*Article* **Sodium Alginate/Chitosan Scaffolds for Cardiac Tissue Engineering: The Influence of Its Three-Dimensional Material Preparation and the Use of Gold Nanoparticles**

**Nohra E. Beltran-Vargas 1,\* , Eduardo Peña-Mercado <sup>1</sup> , Concepción Sánchez-Gómez 2,† , Mario Garcia-Lorenzana <sup>3</sup> , Juan-Carlos Ruiz <sup>1</sup> , Izlia Arroyo-Maya <sup>1</sup> , Sara Huerta-Yepez <sup>4</sup> and José Campos-Terán 1,\***


**Abstract:** Natural biopolymer scaffolds and conductive nanomaterials have been widely used in cardiac tissue engineering; however, there are still challenges in the scaffold fabrication, which include enhancing nutrient delivery, biocompatibility and properties that favor the growth, maturation and functionality of the generated tissue for therapeutic application. In the present work, different scaffolds prepared with sodium alginate and chitosan (alginate/chitosan) were fabricated with and without the addition of metal nanoparticles and how their fabrication affects cardiomyocyte growth was evaluated. The scaffolds (hydrogels) were dried by freeze drying using calcium gluconate as a crosslinking agent, and two types of metal nanoparticles were incorporated, gold (AuNp) and gold plus sodium alginate (AuNp+Alg). A physicochemical characterization of the scaffolds was carried out by swelling, degradation, permeability and infrared spectroscopy studies. The results show that the scaffolds obtained were highly porous (>90%) and hydrophilic, with swelling percentages of around 3000% and permeability of the order of 1 <sup>×</sup> <sup>10</sup>−<sup>8</sup> <sup>m</sup><sup>2</sup> . In addition, the scaffolds proposed favored adhesion and spheroid formation, with cardiac markers expression such as tropomyosin, troponin I and cardiac myosin. The incorporation of AuNp+Alg increased cardiac protein expression and cell proliferation, thus demonstrating their potential use in cardiac tissue engineering.

**Keywords:** alginate; chitosan; scaffolds; nanoparticles; cardiac tissue engineering
