Noninvasive molecular imaging of small living subjects using Raman spectroscopy

Innovative applications of SERS in precision medicine: In situ and real-time live imaging

Surface-enhanced Raman scattering (SERS), a molecular spectroscopic technique with high sensitivity and specificity, has demonstrated groundbreaking potential in precision medicine in recent years. This review systematically summarizes recent advancements in SERS technology for in situ and real-time live imaging, focusing on its core value in early tumor diagnosis, intraoperative navigation, drug delivery monitoring, and dynamic pathological analysis. By optimizing nanoscale probe design-including targeted functionalization, enhanced biocompatibility, and integration with imaging systems-SERS overcomes the sensitivity and spatiotemporal resolution limitations of traditional imaging techniques, enabling precise capture and dynamic tracking of molecular events in live biological environments. The article further analyzes challenges in clinical translation, such as signal stability in complex biological environments, multimodal imaging coordination, and standardized data processing methods. Future directions for personalized therapy and intelligent integrated diagnostics are also discussed.

Targeted Raman Visualization and Mitigation of α-Synuclein Amyloidogenesis in Living Zebrafish by a Nanobody-Decorated Polydiacetylene

α-Synuclein (α-Syn) amyloidogenesis is considered a promising diagnostic marker and therapeutic target for Parkinson's disease (PD). Simultaneously visualizing and mitigating α-Syn amyloidogenesis are essential for future PD theranostics, yet they continue to pose an insurmountable challenge. This study have herein developed a nanobody-decorated polydiacetylene to approach a straightforward solution. Grafting α-Syn61-95 segment into the third complementary determining region of a parent nanobody generates an engineered nanobody X30 that can bind with α-Syn and prevent its amyloidogenesis through homotypic interaction. It next use X30 to decorate poly(deca-4,6-diynedioic acid) (PDDA), a polydiacetylene with an ultrastrong alkyne Raman signal (2120 cm-1) in the cellular silent region, to create an α-Syn targeting Raman probe PX30. The binding affinity between X30 and α-Syn can be further boosted for over 150 times attributed to the rigidity of PDDA backbone and the multivalent effect. Therefore, PX30 not only enables real-time Raman visualization of α-Syn amyloidogenesis with a high signal-to-noise ratio in living zebrafish, but also alleviates amyloidogenesis-mediated damage to zebrafish embryos by effectively inhibiting α-Syn amyloidogenesis at low stoichiometric concentrations and scavenging pathologic reactive oxygen species.

In vivo surface-enhanced Raman scattering techniques: nanoprobes, instrumentation, and applications

Surface-enhanced Raman scattering (SERS) has emerged as a powerful tool in various biomedical applications, including in vivo imaging, diagnostics, and therapy, largely due to the development of near-infrared (NIR) active SERS substrates. This review provides a comprehensive overview of SERS-based applications in vivo, focusing on key aspects such as the design considerations for SERS nanoprobes and advancements in instrumentation. Topics covered include the development of NIR SERS substrates, Raman label compounds (RLCs), protective coatings, and the conjugation of bioligands for targeted imaging and therapy. The review also discusses microscope-based configurations such as scanning, widefield imaging, and fiber-optic setups. Recent advances in using SERS nanoprobes for in vivo sensing, diagnostics, biomolecule screening, multiplex imaging, intraoperative guidance, and multifunctional cancer therapy are highlighted. The review concludes by addressing challenges in the clinical translation of SERS nanoprobes and outlines future directions, emphasizing opportunities for advancing biomedical research and clinical applications.

Review of single-molecule immunoassays: Non-chip and on-chip Assays

Enhancing the sensitivity of immunoassays is an important requirement in the field of immunology, especially in light of rapid developments in genetic testing, making the detection of low-abundance protein biomarkers crucial. Therefore, innovations in highly sensitive immunoassays are imperative. This demand has led to the emergence of single-molecule immunoassays (SMIs), driving advancements in early diagnostic techniques, and ushering in a new era of immunoassays. This review begins by tracing the development of immunoassays and offers a detailed discussion of SMI technology across two distinct pathways: non-chip (SMI without microfluidic chips) and on-chip (SMI with microfluidic chips). Furthermore, we evaluated and compared these methods using two pathways. In addition, this review discusses the significance of SMI techniques in the diagnosis of various diseases and their current applications in laboratory and clinical settings. The progress of SMI in commercial applications and suggestions for innovative directions are also summarized. Despite the considerable potential of SMI, these technologies face challenges in practical application, particularly in developing countries and economically disadvantaged regions. The final section of this review addresses the challenges and prospects of these technologies.

RamanFormer: A Transformer-Based Quantification Approach for Raman Mixture Components

Raman spectroscopy is a noninvasive technique to identify materials by their unique molecular vibrational fingerprints. However, distinguishing and quantifying components in mixtures present challenges due to overlapping spectra, especially when components share similar features. This study presents "RamanFormer", a transformer-based model designed to enhance the analysis of Raman spectroscopy data. By effectively managing sequential data and integrating self-attention mechanisms, RamanFormer identifies and quantifies components in chemical mixtures with high precision, achieving a mean absolute error of 1.4% and a root mean squared error of 1.6%, significantly outperforming traditional methods such as least squares, MLP, VGG11, and ResNet50. Tested extensively on binary and ternary mixtures under varying conditions, including noise levels with a signal-to-noise ratio of up to 10 dB, RamanFormer proves to be a robust tool, improving the reliability of material identification and broadening the application of Raman spectroscopy in fields, such as material science, forensics, and biomedical diagnostics.

A Systematic Approach toward Enabling Maximal Targeting Efficiency of Cell Surface Proteins with Actively Targeted SERS Nanoparticles

With their intricate design, nanoparticles (NPs) have become indispensable tools in the quest for precise cellular targeting. Among various NPs, gold NPs stand out with unique features such as chemical stability, biocompatibility, adjustable shape, and size-dependent optical properties, making them particularly promising for molecular detection by leveraging the surface-enhanced Raman scattering (SERS) effect. Their multiplexing abilities for the simultaneous identification of multiple biomarkers are important in the rapidly evolving landscape of diverse cellular phenotypes and biomolecular profiling. However, the challenge is ensuring that SERS NPs can effectively target specific cells and biomarkers among intricate cell types and biomolecules with high specificity. In this study, we improve the functionalization of SERS NPs, optimizing their targeting efficiency in cellular applications for ca. 160 nm NP-based probes. Spherical SERS NPs, conjugated with antibodies targeting epidermal growth factor receptor and human epidermal growth factor receptor 2, were incubated with cells overexpressing these proteins, and their specific binding potential was quantified at each stage by using flow cytometry to achieve optimal targeting efficiency. We determined that maintaining an average of 3.5 × 105 thiols per NP, 300 antibodies per NP, 18,000 NPs per cell, conducting a 15 min staining incubation at 4 °C in a shaker, and using SM(PEG)12 as a cross-linker for the NP conjugation were crucial to achieve the highest targeting efficiency. Fluorescence and Raman imaging were used with these parameters to observe the maximum ability of these NPs to efficiently target suspended cells. These highly sensitive contrast agents demonstrate their pivotal role in effective active targeting, making them invaluable for multiplexing applications across diverse biological environments.

