Polyhedral Oligomeric Silsesquioxane as a Polarity Mediator and Reinforced Nanofiller for Fabricating Robust and Hierarchical Porous Film for Cell Bioengineering

Abstract

A hierarchical porous polymer film that can provide a balance of mechanical properties and specific surface areas and sustain cell functions has become a major target for material scientists and bioengineers in the past decade. However, the limited availability of materials that exhibit high mechanical performance and easily form hierarchical porous structures hinder the progress in practical application. Here, we show the design of a polyhedral oligomeric silsesquioxane (POSS) hybrid polymer by incorporating a bi-functional glycidyl-propyl POSS (G-POSS) into the epoxy polymer backbone, in which POSS functions as both a nanofiller to reinforce the mechanical performance and as the polarity mediator to induce self-assembly of the polymer chains into a three-dimensional (3D) connected porous structure. Nanoindentation shows that the incorporation of POSS leads to a 25 and 36% increase in modulus and hardness, respectively. Scanning electron microscopy results show that POSS helps tune the hydrophobicity of the polymer and assists in the interface assembly, allowing easy formation of a densely packed two-dimensional or 3D hierarchical porous structure. Culture of mouse embryonic fibroblast cells demonstrates that the hybrid polymer scaffold provides prominent advantages ranging from enhanced cell adhesion to proliferation. Particularly, the 3D hierarchical porous film allows good nutrient supply and cell communication, which better mimics the in vivo microenvironment with less cell morphology change during cell proliferation. Hence, the successful integration of high material strength and easy formation of an interconnected porous structure shows that POSS hybrid polymers have strong potential for applications in the fabrication of cell culture platforms and future translation in tissue repair and regeneration.

A Brief Review on Selected Applications of Hybrid Materials Based on Functionalized Cage-like Silsesquioxanes

“…Double-decker silsesquioxanes can also be used as polarity mediators to obtain hierarchical porous films for bioengineering [ 52 ]. Using DDSQs allows for a balance between cell functions, specific surface area, and mechanical properties of the resulting biomaterial.…”

“… The idea of synthesizing linear double-decker silsesquioxane hybrids P0, P10, P25, and P50 and customized apparatus for hierarchical porous film fabrication [Reprinted with permission from Ref. [ 52 ]. Copyright 2023 American Chemical Society].…”

POSS Engineering of Multifunctional Nanoplatforms for Chemo-Mild Photothermal Synergistic Therapy

“…A typical POSS molecule possesses a three-dimensional cage-like structure consisting of a cubic silica core and eight surrounding organic corner groups. These corner groups can be readily modified into various functional groups, facilitating the convenient preparation of multifunctional polymers with POSS cores [47][48][49]. Moreover, due to the nanoscale size of POSS, diverse types of functional POSS-based nanoplatforms can be constructed.…”

Nanosheets Based on Hard 2-Ureido-4[1H]-pyrimidone Units and Soft Cyclosiloxane Units as Membrane Materials

“…For this study, a cyclosiloxane–UPy hybrid supramolecule was synthesized from “soft” cyclosiloxane and “hard” UPy segments to explore its unique self-assembly structures on a nanometer scale driven by the incompatibility of the two components, providing the driving force for microphase separation. Eight-membered heptamethyl cyclotetrasiloxane (HMCS) having one Si–H reactive site was used to perform a hydrosilylation reaction to obtain low-molecular-weight siloxane–UPy hybrid materials, which combine benefits of organic and inorganic materials and which provides a large area of 2D materials by easy spin coating with great accessibility …”

“…Eightmembered heptamethyl cyclotetrasiloxane (HMCS) having one Si−H reactive site was used to perform a hydrosilylation reaction to obtain low-molecular-weight siloxane−UPy hybrid materials, which combine benefits of organic and inorganic materials and which provides a large area of 2D materials by easy spin coating with great accessibility. 33 ■ EXPERIMENTAL SECTION Materials. The reactants 2-ureido-4-pyrimidone (UPy), allylamine, 2-nitrobenzyl chloride, and trichloro-n-octylsilane were purchased from Tokyo Chemical Industry Co., Ltd. 1,6-Diisocyanatohexane and platinum (0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex solution in xylene, Pt ∼2% (Karstedt's catalyst) were purchased from Sigma-Aldrich Corp. Heptamethyl cyclotetrasiloxane (HMCS) was purchased from Gelest Inc. Anhydrous chloroform, dichloromethane, and N,N-dimethylformamide (for organic synthesis) were purchased from Fujifilm Wako Pure Chemical Corp.…”