. 2022 Nov 10;12(22):3964. doi: 10.3390/nano12223964

Table 1.

Biopolymers used as nanoparticulate materials in agriculture and other fields: sources, structure, characteristics, and uses.

Biopolymer	Source	Structure	Characteristics	References
Galactomannan	Extracted from the endosperm of leguminous seeds	Composed of a linear chain of β-1, 4-D-mannopyranose to which α-1,6-D-galactopyranose units are attached.	Used as films/coatings, gel agents, emulsion stabilizers, and thickeners.	[37,51]
Chitosan	The deacetylation of chitin (found in crustaceans and fungi)	Deacetylated chitin, a linear polysaccharide of deacetylated beta-1, 4-D-glucosamine. Chemical name: (1,4)-2-Amino-2-deoxy- Beta-D-glucan. Functional groups: CH₂OH, O, OH, NH₂.	Biocompatible, biodegradable, non-toxic, polyoxysalt formation, film-forming ability, adsorption properties; used in agriculture, food, pharma, and health sectors.	[41,52]
Tamarind seed polysaccharide	From the seed of the Indian date, tamarind (Tamarind indica L.)	The monomer of three main sugars,2 glucose, galactose, and xylose, in a molar ratio of 3:2:1. Made up of a (1 → 4) β-D-glucan backbone substituted with side chains of α-D-xylopyranose and β-D-galactopyranosy linked (1 → 2)-α-D-xylo-pyranose linked (1 → 6) to glucose residues. Functional groups: CH₂OH, O, OH.	High viscosity, adhesivity, non-carcinogenicity, broad pH tolerance, and biocompatibility.	[53,54]
Starch	Major carbohydrate form that is held in seeds, roots, rhizomes, and tubers	Chemical formula: (C₆H₁₀O₅)n. Amylopectin (α-amylose) and amylose (β-amylose) constitute starch. Amylopectin (α-amylose) is branched, while β-amylose consists of linear chains.	It is a tasteless, odorless powder insoluble in alcohol or cold water. Native starch’s significant swelling and quick enzymatic breakdown make it unsuitable for controlled-release medication delivery systems.	[55,56]
Cellulose	A structural element of the major cell walls of oomycetes, several types of algae, and green plants	Cellulose (C₆H₁₀O₅)n consists of a linear chain of several β(1 → 4) linked D-glucose units. Function group: OH, O.	This non-toxic polymer, with high tensile and compressive strength, is utilized in the food, cosmetics, pharmaceutical, and nanotechnology industries.	[40]
Chitin	The primary sources of chitin are crustacean shells; also found in mycelia and the spores of many fungi	Poly β-(1 → 4)-N-acetyl-D-glucosamine, i.e., N-acetyl-d-glucosamine units with β-(1,4) bonds. Functional groups: CH₂OH, O, OH.	Biocompatible, bioreactive, and biodegradable; used in agriculture, food, environment, pharma, and health sectors.	[42,56]
Pectin	Present in plant cell walls within the middle lamella, occurring as calcium and magnesium salts	IUPAC:(2S,3R,4S,5R,6R)-3,4,5,6-tetrahydroxyoxane-2-carboxylic acid.	It is used as a gelling agent but can also act as a thickener, water binder, and stabilizer and affects texture and viscosity in the food industry.	[38]
Agar	Obtained from Gelidium amansii (Gelidaceae) and other red algae	Agar consists of a mixture of agarose and agaropectin. It is composed of repeating alternate units of β-1,3-linked- D-galactose and α-1,4-linked 3,6 anhydro-L-galactose units.	Insoluble in cold water, dissolves readily in boiling water, and melts above 85 °C. Agar is used as a suspending agent, emulsifying agent, and gelling agent in tissue cultures and microbiology studies.	[43,57]
Alginate	Alginate is an anionic polymer and occurs naturally in the cell walls of brown algae (Phaeophyceae)	The alginates consist of 1,4-β-D-mannuronic acid (M) and 1,4 α-L-guluronic acid (G) monomers, with a homogeneous (poly-G, poly-M).	Acts as an antimicrobial agent to reduce the reproduction of Rhizoctonia (fungi) disease in potatoes and enhances the uptake of some nutrient elements and fertilizers.	[44,58]
