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International Journal of Bioprinting Transdermal vitamin C delivery by MNPs

as skin erythema, dryness, epidermal breakage, wrinkled skin puncture by pressing and somewhat limits the
roughness, and pigmentation. Prolonged exposure to UV application to large areas of curved skin. 17,18 Therefore,
radiation can potentially lead to skin cancer. The UV the development of novel transdermal delivery strategies
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spectrum comprises three different types of UV categorized based on the structural characteristics of microneedles
by ranges of wavelength: UVA (320–400 nm), UVB (280– maintains considerable importance.
320 nm), and UVC (100–280 nm). The ozone layer acts The recent progress in the research of transdermal
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as a barrier that prevents the penetration of UVC, which microneedle particles (MNPs) merits significant attention.
has a shorter wavelength, into the skin’s epidermis. On the These MNPs are typically used in conjunction with
other hand, UVA with a longer wavelength can reach the ointment applied through smearing. In addition to the
dermis, but its biological activity is significantly lower than advantages of conventional microneedles, MNPs are also
UVB. Consequently, UVB is the primary culprit behind
skin photodamage. 4,5 suitable for large and curved skin, requiring only hand
application without auxiliary devices. The MNPs used to
When the skin is exposed to excessive UVB radiation, enhance the skin permeability include sponge Haliclona
the accumulation of reactive oxygen species (ROS) leads to sp. spicules (SHS), elongated microparticles (EMPs),
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oxidative stress. Moreover, ROS-mediated oxidative stress microneedle-like particles (MLP), and star-shaped
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can cause lipid peroxidation and DNA damage. Once DNA particles (STAR particles). Nevertheless, it is challenging
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damage is irreparable, cells will undergo necrosis or genetic to rapidly and cost-effectively fabricate customized MNPs,
mutations. Therefore, the development of pharmaceutical and the processes are cumbersome and costly, in addition
agents aimed at preventing and treating photodamage holds to the difficulties they are facing in large-scale preparations,
significant clinical value. The incorporation of antioxidants materials, and morphological structures.
into cosmetic products and their topical application to the
skin after sunburn have attracted substantial attention In view of the above, we decided to fabricate MNPs
and spawned a series of research on skin photodamage using polymer materials due to their wide applications
management. Currently, low-molecular-weight antioxidants, in biomedical fields. Additionally, the development of
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like vitamin C, are the most widely used antioxidant-based polymeric MNPs has a promising prospect of applications.
skin damage drugs. They have been proven to effectively At the same time, additive manufacturing is an emerging
reduce DNA damage, promote DNA excision repair, and technology capable of better control of the shape, size,
inhibit inflammation and cell proliferation. Topical vitamin projection length, and other parameters of MNPs. It can
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C has been used to prevent the formation of erythema simplify the production process as well as reduce the cost.
as well as sun-damaged cells and to upregulate collagen Our group has developed a novel digital light processing
production. However, vitamin C is a water-soluble charged (DLP)-based 3D printing technique 25,26 that avoids the
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molecule repelled by the stratum corneum barrier. Therefore, generation of stepped layered structure, a common
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the development of a novel transdermal antioxidant drug occurrence with traditional 3D printing technology. The
delivery strategy is of utmost significance. latter can affect the mechanical properties of microneedles
and lead to fracture if a high printing speed is applied.
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Transdermal drug delivery (TDD) is a drug delivery
method that involves administering drugs through the In this study, we utilized a DLP-based micro-printing
skin. It avoids the first-pass effect of the intestines and process to precisely customize MNPs with needle-like
liver, reduces adverse reactions, and improves patient structures. The MNPs are typically less than 1 mm in
compliance. Nevertheless, TDD faces specific challenges, diameter, and their projection lengths vary from 100 to
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since the skin barrier function limits the transdermal 600 μm. They can be fabricated by using photosensitive
absorption of most drugs. Only small-molecule, materials in less than 5 s, then formulated in a medicated
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lipophilic, and low-dose drugs can effectively penetrate ointment, and smeared painlessly to break through
the stratum corneum and enter the blood circulation. the stratum corneum barrier efficiently, significantly
Numerous emerging TDD techniques have developed increasing skin permeability. In addition, the skin can also
rapidly in recent years, such as chemical penetration be pre-treated with MNPs to facilitate drug penetration.
enhancers, laser-assisted delivery, iontophoresis, This process allows the customized preparation of
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sonophoresis, microneedle, 14,15 and electroporation. large batches of MNPs within seconds. It provides a solid
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Currently, microneedle technology has attracted wide basis for their large-scale production while ensuring
attention in direct physical enhancement to promote the high precision indispensable for the manufacturing
drug absorption and plays an important role in the field of high-quality MNPs. More importantly, MNPs with
of medicine. However, using as a microneedle array often needle-like structures may improve the penetration into
requires a specific auxiliary device to achieve effective the stratum corneum, thereby effectively delivering more
Volume 10 Issue 1 (2024) 358 https://doi.org/10.36922/ijb.1285