Contents lists available at ScienceDirect Journal of Drug Delivery Science and Technology journal homepage: www.elsevier.com/locate/jddst The Effect of Process Parameters on Alignment of Tubular Electrospun Nanofibers for Tissue Regeneration Purposes Rossella Dorati 1,5 , Enrica Chiesa 1 , Silvia Pisani 2 , Ida Genta 1,5 , Tiziana Modena 1,5 , Giovanna Bruni 3 , Chiara R.M. Brambilla 1 , Marco Benazzo 4 , Bice Conti 1,5,∗ 1 Department of Drug Sciences and, University pf Pavia, V.le Taramelli 12/14, 27100, Pavia, Italy 2 Department of Paediatric Oncoaematology IRCCS Policlinico S.Matteo, Pavia, P.zzle Golgi 1, 27100, Pavia, Italy 3 Department of Chemistry, University pf Pavia, V.le Taramelli 12/14, 27100, Pavia, Italy 4 Department of Otholaryngology Head Neck Surgery, University of Pavia and IRCCS Policlinico S.Matteo, P.zzle Golgi 1, 27100, Pavia, Italy 5 Polymerix srl, V.le Taramelli 20, 27100, Pavia, Italy ARTICLEINFO Keywords: Electrospinning Nanofibers Theory Design of experiments Polylactide-co-Poly-ε-caprolactone ABSTRACT Electrospinning is known to be an effective and straightforward technique to fabricate polymer non woven matrices made of nano and microfibers. Micro patterned morphology of electrospun matrices results to be outmost advantageous in the biomedical field, since it is able to mimic extracellular matrix (ECM), and favors cell adhesion and proliferation. Controlling electrospun fibers alignment is crucial for the regenerative purposes of certain tissues, such as neuronal and vascular. In this study we investigated the impact of electrospinning process parameters on fiber alignment in tubular nanofibrous matrices made of Poly (L-lactide-co-ε-capro- lactone) (PLA-PCL); a Design of Experiments (DoE) approach is here proposed in order to statistically set up the process parameters. The DoE was studied keeping constants the previously set material and environmental parameters; voltage, flow rate and mandrel rotating speed were the process parameters here investigated as variables.OrientationanalysiswasbasedonImageJandpluginOrientationJanalysisofSEMimages.Theresults show that voltage combined with flow rate has significant impact on electrospun fiber orientation, and the greatest orientation is achieved when all the three input parameters (voltage, flow rate and mandrel rotation speed) are at their maximum value. 1. Introduction Electrospinning is known to be an effective and straightforward technique to fabricate polymer non woven matrices made of nano and microfibers. The technique is based on interfacial phenomena rising when an electric field is applied to a polymer solution. The electric field generates a charge in the polymer solution, and when the electric force overcomes the solution surface tension, a polymeric jet, making a ty- pical Taylor cone, is generated from the surface tension and travels towards the collector [1,2]. Viscosity of the polymer solution and its surface tension are interconnected in the process, since high viscosity stabilizes the forming fiber, while low surface tension promotes its stretching. Electrospun nanofibrous matrix forms due to deposition of entangled polymer fibers on the collector; polymer solvent evaporation is provided along jet pathway between needle and collector. Electrospinning technique has been applied to several fields such as filtration, electronic and photonic technology [3–6], and it has drawn particular attention in the biomedical area of tissue engineering be- cause the electrospun matrices, made of suitable biodegradable and biocompatible polymers, can be seeded with cells and act as scaffold for tissue regeneration [7–12]. An important advantage of the electrospun matrices is their micro patterned morphology that mimics extracellular matrix (ECM), thus favouring cell adhesion and proliferation. It has been demonstrated in the literature that aligned nanofibers are able to orient cells in the specific direction needed to provide the anisotropy encountered in certain organs including blood vessels, muscular tunic of esophagus, urethra, and in general of any hollow organ or tubular structure, and in tissues such as neuronal tissue [13–18]. Thus, the electrospinning parameters should be profitably adjusted in order to control diameter, alignment of fibers, meanwhile keeping suitable spinnable regimen of the polymer solution. These parameters can be classified as follows: i) process parameters (electric field, polymer solution flow rate, syringe needle gauge, man- drel rotating speed), ii) material parameters (polymer solution https://doi.org/10.1016/j.jddst.2020.101781 Received 18 March 2020; Received in revised form 26 April 2020; Accepted 26 April 2020 ∗ Corresponding author.Department of Drug Sciences and, University pf Pavia, V.le Taramelli 12/14, 27100, Pavia, Italy. E-mail address: bice.conti@unipv.it (B. Conti). Journal of Drug Delivery Science and Technology 58 (2020) 101781 Available online 18 May 2020 1773-2247/ © 2020 Elsevier B.V. All rights reserved. T