Assessment of Cellular Uptake Efficiency According to Multiple Inhibitors of Fe3O4-Au Core-Shell Nanoparticles: Possibility to Control Specific Endocytosis in Colorectal Cancer Cells.

Magnetite (Fe3O4)-gold (Au) core-shell nanoparticles (NPs) have unique magnetic and optical properties. When combined with biological moieties, these NPs can offer new strategies for biomedical applications, such as drug delivery and cancer targeting. Here, we present an effective method for the controllable cellular uptake of magnetic core-shell NP systems combined with biological moieties. Vimentin, which is the structural protein, has been biochemically confirmed to affect phagocytosis potently. In addition, vimentin affects exogenic materials internalization into cells even though under multiple inhibitions of biological moieties. In this study, we demonstrate the cellular internalization performance of Fe3O4-Au core-shell NPs with surface modification using a combination of biological moieties. The photofluorescence of vimentin-tagged NPs remained unaffected under multiple inhibition tests, indicating that the NPs were minimally influenced by nystatin, dynasore, cytochalasin D, and even the Muc1 antibody (Ab). Consequently, this result indicates that the Muc1 Ab can target specific molecules and can control specific endocytosis. Besides, we show the possibility of controlling specific endocytosis in colorectal cancer cells.

Nanotopographical regulation of pancreatic islet-like cluster formation from human pluripotent stem cells using a gradient-pattern chip.

Bioengineering approaches to regulate stem cell fates aim to recapitulate the in vivo microenvironment. In recent years, manipulating the micro- and nano-scale topography of the stem cell niche has gained considerable interest for the purposes of controlling extrinsic mechanical cues to regulate stem cell fate and behavior in vitro. Here, we established an optimal nanotopographical system to improve 3-dimensional (3D) differentiation of pancreatic cells from human pluripotent stem cells (hPSCs) by testing gradient-pattern chips of nano-scale polystyrene surface structures with varying sizes and shapes. The optimal conditions for 3D differentiation of pancreatic cells were identified by assessing the expression of developmental regulators that are required for pancreatic islet development and maturation. Our results showed that the gradient chip of pore-part 2 (Po-2, 200-300 nm diameter) pattern was the most efficient setting to generate clusters of pancreatic endocrine progenitors (PDX1+ and NGN3+) compared to those of other pore diameters (Po-1, 100-200 or Po-3, 300-400 nm) tested across a range of pillar patterns and flat surfaces. Furthermore, the Po-2 gradient pattern-derived clusters generated islet-like 3D spheroids and tested positive for the zinc-chelating dye dithizone. The spheroids consisted of more than 30% CD200 + endocrine cells and also expressed NKX6.1 and NKX2.2. In addition, pancreatic ß- cells expressing insulin and polyhormonal cells expressing both insulin and glucagon were obtained at the final stage of pancreatic differentiation. In conclusion, our data suggest that an optimal topographical structure for differentiation to specific cell types from hPSCs can be tested efficiently by using gradient-pattern chips designed with varying sizes and surfaces. STATEMENT OF SIGNIFICANCE: Our study provides demonstrates of using gradient nanopatterned chips for differentiation of pancreatic islet-like clusters. Gradient nanopatterned chips are consisted of two different shapes (nanopillar and nanopore) in three different ranges of nano sizes (100-200, 200-300, 300-400 nm). We found that optimal nanostructures for differentiation of pancreatic islet-like clusters were 200-300 nm nano pores. Cell transplantation is one of the major therapeutic option for type 1 diabetes mellitus (DM) using stem cell-derived ß-like cells. We generated 50 um pancreatic islet-like clusters in size, which would be an optimal size for cell transplantation. Futuremore, the small clusters provide a powerful source for cell therapy. Our findings suggest gradient nanopatterned chip provides a powerful tool to generate specific functional cell types of a high purity for potential uses in cell therapy development.

Nanotopographical control for maintaining undifferentiated human embryonic stem cell colonies in feeder free conditions.

