A Versatile Dynamic Mussel-Inspired Biointerface: From Specific Cell Behavior Modulation to Selective Cell Isolation.

Reported here is a novel dynamic biointerface based on reversible catechol-boronate chemistry. Biomimetically designed peptides with a catechol-containing sequence and a cell-binding sequence at each end were initially obtained. The mussel-inspired peptides were then reversibly bound to a phenylboronic acid (PBA) containing polymer-grafted substrate through sugar-responsive catechol-boronate interactions. The resultant biointerface is thus capable of dynamic presentation of the bioactivity (i.e. the cell-binding sequence) by virtue of changing sugar concentrations in the system (similar to human glycemic volatility). In addition, the sugar-responsive biointerface enables not only dynamic modulation of stem cell adhesion behaviors but also selective isolation of tumor cells. Considering the highly biomimetic nature and biological stimuli-responsiveness, this mussel-inspired dynamic biointerface holds great promise in both fundamental cell biology research and advanced medical applications.

On reactive Ion Etching of Parylene-C with Simple Photoresist Mask for Fabrication of High Porosity Membranes to Capture Circulating and Exfoliated Tumor Cells.

A high porosity micropore arrayed parylene membrane is a promising device that is used to capture circulating and exfoliated tumor cells (CTCs and ETCs) for liquid biopsy applications. However, its fabrication still requires either expensive equipment or an expensive process. Here, we report on the fabrication of high porosity (>40%) micropore arrayed parylene membranes through a simple reactive ion etching (RIE) that uses photoresist as the etching mask. Vertical sidewalls were observed in etched parylene pores despite the sloped photoresist mask sidewalls, which was found to be due to the simultaneous high DC-bias RIE induced photoresist melting and substrate pedestal formation. A theoretical model has been derived to illustrate the dependence of the maximum membrane thickness on the final pore-to-pore spacing, and it is consistent with the experimental data. A simple, yet accurate, low number (<50) cell counting method was demonstrated through counting cells directly inside a pipette tip under phase-contrast microscope. Membranes as thin as 3 µm showed utility for low number tumor cell capture, with an efficiency of 87-92%.

Virus-Mimicking Cell Capture Using Heterovalency Magnetic DNA Nanoclaws.

Synergy represents a natural approach for high-efficiency recognition in biological systems. Inspired by the recognition mechanism of viral infection of mammalian cells, here we develop heterovalency magnetic DNA nanoclaws with octopus arms morphology for synergetic cell capture. We demonstrated that the rigid-flexible DNA nanoclaws can load multiple antibodies (Abs) targeting different epitopes for enhanced capture of cancer cells, especially significantly increasing the capture efficiency of MDA-MB-231 cells up to 82.3 ± 7.1%. We also employed DNA nanoclaws with the combined use of multiple Abs to capture circulating tumor cells from clinical samples with high efficiency and specificity. We expect that the DNA nanoclaws not only could play a key role in liquid biopsy, but also could be expanded, with more applications benefiting from their modularity and programmability to modify various functionalities in future.