Direct Surface Modification of Polycaprolactone-Based Shape Memory Materials to Introduce Positive Charge Aiming to Enhance Cell Affinity.

Takafumi Zako,Toru Hoshi,Takao Aoyagi,Shoko Matsushita

doi:10.3390/ma14195797

Abstract

In this study, the introduction of a positive charge on the surface of a shape memory material was investigated to enhance cell affinity. To achieve this, the direct chemical modification of a material surface was proposed. Sheet-type, crosslinked poly(caprolactone-co-α-bromo-ɤ-butyrolactone) (poly(CL-co-BrBL)) were prepared, and the direct reaction of amino compounds with bromo groups was conducted on the material surface with a positive charge. Branched poly(CL-co-BrBL) was prepared, followed by the introduction of methacryloyl groups to each chain end. Using the branched macromonomers, stable and sheet-type materials were derived through UV-light irradiation. Then, the materials were soaked in an amino compound solution to react with the bromo groups under various conditions. Differential scanning calorimetry and surface analysis of the modified materials indicated that 10 vol% of N, N-dimethylethylenediamine in n-hexane and 1 h soaking time were optimal to maintain the inherent thermal properties. The achievement of increased luminance and a positive zeta potential proved that the direct modification method effectively introduced the positive charge only on the surface, thereby enhancing cell affinity.

Highlights

Mechanobiology has gained considerable attention in the biomaterial research field [1,2,3,4,5,6], because it allows clarification of the relationship between cell functions and mechanical properties
It has been reported that extrinsic factors such as growth environment influences stem cell functions such as differentiation and proliferation in vivo [7]
Previous research has shown that three main factors of scaffold surfaces affect cell functions, namely, chemical, mechanical, and topographical factors [8]

Summary

Introduction

Mechanobiology has gained considerable attention in the biomaterial research field [1,2,3,4,5,6], because it allows clarification of the relationship between cell functions and mechanical properties. By implementing polymer design that improves the affinity of cells to the material surface, the introduction of a positive charge on the PCL surface allowed the enhancement of cell affinity. We intended to introduce a positive charge only to the surface of the film by soaking the film in an amine solution Such direct surface modification would be advantageous because it can be functionalized without influencing bulk properties. To achieve the research objectives, the actual studies consist of (a) copolymer synthesis and its characterization, (b) film preparation and its shape memory property, (c) investigation of optimal condition for introduction of amine groups and confirmation of maintenance of bulk properties, (d) characterization of the positively-charged surface, and (e) preliminary test for cell affinity

Materials and Methods

Characterization

Results and Discussion