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Biopolymers are natural
polymer A polymer (; Greek ''poly- Poly, from the Greek :wikt:πολύς, πολύς meaning "many" or "much", may refer to: Businesses * China Poly Group Corporation, a Chinese business group, and its subsidiaries: ** Poly Property, a Hong Kong inc ...

polymer
s produced by the cells of
living organisms In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, physiological mecha ...

living organisms
. Biopolymers consist of
monomer In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties, behavior and the changes they undergo during a ...

monomer
ic units that are
covalently bonded A covalent bond is a chemical bond A chemical bond is a lasting attraction between atoms, ions or molecules that enables the formation of chemical compounds. The bond may result from the Coulomb's law, electrostatic force of attraction bet ...
to form larger molecules. There are three main classes of biopolymers, classified according to the monomers used and the structure of the biopolymer formed:
polynucleotide A polynucleotide molecule is a biopolymer Biopolymers are natural polymers produced by the cells of Organism, living organisms. Biopolymers consist of monomeric units that are Covalent_bond, covalently bonded to form larger molecules. There are th ...
s,
polypeptides Peptides (from Greek language Greek (modern , romanized: ''Elliniká'', Ancient Greek, ancient , ''Hellēnikḗ'') is an independent branch of the Indo-European languages, Indo-European family of languages, native to Greece, Cyprus, Albania, o ...
, and
polysaccharide Polysaccharides (), or polycarbohydrates, are the most abundant found in . They are long chain carbohydrates composed of units bound together by . This carbohydrate can react with water () using as catalyst, which produces constituent sugars ...
s.
Polynucleotide A polynucleotide molecule is a biopolymer Biopolymers are natural polymers produced by the cells of Organism, living organisms. Biopolymers consist of monomeric units that are Covalent_bond, covalently bonded to form larger molecules. There are th ...
s, such as
RNA Ribonucleic acid (RNA) is a polymer A polymer (; Greek ''wikt:poly-, poly-'', "many" + ''wikt:-mer, -mer'', "part") is a Chemical substance, substance or material consisting of very large molecules, or macromolecules, composed of many Re ...

RNA
and
DNA Deoxyribonucleic acid (; DNA) is a molecule File:Pentacene on Ni(111) STM.jpg, A scanning tunneling microscopy image of pentacene molecules, which consist of linear chains of five carbon rings. A molecule is an electrically neutral gro ...

DNA
, are long polymers composed of 13 or more
nucleotide Nucleotides are organic molecules , CH4; is among the simplest organic compounds. In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen chemical bond, bonds. Due to carbon's ability to Catenation, ...

nucleotide
monomer In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties, behavior and the changes they undergo during a ...

monomer
s.
Polypeptides Peptides (from Greek language Greek (modern , romanized: ''Elliniká'', Ancient Greek, ancient , ''Hellēnikḗ'') is an independent branch of the Indo-European languages, Indo-European family of languages, native to Greece, Cyprus, Albania, o ...
and proteins, are polymers of
amino acid Amino acids are organic compound In , organic compounds are generally any s that contain - . Due to carbon's ability to (form chains with other carbon s), millions of organic compounds are known. The study of the properties, reactions, a ...

amino acid
s and some major examples include
collagen Collagen () is the main structural protein Proteins are large biomolecule , showing alpha helices, represented by ribbons. This poten was the first to have its suckture solved by X-ray crystallography by Max Perutz and Sir John Cowder ...

collagen
,
actin Actin is a protein family, family of Globular protein, globular multi-functional proteins that form microfilaments. It is found in essentially all Eukaryote, eukaryotic cells, where it may be present at a concentration of over 100 Micromolar, μ ...
, and
fibrin Fibrin (also called Factor Ia) is a fibrous Fiber or fibre (from la, fibra, links=no) is a natural Nature, in the broadest sense, is the natural, physical, material world or universe The universe ( la, universus) is all of ...
.
Polysaccharides , a beta-glucan polysaccharide Image:amylose 3Dprojection.svg, 350px, Amylose is a linear polymer of glucose mainly linked with α(1→4) bonds. It can be made of several thousands of glucose units. It is one of the two components of starch, the o ...
are linear or branched polymeric
carbohydrate A carbohydrate () is a biomolecule , showing alpha helices, represented by ribbons. This poten was the first to have its suckture solved by X-ray crystallography by Max Perutz and Sir John Cowdery Kendrew in 1958, for which they received a ...
s and examples include starch, cellulose and alginate. Other examples of biopolymers include
natural rubber Rubber, also called India rubber, latex, Amazonian rubber, ''caucho'', or ''caoutchouc'', as initially produced, consists of polymer A polymer (; Greek ''wikt:poly-, poly-'', "many" + ''wikt:-mer, -mer'', "part") is a Chemical substance, ...

