Polymer nanofiber based materials have been widely investigated for use as tissue engineering scaffolds. While promising, these materials are typically fabricated through techniques that require significant time or cost. Here we report a rapid and cost effective air-brushing method for fabricating nanofiber scaffolds using a simple handheld apparatus, compressed air, and a polymer solution. Air-brushing also facilities control over the scaffold degradation rate without adversely impacting architecture. This was accomplished through a one step blending process of high ( M _w ≈ 100 000 g mol ⁻¹ ) and low ( M _w ≈ 25 000 g mol ⁻¹ ) molecular weight poly(DL-lactide) (PDLLA) polymers at various ratios (100:0, 70:30 and 50:50). Through this approach, we were able to control fiber scaffold degradation rate while maintaining similar fiber morphology, scaffold porosity, and bulk mechanical properties across all of the tested compositions. The impact of altered degradation rates was biologically evaluated in human bone marrow stromal cell (hBMSC) cultures for up to 16 days and demonstrated degradation rate dependence of both total DNA concentration and gene regulation.

Delivering multipotent stem cells in adequate milieu directly to site of injury is important for successful tissue regeneration. Accelerated wound healing has been reported in recent publications when large area wounds were treated with sprayed cells. However, little is known about the basic physics of cell spraying in hydrogel free medium, causes of concomitant cell damage, and whether it can be applied for craniofacial tissue regeneration. To answer some of these questions, a simple co-axial CO ₂ gas operated brush (g-brush) was used to deliver human bone marrow stromal (hBMSC) and mouse gingival fibroblast (ESK-1) cells at low gas flow rates and in a small volume of medium. Live/dead, metabolic activity (MTS-1) and total DNA quantification assays were utilized to evaluate cell cultures after g-brush and typical pipette deposition. Viable hBMSC and ESK-1 cells were uniformly delivered at higher cell concentrations (≥60 000), in a short period of time (15 and 9 s), and in a small fluid volume (0.25 ml). Significantly, after the hBMSC were g-brushed and cultured up to 21 d, the cell multipotency was found to be preserved and comparable to the pipetted cells. Fluid dynamic calculations highlighted importance of low interfacial shear stress (<35 Pa) and gas velocity (<160 m s ⁻¹ ) in delivering concentrated, viable cells. Results of this research support applicability of the g-brushing technique for the quick, large number delivery of viable cells for tissue regeneration applications.