Citation: Andreazza, R.; Morales, A.; Pieniz, S.; Labidi, J. Gelatin-Based Hydrogels: Potential Biomaterials for Remediation. Polymers 2023, 15, 1026. https://doi.org/10.3390/ polym15041026 Academic Editor: Alberto Romero García Received: 31 January 2023 Revised: 14 February 2023 Accepted: 15 February 2023 Published: 18 February 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). polymers Review Gelatin-Based Hydrogels: Potential Biomaterials for Remediation Robson Andreazza 1,2 , Amaia Morales 1 , Simone Pieniz 1,3 and Jalel Labidi 1, * 1 Chemical and Environmental Engineering Department, University of the Basque Country UPV/EHU, Plaza Europa 1, 20018 San Sebastian, Spain 2 Center of Engineering, Federal University of Pelotas, Gomes Carneiro 1, Pelotas 96010-610, Brazil 3 Nutrition Department, Federal University of Pelotas, Gomes Carneiro 1, Pelotas 96010-610, Brazil * Correspondence: jalel.labidi@ehu.es Abstract: Hydrogels have become one of the potential polymers used with great performance for many issues and can be promoted as biomaterials with highly innovative characteristics and different uses. Gelatin is obtained from collagen, a co-product of the meat industry. Thus, converting wastes such as cartilage, bones, and skins into gelatin would give them added value. Furthermore, biodegradability, non-toxicity, and easy cross-linking with other substances can promote polymers with high performance and low cost for many applications, turning them into sustainable products with high acceptance in society. Gelatin-based hydrogels have been shown to be useful for different applications with important and innovative characteristics. For instance, these hydrogels have been used for biomedical applications such as bone reconstruction or drug delivery. Furthermore, they have also shown substantial performance and important characteristics for remediation for removing pollutants from water, watercourse, and effluents. After its uses, gelatin-based hydrogels can easily biodegrade and, thus, can be sustainably used in the environment. In this study, gelatin was shown to be a potential polymer for hydrogel synthesis with highly renewable and sustainable characteristics and multiple uses. Keywords: hydrogel; gelatin; sustainability; remediation 1. Introduction Hydrogels are characterized as three-dimensional cross-linked polymeric networks that can be produced with the most variable compounds and with the most variable uses [1]. In the last decade, hydrogels have been used in many applications and with high technical and economic viability which include biomedical and environmental areas. Gelatin-based hydrogels are one kind of hydrogel in which gelatin is used as the cross- linked polymer and give the gel characteristics such as structure and texture. Many studies have promoted this kind of hydrogel for biomedical uses with promising and important characteristics such as tissue engineering [2,3] and/or drug delivery [4,5] with a high economic impact on society, medicine, and environmental purposes with high applicability. The market for gelatin in 2020 rose to about USD 3.18 billion and is further expected to reach USD 4.08 billion by 2024 as forecasted in the same report [6]. The market of gelatin in 2013 was the highest in the food and beverages sector (28%), followed by nutraceuticals (25.8%) and pharmaceuticals (21%), while their use in the cosmetic industry was only 5.5% [7]. Along with the advancements in drug delivery, it caused the development of new recipients as novel dosage forms to fulfill specific functions which directly or indirectly influence the extent and or rate of drug release. This enhances the development of new and modified recipient sources that continue to emerge for better drug delivery performance [8]. Several studies have shown the high potential of hydrogels as green and renewable materials, with highly efficient and promising uses [1,9]. Gelatin-based hydrogels have sev- eral advantages due to their biocompatibility, biodegradability, and nontoxic features [10]. Polymers 2023, 15, 1026. https://doi.org/10.3390/polym15041026 https://www.mdpi.com/journal/polymers