Citation: Pak, A.M.; Maiorova, E.A.; Siaglova, E.D.; Aliev, T.M.; Strukova, E.N.; Kireynov, A.V.; Piryazev, A.A.; Novikov, V.V. MIL-100(Fe)-Based Composite Films for Food Packaging. Nanomaterials 2023, 13, 1714. https:// doi.org/10.3390/nano13111714 Academic Editors: Teresa Cuberes and Girish M. Joshi Received: 6 May 2023 Revised: 17 May 2023 Accepted: 22 May 2023 Published: 23 May 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/). nanomaterials Article MIL-100(Fe)-Based Composite Films for Food Packaging Alexandra M. Pak 1,2 , Elena A. Maiorova 1,2 , Elizaveta D. Siaglova 1,2 , Teimur M. Aliev 1 , Elena N. Strukova 3 , Aleksey V. Kireynov 4 , Alexey A. Piryazev 5 and Valentin V. Novikov 2,4, * 1 Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilova Str. 28, 119991 Moscow, Russia 2 Moscow Institute of Physics and Technology, National Research University, Institutskiy per. 9, 141700 Dolgoprudny, Russia 3 Gause Institute of New Antibiotics, Russian Academy of Sciences, B. Pirogovskaya Str. 11/1, 119021 Moscow, Russia 4 Scientific and Educational Center “Composites of Russia”, Bauman Moscow State Technical University, 2nd Baumanskaya Str. 5, 105005 Moscow, Russia 5 Research Center for Genetics and Life Sciences, Scientific Direction Biomaterials, Sirius University of Science and Technology, 1 Olympic Ave, 354340 Sochi, Russia * Correspondence: novikov84@gmail.com Abstract: A biocompatible metal–organic framework MIL-100(Fe) loaded with the active compounds of tea tree essential oil was used to produce composite films based on κ-carrageenan and hydrox- ypropyl methylcellulose with the uniform distribution of the particles of this filler. The composite films featured great UV-blocking properties, good water vapor permeability, and modest antibac- terial activity against both Gram-negative and Gram-positive bacteria. The use of metal–organic frameworks as containers of hydrophobic molecules of natural active compounds makes the com- posites made from naturally occurring hydrocolloids attractive materials for active packaging of food products. Keywords: biocompatible metal–organic frameworks; active food packaging; hydrocolloids; composite materials 1. Introduction Materials for active food packaging are among the most trending research topics in the food industry [1]. Increasing the shelf life of food products [2] by inhibiting food spoilage through direct or indirect interactions with the active agents in the packaging, these composite materials are sought to solve global environmental problems, such as plastic and food waste [3]. The sustainability of their production from renewable resources, often waste [4], is crucial in the era of the depletion of natural resources, especially fossil fuels [5]. The sustainability and biocompatibility of such materials motivated the researchers to consider natural compounds both as matrices and active agents in active food pack- aging. The focus of this research is the materials produced from natural hydrocol- loids, polysaccharide-, and protein-based water-soluble polymers able to form strong three-dimensional networks in aqueous solutions. They include starch [6], cellulose derivatives [7], chitosan [8], carrageenans [9], and others [10–13] that feature high bio- compatibility [14], biodegradability [15], availability and variability [16], and good barrier properties [17]. However, the low affinity of hydrocolloids to hydrophobic molecules of most natural active compounds, such as plant essential oils (EOs) [18], hinders their industrial use in active food packaging. Of the popular active agents in functional food packaging, EOs are complex mixtures of bioactive molecules that often act in synergy and are hard to isolate [19]. Tea tree essential oil (TTO) from Melaleuca alternifolia, which contains monoterpenes, sesquiterpenes, and their alcohol derivatives [20], is known for its antimicrobial and antioxidant properties that Nanomaterials 2023, 13, 1714. https://doi.org/10.3390/nano13111714 https://www.mdpi.com/journal/nanomaterials