natural rubber
s (polymers of
isoprene Isoprene, or 2-methyl-1,3-butadiene, is a common with the formula CH2=C(CH3)−CH=CH2. In its pure form it is a colorless volatile liquid. Isoprene is an unsaturated hydrocarbon. It is produced by many plants and animals (including humans) and i ...

isoprene
),
suberin Suberin, cutin and lignins are complex, higher plant Epidermis (botany), epidermis and periderm cell-wall macromolecules, forming a protective barrier. Suberin, a complex polyester biopolymer, is lipophilic, and composed of long chain fatty acids ...

suberin
and
lignin Lignin is a class of complex organic polymer A polymer (; Greek ''poly- Poly, from the Greek :wikt:πολύς, πολύς meaning "many" or "much", may refer to: Businesses * China Poly Group Corporation, a Chinese business group, and its s ...

lignin
(complex polyphenolic polymers),
cutin Cutin is one of two wax , a typical wax ester. Image:Beeswax foundation.jpg, Commercial honeycomb foundation, made by pressing beeswax between patterned metal rollers. Waxes are a diverse class of organic compounds that are lipophilic, malleab ...
and cutan (complex polymers of long-chain
fatty acids In chemistry Chemistry is the scientific Science () is a systematic enterprise that builds and organizes knowledge Knowledge is a familiarity or awareness, of someone or something, such as facts A fact is an occurrence in ...
) and
melanin Melanin (; from el, μέλας ''melas'', "black, dark") is a broad term for a group of natural pigments found in most organisms. Melanin is produced through a multistage chemical process known as melanogenesis, where the oxidation of the ami ...

melanin
. Biopolymers have various applications such as in the food industry, manufacturing, packaging and biomedical engineering.


Biopolymers versus synthetic polymers

A major defining difference between biopolymers and synthetic polymers can be found in their structures. All polymers are made of repetitive units called
monomer In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties, behavior and the changes they undergo during a ...

monomer
s. Biopolymers often have a well-defined structure, though this is not a defining characteristic (example:
lignocelluloseLignocellulose refers to plant dry matter ( biomass), so called lignocellulosic biomass. It is the most abundantly available raw material on the Earth Earth is the third planet from the Sun and the only astronomical object known to harbor l ...
): The exact chemical composition and the sequence in which these units are arranged is called the
primary structure Biomolecular structure is the intricate folded, three-dimensional shape that is formed by a molecule File:Pentacene on Ni(111) STM.jpg, A scanning tunneling microscopy image of pentacene molecules, which consist of linear chains of five carbon ...

primary structure
, in the case of proteins. Many biopolymers spontaneously fold into characteristic compact shapes (see also "
protein folding Protein folding is the physical process by which a protein Proteins are large biomolecules or macromolecules that are comprised of one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of func ...

protein folding
" as well as
secondary structure Biomolecular structure is the intricate folded, three-dimensional shape that is formed by a molecule A scanning tunneling microscopy image of pentacene molecules, which consist of linear chains of five carbon rings. A molecule is an elect ...

secondary structure
and
tertiary structure Biomolecular structure is the intricate folded, three-dimensional shape that is formed by a molecule A scanning tunneling microscopy image of pentacene molecules, which consist of linear chains of five carbon rings. A molecule is an elect ...

tertiary structure
), which determine their biological functions and depend in a complicated way on their primary structures. Structural biology is the study of the structural properties of the biopolymers. In contrast, most ''synthetic polymers have much simpler and more random (or stochastic) structures. This fact leads to a molecular mass distribution that is missing in biopolymers. In fact, as their synthesis is controlled by a template-directed process in most ''in vivo'' systems, all biopolymers of a type (say one specific protein) are all alike: they all contain the similar sequences and numbers of monomers and thus all have the same mass. This phenomenon is called monodispersity in contrast to the polydispersity encountered in synthetic polymers. As a result, biopolymers have a
polydispersity index In chemistry, the dispersity is a measure of the heterogeneity of sizes of molecules or particles in a mixture. A collection of objects is called uniform if the objects have the same size, shape, or mass. A sample of objects that have an inconsist ...
of 1.


