# Poly(lactic acid)-Based Electrospun Fibrous Structures for Biomedical Applications
## 1 Introduction  
Poly(lactic acid) or polylactide (PLA) is a synthetic biopolymer that is widely used in the biomedical field. PLA can be derived from natural raw materials, such as sugar can, rice, and corn starch. It is produced via condensation polymerization or ring-opening polymerization of the lactic acid. PLA has been approved by the Food and Drug Administration (FDA) for human usage in diverse applications, such as implantable medical devices, drug delivery carriers, and tissue regeneration scaffolds. PLA involves three isomeric forms of Poly(D-lactide) (PDLA), Poly(L-lactide) (PLLA), and racemic poly(DL-lactide) (PDLLA) [1, 2, 3, 4, 5]. PLA is a biodegradable, bioassay, and biocompatible thermoplastic aliphatic polyester with good thermal and mechanical performance. These characteristics, including non-toxicity for humans, make it an ideal material for bioengineering applications [6, 7, 8, 9, 3]. In some applications, such as medical implants, targeted drug delivery, and tissue engineering scaffolds, stereocomplex PLA (Sc-PLA) has gained great attention. Sc-PLA can be formed by the strong interaction created by the side-by-side order of the molecular chains of enantiomeric PLA polymers, such as PDLA and PLLA. The creation of stereocompleximproves the mechanical performance, thermal, and hydrolysis resistance of the PLA-based materials [10; 11; 12]. Recently, producing PLA-based nanofibrous structures through the electrospinninghning technique has received growing attention [13]. Electrospinning is an efficient procedure to fabricate ultrafine fibers with unique features. This method is established based on the electrostatic drawing of the polymeric jet. A droplet of a polymer solution or melt is stretched under a strong electrical field to fine fibers, which deposit on a collector to generate a desired structure. Due to flexibility and the possibility of selecting the materials and altering the ultimate features, the electrospinninghning method has been widely applied to develop biomedical devices [9; 14; 15]. PLA nanofibers with distinguished features, such as similarity to the extracellular matrix (ECM), large specific surface area and high porosity with small pore size and appropriate mechanical properties, have recently found advanced applications in the medical area. The morphological, physical, mechanical, and biological characteristics of the PLA-based nanofibrous structures for specified applications can be tuned by altering the solution features, process variables, and controlling the methods of electrospinninghning. Electrospun nanofibrous structures based on PLA have been extensively investigated as sutures [8; 16; 17], artificial blood vessels [18; 19], wound dressings [7; 20; 21; 22], tissue engineering scaffolds [23; 24; 25], and drug delivery carriers [2; 8; 13; 26; 27]. Highlighting and explaining the recent progress in electrospinninghning of PLA-based structures, with a focus on their applications in the biomedical field, are the intention of this review (Figure 1). In the biomedical field, the optimization of polymer-based systems for diverse applications is an interesting issue. This review emphasizes the promising strategies used to optimize the electrospun PLA nanofibrous structures for designing the specified medical devices with appropriate physical, mechanical, and biological functions. Firstly, the fundamental concepts about PLA, with emphasis on specific needs and unique properties for biomedical applications, are presented; further, the electrospinninghning procedure, advantages of electrospun PLA nanofibers for medical use, and the relevance of the electrospinninghning parameters and efficiency of the designed structure are considered. Engineering of the PLA-based nanofibrous structures for biomedical applications by considering the different methods of electrospinninghning, controlling the morphology, architecture, and structure of the nanofiber deposits is another issue that is intended in this review.