Yellow Emissive Carbon Dots - A Robust Nanoprobe for Highly Sensitive Quantification of Jaundice Biomarker and Mitochondria Targeting in Cancer Cells.

The abnormally high level of bilirubin (BR) in biofluids (human serum and urine) indicates a high probability of jaundice and liver dysfunction. However, quantification of BR as the Jaundice biomarker is difficult due to the interference of various biomolecules in serum and urine. To address this issue, we developed a fluorescence-based detection strategy, for which yellow emissive carbon dots (YCDs) were produced from a one-step solvothermal process using phloroglucinol and thionin acetate as chemical precursors. The as-fabricated YCDs exhibited a strong fluorescence peak at the wavelength of 542 nm upon excitation at 390 nm. We used YCDs for detecting BR through the fluorescence turn-off mechanism, unveiling the excellent sensitivity in the linear range of 0.5-12.5 µM with a limit of detection (LOD) of 9.62 nM, which was far below the clinically relevant range. The analytical nanoprobe also offered excellent detection specificity for quantifying BR in real samples. Moreover, the biocompatible fluorescent nanoprobe was successfully employed to target mitochondria in live cancer cells. A colocalization study confirmed that YCDs possessed the ability to target mitochondria and overlapped completely with MitoTracker Red. The developed nanoprobe of YCDs turned out to be straightforward in their synthesis, noninvasive, and can be utilized for biomedical sensors to diagnose the onset of jaundice as well as for mitochondria targeting.

A Fluorescent Furan-based Probe with Protected Functional Groups for Highly Selective and Non-Toxic Imaging of HT-29 Cancer Cells and 4T1 Tumors.

Most of the previously reported fluorescent organic probes for cancer cell and tumor imaging have significant limitations including chemical toxicity, structural instability, low Stokes shift value, and the inability for selective accumulations in tumors during in vivo imaging. To overcome the mentioned challenges, we synthesized the fluorescent probes with protected polar functional groups to enhance the non-toxicity nature and increase the selectivity toward tumors. In addition, the structural rigidity of the fluorescent probes was increased by embedding aromatic rings in the probe structure. This issue enables us to obtain ultrabright cell images due to enhanced fluorescence quantum yield (ΦFL) values. After synthesis and spectral characterizations, the applicability of two furan-based and imidazole-based fluorescent probes ( abbreviated as DCPEF and DBPPI, respectively) was investigated for ultrabright in vitro and in vivo imaging of cancer cells. The probe DCPEF shows the ΦFL value of 0.946 and the Stocks shift of 86 nm. In addition, probe DBPPI offers the ΦFL value of 0.400 and a Stocks shift of 150 nm. The MTT colorimetric cytotoxicity assay showed that probe DCPEF has minimal effects against HT-29 (cancer) and Vero (normal) cells. The probe DCPEF produced ultrabright fluorescence images from HT-29 cells. In addition, in vivo imaging of cancer cells showed that probe DCPEF selectively accumulates in the 4T1 tumor in mice. The spectral and chemical stability, minimal cytotoxicity, significant Stokes shift, and high degree of selectivity for tumor cells during in vivo imaging make DCPEF an appropriate candidate to be used as a standard probe for cancer cell imaging.

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.

Tris-assisted one-step fabrication of functional carbon dots for specific folate receptor positive-expressed cancer cell imaging.

Specific staining of cancer cells is momentous for cancer research. Nanoprobe with multivalent recognition is emerging as powerful tools for bioimaging, but the nonspecific cell uptake and complex functional modification procedures are still obstacles for specific detection and convenient synthesis. Carbon dots (CDs) with an intrinsic targeting ability, excellent optical properties and biocompatibility acquired from an efficient one-step fabrication procedure were urgently desired in specific cancer cells visualization. Herein, inspired by the interrelationships between interface and biomolecular mechanisms, we suggested that it was possible to construct CDs with the desired characteristics for folate receptor (FR) positive-expressed cancer cell imaging via rich hydroxyl groups Tris-assisted one-step hydrothermal treatment of folate acid (FA) and l-Arginine (L-Arg) precursors. The prepared small-sized F-CDs were equipped with abundant hydroxyl, pterin and negative charge surface, and possessed environmental friendliness, outstanding photostability and biocompatibility. Moreover, F-CDs had an intrinsic FR positive-expressed cancer cell targeting ability without any post-modification of the ligands. Rich hydroxyl groups play a vital role in endowing the optical properties and biological effects of F-CDs. F-CDs could be used as a promising candidate for FR-expressed cancer cell labeling and tracking. In addition, the caveolae-mediated endocytosis pathway of F-CDs was ascertained. More importantly, experimental results confirmed that the combination of physicochemical properties may provide an efficient strategy to overcome non-specific cell uptake interactions for cell labeling. Our strategy put forward a promising alternative to design fluorescent CDs for extensive chemical and biomedical applications.