Conventions and nomenclature


Polypeptides

The convention for a
polypeptide Peptides (from Greek language πεπτός, ''peptós'' "digested"; derived from πέσσειν, ''péssein'' "to digest") are short chains of amino acids linked by peptide bonds. Chains of fewer than ten or fifteen amino acids are called oligope ...
is to list its constituent amino acid residues as they occur from the amino terminus to the carboxylic acid terminus. The amino acid residues are always joined by
peptide bond In organic chemistry, a peptide bond is an amide type of Covalent bond, covalent chemical bond linking two consecutive alpha-amino acids from C1 (carbon number one) of one alpha-amino acid and N2 (nitrogen number two) of another, along a peptide o ...

peptide bond
s.
Protein Proteins are large biomolecule , showing alpha helices, represented by ribbons. This poten was the first to have its suckture solved by X-ray crystallography by Max Perutz and Sir John Cowdery Kendrew in 1958, for which they received a No ...

Protein
, though used colloquially to refer to any polypeptide, refers to larger or fully functional forms and can consist of several polypeptide chains as well as single chains. Proteins can also be modified to include non-peptide components, such as
saccharide A carbohydrate () is a biomolecule , showing alpha helices, represented by ribbons. This poten was the first to have its suckture solved by X-ray crystallography by Max Perutz and Sir John Cowdery Kendrew in 1958, for which they received a ...
chains and
lipid In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, physiological mechanis ...
s.


Nucleic acids

The convention for a
nucleic acid Nucleic acids are biopolymer Biopolymers are natural polymer A polymer (; Greek ''wikt:poly-, poly-'', "many" + ''wikt:-mer, -mer'', "part") is a Chemical substance, substance or material consisting of very large molecules, or macromolecule ...

nucleic acid
sequence is to list the nucleotides as they occur from the 5' end to the 3' end of the
polymer chain A polymer (; Greek ''poly- Poly, from the Greek :wikt:πολύς, πολύς meaning "many" or "much", may refer to: Businesses * China Poly Group Corporation, a Chinese business group, and its subsidiaries: ** Poly Property, a Hong Kong inc ...
, where 5' and 3' refer to the numbering of carbons around the ribose ring which participate in forming the phosphate diester linkages of the chain. Such a sequence is called the primary structure of the biopolymer.


Sugar

Sugar polymers can be linear or branched and are typically joined with
glycosidic bond A glycosidic bond or glycosidic linkage is a type of covalent bond that joins a carbohydrate (sugar) molecule to another group, which may or may not be another carbohydrate. A glycosidic bond is formed between the hemiacetal or hemiketal group ...
s. The exact placement of the linkage can vary, and the orientation of the linking functional groups is also important, resulting in α- and β-glycosidic bonds with numbering definitive of the linking carbons' location in the ring. In addition, many saccharide units can undergo various chemical modifications, such as
amination Amination is the process by which an amine In organic chemistry, amines (, ) are organic compound, compounds and functional groups that contain a base (chemistry), basic nitrogen atom with a lone pair. Amines are formally derivative (chemistry ...

amination
, and can even form parts of other molecules, such as
glycoprotein Glycoproteins are protein Proteins are large s and s that comprise one or more long chains of . Proteins perform a vast array of functions within organisms, including , , , providing and , and from one location to another. Proteins dif ...
s.


Structural characterization

There are a number of
biophysical uses protein domain dynamics on nanoscales to walk along a microtubule Microtubules are polymers of tubulin that form part of the cytoskeleton and provide structure and shape to Eukaryote, eukaryotic cells. Microtubules can grow as long as 50&n ...
techniques for determining sequence information. Protein sequence can be determined by
Edman degradationEdman degradation, developed by Pehr Edman, is a method of sequencing amino acids Amino acids are organic compounds that contain amino (–NH2) and Carboxylic acid, carboxyl (–COOH) functional groups, along with a Substituent, side chain (R ...
, in which the N-terminal residues are hydrolyzed from the chain one at a time, derivatized, and then identified. Mass
spectrometer A spectrometer () is a scientific instrument used to separate and measure Spectrum, spectral components of a physical phenomenon. Spectrometer is a broad term often used to describe instruments that measure a continuous variable of a phenomenon ...

spectrometer
techniques can also be used. Nucleic acid sequence can be determined using gel
electrophoresis Electrophoresis (from the Greek "ηλεκτροφόρηση" meaning "to bear electrons") is the motion of Interface and colloid science, dispersed particles relative to a fluid under the influence of a spatially uniform electric field. Electr ...

electrophoresis
and capillary electrophoresis. Lastly, mechanical properties of these biopolymers can often be measured using
optical tweezers Optical tweezers (originally called single-beam gradient force trap) are scientific instruments that use a highly focused laser A laser is a device that emits light Light or visible light is electromagnetic radiation within the port ...
or
atomic force microscopy Atomic force microscopy (AFM) or scanning force microscopy (SFM) is a very-high-resolution type of scanning probe microscopy (SPM), with demonstrated resolution on the order of fractions of a nanometer The nanometre (international spelling as u ...
. Dual-polarization interferometry can be used to measure the conformational changes or self-assembly of these materials when stimulated by pH, temperature, ionic strength or other binding partners.


