Protein arrays on high-surface-area plasma-nanotextured poly(dimethylsiloxane)-coated glass slides

Facile Surface Functionalization of Cyclic Olefin Copolymer Film with Anhydride Groups for Protein Microarray Fabrication

Immobilization of protein at high efficiency is a challenge for fabricating polymer-based protein chips. Here, a simple but effective approach was developed to fabricate a cyclic olefin copolymer (COC)-based protein microarray with a high immobilization density. In this strategy, poly(maleic anhydride-co-vinyl acetate) (poly(MAH-co-VAc)) brushes were facilely attached on the COC surface via UV-induced graft copolymerization. The introduction of poly(MAH-co-VAc) brushes resulted in an obvious increase in the surface roughness of COC. The functionalized COC showed little reduction in transparency compared with pristine COC, indicating that the photografting treatment did not alter its optical property. The graft density of the anhydride groups on the modified COC could be tuned from 0.46 to 3.2 μmol/cm². The immobilization efficiency of immunoglobulin G (IgG) on functionalized COC reached 88% due to the high reactivity between anhydride groups and amine groups of IgGs. An immunoassay experiment demonstrated that the microarray showed high sensitivity to the target analyte.

Plasma Nano-Texturing of Polymers for Wettability Control: Why, What and How

Nano-texturing of polymers offers the possibility to drive important surface properties such as wettability and anti-reflectivity. Interestingly, plasma can lead to the desired characteristic of nanofeatures through a one step process based onto dry plasma etching. In this work, the literature concerning such plasma nano-texturing will be reviewed for different polymers, and in particular, for applications based upon wettability control. Then the mechanism of such processes will be commented upon, with a glance to the different characteristics of the polymers. Finally, some hints onto a feasible approach to plasma nano-texturing of the different polymers will be given.

Bio-orthogonal fluorinated resist for biomolecules patterning applications

The patterning of organic materials on solid substrate surfaces has been demonstrated by several methods, such as photolithography, soft lithography, imprint lithography and ink-jet printing. Fluorinated polymers and solvents provide attractive material systems to develop new patterning approaches, as they are chemically orthogonal to non-fluorinated organic molecules, allowing their efficient incorporation in different devices and systems. Moreover, fluorinated polymers are soluble in hydrofluoroether solvents, benign to biomolecules, and can be properly engineered to enable efficient photolithographic patterning. In this work, we report the development of a new photolithographic process for patterning biomolecules on any kind of surfaces either by physical adsorption or covalent bonding. The photoresist is based on a fluorinated material and hydrofluoroether solvents that have minimum interactions with biomolecules and thus they can be characterized as orthogonal to the biomolecules (bio-orthogonal). In both cases, the creation of patterns with dimensions down to 2 μm was achieved. The implementation of the developed photolithographic procedure for the creation of a multi-protein microarray is demonstrated.

Effects of Nanotexture on Electrical Profiling of Single Tumor Cell and Detection of Cancer from Blood in Microfluidic Channels

Microfluidic channels have been implemented to detect cancer cells from blood using electrical measurement of each single cell from the sample. Every cell provided characteristic current profile based on its mechano-physical properties. Cancer cells not only showed higher translocation time and peak amplitude compared to blood cells, their pulse shape was also distinctively different. Prevalent microfluidic channels are plain but we created nanotexture on the channel walls using micro reactive ion etching (micro-RIE). The translocation behaviors of the metastatic renal cancer cells through plain and nanotextured PDMS microchannels showed clear differences. Nanotexture enhanced the cell-surface interactions and more than 50% tumor cells exhibited slower translocation through nanotextured channels compared to plain devices. On the other hand, most of the blood cells had very similar characteristics in both channels. Only 7.63% blood cells had slower translocation in nanotextured microchannels. The tumor cell detection efficiency from whole blood increased by 14% in nanotextured microchannels compared to plain channels. This interesting effect of nanotexture on translocation behavior of tumor cells is important for the early detection of cancer.

Nanotextured polymer substrates show enhanced cancer cell isolation and cell culture

Detection of circulating tumor cells (CTCs) in the early stages of cancer is a great challenge because of their exceedingly small concentration. There are only a few approaches sensitive enough to differentiate tumor cells from the plethora of other cells in a sample like blood. In order to detect CTCs, several antibodies and aptamers have already shown high affinity. Nanotexture can be used to mimic basement membrane to further enhance this affinity. This article reports an approach to fabricate nanotextured polydimethylsiloxane (PDMS) substrates using micro reactive ion etching (micro-RIE). Three recipes were used to prepare nanotextured PDMS using oxygen and carbon tetrafluoride. Micro-RIE provided better control on surface properties. Nanotexturing improved the affinity of PDMS surfaces to capture cancer cells using surface immobilized aptamers against cell membrane overexpressed with epidermal growth factor receptors. In all cases, nanotexture of PDMS increased the effective surface area by creating nanoscale roughness on the surface. Nanotexture also enhanced the growth rate of cultured cells compared to plain surfaces. A comparison among the three nanotextured surfaces demonstrated an almost linear relationship between the surface roughness and density of captured tumor cells. The nanotextured PDMS mimicked biophysical environments for cells to grow faster. This can have many implications in microfluidic platforms used for cell handling.