β-cyclodextrin	From different starch sources such as potato, corn, wheat, rice, and tapioca	These are cyclic oligosaccharides commonly composed of six, seven, or eight D-glucose units (α-, β-, and γ-cyclodextrins, resp.) joined by α-(1,4) glycosidic bonds.	Form molecular inclusion complexes with many compounds and thus have applications in the fields of medicine, food, pharmaceuticals, and cosmetics.	[59]
Dextran	Dextran is a complex branched glucan (polysaccharide derived from the condensation of glucose)	Branched poly-α-d-glucosides of microbial origin with glycosidic bonds predominantly C-1 → C-6.	Used as plasma volume expanders and anticoagulants. They are also commonly used in biological experimentation.	[60,61]
Lignin	Lignin is the heterophenolic polymer found in the plant cell wall, particularly wood and bark	Lignin is composed of up to three different phenyl propane monomers, such as coniferyl alcohol, syringyl alcohol, and coumaryl alcohol units.	Lignin + sulphated lignosulfonates are used as dispersants, binders, complexing agents, and emulsifying agents. Barrier against attack by insects and fungi.	[38]
β-D-glucan	Found in a wide variety of cereal, plant, algae, bacteria, fungi, and yeast sources	Linear homopolysaccharides composed of D-glucopyranosyl residues (Glc p) linked via a mixture of β-(1 → 3) and β-(1 → 4) linkages.	Its structural conformation and molecular weight make it useful in foods and biological entities.	[62]
Carboxymethylcellulose	Cellulose derivative formed by its reaction with alkali and chloroacetic acid	β-(1 → 4)-D-glucopyranose polymer chain of cellulose.	Low toxicity, biodegradable, and excellent film-forming ability. Strong network structure and hydrophilicity.	[63,64]
Polyhydroxybutyrate	Macromolecules synthesized by bacteria (Bacillus) under stress conditions	[4-Oxo-4-(4-oxobutan-2-yloxy)butan-2-yl] 3-hydroxybutanoate	Biodegradability, use of renewable resources, better physical properties and non-toxic.	[65]
Carrageenan	Extracted from different species of red seaweeds	(β-(1,4)-D-galactose-α-(1,3)-D-galactose).	Types: kappa (κ), iota (ι), and lambda (λ); these are used in the food industry as gelling agents and thickeners. The iota carrageenan contains two sulfated groups per repeating unit.	[57,66]
Gum acacia/gum arabic	Acacia senegal and Acacia seyal tree exudate	1,3-linked β-D-galactopyranosyl unit is present. L-arabinose, L-rhamnose, and D-glucuronic acid have also been identified as components of this polymer.	Ca; Na; K; P; and traces of Pb, Co, Cu, Zn, Ni, Cd, Cr, and Mn are the most common minerals detected. High capacity for polymerization.	[36,67]
Guar gum	From seeds of guar gum (Cyamopsis Tetragonoloba)	1 → 4-linked β-D-mannopyranose backbone with branch points from their 6 positions linked to α-D-galactose (i.e., 1 → 6-linked α-D-galactopyranose), every galactose residue between 1.5–2 mannose residues. Functional groups: CH₂OH, OH, O, H.	Economical thickening and stabilizing agent; viscous pseudoplastic; high low-shear viscosity; shear thinning; less sensitive to ionic strength or pH; synergistic action with xanthan gum.	[43]
Cashew gum	Exudate of the cashew tree (Anacardium occidentale L.)	Cashew gum is built up of D-galactose, L-arabinose, D-galacturonic acid, and L-rhamnose (in traces). Functional groups: OH, O, COOH.	Application as a gelling agent, in polyelectrolyte complexes, as a viscosity enhancer, in controlled delivery systems, as a surfactant, as a drying aid agent, as a coating agent, and in microencapsulation.	[47,68]
Xanthan gum	Obtained by fermentation of Gram-negative bacteria, Xanthomonas campestris	Five sugar residues: two glucose, two mannose, and one glucuronic acid. Functional groups: CH₂OH, OH, O, COOH, H.	High viscosity even at low concentrations. Compatibility with heat, pH, shear, enzymes, and chemicals as well as variations in ionic strength.	[41,69]