Common biopolymers

Collagen:
Collagen Collagen () is the main structural protein Proteins are large biomolecule , showing alpha helices, represented by ribbons. This poten was the first to have its suckture solved by X-ray crystallography by Max Perutz and Sir John Cowder ...

Collagen
is the primary structure of vertebrates and is the most abundant protein in mammals. Because of this, collagen is one of the most easily attainable biopolymers, and used for many research purposes. Because of its mechanical structure, collagen has high tensile strength and is a non toxic, easily absorbable, biodegradable and biocompatible material. Therefore, it has been used for many medical applications such as in treatment for tissue infection, drug delivery systems, and gene therapy. Silk fibroin: Silk Fibroin (SF) is another protein rich biopolymer that can be obtained from different silk worm species, such as the mulberry worm Bombyx mori. In contrast to collagen, SF has a lower tensile strength but has strong adhesive properties due to its insoluble and fibrous protein composition. In recent studies, silk fibroin has been found to possess antiagulation properties and platelet adhesion. Silk fibroin has been additionally found to support stem cell proliferation in vitro. Gelatin: Gelatin is obtained from type I collagen consisting of cysteine, and produced by the partial hydrolysis of collagen from bones, tissues and skin of animals. There are two types of gelatin, Type A and Type B. Type A collagen is derived by acid hydrolysis of collagen and has 18.5% nitrogen. Type B is derived by alkaline hydrolysis containing 18% nitrogen and no amide groups. Elevated temperatures cause the gelatin to melts and exists as coils, whereas lower temperatures result in coil to helix transformation. Gelatin contains many functional groups like NH2, SH, and COOH which allow for gelatin to be modified using nonoparticles and biomolecules. Gelatin is an Extracellular Matrix protein which allows it to be applied for applications such as wound dressings, drug delivery and gene transfection. Starch: Starch is an inexpensive biodegradable biopolymer and copious in supply. Nano fibers and
microfiber Microfiber (or microfibre) is synthetic fiber finer than one denier Denier may refer to: * the French form of ''denarius'' (penny) ** French denier (penny), a type of medieval coin ** Denier (unit), a unit of linear mass density of fibers ** ...

microfiber
s can be added to the polymer
matrix Matrix or MATRIX may refer to: Science and mathematics * Matrix (mathematics), a rectangular array of numbers, symbols, or expressions * Matrix (logic), part of a formula in prenex normal form * Matrix (biology), the material in between a eukaryoti ...
to increase the mechanical properties of starch improving
elasticity Elasticity often refers to: *Elasticity (physics), continuum mechanics of bodies that deform reversibly under stress Elasticity may also refer to: Information technology * Elasticity (data store), the flexibility of the data model and the clu ...
and strength. Without the fibers, starch has poor mechanical properties due to its sensitivity to moisture. Starch being biodegradable and renewable is used for many applications including plastics and pharmaceutical tablets. Cellulose: Cellulose is very structured with stacked chains that result in stability and strength. The strength and stability comes from the straighter shape of cellulose caused by glucose
monomer In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties, behavior and the changes they undergo during a ...

monomer
s joined together by glycogen bonds. The straight shape allows the molecules to pack closely. Cellulose is very common in application due to its abundant supply, its biocompatibility, and is environmentally friendly. Cellulose is used vastly in the form of nano-fibrils called nano-cellulose. Nano-cellulose presented at low concentrations produces a transparent gel material. This material can be used for biodegradable,
homogeneous Homogeneity and heterogeneity are concepts often used in the sciences Science () is a systematic enterprise that Scientific method, builds and organizes knowledge in the form of Testability, testable explanations and predictions about th ...
, dense films that are very useful in the biomedical field. Alginate:
Alginate Alginic acid, also called algin, is a polysaccharide distributed widely in the cell walls of brown algae that is hydrophilic and forms a viscous natural gum, gum when hydrated. With metals such as sodium and calcium, its salts are known as alginat ...
is the most copious marine natural polymer derived from brown seaweed. Alginate biopolymer applications range from packaging, textile and food industry to biomedical and chemical engineering. The first ever application of alginate was in the form of wound dressing, where its gel-like and absorbent properties were discovered. When applied to wounds, alginate produces a protective gel layer that is optimal for healing and tissue regeneration, and keeps a stable temperature environment. Additionally, there have been developments with alginate as a drug delivery medium, as drug release rate can easily be manipulated due to a variety of alginate densities and fibrous composition.