Compressive Raman imaging by combining scattering-projection interleaving with context-aware excitation

Exciting an object with a laser-focus array and randomly interleaving its scattering projection has been proved to be an effective strategy for speeding up Raman imaging. The so-called scattering interleaved Raman imaging (SIRI) method allows Raman hyperspectral imaging with a single snapshot and exhibits excellent reconstruction fidelity and signal-to-noise ratios (SNRs). Here, we show that the performance of SIRI is significantly improved when combined with context-aware excitation. The experiments on micro-plastics demonstrate that the restriction of Raman excitation within a smaller region of interest as guided by bright-field microscopy improves the signal intensity and the SNR, and it is surprising that the spectral resolution is also significantly improved. The context-aware SIRI method is successfully used for imaging of lipid-producing yeast cells, suggesting that it is a promising analytical tool for studying live cells or tissues.

Advancing Brain Research through Surface-Enhanced Raman Spectroscopy (SERS): Current Applications and Future Prospects

Surface-enhanced Raman spectroscopy (SERS) has recently emerged as a potent analytical technique with significant potential in the field of brain research. This review explores the applications and innovations of SERS in understanding the pathophysiological basis and diagnosis of brain disorders. SERS holds significant advantages over conventional Raman spectroscopy, particularly in terms of sensitivity and stability. The integration of label-free SERS presents promising opportunities for the rapid, reliable, and non-invasive diagnosis of brain-associated diseases, particularly when combined with advanced computational methods such as machine learning. SERS has potential to deepen our understanding of brain diseases, enhancing diagnosis, monitoring, and therapeutic interventions. Such advancements could significantly enhance the accuracy of clinical diagnosis and further our understanding of brain-related processes and diseases. This review assesses the utility of SERS in diagnosing and understanding the pathophysiological basis of brain disorders such as Alzheimer's and Parkinson's diseases, stroke, and brain cancer. Recent technological advances in SERS instrumentation and techniques are discussed, including innovations in nanoparticle design, substrate materials, and imaging technologies. We also explore prospects and emerging trends, offering insights into new technologies, while also addressing various challenges and limitations associated with SERS in brain research.

Quantitative Raman chemical imaging of intracellular drug-membrane aggregates and small molecule drug precipitates in cytoplasmic organelles

Raman confocal microscopes have been used to visualize the distribution of small molecule drugs within different subcellular compartments. This visualization allows the discovery, characterization, and detailed analysis of the molecular transport phenomena underpinning the Volume of Distribution - a key parameter governing the systemic pharmacokinetics of small molecule drugs. In the specific case of lipophilic small molecules with large Volumes of Distribution, chemical imaging studies using Raman confocal microscopes have revealed how weakly basic, poorly soluble drug molecules can accumulate inside cells by forming stable, supramolecular complexes in association with cytoplasmic membranes or by precipitating out within organelles. To study the self-assembly and function of the resulting intracellular drug inclusions, Raman chemical imaging methods have been developed to measure and map the mass, concentration, and ionization state of drug molecules at a microscopic, subcellular level. Beyond the field of drug delivery, Raman chemical imaging techniques relevant to the study of microscopic drug precipitates and drug-lipid complexes which form inside cells are also being developed by researchers with seemingly unrelated scientific interests. Highlighting advances in data acquisition, calibration methods, and computational data management and analysis tools, this review will cover a decade of technological developments that enable the conversion of spectral signals obtained from Raman confocal microscopes into new discoveries and information about previously unknown, concentrative drug transport pathways driven by soluble-to-insoluble phase transitions occurring within the cytoplasmic organelles of eukaryotic cells.

Recent development of surface-enhanced Raman scattering for biosensing

Surface-Enhanced Raman Scattering (SERS) technology, as a powerful tool to identify molecular species by collecting molecular spectral signals at the single-molecule level, has achieved substantial progresses in the fields of environmental science, medical diagnosis, food safety, and biological analysis. As deepening research is delved into SERS sensing, more and more high-performance or multifunctional SERS substrate materials emerge, which are expected to push Raman sensing into more application fields. Especially in the field of biological analysis, intrinsic and extrinsic SERS sensing schemes have been widely used and explored due to their fast, sensitive and reliable advantages. Herein, recent developments of SERS substrates and their applications in biomolecular detection (SARS-CoV-2 virus, tumor etc.), biological imaging and pesticide detection are summarized. The SERS concepts (including its basic theory and sensing mechanism) and the important strategies (extending from nanomaterials with tunable shapes and nanostructures to surface bio-functionalization by modifying affinity groups or specific biomolecules) for improving SERS biosensing performance are comprehensively discussed. For data analysis and identification, the applications of machine learning methods and software acquisition sources in SERS biosensing and diagnosing are discussed in detail. In conclusion, the challenges and perspectives of SERS biosensing in the future are presented.

Emergence of Raman Spectroscopy as a Probing Tool for Theranostics

Although medical advances have increased our grasp of the amazing morphological, genetic, and phenotypic diversity of diseases, there are still significant technological barriers to understanding their complex and dynamic character. Specifically, the complexities of the biological systems throw a diverse set of challenges in developing efficient theranostic tools and methodologies that can probe and treat pathologies. Among several emerging theranostic techniques such as photodynamic therapy, photothermal therapy, magnetic resonance imaging, and computed tomography, Raman spectroscopy (RS) is emerging as a promising tool that is a label-free, cost-effective, and non-destructive technique. It can also provide real-time diagnostic information and can employ multimodal probes for detection and therapy. These attributes make it a perfect candidate for the analytical counterpart of the existing theranostic probes. The use of biocompatible nanomaterials for the fabrication of Raman probes provides rich structural information about the biological molecules, cells, and tissues and highly sensitive information down to single-molecule levels when integrated with advanced RS tools. This review discusses the fundamentals of Raman spectroscopic tools such as surface-enhanced Raman spectroscopy and Resonance Raman spectroscopy, their variants, and the associated theranostic applications. Besides the advantages, the current limitations, and future challenges of using RS in disease diagnosis and therapy have also been discussed.