Synthesis and Application of a Near-Infrared Light-Emitting Fluorescent Probe for Specific Imaging of Cancer Cells with High Sensitivity and Selectivity.

Background: The preclinical diagnosis of tumors is of great significance to cancer treatment. Near-infrared fluorescence imaging technology is promising for the in-situ detection of tumors with high sensitivity. Methods: Here, a fluorescent probe was synthesized on the basis of Au nanoclusters with near-infrared light emission and applied to fluorescent cancer cell labeling. Near-infrared methionine-N-Hydroxy succinimide Au nanoclusters (Met-NHs-AuNCs) were prepared successfully by one-pot synthesis using Au nanoclusters, methionine, and N-Hydroxy succinimide as frameworks, reductants, and stabilizers, respectively. The specific fluorescence imaging of tumor cells or tissues by fluorescent probe was studied on the basis of SYBYL Surflex-DOCK simulation model of LAT1 active site of overexpressed receptor on cancer cell surface. The results showed that Met-NHs-AuNCs interacted with the surface of LAT1, and C_Score scored the conformation of the probe and LAT1 as five. Results: Characterization and in vitro experiments were conducted to explore the Met-NHs-AuNCs targeted uptake of cancer cells. The prepared near-infrared fluorescent probe (Met-NHs-AuNCs) can specifically recognize the overexpression of L-type amino acid transporter 1 (LAT1) in cancer cells so that it can show red fluorescence in cancer cells. Meanwhile, normal cells (H9c2) have no fluorescence. Conclusion: The fluorescent probe demonstrates the power of targeting and imaging cancer cells.

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.

Insight into the spatial interaction of D-π-A bridge derived cyanines and nitroreductase for fluorescent cancer hypoxia detection.

Nitroreductase (NTR) detection in tumor is critical because NTR level is correlated with hypoxia degree and cancer prognosis. With the feature of high sensitivity and selectivity, fluorescence organic probes for NTR detection exhibited a promising future for tumor hypoxia detection. However, the discovery and design of such probes have been impeded due to the lack of the understanding of spatial match and mismatch of these probes with NTR. Here, we have developed two new nitrophenyl-functionalized trimethincyanine (Cy3) probes with para- or meta- positions of nitro-group in phenyl ring. Para-nitrophenyl substituted Cy3 (pNP-Cy3) exhibited a remarkable response to NTR (20-fold fluorescence enhancement) with good selectivity and sensitivity. Experimental and theoretical analysis verified that the substituent position of nitro group on phenyl ring of dyes altered the spatial arrangement of nitro-substituent group, thereby modulated the spatial match and mismatch between Cy3 dyes and binding domain of NTR, and consequently led to a different fluorescent turn-on response. In tumor-bearing mice model, hypoxia status of A549 xenografted tumor of mice was successfully delineated by using pNP-Cy3. These results may provide a clue for designing new cyanine-derived NTR probe to monitor NTR-overexpressed hypoxia cancer cells.

Hyaluronic acid-graphene quantum dot nanocomposite: Potential target drug delivery and cancer cell imaging.