Biopolymer applications

The applications of biopolymers can be categorized under two main fields, which differ due to their biomedical and industrial use.


Biomedical

Because one of the main purposes for biomedical engineering is to mimic body parts to sustain normal body functions, due to their biocompatible properties, biopolymers are used vastly for
tissue engineering Tissue engineering is a biomedical engineering discipline that uses a combination of cells Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Closed spaces * Monastic cell, a small room, ...
, medical devices and the pharmaceutical industry. Many biopolymers can be used for
regenerative medicine Regenerative medicine deals with the "process of replacing, engineering or regenerating human or animal cells, tissues or organs to restore or establish normal function". This field holds the promise of engineering damaged tissues and organs by sti ...

regenerative medicine
, tissue engineering, drug delivery, and overall medical applications due to their mechanical properties. They provide characteristics like wound healing, and catalysis of bio-activity, and non-toxicity. Compared to synthetic polymers, which can present various disadvantages like immunogenic rejection and toxicity after degradation, many biopolymers are normally better with bodily integration as they also possess more complex structures, similar to the human body. More specifically, polypeptides like collagen and silk, are biocompatible materials that are being used in ground breaking research, as these are inexpensive and easily attainable materials. Gelatin polymer is often used on dressing wounds where it acts as an adhesive. Scaffolds and films with gelatin allow for the scaffolds to hold drugs and other nutrients that can be used to supply to a wound for healing. As collagen is one of the more popular biopolymer used in biomedical science, here are some examples of their use: Collagen based drug delivery systems: collagen films act like a barrier membrane and are used to treat tissue infections like infected corneal tissue or liver cancer. Collagen films have all been used for gene delivery carriers which can promote bone formation. Collagen sponges: Collagen sponges are used as a dressing to treat burn victims and other serious wounds. Collagen based implants are used for cultured skin cells or drug carriers that are used for burn wounds and replacing skin. Collagen as haemostat: When collagen interacts with
platelet Platelets, also called thrombocytes (from Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. ...

platelet
s it causes a rapid coagulation of blood. This rapid coagulation produces a temporary framework so the fibrous stroma can be regenerated by host cells. Collagen bases haemostat reduces blood loss in tissues and helps manage bleeding in cellular organs like the liver and spleen.
Chitosan Chitosan is a linear polysaccharide composed of randomly distributed β-(1→4)-linked Glucosamine, D-glucosamine (deacetylated unit) and N-Acetylglucosamine, ''N''-acetyl-D-glucosamine (acetylated unit). It is made by treating the chitin shells ...

Chitosan
is another popular biopolymer in biomedical research. Chitosan is derived from
chitin Chitin (carbon, C8hydrogen, H13oxygen, O5nitrogen, N)n ( ) is a long-chain polymer of N-Acetylglucosamine, ''N''-acetylglucosamine, an amide derivative of glucose. The second most abundant polysaccharide in nature (behind only cellulose), it ...

chitin
, the main component in the
exoskeleton An exoskeleton (from Greek έξω, ''éxō'' "outer" and σκελετός, ''skeletós'' "skeleton") is the external skeleton A skeleton is a structural frame that supports an animal Animals (also called Metazoa) are multicellular ...

exoskeleton
of crustaceans and insects and the second most abundant biopolymer in the world. Chitosan has many excellent characteristics for biomedical science. Chitosan is biocompatible, it is highly bioactive, meaning it stimulates a beneficial response from the body, it can biodegrade which can eliminate a second surgery in implant applications, can form gels and films, and is . These properties allow for various biomedical applications of Chitosan. Chitosan as drug delivery: Chitosan is used mainly with drug targeting because it has potential to improve drug absorption and stability. in addition Chitosan conjugated with anticancer agents can also produce better anticancer effects by causing gradual release of free drug into cancerous tissue. Chitosan as an anti-microbial agent: Chitosan is used to stop the growth of
microorganism A microorganism, or microbe,, ''mikros'', "small") and ''organism In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes ...
s. It performs antimicrobial functions in microorganisms like algae, fungi, bacteria, and
gram positive 300px, Violet-stained gram-positive bacilli_.html" ;"title="bacillus_(shape).html" ;"title="gram-negative.html" ;"title="cocci and pink-stained gram-negative">cocci and pink-stained gram-negative bacillus (shape)">bacilli ">bacillus_(shape).html" ...
bacteria of different yeast species. Chitosan composite for tissue engineering: Blended power of Chitosan along with alginate are used together to form functional wound dressings. These dressings create a moist environment which aids in the healing process. This wound dressing is also very biocompatible, biodegradable and has porous structures that allows cells to grow into the dressing.