Nanomaterials for Fluorescence and Multimodal Bioimaging

Bioconjugated nanomaterials replace molecular probes in bioanalysis and bioimaging in vitro and in vivo. Nanoparticles of silica, metals, semiconductors, polymers, and supramolecular systems, conjugated with contrast agents and drugs for image-guided (MRI, fluorescence, PET, Raman, SPECT, photodynamic, photothermal, and photoacoustic) therapy infiltrate into preclinical and clinical settings. Small bioactive molecules like peptides, proteins, or DNA conjugated to the surfaces of drugs or probes help us to interface them with cells and tissues. Nevertheless, the toxicity and pharmacokinetics of nanodrugs, nanoprobes, and their components become the clinical barriers, underscoring the significance of developing biocompatible next-generation drugs and contrast agents. This account provides state-of-the-art advancements in the preparation and biological applications of bioconjugated nanomaterials and their molecular, cell, and in vivo applications. It focuses on the preparation, bioimaging, and bioanalytical applications of monomodal and multimodal nanoprobes composed of quantum dots, quantum clusters, iron oxide nanoparticles, and a few rare earth metal ion complexes.

Design and Synthesis of SERS Materials for In Vivo Molecular Imaging and Biosensing

Surface-enhanced Raman scattering (SERS) is a feasible and ultra-sensitive method for biomedical imaging and disease diagnosis. SERS is widely applied to in vivo imaging due to the development of functional nanoparticles encoded by Raman active molecules (SERS nanoprobes) and improvements in instruments. Herein, the recent developments in SERS active materials and their in vivo imaging and biosensing applications are overviewed. Various SERS substrates that have been successfully used for in vivo imaging are described. Then, the applications of SERS imaging in cancer detection and in vivo intraoperative guidance are summarized. The role of highly sensitive SERS biosensors in guiding the detection and prevention of diseases is discussed in detail. Moreover, its role in the identification and resection of microtumors and as a diagnostic and therapeutic platform is also reviewed. Finally, the progress and challenges associated with SERS active materials, equipment, and clinical translation are described. The present evidence suggests that SERS could be applied in clinical practice in the future.

Highly Excretable Gold Supraclusters for Translatable In Vivo Raman Imaging of Tumors

Raman spectroscopy provides excellent specificity for in vivo preclinical imaging through a readout of fingerprint-like spectra. To achieve sufficient sensitivity for in vivo Raman imaging, metallic gold nanoparticles larger than 10 nm were employed to amplify Raman signals via surface-enhanced Raman scattering (SERS). However, the inability to excrete such large gold nanoparticles has restricted the translation of Raman imaging. Here we present Raman-active metallic gold supraclusters that are biodegradable and excretable as nanoclusters. Although the small size of the gold nanocluster building blocks compromises the electromagnetic field enhancement effect, the supraclusters exhibit bright and prominent Raman scattering comparable to that of large gold nanoparticle-based SERS nanotags due to high loading of NIR-resonant Raman dyes and much suppressed fluorescence background by metallic supraclusters. The bright Raman scattering of the supraclusters was pH-responsive, and we successfully performed in vivo Raman imaging of acidic tumors in mice. Furthermore, in contrast to large gold nanoparticles that remain in the liver and spleen over 4 months, the supraclusters dissociated into small nanoclusters, and 73% of the administered dose to mice was excreted during the same period. The highly excretable Raman supraclusters demonstrated here offer great potential for clinical applications of in vivo Raman imaging.

The emerging applications and advancements of Raman spectroscopy in pediatric cancers

Although the survival rate of pediatric cancer has significantly improved, it is still an important cause of death among children. New technologies have been developed to improve the diagnosis, treatment, and prognosis of pediatric cancers. Raman spectroscopy (RS) is a non-destructive analytical technique that uses different frequencies of scattering light to characterize biological specimens. It can provide information on biological components, activities, and molecular structures. This review summarizes studies on the potential of RS in pediatric cancers. Currently, studies on the application of RS in pediatric cancers mainly focus on early diagnosis, prognosis prediction, and treatment improvement. The results of these studies showed high accuracy and specificity. In addition, the combination of RS and deep learning is discussed as a future application of RS in pediatric cancer. Studies applying RS in pediatric cancer illustrated good prospects. This review collected and analyzed the potential clinical applications of RS in pediatric cancers.

Expanding the Multiplexing Capabilities of Raman Imaging to Reveal Highly Specific Molecular Expression and Enable Spatial Profiling

Profiling the heterogeneous landscape of cell types and biomolecules is rapidly being adopted to address current imperative research questions. Precision medicine seeks advancements in molecular spatial profiling techniques with highly multiplexed imaging capabilities and subcellular resolution, which remains an extremely complex task. Surface-enhanced Raman spectroscopy (SERS) imaging offers promise through the utilization of nanoparticle-based contrast agents that exhibit narrow spectral features and molecular specificity. The current renaissance of gold nanoparticle technology makes Raman scattering intensities competitive with traditional fluorescence methods while offering the added benefit of unsurpassed multiplexing capabilities. Here, we present an expanded library of individually distinct SERS nanoparticles to arm researchers and clinicians. Our nanoparticles consist of a ∼60 nm gold core, a Raman reporter molecule, and a final inert silica coating. Using density functional theory, we have selected Raman reporters that meet the key criterion of high spectral uniqueness to facilitate unmixing of up to 26 components in a single imaging pixel in vitro and in vivo. We also demonstrated the utility of our SERS nanoparticles for targeting cultured cells and profiling cancerous human tissue sections for highly multiplexed optical imaging. This study showcases the far-reaching capabilities of SERS-based Raman imaging in molecular profiling to improve personalized medicine and overcome the major challenges of functional and structural diversity in proteomic imaging.