Nowadays, the use of nanoparticle-based drug delivery systems has received much more attention. In this regard, here, graphene quantum dots (GQD) were used as drug carriers as well as imaging agents for cancer cells. In order to optimize the dose of the drug and reduce its side effects for healthy cells, hyaluronic acid was decorated on the surface of GQD to target cancer cells. The morphology and size of the synthesized nanoparticles alone and conjugated with hyaluronic acid were investigated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM); TEM images revealed a particles size of ∼5.67 and ∼8.69 nm, respectively. In the presence of 1-ethyl-3-[3(dimethylamino)propyl]carbodiimide hydrochloride/N-hydroxysuccinimide (EDC/NHS), hyaluronic acid was bounded to dopamine hydrochloride and was prepared to react with GQD. After synthesis of graphene quantum dot-hyaluronic acid nanocomposite, curcumin (CUR) as a drug model was loaded on the synthesized nanocarriers, and its loading percentage was measured. The results showed that 98.02% of the drug was loaded on the nanocarriers. Also, the conjugation of each agent on the nanocarrier was approved by photoluminescence spectroscopy, Fourier transform infrared spectroscopy (FTIR), and UV-visible absorption techniques, and the results showed that the reactions were performed correctly. The effect of GQD, graphene quantum dot-hyaluronic acid, CUR, graphene quantum dot-hyaluronic acid-CUR on the viability of HeLa and L929 cells was evaluated by the MTT test. The results showed that the synthesized nanocarrier is completely biocompatible, and the drug nanocarriers reduce HeLa cell viability significantly due to the mediation of hyaluronic acid-CD44 for drug cell uptake. Simultaneously with drug delivery, the other goal of these nanocarriers is to image cancer cells by emitting fluorescent light. Fluorescent microscopy showed that these nanocarriers were adsorbed on HeLa cells, unlike L929 cells.

Spider Toxin Peptide-Induced NIR Gold Nanocluster Fabrication for GSH-Responsive Cancer Cell Imaging and Nuclei Translocation.

Goldnanoclusters (GNCs) have become a promising nanomaterial for bioimaging because of their unique optical properties and biocompatibility. In this study, lycosin-I peptide, which possesses a highly selective anticancer activity by affecting the permeability of cancer cell membrane, was firstly modified for constructing fluorescent GNCs (LGNCs) for bioimaging of tumor cells. The obtained LGNCs exhibited strong near-infrared (NIR) fluorescence, which can be further enhanced by the peptide-induced aggregation and selectively stained three cancerous cell lines over normal cell lines with low intrinsic toxicity. After uptake by tumor cells, LGNC aggregates can be depolymerized into ultrasmall nanoclusters by high-level glutathione (GSH) and realize the nuclear targeting translocation. Collectively, our work suggests the potential of natural active biomolecules in designing NIR fluorescent GNCs for bioimaging.

Targeted Bioimaging of Cancer Cells Using Free Folic Acid-Sensitive Molybdenum Disulfide Quantum Dots through Fluorescence "Turn-Off".

In the present study, a proficient way for targeted bioimaging of folate receptor (FR)-positive cancer cells using free folic acid (FA)- and MoS2 QD-based nanoprobes is discussed along with its advantages over the preparation of orthodox direct FA-nanoprobe bioconjugates for the imaging. The water-soluble MoS2 QDs of size 4-5 nm with cysteine functionalization are synthesized by a simplistic bottom-up hydrothermal method. The as-prepared MoS2 QDs exhibit the blue emission with the highest emission intensity at 444 nm upon excitation of 370 nm. The MoS2 QDs are too sensitive toward FA to produce an effective and stable nanofiber structure through supramolecular interaction, which demonstrates ∼97% quenching of fluorescence. Moreover, the high selectivity and sensitivity of MoS2 QDs toward FA make the MoS2 QD-based nanoprobe an appropriate candidate for FA-targeted "turn-off" imaging probes for in vivo study of FA-pretreated FR-overexpressed cancer cells. It is obvious from the confocal microscopy images that the FA-pretreated B16F10 cancer cells show higher population of dimmed fluorescence compared to untreated cancer cells and HEK-293 normal cells. The flow cytometry study quantitatively reveals the significant difference of the geometric mean of fluorescence between FA-pretreated and untreated B16F10 cancer cells. Hence, these MoS2 QD-based nanoprobes can be applied as potential nanoprobes for the prediagnosis of cancer through targeted bioimaging.

A weakly supervised deep learning approach for label-free imaging flow-cytometry-based blood diagnostics.

The application of machine learning approaches to imaging flow cytometry (IFC) data has the potential to transform the diagnosis of hematological diseases. However, the need for manually labeled single-cell images for machine learning model training has severely limited its clinical application. To address this, we present iCellCnn, a weakly supervised deep learning approach for label-free IFC-based blood diagnostics. We demonstrate the capability of iCellCnn to achieve diagnosis of Sézary syndrome (SS) from patient samples on the basis of bright-field IFC images of T cells obtained after fluorescence-activated cell sorting of human peripheral blood mononuclear cell specimens. With a sample size of four healthy donors and five SS patients, iCellCnn achieved a 100% classification accuracy. As iCellCnn is not restricted to the diagnosis of SS, we expect such weakly supervised approaches to tap the diagnostic potential of IFC by providing automatic data-driven diagnosis of diseases with so-far unknown morphological manifestations.

