Engineered Nanotopography on Electrospun PLLA Microfibers Modifies RAW 264.7 Cell Response

Abstract

In this study, we created a new method of electrospinning capable of controlling the surface structure of individual fibers (fiber nanotopography). The nanotopographical features were created by a phase separation in the fibers as they formed. To control the phase separation, a nonsolvent (a chemical insoluble with the polymer) was added to an electrospinning solution containing poly-l-lactic acid (PLLA) and chloroform. The nanotopography of electrospun fibers in the PLLA/chloroform solution was smooth. However, adding a small weight (<2% of total solution) of a single nonsolvent (water, ethanol, or dimethyl sulfoxide) generated nanoscale depressions on the surface of the fibers unique to the nonsolvent added. Additionally, nanoscale depressions on electrospun fibers were observed to change with dimethyl sulfoxide (DMSO) concentration in the PLLA/chloroform solution. A nonlinear relationship was found between the concentration of DMSO and the number and size of nanotopographical features. The surface depressions did not alter the hydrophobicity of the scaffold or degradation of the scaffold over a two-day period. To determine if fiber nanotopography altered cell behavior, macrophages (RAW 264.7 cells) were cultured on fibers with a smooth nanotopography or fibers with nanoscale depressions. RAW 264.7 cells spread less on fibers with nanoscale depressions than fibers with a smooth topography (p<0.05), but there were no differences between groups with regard to cell metabolism or the number of adherent cells. The results of this study demonstrate the necessity to consider the nanotopography of individual fibers as these features may affect cellular behavior. More importantly, we demonstrate a versatile method of controlling electrospun fiber nanotopography.

Fabrication of aligned, porous and conductive fibers and their effects on cell adhesion and guidance

“…However, there were no pores in Fig. 1a, because high proportional solvent inhibited phase separation during the electrospinning [26]. For further investigation, the fibers in Fig.…”

Overcoming foreign-body reaction through nanotopography: Biocompatibility and immunoisolation properties of a nanofibrous membrane

“…Previously, it was shown that macrophage activation could be modulated by the topographical characteristics of biomaterials [15,16,28e30]. Some studies found nanofibers minimized the secretion of pro-inflammatory cytokines [15] while some showed cell-invasive microfibrous materials favored M2 phenotype and angiogenesis [16,29,30]. However, these studies were conducted in vitro for a relatively short period of time and the long-term effects of biomaterial architecture on FBR are unclear.…”

Electrospun Fibers for Drug Delivery after Spinal Cord Injury and the Effects of Drug Incorporation on Fiber Properties

“…The distance between the needle and the rotating collector (22cm in diameter) was fixed at 5.5 cm, the voltage was held constant at 20 kV, and the humidity was maintained between 30% and 40%. Recently, the electrospinning apparatus was further optimized to control the humidity within 1–2% because uncontrolled humidity can place surface nanotopography onto the fibers which may influence cell behavior [Schaub et al, 2013]. …”