Citation: Ghilan, A.; Nicu, R.; Ciolacu, D.E.; Ciolacu, F. Insight into the Latest Medical Applications of Nanocellulose. Materials 2023, 16, 4447. https://doi.org/10.3390/ ma16124447 Academic Editor: Alexey N. Pestryakov Received: 25 May 2023 Revised: 14 June 2023 Accepted: 15 June 2023 Published: 17 June 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/). materials Review Insight into the Latest Medical Applications of Nanocellulose Alina Ghilan 1 , Raluca Nicu 1 , Diana E. Ciolacu 1, * and Florin Ciolacu 2, * 1 Department of Natural Polymers, Bioactive and Biocompatible Materials, “Petru Poni” Institute of Macromolecular Chemistry, 700487 Iasi, Romania; diaconu.alina@icmpp.ro (A.G.); nicu.raluca@icmpp.ro (R.N.) 2 Department of Natural and Synthetic Polymers, “Gheorghe Asachi” Technical University of Iasi, 700050 Iasi, Romania * Correspondence: dciolacu@icmpp.ro (D.E.C.); fciolacu@tuiasi.ro (F.C.); Tel.: +40-332-880-220 (D.E.C.); +40-232-278-683 (ext. 2200) (F.C.) Abstract: Nanocelluloses (NCs) are appealing nanomaterials that have experienced rapid develop- ment in recent years, with great potential in the biomedical field. This trend aligns with the increasing demand for sustainable materials, which will contribute both to an improvement in wellbeing and an extension of human life, and with the demand to keep up with advances in medical technology. In recent years, due to the diversity of their physical and biological properties and the possibility of tuning them according to the desired goal, these nanomaterials represent a point of maximum interest in the medical field. Applications such as tissue engineering, drug delivery, wound dressing, medical implants or those in cardiovascular health are some of the applications in which NCs have been successfully used. This review presents insight into the latest medical applications of NCs, in the forms of cellulose nanocrystals (CNCs), cellulose nanofibers (CNFs) and bacterial nanocellulose (BNC), with an emphasis on the domains that have recently experienced remarkable growth, namely wound dressing, tissue engineering and drug delivery. In order to highlight only the most recent achievements, the presented information is focused on studies from the last 3 years. Approaches to the preparation of NCs are discussed either by top-down (chemical or mechanical degradation) or by bottom-up (biosynthesis) techniques, along with their morphological characterization and unique properties, such as mechanical and biological properties. Finally, the main challenges, limitations and future research directions of NCs are identified in a sustained effort to identify their effective use in biomedical fields. Keywords: nanocellulose; biological properties; tissue engineering; drug delivery; wound dressing 1. Introduction Nanocelluloses (NCs) represent a unique category of engineering materials made from cellulose and are considered one of the most promising green resources of today due to their particular properties [1]. NCs are attractive for a wide range of applications, including biomedical engineering (e.g., medical implants, wound healing, skin sensors) [2], smart packaging materials [3], environmental remediation (e.g., water and air filtration membranes, photocatalysis, flocculation) [4] or energy harvesting and storage (e.g., fuel cell membranes, stretchable and flexible electrodes) [5]. Widespread interest in NCs-based materials in medical applications has been centered on their availability, sustainability, low cost, biodegradability, biocompatibility, outstanding mechanical properties and low cytotoxicity [6]. Over the last ten years, the number of scientific publications related to NCs has increased significantly, but the most explosive growth was recorded in the last three years, namely between 2020 and 2022, when more than 50% of the publications were published. Regarding the term “nanocellulose”, searches in the Web of Science (WOS) online database core collection for the period 2020–2022 led to the finding of a total of 5018 publications, Materials 2023, 16, 4447. https://doi.org/10.3390/ma16124447 https://www.mdpi.com/journal/materials