Modulation of Living Cell Behavior with Ultra‐Low Fouling Polymer Brush Interfaces

Abstract

Ultra‐low fouling and functionalizable coatings represent emerging surface platforms for various analytical and biomedical applications such as those involving examination of cellular interactions in their native environments. Ultra‐low fouling surface platforms as advanced interfaces enabling modulation of behavior of living cells via tuning surface physicochemical properties are presented and studied. The state‐of‐art ultra‐low fouling surface‐grafted polymer brushes of zwitterionic poly(carboxybetaine acrylamide), nonionic poly(N‐(2‐hydroxypropyl)methacrylamide), and random copolymers of carboxybetaine methacrylamide (CBMAA) and HPMAA [p(CBMAA‐co‐HPMAA)] with tunable molar contents of CBMAA and HPMAA are employed. Using a model Huh7 cell line, a systematic study of surface wettability, swelling, and charge effects on the cell growth, shape, and cytoskeleton distribution is performed. This study reveals that ultra‐low fouling interfaces with a high content of zwitterionic moieties (>65 mol%) modulate cell behavior in a distinctly different way compared to coatings with a high content of nonionic HPMAA. These differences are attributed mostly to the surface hydration capabilities. The results demonstrate a high potential of carboxybetaine‐rich ultra‐low fouling surfaces with high hydration capabilities and minimum background signal interferences to create next‐generation bioresponsive interfaces for advanced studies of living objects.

Functionalizable Antifouling Coatings as Tunable Platforms for the Stress-Driven Manipulation of Living Cell Machinery

“…Hepatocytes are very sensitive cells [35][36][37], which makes them a good model system for mechanotransduction-signaling studies. Recently we showed that nonfunctionalized antifouling polymer brush coatings pCBAA, pCBMAA, pHPMAA, and their copolymers are not cytotoxic for Huh7 cells [31]. Here, we confirmed no cytotoxicity, even for activated and deactivated or RGD-functionalized pCB antifouling coatings.…”

“…However, even the RGD-functionalized homopolymer of 100% pCBMAA (functionalizable part of the copolymer brushes) did not reach the level of YAP colocalization induced by the control or the RGD-functionalized homopolymer of pCBAA ( Figure 3B). In our previous study, the sensitivity of cell growth and spreading on the surface swelling characteristics was noticed, causing the higher growth and cytoskeleton distribution of cells growing on the nonfunctionalized pCBAA compared to pCBMAA [31]. Such a phenomenon can explain the different responses of the cells on functionalized pCBAA (method A-1 in Figure 1) and pCBMAA (method B-1 in Figure 1) and opens new possibilities in the design of coatings for the even finer modulation of cell growth and cell-signaling pathways.…”

“…pCB brushes were prepared by surface-initiated atom transfer radical polymerization (SI-ATRP), as described elsewhere [31], and their structures were checked by infrared spectroscopy (data not shown). After polymerization, all coatings were stored in PBS.…”

“…A set of pCB brush coatings and OEG-based SAM coatings functionalized with variable concentrations of RGD peptides were prepared to investigate the effects of the RGD peptide-decorated antifouling background on mechanotransduction cell signaling. Based on our previous study [31], we used optimized biocompatible and highly hydratable antifouling pCB brush coatings with wet thicknesses around~80 nm (characterized by spectroscopic ellipsometry; data not shown). Two different approaches to the preparation of the coatings functionalized with varying RGD concentrations were employed as follows: first, only carboxy-functional coatings of pCBAA or SAM of HS-(CH 2 ) 11 -(EG) 6 -OCH 2 -COOH were RGD-functionalized using immobilization solutions of RGD peptides of different concentrations ( Figure 1A1,A2).…”

“…To define the level of mechanical stress, we monitored the colocalization of YAP in the cell nucleus. Two distinct types of state-of-art functionable antifouling coatings based on pCB zwitterionic brushes [29][30][31] were employed and compared. First, a set of RGD-functionalized homopolymers poly(carboxybetaine acrylamide) (pCBAA) was prepared by employing different concentrations of the RGD peptide during the immobilization.…”