A Polymer Canvas with the Stiffness of the Bone Matrix to Study and Control Mesenchymal Stem Cell Response

Abstract

Reproducing in vitro the complex multiscale physical features of human tissues creates novel biomedical opportunities and fundamental understanding of cell−environment interfaces and interactions. While stiffness has been recognized as a key driver of cell behavior, systematic studies on the role of stiffness have been limited to values in the KPa−MPa range, significantly below the stiffness of bone. Here, a platform enabling the tuning of the stiffness of a biocompatible polymeric interface up to values characteristic of human bone is reported, which are in the GPa range, by using extremely thin polymer films on glass and cross‐linking the films using ultraviolet (UV) light irradiation. It is shown that a higher stiffness is related to better adhesion, proliferation, and osteogenic differentiation, and that it is possible to switch on/off cell attachment and growth by solely tuning the stiffness of the interface, without any surface chemistry or topography modification. Since the stiffness is tuned directly by UV irradiation, this platform is ideal for rapid and simple fabrication of stiffness patterns and gradients, thus representing an innovative tool for combinatorial studies of the synergistic effect of tissue environmental cues on cell behavior, and creates new opportunities for next‐generation biosensors, single‐cell patterning, and lab‐on‐a‐chip devices.

Transistors platform for rapid and parallel detection of multiple pathogens by nanoscale-localized multiplexed biological activation

“…Polymer synthesis 1b). More information are reported in [25][26][27][28][29]. The purity is determined via 1H nuclear magnetic resonance spectroscopy.…”

“…To implement a scalable strategy capable of locally functionalizing individual FETs at sub-100 nm resolution with desired bioreceptors (from antibodies to aptamers), and applicable to any channel material (e.g., graphene, oxides or silicon), we use thermal scanning probe lithography (tSPL) [23,24]. In our approach, tSPL uses a hot nanotip to expose amine groups with nanoscale resolution on a thermally sensitive biocompatible polymer resist [25][26][27][28][29], which is spin coated on a fully-fabricated array of FETs (see Fig. 1b).…”

“…The stack comprises a rst lm of about 70nm-thick polymethacrylate-carbamate-cinnamate copolymer (PMCC) [26][27][28], which provides amine groups on demand in designated FET regions upon local heating by tSPL. PMCC can be locally patterned through local heat-induced deprotection of amine groups from tetrahydropyranyl carbamates in the carbamate block of PMCC [25][26][27][28][29] (see Methods). The second lm is poly(phthalaldehyde) (PPA) [23,32] which serves as a top layer resist (10-20 nm thick) to reduce non-speci c binding outside the FET channel region (see Supplementary Note 1).…”