obtained for paclitaxel in folate-decorated albumin nanoparticles. Such a high
entrapment efficiency of paclitaxel can be attributed to the high ionic interactions
of the drug with the reactive side chains of albumin [51].
Gelatin, a denaturized form of protein obtained from collagen by either acid or
alkaline hydrolysis, has been extensively investigated for its drug bearing and
delivering ability [52]. Gelatin is rich in its surface composition with cationic,
anionic and hydrophobic domains and, hence, is regarded as a polyampholyte.
These surface groups on gelatin are readily available for ligand decoration or
drug conjugation [53]. Gelatin nanoparticles have demonstrated success for the
delivery of a large category of drugs including anticancer [54–56], antiinflammatory [57], anti-HIV [58], and antimicrobial drugs [59, 60], as well as
activators and growth factors [52, 61, 62]. Two classical methods have been
adopted for drug loading in gelatin nanoparticles, i.e., incorporation of the payload
within the crosslinked gelatin core, and the use of hybrid nanocarriers by
conjugating gelatin with natural or synthetic polymers. Whereas drug loading is
typically low and varies between 25 and 40% in the first case, the use of hybrid
nanocarriers aids in high drug retention in the gelatin core [58, 62, 63].
Collagen is the parent molecule of gelatin and the most abundant natural protein
in the living body, comprising of 20–30% of the total protein pool [64]. It is also
widely explored for applications in drug delivery. Biomedical applications of
collagen are wide and varied, ranging from implants, shields, particles, drugeluting gels and sponges to films [64, 65]. A study by Kaufman and Gebhardt,
using cyclosporin as a model drug, have identified collagen as an ideal delivery
agent for hydrophobic drugs [66]. Entrapment and efficacy of cyclosporine
entrapped in collagen nanocarriers were found to be significantly high [66, 67].
The features that make collagen a favorable drug delivery system for hydrophobic
payloads are its small size with high surface area, high adsorption capacity, and
ability to dispense in water to form a clear colloidal solution [68]. Anticancer drugs
such as vinblastin [69], cisplatin [70], 5-flourouracil [71], and paclitaxel have been
incorporated within a collagen matrix for localized cancer treatment. In addition to
antitumor drugs, antimicrobials, tissue-regulating agents, and growth factors have
all been effectively delivered to their site of action by entrapping them in a collagen
matrix [64, 65, 72, 73].
Milk proteins routinely transport nutrients to the digestive system in bulk and,
hence, are the natural carriers of bioactive molecules in the human body. Two kinds
of milk proteins, (flexible caseins and globular whey proteins) have been utilized
for drug delivery applications by mimicking their natural transport mechanism [7,
74, 75]. Caseins are exceptionally surface active and stable, and have very high
water and ion binding capacity, which makes them favorable candidates for drug
delivery [75]. Casein, especially β-casein, is valuable in the oral delivery of
hydrophobic bioactives. β-Casein nanovehicles for mitoxantrone, paclitaxel, and
vitamin D have been developed [74, 76, 77]. Livney et al. have prepared paclitaxel
entrapped in a highly stable formulation of β-casein, with an entrapment efficiency
of nearly 100%, and shown its activity on gastric cancer cell lines [77]. Whey
proteins have also emerged successful in drug delivery, with an interesting
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D. Narayanan et al.
entrapment efficiency of paclitaxel can be attributed to the high ionic interactions
of the drug with the reactive side chains of albumin [51].
Gelatin, a denaturized form of protein obtained from collagen by either acid or
alkaline hydrolysis, has been extensively investigated for its drug bearing and
delivering ability [52]. Gelatin is rich in its surface composition with cationic,
anionic and hydrophobic domains and, hence, is regarded as a polyampholyte.
These surface groups on gelatin are readily available for ligand decoration or
drug conjugation [53]. Gelatin nanoparticles have demonstrated success for the
delivery of a large category of drugs including anticancer [54–56], antiinflammatory [57], anti-HIV [58], and antimicrobial drugs [59, 60], as well as
activators and growth factors [52, 61, 62]. Two classical methods have been
adopted for drug loading in gelatin nanoparticles, i.e., incorporation of the payload
within the crosslinked gelatin core, and the use of hybrid nanocarriers by
conjugating gelatin with natural or synthetic polymers. Whereas drug loading is
typically low and varies between 25 and 40% in the first case, the use of hybrid
nanocarriers aids in high drug retention in the gelatin core [58, 62, 63].
Collagen is the parent molecule of gelatin and the most abundant natural protein
in the living body, comprising of 20–30% of the total protein pool [64]. It is also
widely explored for applications in drug delivery. Biomedical applications of
collagen are wide and varied, ranging from implants, shields, particles, drugeluting gels and sponges to films [64, 65]. A study by Kaufman and Gebhardt,
using cyclosporin as a model drug, have identified collagen as an ideal delivery
agent for hydrophobic drugs [66]. Entrapment and efficacy of cyclosporine
entrapped in collagen nanocarriers were found to be significantly high [66, 67].
The features that make collagen a favorable drug delivery system for hydrophobic
payloads are its small size with high surface area, high adsorption capacity, and
ability to dispense in water to form a clear colloidal solution [68]. Anticancer drugs
such as vinblastin [69], cisplatin [70], 5-flourouracil [71], and paclitaxel have been
incorporated within a collagen matrix for localized cancer treatment. In addition to
antitumor drugs, antimicrobials, tissue-regulating agents, and growth factors have
all been effectively delivered to their site of action by entrapping them in a collagen
matrix [64, 65, 72, 73].
Milk proteins routinely transport nutrients to the digestive system in bulk and,
hence, are the natural carriers of bioactive molecules in the human body. Two kinds
of milk proteins, (flexible caseins and globular whey proteins) have been utilized
for drug delivery applications by mimicking their natural transport mechanism [7,
74, 75]. Caseins are exceptionally surface active and stable, and have very high
water and ion binding capacity, which makes them favorable candidates for drug
delivery [75]. Casein, especially β-casein, is valuable in the oral delivery of
hydrophobic bioactives. β-Casein nanovehicles for mitoxantrone, paclitaxel, and
vitamin D have been developed [74, 76, 77]. Livney et al. have prepared paclitaxel
entrapped in a highly stable formulation of β-casein, with an entrapment efficiency
of nearly 100%, and shown its activity on gastric cancer cell lines [77]. Whey
proteins have also emerged successful in drug delivery, with an interesting
248
D. Narayanan et al.