Functionalized vertical GaN micro pillar arrays with high signal-to-background ratio for detection and analysis of proteins secreted from breast tumor cells.

The detection of cancer biomarkers has recently attracted significant attention as a means of determining the correct course of treatment with targeted therapeutics. However, because the concentration of these biomarkers in blood is usually relatively low, highly sensitive biosensors for fluorescence imaging and precise detection are needed. In this study, we have successfully developed vertical GaN micropillar (MP) based biosensors for fluorescence sensing and quantitative measurement of CA15-3 antigens. The highly ordered vertical GaN MP arrays result in the successful immobilization of CA15-3 antigens on each feature of the arrays, thereby allowing the detection of an individual fluorescence signal from the top surface of the arrays owing to the high regularity of fluorophore-tagged MP spots and relatively low background signal. Therefore, our fluorescence-labeled and CA15-3 functionalized vertical GaN-MP-based biosensor is suitable for the selective quantitative analysis of secreted CA15-3 antigens from MCF-7 cell lines, and helps in the early diagnosis and prognosis of serious diseases as well as the monitoring of the therapeutic response of breast cancer patients.

Microfluidic channel-coupled 3D quartz nanohole arrays for high capture and release efficiency of BT20 cancer cells.

Nanostructured materials, such as silicon nanowires, quartz nanostructures, and polymer-modified nanostructures, are a promising new class of materials for the capture and enumeration of very rare tumor cells, including circulating tumor cells (CTCs), to examine their biological characteristics in whole blood of cancer patients. These cells can then be used for transplantation, anti-tumor cell therapy, and cell-secreted protein studies. It is believed that 3-dimensional (3D) nanostructured substrates efficiently enhance cell capture yields due to the increased local contacts between the 3D nanostructures and extracellular extensions of the tumor cells. Recent studies have been performed with enhanced cell capture yields thanks to various nanostructured platforms; however, there remains an urgent need both to capture and release viable rare tumor cells for further molecular (i.e., protein) analysis and to develop patient-specific drugs. Here, we first demonstrate that our 3D quartz nanohole array (QNHA) tumor cell capture and release system allows us not only to selectively capture rare tumor cells, but also to release the cells with high capture and release rates. This system was developed using streptavidin (STR)-functionalized QNHA (STR-QNHA) with a microfluidic channel. Our system has ideal cell-separation yields of as high as 85-91% and high release rates of >90% for the BT20 cell line. We suggest that the use of a microfluidic channel technique coupled with a STR-QNHA cell capture and release chip (STR-QNHA cell chip) would be a powerful and simple process to evaluate the capture, enumeration, and release of CTCs from patient whole blood for studying further cell therapy and tumor-cell-secreted molecules.

Effect of graphene oxide ratio on the cell adhesion and growth behavior on a graphene oxide-coated silicon substrate.

Control of living cells on biocompatible materials or on modified substrates is important for the development of bio-applications, including biosensors and implant biomaterials. The topography and hydrophobicity of substrates highly affect cell adhesion, growth, and cell growth kinetics, which is of great importance in bio-applications. Herein, we investigate the adhesion, growth, and morphology of cultured breast cancer cells on a silicon substrate, on which graphene oxides (GO) was partially formed. By minimizing the size and amount of the GO-containing solution and the further annealing process, GO-coated Si samples were prepared which partially covered the Si substrates. The coverage of GO on Si samples decreases upon annealing. The behaviors of cells cultured on two samples have been observed, i.e. partially GO-coated Si (P-GO) and annealed partially GO-coated Si (Annealed p-GO), with a different coverage of GO. Indeed, the spreading area covered by the cells and the number of cells for a given culture period in the incubator were highly dependent on the hydrophobicity and the presence of oxygenated groups on GO and Si substrates, suggesting hydrophobicity-driven cell growth. Thus, the presented method can be used to control the cell growth via an appropriate surface modification.

Enhancement of Capture Sensitivity for Circulating Tumor Cells in a Breast Cancer Patient's Blood by Silicon Nanowire Platform.

The separation of circulating tumor cells (CTCs) from the blood of cancer patients with high sensitivity is an essential technique for selecting chemotherapeutic agents at a patient-by-patient level. Recently, various research groups have reported a nanostructure-based platform for rare cell capture due to its high surface area and 3D nanotopographic features. However, evaluation of capture sensitivity based on chemical modification of the nanostructure surface has not yet been performed. Here, we evaluated the capture sensitivity for CTCs from the blood of three patients diagnosed with stage IV metastatic breast cancer by using the following three platforms: streptavidin-conjugated silicon nanowire (STR-SiNW), poly-l-lysine-coated silicon nanowire (PLL-SiNW), and poly-l-lysine-coated glass (PLL-glass). The number of evaluated CTCs on STR-SiNW, PLL-SiNW, and PLL-glass were 16.2 ± 5.5 cells, 7.3 ± 2.9 cells, and 4.7 ± 1.5 cells, respectively, per 0.5 ml. Therefore, we suggest that the STR-SiNW platform is highly adaptable for the quantitative evaluation of CTCs from the blood of cancer patients in the clinical setting.