Industrial

Food: Biopolymers are being used in the food industry for things like packaging, edible encapsulation films and coating foods. Polylactic Acid (PLA) is very common in the food industry due to is clear color and resistance to water. However, most polymers have a
hydrophilic A hydrophile is a molecule A molecule is an electrically Electricity is the set of physical phenomena associated with the presence and motion Image:Leaving Yongsan Station.jpg, 300px, Motion involves a change in position In phys ...
nature and start deteriorating when exposed to moisture. Biopolymers are also being used as edible films that encapsulate foods. These films can carry things like
antioxidant Antioxidants are compounds Compound may refer to: Architecture and built environments * Compound (enclosure), a cluster of buildings having a shared purpose, usually inside a fence or wall ** Compound (fortification), a version of the above ...

antioxidant
s,
enzyme Enzymes () are proteins that act as biological catalysts (biocatalysts). Catalysts accelerate chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates in ...

enzyme
s,
probiotic Probiotics are live microorganisms promoted with claims that they provide health benefits when consumed, generally by improving or restoring the gut flora. Probiotics are considered GRAS, generally safe to consume, but may cause bacteria-Host (b ...

probiotic
s, minerals, and vitamins. The food consumed encapsulated with the biopolymer film can supply these things to the body. Packaging: The most common biopolymers used in packaging are
polyhydroxyalkanoate ), a polyhydroxyalkanoate Polyhydroxyalkanoates or PHAs are polyesters produced in nature by numerous microorganisms, including through bacterial fermentation (biochemistry), fermentation of sugars or lipids. When produced by bacteria they serve a ...

polyhydroxyalkanoate
(PHA),
polylactic acid Polylactic acid, or polylactide (PLA) is a thermoplastic polyester with backbone formula or , formally obtained by condensation reaction, condensation of lactic acid with loss of water (hence its name). It can also be prepared by ring-opening p ...
(PLA), and
starch Starch or amylum is a polymeric A polymer (; Greek '' poly-'', "many" + '' -mer'', "part") is a substance Substance may refer to: * Substance (Jainism), a term in Jain ontology to denote the base or owner of attributes * Chemical substance ...
. Starch and PLA are commercially available biodegradable making them a common choice for packaging. However, their barrier properties and thermal properties are not ideal. Hydrophilic polymers are not water resistant and allow water to get through the packaging which can affect the contents of the package.
Polyglycolic acid Polyglycolide or poly(glycolic acid) (PGA), also spelled as polyglycolic acid, is a biodegradable, thermoplastic A thermoplastic, or thermosoftening plastic, is a plastic polymer material that becomes pliable or moldable at a certain elevated tem ...
(PGA) is a biopolymer that has great barrier characteristics and is now being used to correct the barrier obstacles from PLA and starch. Water purification: A newer biopolymer called
chitosan Chitosan is a linear polysaccharide Polysaccharides (), or polycarbohydrates, are the most abundant found in . They are long chain carbohydrates composed of units bound together by . This carbohydrate can react with water () using as ca ...

chitosan
has been used for water purification. Chitosan is used as a flocculant that only takes a few weeks or months rather than years to degrade into the environment. Chitosan purify's water by Chelation when it removes metals from the water. Chelation is when binding sites along the polymer chain bind with the metal in the water forming clelates. Chitosan has been used in many situations to clean out storm or waste water that may have been contaminated.


As materials

Some biopolymers- such as
PLA PLA may refer to: Organizations Politics and military * People's Liberation Army The People's Liberation Army (PLA) is the regular army, regular armed forces of the China, People's Republic of China (PRC) and the armed wing of the PRC's foun ...
, naturally occurring
zein Zein is a class of prolamine Prolamins are a group of plant storage proteins having a high proline amino acid content. They are found in plants, mainly in the seeds of cereal grains such as wheat (gliadin), barley (hordein), rye (secalin), maize ...
, and
poly-3-hydroxybutyrate Polyhydroxybutyrate (PHB) is a polyhydroxyalkanoate (PHA), a polymer A polymer (; Greek '' poly-'', "many" + '' -mer'', "part") is a substance or material consisting of very large molecule File:Pentacene on Ni(111) STM.jpg, A scanning t ...
can be used as plastics, replacing the need for
polystyrene Polystyrene (PS) is a synthetic Aromaticity, aromatic hydrocarbon polymer made from the monomer known as styrene. Polystyrene can be solid or foamed. General-purpose polystyrene is clear, hard, and brittle. It is an inexpensive resin per un ...

polystyrene
or
polyethylene Polyethylene or (incorrectly) polythene (abbreviated PE; IUPAC name polyethene or poly(methylene)) is the most common plastic in use today. It is a polymer, primarily used for packaging (plastic bags, plastic films, geomembranes and container ...