Phenotype Identification of HeLa Cells Knockout CDK6 Gene Based on Label-Free Raman Imaging

Identifying cell phenotypes is essential for understanding the function of biological macromolecules and molecular biology. We developed a noninvasive, label-free, single-cell Raman imaging analysis platform to distinguish between the cell phenotypes of the HeLa cell wild type (WT) and cyclin-dependent kinase 6 (CDK6) gene knockout (KO) type. Via large-scale Raman spectral and imaging analysis, two phenotypes of the HeLa cells were distinguished by their intrinsic biochemical profiles. A significant difference was found between the two cell lines: large lipid droplets formed in the knockout HeLa cells but were not observed in the WT cells, which was confirmed by Oil Red O staining. The band ratio of the Raman spectrum of saturated/unsaturated fatty acids was identified as the Raman spectral marker for HeLa cell WT or gene knockout type differentiation. The interaction between organelles involved in lipid metabolism was revealed by Raman imaging and Lorentz fitting, where the distribution intensity of the mitochondria and the endoplasmic reticulum membrane decreased. At the same time, lysosomes increased after the CDK6 gene knockout. The parameters obtained from Raman spectroscopy are based on hierarchical cluster analysis and one-way ANOVA, enabling highly accurate cell classification.

Nonlinear Temperature-Dependent Phonon Decay in Heavily Doped Silicon: Predominant Interferon-Mediated Cold Phonon Annihilation

A nonlinear Fano interaction has been reported here which is manifest in terms of a parabolic temperature-dependent phonon decay process observable in terms of a Raman spectral parameter. Temperature-dependent Raman spectroscopic studies have been carried out on heavily and moderately doped crystalline silicon to investigate the behavior of anharmonic phonon decay in semiconductor systems where Fano interactions are present inherently. Systematic study reveals that in heavily doped systems an interferon-mediated decay route exists for cold phonons present at lower temperatures (<475 K) where Fano coupling is stronger and dominates over the typical multiple-phonon decay process. On the other hand, the anharmonic phonon decay remains the predominant process at higher temperatures irrespective of the doping level. Temperature-dependent phonon self-energy has been calculated using experimentally observed Raman line-shape parameters to validate the fact that the nonlinear decay of phonons through interferon mediation is a thermodynamically favorable process at low temperatures.

Advanced metal and carbon nanostructures for medical, drug delivery and bio-imaging applications

Nanoparticles (NPs) offer great promise for biomedical, environmental, and clinical applications due to their several unique properties as compared to their bulk counterparts. In this review article, we overview various types of metal NPs and magnetic nanoparticles (MNPs) in monolithic form as well as embedded into polymer matrices for specific drug delivery and bio-imaging fields. The second part of this review covers important carbon nanostructures that have gained tremendous attention recently in such medical applications due to their ease of fabrication, excellent biocompatibility, and biodegradability at both cellular and molecular levels for phototherapy, radio-therapeutics, gene-delivery, and biotherapeutics. Furthermore, various applications and challenges involved in the use of NPs as biomaterials are also discussed following the future perspectives of the use of NPs in biomedicine. This review aims to contribute to the applications of different NPs in medicine and healthcare that may open up new avenues to encourage wider research opportunities across various disciplines.

Highly sensitive near-infrared SERS nanoprobes for in vivo imaging using gold-assembled silica nanoparticles with controllable nanogaps

BACKGROUND

To take advantages, such as multiplex capacity, non-photobleaching property, and high sensitivity, of surface-enhanced Raman scattering (SERS)-based in vivo imaging, development of highly enhanced SERS nanoprobes in near-infrared (NIR) region is needed. A well-controlled morphology and biocompatibility are essential features of NIR SERS nanoprobes. Gold (Au)-assembled nanostructures with controllable nanogaps with highly enhanced SERS signals within multiple hotspots could be a breakthrough.

RESULTS

Au-assembled silica (SiO2) nanoparticles (NPs) (SiO2@Au@Au NPs) as NIR SERS nanoprobes are synthesized using the seed-mediated growth method. SiO2@Au@Au NPs using six different sizes of Au NPs (SiO2@Au@Au50-SiO2@Au@Au500) were prepared by controlling the concentration of Au precursor in the growth step. The nanogaps between Au NPs on the SiO2 surface could be controlled from 4.16 to 0.98 nm by adjusting the concentration of Au precursor (hence increasing Au NP sizes), which resulted in the formation of effective SERS hotspots. SiO2@Au@Au500 NPs with a 0.98-nm gap showed a high SERS enhancement factor of approximately 3.8 × 106 under 785-nm photoexcitation. SiO2@Au@Au500 nanoprobes showed detectable in vivo SERS signals at a concentration of 16 μg/mL in animal tissue specimen at a depth of 7 mm. SiO2@Au@Au500 NPs with 14 different Raman label compounds exhibited distinct SERS signals upon subcutaneous injection into nude mice.

CONCLUSIONS

SiO2@Au@Au NPs showed high potential for in vivo applications as multiplex nanoprobes with high SERS sensitivity in the NIR region.

Raman Spectroscopy: A Personalized Decision-Making Tool on Clinicians' Hands for In Situ Cancer Diagnosis and Surgery Guidance

Accurate in situ diagnosis and optimal surgical removal of a malignancy constitute key elements in reducing cancer-related morbidity and mortality. In surgical oncology, the accurate discrimination between healthy and cancerous tissues is critical for the postoperative care of the patient. Conventional imaging techniques have attempted to serve as adjuvant tools for in situ biopsy and surgery guidance. However, no single imaging modality has been proven sufficient in terms of specificity, sensitivity, multiplexing capacity, spatial and temporal resolution. Moreover, most techniques are unable to provide information regarding the molecular tissue composition. In this review, we highlight the potential of Raman spectroscopy as a spectroscopic technique with high detection sensitivity and spatial resolution for distinguishing healthy from malignant margins in microscopic scale and in real time. A Raman spectrum constitutes an intrinsic "molecular finger-print" of the tissue and any biochemical alteration related to inflammatory or cancerous tissue state is reflected on its Raman spectral fingerprint. Nowadays, advanced Raman systems coupled with modern instrumentation devices and machine learning methods are entering the clinical arena as adjunct tools towards personalized and optimized efficacy in surgical oncology.

Graphene-Based Nanomaterials for Biomedical Imaging

Graphene is sp²-hybridized carbon structure-based two-dimensional (2D) sheet. Graphene-based nanomaterials possess several features such as unique mechanical, electronic, thermal, and optical properties, high specific surface area, versatile surface functionalization, and biocompatibility, which attracted researcher's interests in various fields including biomedicine. In this chapter, we particularly focused on the biomedical imaging applications of graphene-based nanomaterials like graphene oxide (GO), reduced graphene oxide (rGO), graphene quantum dots (GQDs), graphene oxide quantum dots (GOQDs), and other derivatives, which utilize their outstanding optical properties. There are some biomedical imaging modalities using Graphene-based Nanomaterials, among which we will highlight fluorescence imaging, Raman imaging, magnetic resonance imaging, and photoacoustic imaging. We also discussed the brief perspectives and future application related to them.

