Saeyoung Ahn

Evidence for an Additional Metastatic Route: In Vivo Imaging of Cancer Cells in the Primo-Vascular System Around Tumors and Organs

PurposeResearchers have been studying the mechanisms by which metastasis can be prevented via blocking the hematogenous and the lymphatic routes for a long time now. However, metastasis is still the single most challenging obstacle for successful cancer management. In a new twist that may require some retooling of this established approach, we investigated the hypothesis that tumor metastases can occur via an independent fluid-conducting system called the primo-vascular system.ProceduresThe dissemination and growth of near-infrared quantum dot (NIR QD)-electroporated cancer cells in metastatic sites were investigated using in vivo multispectral imaging techniques.ResultsOur results show that the NIR QD-labeled cancer cells were able to migrate through not only the blood vascular and lymphatic systems but also the primo-vascular system extending from around the tumor to inside the abdominal cavity. Furthermore, the NIR QD-labeled cancer cells, which had been seeded intraperitoneally, specifically infiltrated the primo-vascular system in the omentum and in the gonadal fat.ConclusionsThese findings strongly suggest that the primo-vascular system may be an additional metastasis route, complementing the lymphatic and hematogenous routes, which facilitate the dissemination and colonization of cancer cells at secondary sites.

Bonghan Ducts as Possible Pathways for Cancer Metastasis

OBJECTIVEnThe present study has been designed to find a possible new route for the metastasis of cancer cells on the fascia surrounding tumor tissue using a novel technique of trypan blue staining.nnnMATERIALS AND METHODSnTumor tissues were grown in the skin of nude mice after sub-cutaneous inoculation with human lung cancer cells. Trypan blue was recently identified as a dye with specificity for Bonghan ducts (BHDs) and not other tissues, such as blood or lymph vessels or nerves.nnnRESULTSnWe demonstrate that the trypan blue staining technique allows the first visualization of BHDs which are connected to tumor tissues.nnnCONCLUSIONnSince BHDs are known to make up a circulatory system corresponding to acupuncture meridians or collaterals, we propose that, in addition to the currently known blood or lymph vessels, BHDs on tumor tissue fascia may be a novel pathway for metastasis.

Observations of highly nonlinear internal solitons generated by near‐inertial internal waves off the east coast of Korea

Solitary internal wave packets were observed in May 1999, propagating toward the east coast of Korea with thermocline displacements up to twentysix meters downward from the initial depth of twenty meters. High nonlinearity of these waves is represented by the second-order KdV model better than KdV equations. Regular occurrence of solitary internal wave packets with the period of about nineteen hours suggests the generation by near-inertial internal waves, which has not been reported in the literature yet.

In vivo imaging of cancer cells with electroporation of quantum dots and multispectral imaging

Our understanding of dissemination and growth of cancercells is limited by our inability for long-term followup of this process in vivo. Fluorescence molecular imaging has the potential to track cancercells with high contrast and sensitivity in living animals. For this purpose, intracellular delivery of near-infraredfluorescencequantum dots(QDs) by electroporation offers considerable advantages over organic fluorophores and other cell tagging methods. In this research we developed a multispectral imaging system that could eliminate two major parameters compromising in vivofluorescenceimaging performance, i.e., variations in the tissue optical properties and tissueautofluorescence. We demonstrated that electroporation of QDs and multispectral imaging allowed in vivo assessment of cancer development and progression in the xenograft mouse tumor model for more than 1 month, providing a powerful means to learn more about the biology of cancer and metastasis.

Scanning Spontaneous Photon Emission From Transplanted Ovarian Tumor of Mice Using a Photomultiplier Tube

A scanning system for the detection of spontaneous ultraweak photon emission from nude mice with transplanted tumors is presented. A photomultiplier tube (PMT) with an effective area of 15 mm diameter was used for measuring photon emission in a wavelength range from 300 to 650 nm. Tumors were induced in nude mice by transplantation of an ovarian cancer cell line into the back of mice. The PMT was moved for scanning over the whole body of a mouse placed in a dark box. The profiles of the intensities of photon emissions from the tumor mice are presented and compared with those obtained from the control mice.

Targeting Antibodies to Carbon Nanotube Field Effect Transistors by Pyrene Hydrazide Modification of Heavy Chain Carbohydrates

Many carbon nanotube field-effect transistor (CNT-FET) studies have used immobilized antibodies as the ligand binding moiety. However, antibodies are not optimal for CNT-FET detection due to their large size and charge. Their size can prevent ligands from reaching within the Debye length of the CNTs and a layer of charged antibodies on the circuits can drown out any ligand signal. In an attempt to minimize the antibody footprint on CNT-FETs, we examined whether pyrene hydrazide modification of antibody carbohydrates could reduce the concentration required to functionalize CNT circuits. The carbohydrates are almost exclusively on the antibody Fc region and this site-specific modification could mediate uniform antibody orientation on the CNTs. We compared the hydrazide modification of anti-E. coli O157:H7 polyclonal antibodies to pyrenebutanoic acid succinimidyl ester-coated CNTs and carbodiimide-mediated antibody CNT attachment. Our results show that the pyrene hydrazide modification was superior to those methods with respect to bacteria detection and less than 1u2009nM labeled antibody was required to functionalize the circuits.

