12.7 Applications
279
hydrogel microneedles which in the dry state are rigid enough to pierce the skin;
however, once inserted into the skin it will absorb water and release the entrapped
loaded compound into the lower layer of the skin from where it can be absorbed into
the bloodstream more easily. In vitro studies showed that these hydrogel microneedles
have sufficient strength to pierce the skin and can swell and release loaded drug
compound when in contact with water. The hydrogels were made using hydrolyzed
collagen extracted from fish scales of croaker fish using the hydrothermal extraction
method.
Delivery of collagen into the skin using microneedles also serves cosmetic purpose of boosting the skin collagen content. This could be a means to address the
decreased collagen production rate associated with aging and by so doing decrease
the appearance of wrinkles. Due to its large molecular weight collagen or hydrolyzed
collagen cannot pierce the upper layer of the skin; therefore, delivering the collagen
through topical means might not achieve the same goal as the collagen will not penetrate the impermeable top layer of the skin (Stratum corneum). Another option is the
use of hypodermic injections to deliver collagen underneath the skin. However, this
method comes with the disadvantage of discomfort and risk of accidental injury from
the injection. Dissolving microneedles made of lower molecular weight hydrolyzed
collagen can therefore be used as painless means to deliver collagen into the skin.
This also has the advantage of self-administration by the user without requiring medical expertise unlike with injection using hypodermic needles. The microneedle could
either be made entirely of collagen (Olatunji et al. 2014) or it could be blended with
another polymer such as polyvinylpyrrolidone (Sun et al. 2014).
12.7.6 Cosmetics and Skin Care
The skin is the outermost layer of the body and by virtue of this it has a significant
role to play in appearance. People are constantly seeking to smoothen, moisturize,
color, bleach and dye or improve the appearance of the skin in one way or the other.
This makes collagen also suitable as an active compound in cosmetics and skin care
products. Collagen has become a key part of the billion dollar cosmetics industry.
They have been applied in a range of products from topical skin care to cosmeceutical
oral gels to injectables (Alves et al. 2017; Devgan et al. 2019).
Collagen plays a significant role in cosmetics either in attaining the desired physical or rheological properties in terms of thickening and gelling property, and it also
plays a role as an active ingredient, mostly in the form of collagen hydrolysate where
it is intended to penetrate into the epidermis and improve the skin mechanical properties which result in smoother and more youthful looking skin (Savary et al. 2016).
Oligomeric forms of collagen which are very short polypeptide fragments are used
in skin care products such as skin lotions where they are thought to easier penetrate
the epidermis from where they can reach the dermis and induce skin rejuvenating
effect. There are further studies into confirming the exact manner or extent to which
279
hydrogel microneedles which in the dry state are rigid enough to pierce the skin;
however, once inserted into the skin it will absorb water and release the entrapped
loaded compound into the lower layer of the skin from where it can be absorbed into
the bloodstream more easily. In vitro studies showed that these hydrogel microneedles
have sufficient strength to pierce the skin and can swell and release loaded drug
compound when in contact with water. The hydrogels were made using hydrolyzed
collagen extracted from fish scales of croaker fish using the hydrothermal extraction
method.
Delivery of collagen into the skin using microneedles also serves cosmetic purpose of boosting the skin collagen content. This could be a means to address the
decreased collagen production rate associated with aging and by so doing decrease
the appearance of wrinkles. Due to its large molecular weight collagen or hydrolyzed
collagen cannot pierce the upper layer of the skin; therefore, delivering the collagen
through topical means might not achieve the same goal as the collagen will not penetrate the impermeable top layer of the skin (Stratum corneum). Another option is the
use of hypodermic injections to deliver collagen underneath the skin. However, this
method comes with the disadvantage of discomfort and risk of accidental injury from
the injection. Dissolving microneedles made of lower molecular weight hydrolyzed
collagen can therefore be used as painless means to deliver collagen into the skin.
This also has the advantage of self-administration by the user without requiring medical expertise unlike with injection using hypodermic needles. The microneedle could
either be made entirely of collagen (Olatunji et al. 2014) or it could be blended with
another polymer such as polyvinylpyrrolidone (Sun et al. 2014).
12.7.6 Cosmetics and Skin Care
The skin is the outermost layer of the body and by virtue of this it has a significant
role to play in appearance. People are constantly seeking to smoothen, moisturize,
color, bleach and dye or improve the appearance of the skin in one way or the other.
This makes collagen also suitable as an active compound in cosmetics and skin care
products. Collagen has become a key part of the billion dollar cosmetics industry.
They have been applied in a range of products from topical skin care to cosmeceutical
oral gels to injectables (Alves et al. 2017; Devgan et al. 2019).
Collagen plays a significant role in cosmetics either in attaining the desired physical or rheological properties in terms of thickening and gelling property, and it also
plays a role as an active ingredient, mostly in the form of collagen hydrolysate where
it is intended to penetrate into the epidermis and improve the skin mechanical properties which result in smoother and more youthful looking skin (Savary et al. 2016).
Oligomeric forms of collagen which are very short polypeptide fragments are used
in skin care products such as skin lotions where they are thought to easier penetrate
the epidermis from where they can reach the dermis and induce skin rejuvenating
effect. There are further studies into confirming the exact manner or extent to which