Cell and Tissue Imaging by TOF-SIMS and MALDI-TOF: An Overview for Biological and Pharmaceutical Analysis

The potential of mass spectrometry imaging (MSI) has been demonstrated in cell and tissue research since 1970. MSI can reveal the spatial distribution of a wide range of atomic and molecular ions detected from biological sample surfaces, it is a powerful and valuable technique used to monitor and detect diverse chemical and biological compounds, such as drugs, lipids, proteins, and DNA. MSI techniques, notably matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) and time of flight secondary ion mass spectrometry (TOF-SIMS), witnessed a dramatic upsurge in studying and investigating biological samples especially, cells and tissue sections. This advancement is attributed to the submicron lateral resolution, the high sensitivity, the good precision, and the accurate chemical specificity, which make these techniques suitable for decoding and understanding complex mechanisms of certain diseases, as well as monitoring the spatial distribution of specific elements, and compounds. While the application of both techniques for the analysis of cells and tissues is thoroughly discussed, a briefing of MALDI-TOF and TOF-SIMS basis and the adequate sampling before analysis are briefly covered. The importance of MALDI-TOF and TOF-SIMS as diagnostic tools and robust analytical techniques in the medicinal, pharmaceutical, and toxicology fields is highlighted through representative published studies.

Adaptive partial scanning transmission electron microscopy with reinforcement learning

Compressed sensing can decrease scanning transmission electron microscopy electron dose and scan time with minimal information loss. Traditionally, sparse scans used in compressed sensing sample a static set of probing locations. However, dynamic scans that adapt to specimens are expected to be able to match or surpass the performance of static scans as static scans are a subset of possible dynamic scans. Thus, we present a prototype for a contiguous sparse scan system that piecewise adapts scan paths to specimens as they are scanned. Sampling directions for scan segments are chosen by a recurrent neural network (RNN) based on previously observed scan segments. The RNN is trained by reinforcement learning to cooperate with a feedforward convolutional neural network that completes the sparse scans. This paper presents our learning policy, experiments, and example partial scans, and discusses future research directions. Source code, pretrained models, and training data is openly accessible at https://github.com/Jeffrey-Ede/adaptive-scans.

Vibrational Fingerprint Analysis of an Azo-based Resonance Raman Scattering Probe for Imaging Proton Distribution in Cellular Lysosomes

Due to the fundamental mechanism of vibrational state transitions for chemical bonds, the spectra of Raman scattering are narrow-banded and photostable signals capable of probing specific reactions. In the case of protonation/deprotonation reactions, certain chemical bonds are broken and new bonds are formed. Based on the changes of the vibrational modes for the corresponding bonds, fingerprint analysis of multiple Raman bands may allow for the in situ visualization of proton distribution in live cells. However, Raman scattering faces the well-known challenge of low sensitivity. To perform the vibrational fingerprint analysis of Raman scattering by overcoming this challenge, we developed an azo-based resonance Raman pH probe. It was an azobenzene-featured small molecule responsive to protons with the inherent Raman signal ∼10⁴-fold more intense than that of the conventional alkyne-type Raman reporter 5-ethynyl-2'-deoxyuridine. Through the substitution of the electron-donating and -withdrawing entities to the azobenzene group, the effect of resonance Raman scattering and fluorescence quenching was obtained. This effect resulted in a significant Raman enhancement factor of ∼10³ compared to the counterpart molecules without the molecular design. Based on the enhanced Raman sensitivity of the azo-based resonance Raman pH probe, the identification of vibrational fingerprint changes at the azo group was achieved during the protonation/deprotonation reactions, and the vibrational fingerprint analysis resolved a pH difference of less than 0.2 unit. The method enabled sensitive hyperspectral cell imaging that clearly visualized the change of proton distribution in autophagic cells.

Complex cellular environments imaged by SERS nanoprobes using sugars as an all-in-one vector

Raman spectroscopy coupled with confocal microscopy offers an alternative bioimaging technique overcoming limitations associated with sensitivity, tissue penetration and image resolution. Allied to the surface-enhanced Raman scattering (SERS) properties of gold nanoparticles (AuNP), we designed SERS nanoprobes with enhanced properties and straightforward application as bio-labelling agents for gliomas. The ensuing nanoprobes coated with simple sugar units (galactose or glucose) allowed assessing information about their intracellular localization (vesicular structures), with impressive sensitivity towards complex environments and proved the ability to overcome biological auto-fluorescence and high penetration in tissues. We validate the use of sugars as an all-in-one vector (Raman reporter, conferring high stability, biocompatibility and affinity to glioma cells) as imaging agents using an impressive technique.

Synergistic strategy of rare-earth doped nanoparticles for NIR-II biomedical imaging

Featuring simultaneous multicolor imaging for multiple targets, a synergistic strategy has become promising for fluorescence imaging applications. Visible and first near infrared (NIR-I, 700-900 nm) fluorophores have been explored for multicolor imaging to achieve good multi-target capacity, but they are largely hampered by the narrow imaging bands available (400-900 nm, bandwidth 500 nm), the broad emission spectra of many fluorophores, shallow tissue penetration and scattering loss. With attractive characteristic emission peaks in the second NIR window (NIR-II, 1000-1700 nm), a narrow emission spectrum, and deeper tissue penetration capability, rare-earth doped nanoparticles (RENPs) have been considered by us to be outstanding candidates for multicolor bioimaging. Herein, two RENPs, NaYF4:Yb20Er2@NaYF4 and NaYF4:Nd5@NaYF4, were prepared and modified with polyethylene glycol (PEG) to explore simultaneous imaging in the NIR-IIb (1530 nm, under 980 nm laser excitation) and the NIR-II (1060 nm, under 808 nm laser excitation) windows. The PEGylated-RENPs (RENPs@PEG) were able to simultaneously visualize the circulatory system, trace the lymphatic system, and evaluate the skeletal system. Our study demonstrates that RENPs have high synergistic imaging capability in multifunctional biomedical applications using their NIR-II fluorescence. Importantly, the two RENPs@PEG are complementary to each other for higher temporal resolution in NaYF4:Nd5@NaYF4@PEG and higher spatial resolution in NaYF4:Yb20Er2@NaYF4@PEG, which may provide more comprehensive and accurate imaging diagnosis. In conclusion, RENPs are highly promising nanomaterials for multicolor imaging in the NIR-II window.

