This paper presents a simple approach to create a two-tiered surface for superior cancer cell isolation. The idea is inspired by the interactions of cells with a nanotextured basement membrane. The texture mimicked the extracellular matrix and basement membrane for superior target cell adhesion. Prepared micro+nanotextured surfaces showed enhanced cell capture. Preparation of the two-tiered surface was done using micro- and nanotexturing and was easily reproducible. It has been shown before that the larger surface area of a nanotextured surface assists the cell's attachment through surface-anchored ligands. Taking it a step further, ligand functionalized two-level micro+nanotextured surfaces improved the sensitivity of the cancer cell isolation over simple flat nanotexturing. The isolation efficiency increased by 208% compared to the surface with a single-level nanotexture. The two-tiered surface was compatible with previously reported nanotextured devices used for cancer cell isolation. Micro-texture on the glass surface was created using simple sand gritting, followed by reactive ion etching (RIE) of the entire surface. The approach could create large surface areas within a short time while maintaining superior cell isolation efficiency.
Biomarker-binding nucleotide sequences, like aptamers, have gained recent attention in cancer cell isolation and detection works. Self-assembly and 3D conformation of aptamers enable them to selectively capture and bind diseased cells and related biomarkers. One mode of utilizing such an extraordinary selective property of the aptamers is by grafting these in nanopores. Coating the inside walls of the nanopore with biomarker specific ligands, like DNA, changes the statistics of the dynamic translocation events. When the target protein passes through the nanopore, it interacts with ligand coated inside the nanopore, and the process alters the overall potential energy profile which is essentially specific to the protein detected. The fundamental goal in this process is to ensure that these detection motifs hold their structure and functionality under applied electric field and experimental conditions. We report here all-atom molecular dynamics simulations of the effects of external electric field on the 3D conformation of such DNA structures. The simulations demonstrate how the grafted moieties affect the translocation time, velocity, and detection frequency of the target molecule. We also investigated a novel case of protein translocation, where DNA is prebound to the protein. As model, a thrombin-specific G-quartet and thrombin pair was used for this study.
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