early cancer in different organs, such as in head and neck, colon and stomach, but also different pathologies, for example, inflammation and atherosclerotic plaques. Bladder pathology has also been studied but only with little attention to aspects that can influence the diagnosis, such as tissue heterogeneity, data preprocessing and model development. The present study presents a clinical investigative study on bladder biopsies to characterize the tumor grading ex vivo, using a compact fiber probe-based imaging Raman system, as a crucial step towards in vivo Raman endoscopy. Furthermore, this study presents an evaluation of the tissue heterogeneity of highly fluorescent bladder tissues, and the multivariate statistical analysis for discrimination between nontumor tissue, and low- and high-grade tumor., (© 2019 The Authors. Journal of Biophotonics published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

With brain tumour incidence increasing, there is an urgent need for better diagnostic tools. Intraoperatively, brain tumours are diagnosed using a smear preparation reported by a neuropathologist. These have many limitations, including the time taken for the specimen to reach the pathology department and for results to be communicated to the surgeon. There is also a need to assist with resection rates and identifying infiltrative tumour edges intraoperatively to improve clearance. We present a novel study using a handheld Raman probe in conjunction with gold nanoparticles, to detect primary and metastatic brain tumours from fresh brain tissue sent for intraoperative smear diagnosis. Fresh brain tissue samples sent for intraoperative smear diagnosis were tested using the handheld Raman probe after application of gold nanoparticles. Derived Raman spectra were inputted into forward feature extraction algorithms to build a predictive model for sensitivity and specificity of outcome. These results demonstrate an ability to detect primary from metastatic tumours (especially for normal and low grade lesions), in which accuracy, sensitivity and specificity were respectively equal to 98.6%, 94.4% and 99.5% for normal brain tissue; 96.1%, 92.2% and 97.0% for low grade glial tumours; 90.3%, 89.7% and 90.6% for high grade glial tumours; 94.8%, 63.9% and 97.1% for meningiomas; 95.4%, 79.2% and 98.8% for metastases; and 99.6%, 88.9% and 100% for lymphoma, based on smear samples (κ = 0.87). Similar results were observed when compared to the final formalin-fixed paraffin embedded tissue diagnosis (κ = 0.85). Overall, our results have demonstrated the ability of Raman spectroscopy to match results provided by intraoperative smear diagnosis and raise the possibility of use intraoperatively to aid surgeons by providing faster diagnosis. Moving this technology into theatre will allow it to develop further and thus reach its potential in the clinical arena. [ABSTRACT FROM AUTHOR]

In this paper, using thiolated graphene oxide (GO‐O‐SH) as substrate, gold nanorods (AuNRs) covalently linked to the GO surface by in‐situ seed growth method were first reported. The as‐prepared composites were characterized by UV–vis spectrum, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT‐IR). Experimental results indicated that the introduction of short flexible organic chain between GO and AuNRs contributed to the homogenous synthesis of gold rods, and uniform gold nanorods with aspect ratio within 3~8 were covalently linked to the surface of GO with high stability and yield. The strategy represented an outstanding improvement in comparison to the traditional route for fabricating GO@AuNRs composites. Furthermore, based on coupling of the two nanomaterials, the composites could act as high sensitive Raman probe with limit of detection (LOD) reaching 1 × 10−12 M. In this paper, using thiolated graphene oxide (GO‐O‐SH) as substrate, gold nanorods (AuNRs) were covalently synthesized on the GO surface by in‐situ seed growth method. The strategy represents an outstanding improvement in comparison to the traditional route for fabricating GO@AuNRs composites. The as‐prepared GO@AuNRs can act as ultrasensitive Raman probe with limit of detection (LOD) reaching 1 × 10−12 M. [ABSTRACT FROM AUTHOR]

The Raman probe plays an essential role in sensitive surface-enhanced Raman scattering (SERS) assay. Here, a novel Raman probe was developed by assembling gold nanoparticles in triangular pyramid DNA (TP-Au NPs). Such probe with intense electromagnetic hot spots can provide dramatically enhanced Raman scattering. Through assembling recognition DNA on one corner of the TP-DNA, the recognition event is definite and designable. The probe was characterized through TEM, and its SERS superiority was investigated. As models, circulating tumor cells and exosomes were detected with high sensitivity and selectivity by using this probe. Meanwhile, the developed SERS probe can also perform well in real world samples.

A miniature Raman probe was successfully developed and navigated through the lung architecture into the narrow peripheral airways. Using this probe and a home‐made rapid Raman spectroscopy system, in vivo Raman spectra were successfully obtained from the periphery lung for the first time. Further details can be found in the article by Hanna C. McGregor, Michael A. Short, Stephen Lam, et al. (e201800055). A miniature Raman probe was successfully developed and navigated through the lung architecture into the narrow peripheral airways. Using this probe and a home‐made rapid Raman spectroscopy system, in vivo Raman spectra were successfully obtained from the periphery lung for the first time. Further details can be found in the article by Hanna C. McGregor, Michael A. Short, Stephen Lam, et al. (e201800055). [ABSTRACT FROM AUTHOR]

The management of cancer in the periphery lung is in critical need of new strategies. Here, the development and test of a novel miniature Raman probe capable of navigating the peripheral lung architecture is reported. The probe was 1.35 mm in diameter, with a minimum bend radius of 13 mm and had a large light collection area for its size. Peripheral lung Raman spectra were successfully obtained from normal tissue and cancerous nodule using the probe coupled to a home‐made rapid Raman spectroscopy system with a fast integration time of 1 second and a low excitation power of 15 mW. This is the first time in vivo Raman spectra from the periphery lung being reported. The collected spectra showed lipid, protein and deoxyhemoglobin signatures that might be useful for classifying pathology. Large scale clinical study is planned to confirm the utility of this new technology for improving periphery lung cancer detection. Left: Radial ultrasound image of a peripheral lung nodule: size given by crosshairs D1 and D2. Right: Truncated Raman spectra of a cancerous nodule, whole blood, and normal peripheral airway tissue. Spectra were shifted on intensity scale for clarity. A miniature Raman probe was successfully developed and navigated through the lung architecture into the narrow peripheral airways. Using this probe and our rapid Raman system, in vivo Raman spectra were successfully obtained from the periphery lung for the first time. [ABSTRACT FROM AUTHOR]