Table 1.

CS-EOs NPs characteristics and potential applications.

Characteristics of CS used	EOs loaded into CS NPs	NPs size (nm)	NPs polydispersity index	NPs zeta potential (mV)	Methods used	Functionality	Type of study	Medical or veterinary applications	References
Medium molecular weight (mw) chitosan	Mint (Mentha piperita), Thyme (Thymus vulgaris), Cinnamon (Cinnamomum verum)	40–100	Not reported	Not reported	Ionic gelation	Nanoencapsulation improves body weight gain, feed conversion ratio and feed intake on broiler chickens	In vitro and in vivo	A suitable alternative to synthetic antibiotic growth promoter used as in-feed in poultry production thanks to antibacterial activity against pathogenic bacteria (Escherichia coli), while preserving the bacteria of the intestinal flora, such as Lactobacillus spp.	(Nouri, 2019)
Medium mw chitosan, 75–85% degree of deacetylation	Cardamom (Elettaria cardamomum)	50–100	Not reported	> +50	Ionic gelation	Encapsulation efficiency of more than 90%. Long term stability. Extension of antimicrobial potential up to 7 days compared to 2 days with CSNPs alone	In vitro	Antimicrobial potential against extended-spectrum β-lactamase producing Escherichia coli and methicillin-resistant Staphylococcus aureus	(Jamil et al., 2016)
Medium mw chitosan	Homalomena pineodora	70	0.176	> +24	Ionic gelation	High encapsulation efficiency and loading capacity. Initial burst release followed by a slower release, up to complete release at 72 h. Release profile controlled by the first order kinetic model. Concentration-dependent killing behavior on time–kill assay	In vitro	Antimicrobial activity broad-spectrum against diabetic wound pathogens: Bacillus cereus, Bacillus subtilis, Staphylococcus aureus, and methicillin-resistant Staphylococcus aureus (Gram+). Escherichia coli, Proteus mirabilis, Yersinia spp., Klebsiella pneumoniae, Shigella boydii, Salmonella typhimurium, Acinetobacter anitratus and Pseudomonas aeruginosa (Gram-)	(Rozman et al., 2020)
Not reported	Garlic (Allium sativum)	Not reported	Not reported	Not reported	Ionic gelation	Nanoencapsulation improves body weight gain, feed conversion ratio and feed intake on broiler chickens	In vitro and in vivo	A suitable alternative to synthetic antibiotic growth promoter used as in-feed in broiler production thanks to antibacterial activity against Escherichia coli	(Amiri et al., 2020)
Medium mw chitosan (684 kDa), Roughly 85 % degree of deacetylation	Cinnamon (Cinnamomum zeylanicum)	100–200	<1	> +38	Ionic gelation	Initial burst release in the first 9 days, followed by a slow release. Release faster at low pH. Release profile follows a Fickian behavior	In vitro	Antibacterial activity against Escherichia coli, Erwinia carotovora, and Pseudomonas fluorescens (Gram-)	(Mohammadi et al., 2020)
Medium mw chitosan	Thyme (Thymus vulgaris)	30–100	Not reported	Not reported	Ionotropic gelation	Nanoencapsulation improves body weight gain and feed conversion ratio on broiler chickens. Initial burst release (97%) in the first 96 hours, followed by a slower release	In vitro and in vivo	A suitable alternative to synthetic antibiotic growth promoter used as in-feed in poultry production thanks to antibacterial activity against pathogenic bacteria (coliforms, aerobes), while preserving the bacteria of the intestinal flora, such as Lactobacillus spp.	(Hosseini and Meimandipour, 2018)
Medium mw chitosan 75–85% degree of deacetylation	Rosemary (Rosmarinus officinalis) Oregano (Origanum vulgare subsp. hirtum) Lavender (Lavandula angustifolia) Marine criste (Crithmum maritimum) White fir (Abies alba) Wild chamomile (Matricaria chamomilla) Pennyroyal (Mentha pulegium) Sage (Salvia officinalis) Anise (Pimpinella anisum)	250–300 and 500–600	Not reported	Not reported	Ionotropic gelation	Initial burst release followed by a slower release reaching a plateau	In vitro	Antibacterial activity against Staphylococcus aureus, Bacillus subtilis, Bacillus cereus (Gram+) and Escherichia coli, Xanthomonas campestris (Gram)	(Halevas et al., 2017)
Medium mw chitosan, 84.8% degree of dealkylation	Peppermint (Mentha piperita) Green Tea (Camellia sinensis)	20–60	Not reported	+20–+23and +24–+29	Emulsification/ionic gelation	Thermal stability of EOs-CS NPs reaching 350 °C. Initial burst release in the first 12 h, followed by a slower release up to 72 h. Release faster at low pH. Release profile follows a Fickian behavior	In vitro	Antibacterial activity against Staphyloccocus aureus (Gram+) and Escherichia coli (Gram-)	(Shetta et al., 2019)
Low mw chitosan (50–190 kDa), 80% degree of deacetylation	Nettle (Urtica dioica L)	208–369	0.153–0.412	+14–+30	Emulsion-ionic gelation in two stages: oil-in-water emulsification and then, ionic gelation	Not reported	Not reported	Antibacterial activity against Staphylococcus aureus, Bacillus cereus, Listeria monocytogenes (Gram+) and Escherichia coli, Salmonella typhi (Gram-)	(Bagheri et al., 2021)
Low mw chitosan (50–190 kDa), 75–85 % degree of deacetylation	Clove (Eugenia caryophyllata)	223–445	0.117–0.337	+10–+34	Emulsion-ionic gelation in two stages: oil-in-water emulsification and then, ionic gelation	Not reported	In vitro	Antibacterial activity against Staphylococcus aureus, Listeria monocytogenes (Gram+) and Escherichia coli, Salmonella typhi (Gram-)	(Hadidi et al., 2020)
Medium mw chitosan 75–85% degree of deacetylation	Oregano (Origanum vulgare)	282–402	Not reported	Not reported	Oil-in-water emulsion and ionic gelation	Initial burst release followed by a slower release	In vitro	Not reported	(Hosseini et al., 2013)
Medium mw chitosan 75–85% degree of deacetylation	Ajwain (Carum copticum)	236–721	Not reported	Not reported	Emulsion-ionic gelation	Initial burst effect for the first 24 h, followed by a steady release for 72 h, before decreasing and reaching a plateau. Release faster at low pH	In vitro	Antibacterial activity against Staphylococcus aureus, Staphylococcus epidermidis, Bacillus cereus (Gram+) and Escherichia coli, Salmonella typhimurium, Proteus vulgaris (Gram-)	(Esmaeili and Asgari 2015)
Medium mw chitosan 75–85% degree of deacetylation	Thyme (Thymus vulgaris)	6	Not reported	Not reported	Nanoprecipitation	Release time between 360 and 390 min	In vitro	Antibacterial activity against Staphylococcus aureus, Bacillus cereus, Listeria monocytogenes (Gram+) and Escherichia coli, Salmonella typhi, Shigella dysenteriae (Gram-)	(Sotelo-Boyás et al., 2017)