polyethylene
based plastics. Some plastics are now referred to as being 'degradable', 'oxy-degradable' or 'UV-degradable'. This means that they break down when exposed to light or air, but these plastics are still primarily (as much as 98 per cent)
oil An oil is any nonpolar In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound ...

oil
-based and are not currently certified as 'biodegradable' under the
European Union directive A directive is a legal act of the European Union The European Union (EU) is a political and economic union of member states that are located primarily in Europe Europe is a which is also recognised as part of , located entire ...
on Packaging and Packaging Waste (94/62/EC). Biopolymers will break down, and some are suitable for domestic
composting Compost is a mixture of ingredients used to fertilize and improve the soil. It is commonly prepared by decomposing plant and food waste and recycling Recycling is the process of converting waste Waste (or wastes) are unwanted ...

composting
. Biopolymers (also called renewable polymers) are produced from
biomass Biomass is plant or animal material used as fuel to produce electricity Electricity is the set of physical phenomena associated with the presence and motion Image:Leaving Yongsan Station.jpg, 300px, Motion involves a change in position ...

biomass
for use in the packaging industry. Biomass comes from crops such as sugar beet, potatoes or wheat: when used to produce biopolymers, these are classified as non food crops. These can be converted in the following pathways:
Sugar beet A sugar beet is a plant whose root contains a high concentration of sucrose Sucrose is a type of sugar Sugar is the generic name for Sweetness, sweet-tasting, soluble carbohydrates, many of which are used in food. Table sugar, granulated ...
> Glyconic acid > Polyglyconic acid
Starch Starch or amylum is a polymeric A polymer (; Greek '' poly-'', "many" + '' -mer'', "part") is a substance Substance may refer to: * Substance (Jainism), a term in Jain ontology to denote the base or owner of attributes * Chemical substance ...
> (fermentation) >
Lactic acid Lactic acid is an organic acid An organic acid is an organic compound with acidic properties. The most common organic acids are the carboxylic acids, whose acidity is associated with their carboxyl group –COOH. Sulfonic acids, conta ...

Lactic acid
>
Polylactic acid Polylactic acid, also known as poly(lactic acid) or polylactide (abbreviation PLA) is a thermoplastic A thermoplastic, or thermosoft plastic, is a plastic polymer material that becomes pliable or moldable at a certain elevated temperature and s ...
(PLA)
Biomass Biomass is plant or animal material used as fuel to produce electricity Electricity is the set of physical phenomena associated with the presence and motion Image:Leaving Yongsan Station.jpg, 300px, Motion involves a change in position ...

Biomass
> (fermentation) >
Bioethanol Ethanol (also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic Organic may refer to: * Organic, of or relating to an organism, a living entity * Organic, of or relating to an anatomical organ (anatomy), ...
>
Ethene Ethylene (IUPAC The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering OrganizationsNational Adhering Organizations in chemistry are the organizations that work as the authoritativ ...
>
Polyethylene Polyethylene or (incorrectly) polythene (abbreviated PE; IUPAC name polyethene or poly(methylene)) is the most common plastic in use today. It is a polymer, primarily used for packaging (plastic bags, plastic films, geomembranes and container ...

Polyethylene
Many types of packaging can be made from biopolymers: food trays, blown starch pellets for shipping fragile goods, thin films for wrapping.


Environmental impacts

Biopolymers can be sustainable, carbon neutral and are always
renewable A renewable resource, also known as a flow resource, is a natural resource which will replenish to replace the portion resource depletion, depleted by usage and consumption, either through natural reproduction or other recurring processes in a ...

renewable
, because they are made from plant materials which can be grown indefinitely. These plant materials come from agricultural non food crops. Therefore, the use of biopolymers would create a
sustainable Sustainability is the capacity to endure in a relatively ongoing way across various domains of life. In the 21st century The 21st (twenty-first) century is the current century A century is a period of 100 years. Centuries are numbered nam ...

sustainable
industry. In contrast, the feedstocks for polymers derived from petrochemicals will eventually deplete. In addition, biopolymers have the potential to cut
carbon emissions Greenhouse gas emissions are emissions of greenhouse gases created from a range of human activities that cause climate change, as they have increased concentrations in the earth's atmosphere. These emissions mainly include carbon dioxide emissions ...
and reduce CO2 quantities in the atmosphere: this is because the CO2 released when they degrade can be reabsorbed by crops grown to replace them: this makes them close to
carbon neutral Carbon neutrality refers to achieving net-zero carbon dioxide emissions. This can be done by balancing emissions of carbon dioxide with its removal (often through carbon offsetting) or by eliminating emissions from society (the transition to the ...
. Biopolymers are biodegradable, and some are also compostable. Some biopolymers are
biodegradable Biodegradation is the breakdown of organic matter by microorganisms, such as bacteria and fungi. Mechanisms The process of biodegradation can be divided into three stages: biodeterioration, biofragmentation, and assimilation (biology), assimila ...

