Selective Adhesion and Switchable Release of Breast Cancer Cells via Hyaluronic Acid Functionalized Dual Stimuli-Responsive Microgel Films

Abstract

The detection of tumor cells from liquid biopsy samples is of critical importance for early cancer diagnosis, malignancy assessment, and treatment. In this work, coatings of hyaluronic acid (HA)-functionalized dualstimuli responsive poly(N-isopropylacrylamide) (PNIPAM) microgels are used to study the specificity of breast cancer cell binding and to assess cell friendly release mechanisms for further diagnostic procedures. The microgels are established by straightforward precipitation polymerization with amine bearing comonomers and postfunctionalization with a UV-labile linker that covalently binds HA to the microgel network. Well-defined microgel coatings for cell binding are established via simple physisorption and annealing. The HA-presenting PNIPAM microgel films are shown to specifically adhere CD44 expressing breast cancer cell lines (MDA-MB-231 and MCF-7), where an increase in adhesion correlates with higher CD44 expression and HA functionalization. Upon cooling below the lower critical solution temperature of PNIPAM microgels, the cells could be released; however, 10−30% of the cells still remained on the surface even after prolonged cooling and mild mechanical agitation. A complete cell release is achieved after applying the light stimulus by short UV treatment cleaving HA units from the microgels. Owing to the comparatively straightforward preparation procedures, such dual-responsive microgel films could be considered for the effective capture, release, and diagnostics of tumor cells.

Tumor Microenvironment-Inspired Glutathione-Responsive Three-Dimensional Fibrous Network for Efficient Trapping and Gentle Release of Circulating Tumor Cells

“…In addition, the fragility of CTCs is another key issue that needs to be considered. Current 3D micro-/nanostructures are mostly focused on inorganic materials, which cannot match the soft nature of cells to retain their maximum viability. − A majority of stimuli-responsive strategies (enzymatic treatment, voltage, UV irradiation, etc.) for controlled release of captured cells more or less negatively affect the overall cell viability, seriously influencing downstream analysis.…”

Recent progress of nanostructure-based enrichment of circulating tumor cells and downstream analysis

“…6C. 93 The HA-modified PNIPAM microgel membrane can specifically capture the breast cancer cell line MDA-MB-231 expressing CD44, and the captured cells can be released by light stimulation and changing temperature.…”

Specific Binding of Ligand-Functionalized Thermoresponsive Microgels: Effect of Architecture, Ligand Density, and Hydrophobicity

“…14−16 Other examples are hyaluronic acid-functionalized microgels that were shown to selectively capture tumor cells above the VPTT. 17 In both cases, the carbohydrate ligand density was increased above the VPTT, which leads to an increased ligand density, larger avidity, and overall stronger binding. 18 It is assumed that the hydrophilic carbohydrate ligands are also enriched at the microgel−water interface in the collapsed, hydrophobic state of the microgel network, further increasing binding by multivalency effects.…”

“…By adjusting the temperature below or above the VPTT, the microgels swell or collapse in aqueous solutions, which leads to notable changes in the polymer segment density. − This change in swelling state can control the density and accessibility of ligand molecules attached to the microgel network and their affinity to protein receptors. We established microgels decorated with α- d -mannose (Man) units that showed increased affinity to Man binding proteins and pathogens in the collapsed state at temperatures above the VPTT. − Other examples are hyaluronic acid-functionalized microgels that were shown to selectively capture tumor cells above the VPTT . In both cases, the carbohydrate ligand density was increased above the VPTT, which leads to an increased ligand density, larger avidity, and overall stronger binding .…”