Fluorescent Terpolymers Using Two Non-Emissive Monomers for Cr(III) Sensors, Removal, and Bio-Imaging.

The nonconventional purely aliphatic intrinsically fluorescent multifunctional terpolymers, such as 2-acrylamido-2-methylpropane sulfonic acid-co-2-(3-acrylamidopropylamido)-2-methylpropane sulfonic acid-co-acrylamide (AMPS-co-APMPS-co-AM, 1), acrylic acid-co-3-acrylamidopropanoic acid-co-acrylamide (AA-co-APA-co-AM, 2), and methacrylic acid-co-3-acrylamido-2-methyl propanoic acid-co-acrylamide (MAA-co-AMPA-co-AM, 3), were synthesized via N-H functionalized multi-C-C/N-C coupled in situ attachments of fluorophore monomers, that is, APMPS, APA, and AMPA, in solution polymerization of two non-fluorescent monomers. These terpolymers were suitable for selective Cr(III) sensors, high-performance exclusions of Cr(III), and fluorescence imaging of human osteosarcoma cancer cells. The structures of 1, 2, and 3, in situ attachments of fluorescent amino acid monomers, locations of fluorophores, aggregation-induced enhanced emissions, and the superadsorption mechanism were understood via microstructural analyses. The geometries, electronic structures, and the low-lying singlet-singlet absorption and emission of 1, 2, and 3 were explored using density functional theory (DFT), time-dependent DFT, and natural transition orbital analyses. The ionic and variable interactions of 1, 2, and 3 with Cr(III) were envisaged via analyses of adsorbed microstructures, fitting of kinetics data to a pseudo-second-order model, and the measurements of activation energies. For 1/2/3, limit of detection values and adsorption capacities were 1.88 × 10-7/3.75 × 10-7/1.25 × 10-7 M and 1316.35/1431.40/1372.18 mg g-1, respectively, at pHi = 7.0, 303 K, and 1000 ppm. The better overall properties made 3 to be more suitable in sensing and cell imaging.

Label Free, Nontoxic Cu-GSH NCs as a Nanoplatform for Cancer Cell Imaging and Subcellular pH Monitoring Modulated by a Specific Inhibitor: Bafilomycin A1.

Metal nanoparticles-based sensors invoked much research attention in the biomedical field, especially in applications involving live cell imaging and monitoring. Here, a simple cost-effective method is adopted to synthesize glutathione coated copper nanoclusters (Cu-GSH NCs) with strong bright red fluorescence (625 nm). The clusters were found to be containing five Cu(0) atoms complexed with one molecule of glutathione (GSH) as evidenced by MALDI-TOF MS analysis. The synthesized Cu-GSH NCs system responds linearly to the pH in the acidic and alkaline ranges with a high degree of in vitro pH reversibility, projecting its potential as a real time pH sensor. Higher intensity emission observed in acidic conditions can be exploited for its employability as cellular organelle markers. The imaging and sensing potential of Cu-GSH NCs in the live human adenocarcinoma cell line, the HeLa cells, was tested. The treatment of HeLa cells for 48 h imparted deep red fluorescence, owing to the lower level of intracellular pH in cancer cells. In contrast, the imaging using normal cell lines (L-132, lung epithelial cell line) showed significantly lower fluorescence intensity as compared to that of HeLa cells. The subcellular pH-dependent fluorescence emission of Cu-GSH NCs was further assessed by treating HeLa cells with proton pump (V-ATPase) inhibitor Bafilomycin A1, which increases the vesicular pH. Interestingly, the fluorescent intensity of HeLa cells decreases with increasing concentration of Bafilomycin A1 in the presence of Cu-GSH NCs, as evidenced by the fluorescence microscopic images and quantitative fluorescent output. Accordingly, the developed Cu-GSH NCs system can be employed as an efficient pH-based bioimaging probe for the detection of cancer cells with an implied potential for the label free subcellular organelle tracking and marking. Importantly, the Cu-GSH NCs can be used for live cell pH imaging owing to their high degree of reversibility in sensing of pH variation.