Multiplexed Liquid Biopsy and Tumor Imaging Using Surface-Enhanced Raman Scattering

The recent improvements in diagnosis enabled by advances in liquid biopsy and oncological imaging significantly better cancer care. Both these complementary approaches, which are used for early tumor detection, characterization, and monitoring, can benefit from applying techniques based on surface-enhanced Raman scattering (SERS). With a detection sensitivity at the single-molecule level, SERS spectroscopy is widely used in cell and molecular biology, and its capability for the in vitro detection of several types of cancer biomarkers is well established. In the last few years, several intriguing SERS applications have emerged, including in vivo imaging for tumor targeting and the monitoring of drug release. In this paper, selected recent developments and trends in SERS applications in the field of liquid biopsy and tumor imaging are critically reviewed, with a special emphasis on results that demonstrate the clinical utility of SERS.

Modeling the distribution of malachite green in zebrafish using matrix-assisted laser desorption/ionization mass spectrometry imaging

Understanding the spatial distribution of bioactive small molecules is indispensable for elucidating their biological or pharmaceutical roles. Here, a rapid and effective analysis strategy was introduced to study the distribution of veterinary drugs in aquatic products. Malachite green (MG), one of the most widely used veterinary drugs in aquaculture, was selected as the targeted compound. Zebrafish (Danio rerio) was used as a model organism. After an exposure test, the matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) technique was applied to directly analyze the content changes of malachite green in zebrafish tissues. The reliable relationship of exposure time and content change of MG was described precisely by the extended Freundlich equation. The process of modeling was discussed in detail, and some important parameters or trend information was obtained, including the maximum content of MG in different fish tissues, time to maximum content, elimination time, equilibrium content, and so on. With a simplification of sample pretreatment, this research strategy can be used for monitoring the spatial distribution of veterinary drugs and related metabolites of laboratory-exposed fish. The obtained model can provide a perspective for rational drug use in aquaculture and precise drug residue detection in production activities.

Conjugated Polymers: Optical Toolbox for Bioimaging and Cancer Therapy

Conjugated polymers (CPs) are capable of coordinating the electron coupling phenomenon to bestow powerful optoelectronic features. The light-harvesting and light-amplifying properties of CPs are extensively used in figuring out the biomedical issues with special emphasis on accurate diagnosis, effective treatment, and precise theranostics. This review summarizes the recent progress of CP materials in bioimaging, cancer therapeutics, and introduces the design strategies by rationally tuning the optical properties. The recent advances of CPs in bioimaging applications are first summarized and the challenges to clear the future directions of CPs in the respective area are discussed. In the following sections, the focus is on the burgeoning applications of CPs in phototherapy of the tumor, and illustrates the underlying photo-transforming mechanism for further molecular designing. Besides, the recent progress in the CPs-assistant drug therapy, mainly including drug delivery, gene therapeutic, the optical-activated reversion of tumor resistance, and synergistic therapy has also been discussed elaborately. In the end, the potential challenges and future developments of CPs on cancer diagnosis and therapy are also illuminated for the improvement of optical functionalization and the promotion of clinical translation.

Recent Advances and Challenges in Nanodelivery Systems for Antimicrobial Peptides (AMPs)

Antimicrobial peptides (AMPs) can be used as alternative therapeutic agents to traditional antibiotics. These peptides have abundant natural template sources and can be isolated from animals, plants, and microorganisms. They are amphiphilic and mostly net positively charged, and they have a broad-spectrum inhibitory effect on bacteria, fungi, and viruses. AMPs possess significant rapid killing effects and do not interact with specific receptors on bacterial surfaces. As a result, drug resistance is rarely observed with treatments. AMPs, however, have some operational problems, such as a susceptibility to enzymatic (protease) degradation, toxicity in vivo, and unclear pharmacokinetics. However, nanodelivery systems loaded with AMPs provide a safe mechanism of packaging such peptides before they exert their antimicrobial actions, facilitate targeted delivery to the sites of infection, and control the release rate of peptides and reduce their toxic side effects. However, nanodelivery systems using AMPs are at an early stage of development and are still in the laboratory phase of development. There are also some challenges in incorporating AMPs into nanodelivery systems. Herein, an insight into the nanotechnology challenges in delivering AMPs, current advances, and remaining technological challenges are discussed in depth.

Selecting Surface-Enhanced Raman Spectroscopy Flavors for Multiplexed Imaging Applications: Beyond the Experiment

Multiplexing capabilities and sensitivity of surface-enhanced Raman spectroscopy (SERS) nanoparticles (NPs) are strongly dependent on the selected Raman reporter. These Raman-active molecules are responsible for giving each batch of SERS NPs its unique spectral fingerprint. Herein, we studied four types of SERS NPs, namely, AuNPs labeled with trans-1,2-bis(4-pyridyl)ethylene (BPE), 4,4'-bis(mercaptomethyl)biphenyl (BMMBP), 5-(4-pyridyl)-1,3,4-oxadiazole-2-thiol (PODT), and 5-(4-pyridyl)-1H-1,2,4-triazole-3-thiol (PTT), and demonstrated that the best level of theory could be chosen based on inner products of DFT-calculated and experimental Raman spectra. We also calculated the theoretical spectra of these Raman reporters bound to Au₂₀ clusters to interrogate how SERS enhancement would affect their spectral fingerprint. Importantly, we found a correlation between B3LYP-D3 calculated and experimental enhancement factors, which opens up an avenue toward predicting which Raman reporters could offer improved sensitivity. We observed 0.5 and 3 fM limits of detection for BMMBP- and PTT-labeled 60 nm AuNPs, respectively.

