abundance, ease of availability, cost-effectiveness, low toxicity, ease of chemical
modification due to their complex heterogeneity, and versatile routes of administration [7, 15–18]. Most carbohydrates and proteins have an impeccable capacity to integrate themselves with the host once administered and can be easily
absorbed, digested/degraded to release the payload, and forms harmless byproducts. Additionally, the availability of diverse functional groups on the
surface of nanocarriers developed from carbohydrates and proteins makes them
interesting ligands for targeted and site-specific delivery [7]. The possibility to
modify the surface helps the nanocarrier to avoid its capture by the host immune
or digestive systems, enabling a long sustained release of the encapsulated
molecule [19].
The major carbohydrates that are being explored as drug carriers include
chitosan and its derivatives, starch, alginate, hyaluronan and dextran. Major protein
molecules identified as useful drug carriers are gelatin, albumin, collagen, fibrin/
fibrinogen, and milk proteins like casein and whey proteins. Many other proteins
like apo-lipoproteins and molecules of plant origin are also being investigated for
their utility in drug delivery. Different categories of carbohydrates and protein
molecules have varying degrees of drug loading, release, stability, and circulation.
These properties also depend upon the method of preparation and the kind of
modifications done on their surface. The following section analyzes the utility of
the major carbohydrate and protein drug carriers on the basis of the essential
hallmarks mentioned earlier.
2.1 Drug Loading
The quantity of drug entrapped within a nanocarrier varies according to the nature
of the carrier and the drug used, the method and conditions of particle preparation
and its surface modifications. Drug loading in carbohydrate and protein
nanocarriers can be accomplished by two different methods: (1) the
incorporation/active method, whereby the drug is loaded during preparation of
nanoparticles, and (2) the incubation/passive method, whereby the drug is loaded
after preparation of particles. The efficiency of drug loading is found to be maximum for the incorporation method, but is also greatly influenced by the method of
preparation. For systems requiring faster release, the incubation method would be
ideal because this involves only the physical adsorption of drugs to the matrix.
Various other processing parameters as well as the presence of additives such as
stabilizers, crosslinkers etc., also critically influence drug loading. Both hydrophilic
and hydrophobic drugs can be incorporated into any nanoparticulate system but, as
mentioned, the loading efficiency and release rate is dictated by the matrix–drug
interaction and the nanoparticle preparation route.
Proteins and Carbohydrates as Polymeric Nanodrug Delivery Systems. . .
245
modification due to their complex heterogeneity, and versatile routes of administration [7, 15–18]. Most carbohydrates and proteins have an impeccable capacity to integrate themselves with the host once administered and can be easily
absorbed, digested/degraded to release the payload, and forms harmless byproducts. Additionally, the availability of diverse functional groups on the
surface of nanocarriers developed from carbohydrates and proteins makes them
interesting ligands for targeted and site-specific delivery [7]. The possibility to
modify the surface helps the nanocarrier to avoid its capture by the host immune
or digestive systems, enabling a long sustained release of the encapsulated
molecule [19].
The major carbohydrates that are being explored as drug carriers include
chitosan and its derivatives, starch, alginate, hyaluronan and dextran. Major protein
molecules identified as useful drug carriers are gelatin, albumin, collagen, fibrin/
fibrinogen, and milk proteins like casein and whey proteins. Many other proteins
like apo-lipoproteins and molecules of plant origin are also being investigated for
their utility in drug delivery. Different categories of carbohydrates and protein
molecules have varying degrees of drug loading, release, stability, and circulation.
These properties also depend upon the method of preparation and the kind of
modifications done on their surface. The following section analyzes the utility of
the major carbohydrate and protein drug carriers on the basis of the essential
hallmarks mentioned earlier.
2.1 Drug Loading
The quantity of drug entrapped within a nanocarrier varies according to the nature
of the carrier and the drug used, the method and conditions of particle preparation
and its surface modifications. Drug loading in carbohydrate and protein
nanocarriers can be accomplished by two different methods: (1) the
incorporation/active method, whereby the drug is loaded during preparation of
nanoparticles, and (2) the incubation/passive method, whereby the drug is loaded
after preparation of particles. The efficiency of drug loading is found to be maximum for the incorporation method, but is also greatly influenced by the method of
preparation. For systems requiring faster release, the incubation method would be
ideal because this involves only the physical adsorption of drugs to the matrix.
Various other processing parameters as well as the presence of additives such as
stabilizers, crosslinkers etc., also critically influence drug loading. Both hydrophilic
and hydrophobic drugs can be incorporated into any nanoparticulate system but, as
mentioned, the loading efficiency and release rate is dictated by the matrix–drug
interaction and the nanoparticle preparation route.
Proteins and Carbohydrates as Polymeric Nanodrug Delivery Systems. . .
245