Hemicyanine-based near-infrared fluorescent probe for the ultrasensitive detection of hNQO1 activity and discrimination of human cancer cells.

NAD(P)H: Quinone Oxidoreductase 1 (hNQO1) is a cytosolic flavin two-electron reductase involved in many physiological and pathological processes that is overexpressed in many cancers and recognized as a potential cancer biomarker. However, it is still challenging for highly sensitive and selective monitoring hNQO1 in living cells. Here, we developed a highly selective and ultrasensitive hemicyanine-based near-infrared (NIR) fluorescence probe (probe HCYSN) for the sensing of hNQO1 activity and discrimination of human cancer cells. The fluorescent sensing system with NIR emission is low phototoxic to normal cells but is highly selective and ultrasensitive to hNQO1 in a linear range from 0.03 µg/mL to 0.6 µg/mL with detection limit (LOD) of 4.9 ng/mL (0.49 mU/mL), which is better than most of other hNQO1 probes reported. In particular, the NIR fluorescent probe was successfully applied to distinguish various cancer cells through the different distribution of endogenous hNQO1. All the present results demonstrated that the probe HCYSN exhibited great potential for human hNQO1 assay and in vivo imaging for the early cancers diagnosis and pathological studies.

Surface-Engineered Design of Efficient Luminescent Europium(III) Complex-Based Hydroxyapatite Nanocrystals for Rapid HeLa Cancer Cell Imaging.

We synthesized hydroxyapatite nanocrystals under the existence of tris(2,2,6,6-tetramethyl-3,5-heptanedionato)europium(III) (EuTH) complex to form inorganic/organic hybrid nanocrystal (EHA). Then, the folic acid derivative (folate N-hydroxysuccinimidyl ester (FA-NHS)) as the targeting ligand for the HeLa cancer cells was immobilized on the EHA by the mediation of both 3-aminopropyltriethoxysilane and methyltriethoxysilane molecules. Here, we investigated the photofunctions based on the interfacial interactions between the FA-NHS and EHA nanohybrids for preparing the novel bioimaging nanomaterials. As a result, the photofunctions could be changed by the FA-NHS molecular occupancy on the EHA. When the molecular occupancy ratio to the EHA surfaces is at around 3-5%, the intense luminescence from the f-f transition of the Eu3+ ions as well as the charge transfer between the EuTH-FA-NHS was observed to exhibit higher quantum efficiency. Moreover, effective dispersibility in phosphate-buffered saline was confirmed with immobilizing the positively charged FA-NHS. The cytotoxicity against the HeLa cells was also evaluated to verify whether the nanohybrids can be the candidate for cell imaging. The affinity and noncytotoxicity between the FA-NHS-immobilized EHA nanohybrids and cells were monitored for 3 days. Red luminescence from the cells could be observed, and the labels with following the cellular shapes were achieved by an additional culture time of 1 h after injecting the FA-NHS-immobilized EHA nanohybrids to the spheres, indicating the rapid bioimaging process. Therefore, this is the first successful report to describe the synthesis of inorganic-organic nanohybrid systems for controlling the EuTH-FA-NHS interactions. The photofunction of the interfacial interactions was successfully designed to provide "efficient luminescent ability" as well as "rapid targeting to the cancer cells" in one particle.

Cancer cell specific fluorescent methionine protected gold nanoclusters for in-vitro cell imaging studies.

Benefiting from the excellent photostability and biocompatibility, fluorescent nanoclusters have recently emerged as a highly attractive bio-sensing and imaging material, especially in early diagnosis of cancer. However, their clinic applications were limited by the unsatisfactory specificity and the complex synthesis. In this study, novel methionine coated gold nanoclusters (Met-AuNCs) have been prepared via an easily-achievable one-pot synthetic method. The prepared Met-AuNCs showed high imaging-specificity: after incubating with Met-AuNCs for 1 h, cancer cells (including A549, Hela, MCF-7, HepG2) were fluorescent, while the normal cells (WI-38 and CHO) showed no fluorescence. According to a series of controlled experiments, the reason for the high imaging-selectivity was proposed to originate from the specific recognition of L-type amino acid transporter overexpressed in cancer cells.

Fluorescent gold nanoclusters for efficient cancer cell targeting.

