Electrospun poly(ε‐caprolactone) nanofiber shish kebabs mimic mineralized bony surface features

Abstract

Electrospinning of nanofiber is of growing interest especially in bone tissue engineering because of its similar fibrous properties to the extracellular matrix. To this end, we have fabricated polycaprolactone (PCL) nanofiber shish kebab (NFSK) templates. The novelty of this work is the ability to control the mineral orientation and spatial location on the nanofiber, mimicking natural collagen fibers. However, NFSK templates have properties that need to be investigated in terms of cellular response including fiber alignment and crystallization. In this study, MC3T3 E1 preosteoblast cells were seeded onto the templates to determine the effect of both fiber orientation and kebab size on the cell metabolic activity. PCL was electrospun to form aligned and randomly oriented nanofibers, which were then crystallized in a PCL solution in pentyl acetate for 15 and 60 min, resulting in the formation of homopolymer PCL NFSK templates. We evaluated the cell proliferation and alkaline phosphatase activity of MC3T3 E1 cells after 3, 7, and 14 days in coculture. Aligned nanofiber and polymer crystallization both significantly increased the cell proliferation and alkaline phosphatase activity at each time point. The aligned nanofibers and polymer crystallization resulted in the highest metabolic activities of the cells compared to the randomly oriented fibers and noncrystallized controls.

How Fiber Surface Topography Affects Interactions between Cells and Electrospun Scaffolds: A Systematic Review

“…The justification for the exclusions is listed in Supplementary Information File S1 . Twenty-six full-text articles were selected [ 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 ]. It is worth noting that, at this point, it became apparent that cell viability was often measured in these studies, and it was added as an outcome.…”

MC3T3 E1 cell response to mineralized nanofiber shish kebab structures

“…The surface roughness of the NFSK templates can be further investigated via varying the kebab size and periodicity. An increase in surface roughness of kebab period from 1 to 2 μm have been shown to increase osteoblast cell proliferation and ALP activity 8,25,32 . It was hypothesized that the increased surface roughness allows for more and better cellular attachment and stability, which promotes higher ALP activity 33 .…”

“…PCL (average molar mass M n = 80,000 Da, Sigma Aldrich) nanofibers were electrospun onto a sheet of aluminum foil using a collecting drum, as previously described 8 . Briefly, a 12% w/v PCL solution in trifluoroethanol was prepared and extruded from a syringe at rate of 0.25 ml/hr and a voltage of 13 kV.…”

“…This structure was developed following classical shish kebab crystallization during polymer processing and the recently discovered nanohybrid shish kebabs in carbon nanotube‐based polymer nanocomposites 6,7 . We have previously shown that homopolymer polycaprolactone (PCL) NFSK templates were cytocompatible with MC3T3 E1 preosteoblast cells by evaluating the ALP activity and cell proliferation in vitro 8 . The formation of the kebabs not only provided a microenvironment to promote cell proliferation, but also significantly promoted ALP activity.…”

Polymer crystallization at liquid‐liquid interface

“…Crystallization from solution was originally investigated to produce polymer single crystals (PSC), which served as a new clean platform to understand polymer crystallization habit (such as chain folding) as well as providing a model system for determining polymer crystal structures, and elucidating detailed crystalline morphologies . Most recent developments are on how to utilize the unique polymer single crystals as nanomaterials for applications such as nanoparticle assembly and synthesis, artificial nanomotor, catalysis support, Surface enhanced Raman spectroscopy, tissue engineering, surface coating, ultrathin actuator, and polymer brush synthesis . Another interesting direction that has gradually appeared is crystallization driven self‐assembly, where crystalline block copolymers (BCPs) are typically used, and crystallization is employed as the main driving force to induce/tune self‐assembled nanostructures .…”