Azo-Enhanced Raman Scattering for Enhancing the Sensitivity and Tuning the Frequency of Molecular Vibrations

Raman scattering provides stable narrow-banded signals that potentially allow for multicolor microscopic imaging. The major obstacle for the applications of Raman spectroscopy and microscopy is the small cross section of Raman scattering that results in low sensitivity. Here, we report a new concept of azo-enhanced Raman scattering (AERS) by designing the intrinsic molecular structures using resonance Raman and concomitant fluorescence quenching strategies. Based on the selection of vibrational modes and the enhancing unit of azobenzenes, we obtained a library of AERS molecules with specific Raman signals in the fingerprint and silent frequency regions. The spectral characterization and molecular simulation revealed that the azobenzene unit conjugated to the vibrational modes significantly enhanced Raman signals due to the mechanism of extending the conjugation system, coupling the electronic-vibrational transitions, and improving the symmetry of vibrational modes. The nonradiative decay of azobenzene from the excited state quenched the commitment fluorescence, thus providing a clean background for identifying Raman scattering. The most sensitive AERS molecules produced Raman signals of more than 4 orders of magnitude compared to 5-ethynyl-2'-deoxyuridine (EdU). In addition, a frequency tunability of 10 distinct Raman bands was achieved by selecting different types of vibrational modes. This methodology of AERS allows for designing small-molecule Raman probes to visualize various entities in complex systems by multicolor spontaneous Raman imaging. It will open new prospects to explore innovative applications of AERS in interdisciplinary research fields.

Deep learning in electron microscopy

Deep learning is transforming most areas of science and technology, including electron microscopy. This review paper offers a practical perspective aimed at developers with limited familiarity. For context, we review popular applications of deep learning in electron microscopy. Following, we discuss hardware and software needed to get started with deep learning and interface with electron microscopes. We then review neural network components, popular architectures, and their optimization. Finally, we discuss future directions of deep learning in electron microscopy.

Gold nanoparticle detection and quantification in therapeutic MV beams via pair production

PURPOSE

We propose a new detection method of gold nanoparticles (AuNP) in therapeutic megavoltage (MV) x-ray beams by means of coincidence counting of annihilation photons following pair production in gold.

METHODS

The proposed MV x-ray induced positron emission (MVIPE) imaging technique is studied by radiation transport computations using MCNP6 (3D) and CEPXS/ONEDANT (1D) codes for two water phantoms: a 35 cm slab and a similarly sized cylinder, both having a 5 cm AuNP filled region in the center. MVIPE is compared to the standard x-ray fluorescence computed tomography (XFCT). MVIPE adopts MV x-ray sources (Co-60, 2 MV, 6 MV, 6 MV with closed MLC and 15 MV) and relies on the detection of 511 keV photon-pairs. XFCT uses kilovoltage sources (100 kVp, 120 kVp and 150 kVp) and imaging is characterized by analysis of k _α1,2 Au characteristic lines. Three levels of AuNP concentration were studied: 0.1%, 1% and 10% by weight.

RESULTS

Annihilation photons in the MVIPE technique originate both in the AuNP and in water along the x-ray beam path with significantly larger production in the AuNP-loaded region. MVIPE signal from AuNP is linearly increasing with AuNP concentration up to 10%wt, while XFCT signal reaches saturation due to self-absorption within AuNP. The production of annihilation photons is proportional to the MV source energy. MVIPE technique using a 15 MV pencil beam and 10 wt% AuNP detects about 4.5 × 10³ 511 keV-photons cm^-2 at 90° w/r to the incident beam per 10⁹ source photons cm^-2; 500 of these come from AuNP. In contrast, the XFCT technique using 150 kVp detects only about 100 k _α1-photons cm^-2 per 10⁹ source photons cm^-2.

CONCLUSIONS

In MVIPE, the number of annihilation photons produced for different MV-beam energies and AuNP concentrations is significantly greater than the k _α1 photons generated in XFCT. Coincidence counting in MVIPE allows to avoid collimation, which is a major limiting factor in XFCT. MVIPE challenges include the filtering of Compton scatter and annihilation photons originating in water.

Ultra-bright Raman dots for multiplexed optical imaging

Imaging the spatial distribution of biomolecules is at the core of modern biology. The development of fluorescence techniques has enabled researchers to investigate subcellular structures with nanometer precision. However, multiplexed imaging, i.e. observing complex biological networks and interactions, is mainly limited by the fundamental ‘spectral crowding’ of fluorescent materials. Raman spectroscopy-based methods, on the other hand, have a much greater spectral resolution, but often lack the required sensitivity for practical imaging of biomarkers. Addressing the pressing need for new Raman probes, herein we present a series of Raman-active  nanoparticles (Rdots) that exhibit the combined advantages of ultra-brightness and compact sizes (~20 nm). When coupled with the emerging stimulated Raman scattering (SRS) microscopy, these Rdots are brighter than previously reported Raman-active organic probes by two to three orders of magnitude. We further obtain evidence supporting for SRS imaging of Rdots at single particle level. The compact size and ultra-brightness of Rdots allows immunostaining of specific protein targets (including cytoskeleton and low-abundant surface proteins) in mammalian cells and tissue slices with high imaging contrast. These Rdots thus offer a promising tool for a large range of studies on complex biological networks.

Raman-based imaging of biomarkers is often challenging due to low sensitivity. Here, the authors use a swelling-diffusion approach to develop a series of Raman probes that are both ultra-bright and compact in size, and demonstrate multiplexed imaging of specific protein targets in cells and tissue slices.

A colorful approach towards developing new nano-based imaging contrast agents for improved cancer detection

Providing physicians with new imaging agents to help detect cancer with better sensitivity and specificity has the potential to significantly improve patient outcomes. Development of new imaging agents could offer improved early cancer detection during routine screening or help surgeons identify tumor margins for surgical resection. In this study, we evaluate the optical properties of a colorful class of dyes and pigments that humans routinely encounter. The pigments are often used in tattoo inks and the dyes are FDA approved for the coloring of foods, drugs, and cosmetics. We characterized their absorption, fluorescence and Raman scattering properties in the hopes of identifying a new panel of dyes that offer exceptional imaging contrast. We found that some of these coloring agents, coined as "optical inks", exhibit a multitude of useful optical properties, outperforming some of the clinically approved imaging dyes on the market. The best performing optical inks (Green 8 and Orange 16) were further incorporated into liposomal nanoparticles to assess their tumor targeting and optical imaging potential. Mouse xenograft models of colorectal, cervical and lymphoma tumors were used to evaluate the newly developed nano-based imaging contrast agents. After intravenous injection, fluorescence imaging revealed significant localization of the new "optical ink" liposomal nanoparticles in all three tumor models as opposed to their neighboring healthy tissues (p < 0.05). If further developed, these coloring agents could play important roles in the clinical setting. A more sensitive imaging contrast agent could enable earlier cancer detection or help guide surgical resection of tumors, both of which have been shown to significantly improve patient survival.