Specific Binding of Alzheimer’s Aβ Peptide Fibrils to Single Walled Carbon Nanotubes

Amyloids constitute a class of protein and protein fragments believed to be involved in the pathologies associated with Alzheimers, Parkinsons and Creutzfeldt-Jakob diseases. These proteins can self-assemble into unique fibrillar structures that are resistant to normal protein degradation. Interesting recent developments in the study of amyloid fibrils demonstrate that they bind carbon allotropes. In this study using single-walled carbon nanotube field-effect transistors (SWCNT-FETs), we show that the fibrillar form of Alzheimers amyloid β (1–40) and (1–42) peptides specifically bind non-functionalized SWCNT in a saturable manner. Both peptides exhibited near identical binding curves with half-maximal binding concentrations of approximately 12 μg/ml. Binding of the peptides to SWCNTs was diminished by including dimethyl sulphoxide (DMSO) at concentrations that inhibits fibril formation. Lastly a monoclonal antibody (BAM-10), which binds to the N-terminal region of Alzheimers amyloid fibrils, recognize...

Evaluation of Aromatic Boronic Acids as Ligands for Measuring Diabetes Markers on Carbon Nanotube Field-Effect Transistors

Biomolecular detections performed on carbon nanotube field-effect transistors (CNT-FETs) frequently use reactive pyrenes as an anchor to tether bioactive ligands to the hydrophobic nanotubes. In this paper, we explore the possibility of directly using bioactive aromatic compounds themselves as CNT-FET ligands. This would be an efficient way to functionalize CNT-FETs since many aromatic compounds bind avidly to nanotubes, and it would also ensure that ligand-binding molecules would be brought in close proximity to the nanotubes. Using a model system consisting of pyrene, phenanthrene, naphthalene, or phenyl boronic acids immobilized on CNT-FET wafers, we show that all are able to bind glycated human serum albumin (gHSA), which is an important diabetes marker. Pyrene boronic acid proved to bind CNTs with the greatest apparent affinity as measured by gHSA impedance. Interestingly, gHSA CNT-FET signal intensity, which is proportional to amount of protein bound, remained essentially unchanged for all the boronic acids tested.

High-Throughput Peptide Epitope Mapping Using Carbon Nanotube Field-Effect Transistors

Label-free and real-time detection technologies can dramatically reduce the time and cost of pharmaceutical testing and development. However, to reach their full promise, these technologies need to be adaptable to high-throughput automation. To demonstrate the potential of single-walled carbon nanotube field-effect transistors (SWCNT-FETs) for high-throughput peptide-based assays, we have designed circuits arranged in an 8 × 12 (96-well) format that are accessible to standard multichannel pipettors. We performed epitope mapping of two HIV-1 gp160 antibodies using an overlapping gp160 15-mer peptide library coated onto nonfunctionalized SWCNTs. The 15-mer peptides did not require a linker to adhere to the non-functionalized SWCNTs, and binding data was obtained in real time for all 96 circuits. Despite some sequence differences in the HIV strains used to generate these antibodies and the overlapping peptide library, respectively, our results using these antibodies are in good agreement with known data, indicating that peptides immobilized onto SWCNT are accessible and that linear epitope mapping can be performed in minutes using SWCNT-FET.

Purification of semiconducting single-walled carbon nanotubes by spiral counter-current chromatography ☆

Over the last decade man-made carbon nanostructures have shown great promise in electronic applications, but they are produced as very heterogeneous mixtures with different properties so the achievement of a significant commercial application has been elusive. The dimensions of single-wall carbon nanotubes are generally a nanometer wide, up to hundreds of microns long and the carbon nanotubes have anisotropic structures. They are processed to have shorter lengths but they need to be sorted by diameter and chirality. Thus counter-current chromatography methods developed for large molecules are applied to separate these compounds. A modified mixer-settler spiral CCC rotor made with 3 D printed disks was used with a polyethylene glycol-dextran 2-phase solvent system and a surfactant gradient to purify the major species in a commercial preparation. We isolated the semi-conducting single walled carbon nanotube chiral species identified by UV spectral analysis. The further development of spiral counter-current chromatography instrumentation and methods will enable the scalable purification of carbon nanotubes useful for the next generation electronics.