biodegradable
: they are broken down into CO2 and water by
microorganisms A microorganism, or microbe,, ''mikros'', "small") and ''organism In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes ...

microorganisms
. Some of these biodegradable biopolymers are
compostable Compost is a mixture of ingredients used to fertilize and improve the soil. It is commonly prepared by decomposing plant and food waste and recycling Recycling is the process of converting waste Waste (or wastes) are unwanted ...
: they can be put into an industrial composting process and will break down by 90% within six months. Biopolymers that do this can be marked with a 'compostable' symbol, under European Standard EN 13432 (2000). Packaging marked with this symbol can be put into industrial composting processes and will break down within six months or less. An example of a compostable polymer is PLA film under 20μm thick: films which are thicker than that do not qualify as compostable, even though they are "biodegradable".NNFCC Newsletter – Issue 5. Biopolymers: A Renewable Resource for the Plastics Industry
/ref> In Europe there is a home composting standard and associated logo that enables consumers to identify and dispose of packaging in their compost heap.


See also

*
Biomaterial A biomaterial is a substance that has been engineered to interact with biological systems for a medical purpose, either a therapeutic (treat, augment, repair, or replace a tissue function of the body) or a diagnostic one. As a science, biomateria ...
s *
Bioplastic Bioplastics are plastic Plastics are a wide range of synthetic polymers, synthetic or semi-synthetic materials that use polymers as a main ingredient. Their Plasticity (physics), plasticity makes it possible for plastics to be Injection mouldin ...
* '' Biopolymers & Cell'' (journal) *
Condensation polymer Condensation polymers are any kind of polymer A polymer (; Greek '' poly-'', "many" + '' -mer'', "part") is a substance or material consisting of very large molecule File:Pentacene on Ni(111) STM.jpg, A scanning tunneling microscopy imag ...
s *
Condensed tannin Condensed tannins (proanthocyanidins, polyflavonoid tannins, catechol-type tannins, pyrocatecollic type tannins, non-hydrolyzable tannins or flavolans) are biopolymer, polymers formed by the Condensation reaction, condensation of flavans. They do n ...
s *
DNA sequence DNA sequencing is the process of determining the nucleic acid sequence A nucleic acid sequence is a succession of bases signified by a series of a set of five different letters that indicate the order of nucleotides Nucleotides are organic ...

DNA sequence
* *
Melanin Melanin (; from el, μέλας ''melas'', "black, dark") is a broad term for a group of natural pigments found in most organisms. Melanin is produced through a multistage chemical process known as melanogenesis, where the oxidation of the ami ...

Melanin
* Non food crops *
Phosphoramidite A phosphoramidite (RO)2PNR2 is a monoamide of a phosphite diester. The key feature of phosphoramidites is their markedly high reactivity towards nucleophile In chemistry, a nucleophile is a chemical species that forms bonds with Electrophile, electr ...

Phosphoramidite
*
Polymer chemistry Polymer chemistry is a sub-discipline of chemistry Chemistry is the scientific Science () is a systematic enterprise that builds and organizes knowledge Knowledge is a familiarity or awareness, of someone or something, such as ...
*
Sequence-controlled polymer A sequence-controlled polymer is a macromolecule macromolecule A macromolecule is a very large molecule, such as a protein. They are composed of thousands of covalent bond, covalently bonded atoms. Many macromolecules are the polymerization of ...

Sequence-controlled polymer
s *
Sequencing In genetics Genetics is a branch of biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interaction ...

Sequencing
*
Small molecule Within the fields of molecular biology Molecular biology is the branch of biology that seeks to understand the molecule, molecular basis of biological activity in and between Cell (biology), cells, including biomolecule, molecular synthesis, mo ...
s *
Worm-like chainThe worm-like chain (WLC) model in polymer physics is used to describe the behavior of polymers A polymer (; Greek '' poly-'', "many" + '' -mer'', "part") is a substance or material consisting of very large molecule File:Pentacene on Ni(1 ...


References


External links


NNFCC: The UK's National Centre for Biorenewable Energy, Fuels and MaterialsBioplastics MagazineBiopolymer groupBio-Polym BlogWhat’s Stopping Bioplastic?
{{Authority control Biomolecules Polymers Molecular biology Molecular genetics Biotechnology products Bioplastics Biomaterials