Recently emerging evidence has indicated surface nanotopography as an important physical parameter in the stem cell niche for regulating cell fate and behaviors for various types of stem cells. In this study, a substrate featuring arrays of increasing nanopillar diameter was devised to investigate the effects of varying surface nanotopography on the maintenance of undifferentiated human embryonic stem cells (hESC) colonies in the absence of feeder cells. Single hESCs cultured across gradient nanopattern (G-Np) substrate were generally organized into compact colonies, and expressed higher levels of undifferentiated markers compared to those cultured on the unstructured control substrate. In particular, hESC demonstrates a propensity to organize into more compact colonies expressing higher levels of undifferentiated markers towards a smaller nanopillar diameter range (D = 120-170 nm). Cell-nanotopography interactions modulated the formation of focal adhesions and cytoskeleton reorganization to restrict colony spreading, which reinforced E-cadherin mediated cell-cell adhesions in hESC colonies. Maintaining compact hESC colony integrity revealed to be indispensable for hESC undifferentiated state as the loss of cell-cell adhesions within spreading hESC on the control substrate exhibited morphological and gene expression signatures of epithelial-to-mesenchymal transition-like processes. Findings in this study demonstrated a feasible approach to screen the optimal nanotopographical cues for maintaining undifferentiated hESC colonies in feeder free conditions, which provides a platform for further investigations into developing hESC feeder free culture systems for the purpose of regenerative medicine.

A simple and fast fabrication of a both self-cleanable and deep-UV antireflective quartz nanostructured surface.

Both self-cleanability and antireflectivity were achieved on quartz surfaces by forming heptadecafluoro-1,1,2,2-tetrahydrodecyltrichlorosilane self-assembled monolayer after fabrication of nanostructures with a mask-free method. By exposing polymethylmethacrylate spin-coated quartz plates to O2 reactive ion etching (RIE) and CF4 RIE successively, three well-defined types of nanopillar arrays were generated: A2, A8, and A11 patterns with average pillar widths of 33 ± 4 nm, 55 ± 5 nm, and 73 ± 14 nm, respectively, were formed. All the fabrication processes including the final cleaning can be finished within 4 h. All nanostructured quartz surfaces exhibited contact angles higher than 155° with minimal water droplet adhesiveness and enhanced transparency (due to antireflectivity) over a broad spectral range from 350 to 900 nm. Furthermore, A2 pattern showed an enhanced antireflective effect that extends to the deep-UV range near 190 nm, which is a drawback region in conventional thin-film-coating approaches as a result of thermal damage. Because, by changing the conditions of successive RIE, the geometrical configurations of nanostructure arrays can be easily modified to meet specific needs, the newly developed fabrication method is expected to be applied in various optic and opto-electrical areas.PACS codes: 06.60.Ei; 81.65.Cf; 81.40.Vw.

Size-controllable quartz nanostructure for signal enhancement of DNA chip.

A mask-free, cost-effective dry-etching method for the fabrication of height- and spacing-controlled, pillar-like nanostructures was established in order to detect DNA molecules. The height and spacing of the quartz nanostructure were regulated by successive O(2) and CF(4) reactive ion etching times. The height and spacing of the nanostructures were tuned between 118 and 269 nm and between 107 and 161 nm, respectively. Probe DNA was immobilized on the structure and hybridized with fluorescently-labeled target DNA. Increases in the height and spacing of the nanopillar structure positively correlated with the fluorescence intensity of bound DNA. Usage of the nanostructure increased the DNA detection limit by up to 100-fold.

Nanostructure-dependent water-droplet adhesiveness change in superhydrophobic anodic aluminum oxide surfaces: from highly adhesive to self-cleanable.

Water-droplet adhesiveness was freely controlled on a single platform of superhydrophobic anodized aluminum oxide (AAO) within the range from highly adhesive to self-cleanable. Changing the structure from nanopore to nanopillar arrays at the surface caused a dramatic increase in the receding angle and a decrease in the hysteresis of water contact angles. The presence of dead-end nanopores but not through nanoholes was recognized as one of the main causes of the adhesiveness of superhydrophobic surfaces. The adhesiveness-controllable superhydrophobic AAO can be an excellent platform on which to elucidate the physical nature of the wetting phenomenon related to the nanostructure and has promising potential in technological applications.