Introduction to Infrared and Raman-Based Biomedical Molecular Imaging and Comparison with Other Modalities

Molecular imaging has rapidly developed to answer the need of image contrast in medical diagnostic imaging to go beyond morphological information to include functional differences in imaged tissues at the cellular and molecular levels. Vibrational (infrared (IR) and Raman) imaging has rapidly emerged among the molecular imaging modalities available, due to its label-free combination of high spatial resolution with chemical specificity. This article presents the physical basis of vibrational spectroscopy and imaging, followed by illustration of their preclinical in vitro applications in body fluids and cells, ex vivo tissues and in vivo small animals and ending with a brief discussion of their clinical translation. After comparing the advantages and disadvantages of IR/Raman imaging with the other main modalities, such as magnetic resonance imaging (MRI), computed tomography (CT), positron emission tomography/single-photon emission-computed tomography (PET/SPECT), ultrasound (US) and photoacoustic imaging (PAI), the design of multimodal probes combining vibrational imaging with other modalities is discussed, illustrated by some preclinical proof-of-concept examples.

Recent advances in applications of nanoparticles in SERS in vivo imaging

Surface-enhanced Raman scattering (SERS) technique has been regarded as one of the most important research methods in the field of single-molecule science. Since the previous decade, the application of nanoparticles for in vivo SERS imaging becomes the focus of research. To enhance the performance of SERS imaging, researchers have developed several SERS nanotags such as gold nanostars, copper-based nanomaterials, semiconducting quantum dots, and so on. The development of Raman equipment is also necessary owing to the current limitations. This review describes the recent advances of SERS nanoparticles and their applications for in vivo imaging in detail. Specific examples highlighting the in vivo cancer imaging and treatment application of SERS nanoparticles. A perspective on the challenges and opportunities of nanoparticles in SERS in vivo imaging is also provided. This article is categorized under: Diagnostic Tools > in vivo Nanodiagnostics and Imaging Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Raman Microscopy: Progress in Research on Cancer Cell Sensing

In the last decade, Raman Spectroscopy (RS) was demonstrated to be a label-free, non-invasive and non-destructive optical spectroscopy allowing the improvement in diagnostic accuracy in cancer and analytical assessment for cell sensing. This review discusses how Raman spectra can lead to a deeper molecular understanding of the biochemical changes in cancer cells in comparison to non-cancer cells, analyzing two key examples, leukemia and breast cancer. The reported Raman results provide information on cancer progression and allow the identification, classification, and follow-up after chemotherapy treatments of the cancer cells from the liquid biopsy. The key obstacles for RS applications in cancer cell diagnosis, including quality, objectivity, number of cells and velocity of the analysis, are considered. The use of multivariant analysis, such as principal component analysis (PCA) and linear discriminate analysis (LDA), for an automatic and objective assessment without any specialized knowledge of spectroscopy is presented. Raman imaging for cancer cell mapping is shown and its advantages for routine clinical pathology practice and live cell imaging, compared to single-point spectral analysis, are debated. Additionally, the combination of RS with microfluidic devices and high-throughput screening for improving the velocity and the number of cells analyzed are also discussed. Finally, the combination of the Raman microscopy (RM) with other imaging modalities, for complete visualization and characterization of the cells, is described.

Tissue Phantoms for Biomedical Applications in Raman Spectroscopy: A Review

Raman spectroscopy is a group of analytical techniques, currently applied in several research fields, including clinical diagnostics. Tissue-mimicking optical phantoms have been established as an essential intermediate stage for medical applications with their employment from spectroscopic techniques to be constantly growing. This review outlines the types of tissue phantoms currently employed in different biomedical applications of Raman spectroscopy, focusing on their composition and optical properties. It is therefore an attempt to present an informed range of options for potential use to the researchers.

When Prussian Blue Meets Porous Gold Nanoparticles: A High Signal-to-Background Surface-Enhanced Raman Scattering Probe for Cellular Biomarker Imaging

Profiling cellular biomarkers without the interference of endogenous signals could facilitate the investigation of complex intracellular biological events and provide new possibilities for precision disease diagnosis. Herein, a surface-enhanced Raman scattering (SERS) probe with a high signal-to-background ratio (SBR) for cellular biomarker imaging is constructed. The probes are prepared by incorporating Prussian blue (PB) with porous gold nanoparticles (p-Au NPs). Due to their rich built-in Raman hotspots, the p-Au NPs are excellent SERS substrates that can significantly amplify the signals of the incorporated PB. In parallel, PB shows a single peak in the cellular silent region, where the signals from the probes and endogenous molecules can be completely resolved without the need of complex spectral unmixing. As a consequence, the combination of probe signal enhancement and background elimination endows the SERS probes with an extremely high SBR. To evaluate their performance in biomarker imaging, the high-SBR SERS probes are utilized to profile folic acids at a single-cell level. This background-free, high-precision imaging technique is conducive to early diagnosis and therapeutic response of cancer that is of great importance in clinical settings.

From Synthesis to Utilization: The Ins and Outs of Mitochondrial Heme

Heme is a ubiquitous and essential iron containing metallo-organic cofactor required for virtually all aerobic life. Heme synthesis is initiated and completed in mitochondria, followed by certain covalent modifications and/or its delivery to apo-hemoproteins residing throughout the cell. While the biochemical aspects of heme biosynthetic reactions are well understood, the trafficking of newly synthesized heme-a highly reactive and inherently toxic compound-and its subsequent delivery to target proteins remain far from clear. In this review, we summarize current knowledge about heme biosynthesis and trafficking within and outside of the mitochondria.

Probing Cancer Metastasis at a Single-Cell Level with a Raman-Functionalized Anionic Probe

Cancer metastasis is the primary reason for cancer-related deaths, yet there is no technique capable of detecting it due to cancer pathogenesis. Current cancer diagnosis methods evaluate tumor samples as a whole/pooled sample process loses heterogeneous information in the metastasis state. Hence, it is not suitable for metastatic cancer detection. In order to gain complete information on metastasis, it is desirable to develop a nondestructive detection method that can evaluate metastatic cells with sensitivity down to single-cell resolution. Here we demonstrated self-functionalized anionic quantum probes for in vitro metastatic cancer detection at a single-cell concentration. We achieved this by incorporating a nondestructive SERS ability within the generated probes by integrating anionic surface species and NIR plasmon resonance. To the best of our knowledge, this was the first time that metastatic cancer cells were detected through their neoplastic transformations. With reliable diagnostic information at the single-cell sensitivity in an in vitro state, we successfully discriminated against cancer malignancy states.