Well-known surface properties of gold nanoparticles (AuNPs) offer easy surface modification with desired biomolecule, thus enabling them to be used for targeting and imaging of cancer cells/tissues. However, targeting and imaging capability come through after synthesis coating of AuNPs' surface with targeting or imaging molecules. Attempts have been made to conjugate both imaging and targeting molecules over the AuNPs, but have seen limited success. Hence, exploiting the fluorescence properties of gold nanoclusters (AuNCs), we have synthesized glucose-coated AuNCs for exhibiting both the imaging and targeting properties. These clusters have shown rapid and selective uptake in cancerous (A549) cells when compared with bovine serum albumin-coated AuNCs.

Tracking Hyaluronan: Molecularly Imprinted Polymer Coated Carbon Dots for Cancer Cell Targeting and Imaging.

War against cancer constantly requires new affinity tools to selectively detect, localize, and quantify biomarkers for diagnosis or prognosis. Herein, carbon nanodots (CDs), an emerging class of fluorescent nanomaterials, coupled with molecularly imprinted polymers (MIPs), are employed as a biocompatible optical imaging tool for probing cancer biomarkers. First, N-doped CDs were prepared by hydrothermal synthesis using starch as carbon source and l-tryptophan as nitrogen atom provider to achieve a high quantum yield of 25.1 ± 2%. The CDs have a typical size of ∼3.2 nm and produce an intense fluorescence at 450 nm upon excitation with UV light. A MIP shell for specific recognition of glucuronic acid (GlcA) was then synthesized around the CDs, using the emission of the CDs as an internal light source for photopolymerization. GlcA is a substructure (epitope) of hyaluronan, a biomarker for certain cancers. The biotargeting and bioimaging of hyaluronan on fixated human cervical cancer cells using CD core-MIP shell nanocomposites is demonstrated. Human keratinocytes were used as noncancerous reference cells and indeed, less staining was observed by the CD-MIP.

Highly Selective Red-Emitting Fluorescent Probe for Imaging Cancer Cells in Situ by Targeting Pim-1 Kinase.

Based on the fact that enzyme-targeting probes are highly sensitive and selective, a novel red-emitting probe (NB-BF) for Pim-1 kinase including three parts, fluorophore (NB), linker, and inhibitor (BF), has been designed for cancer optical imaging. In its free state, NB-BF is folded and the fluorescence quenched by PET between fluorophore and inhibitor both in PBS buffer and in normal cells. Significantly, it emitted strong red fluorescence in Pim-1 overexpressed cancer cells. The specificity of NB-BF for Pim-1 kinase was directly demonstrated by gene silencing analysis. Furthermore, it is the first time to know where Pim-1 kinase mainly distributes at mitochondria with Pearson's correlation factor (Rr) of 0.965 and to provide a fluorescent tool to verify the function of the Pim-1 kinase. More importantly, NB-BF was applied in tissue imaging and preferentially labeled tumors in vivo.

Click-Functionalized SERS Nanoprobes with Improved Labeling Efficiency and Capability for Cancer Cell Imaging.

Precise identification and detection of cancer cells using nanoparticle probes are critically important for early cancer diagnosis and subsequent therapy. We herein develop novel folate receptor (FR)-targeted surface-enhanced Raman scattering (SERS) nanoprobes for cancer cell imaging based on a click coupling strategy. A Raman-active derivative (5,5'-dithiobis(2-nitrobenzoic acid)-N3 (DNBA-N3)) is designed with a disulfide bond for covalently anchoring to the surface of hollow gold nanoparticles (HAuNPs) and a terminal azide group for facilitating highly efficient conjugation with the bioligand. Modification of HAuNPs with DNBA-N3 yields monolayer coverage of Raman labels absorbed on the nanoparticle surface (HAuNP-DNBA-N3) and strong SERS signals. HAuNP-DNBA-N3 can be simply and effectively conjugated with folate bicyclo[6.1.0]nonyne derivatives via a copper-free click reaction. The synthesized nanoprobes (HAuNP-DNBA-folic acid (FA)) exhibit excellent targeted capacities to FR-positive cancer cells relative to FR-negative cells through SERS mappings. The receptor-mediated delivery behaviors are confirmed by comparison with the uptake of HAuNP-DNBA-N3 and free FA competition experiments. In addition to its good stability and benign biocompatibility, the developed SERS nanoprobes have great potential for applications in targeted tumor imaging.