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Digital light processing based 3D printing for medical applications
and antibacterial activity of antibiotics. Thus, can also mix or print multi-drug layers to control
DLP-based 3D printing provides a rapid method drug release. Adding drugs at fixed points on drug
for disease modeling. Especially for precision delivery vectors can control the time of drug release
medicine, high throughput drug screening is very to achieve the purpose of accelerating or delaying
important. The disease model based on patient’s drug release. Printing different drug layers can
cell can get an accurate screening result. Besides make drugs release at intervals according to their
drug screening, the researches of cancer models structural characteristics. Changing 3D printing
can provide new solutions for cancer therapy. can make drug release at intervals according
Developing a drug, it is required to study its to their structural characteristics . The filling
[72]
absorption, metabolization, excretion, optimal degree of the printed preparation can accurately
dosage, and toxicity. Most measurements are customize personalized drugs containing different
carried out in the traditional 2D monolayer dosages. Liu et al. fabricated microhydrogels with
culture system, which cannot simulate the natural predesigned shapes and sizes to carry drugs. The
3D tissue microenvironment. Hence, the results microhydrogels are small enough to be injected
are greatly different between the in vivo and in through a 1-mL syringe in a noninvasive way .
[10]
vitro tests . Artificial tissue fabricated by 3D Tao et al. encapsulated PDA nanoparticles into
[69]
printing can simulate the state of the tissue in vivo the microhydrogels (Figure 4A). Then, the
more effectively and can quickly and cheaply microhydrogels are injected into the location of
carry out pharmacological, toxicological, and bacterial infection to improve tissue recovery .
[73]
pharmacokinetic studies, so as to reduce the The 3D printed implants can act as drug delivery
losses caused by pharmacodynamic, and toxicity systems. The 3D printed post-operative filler
problems found only in animal or clinical trials [14,70] . of drug-loaded gene drugs for patients with
The 3D printed liver and kidney tissues have been glioma, which can continuously release drugs
applied to testing drug metabolism. For example, to eliminate residual tumor cells and avoid
Ma et al. studied drug metabolism by their printed recurrence of tumors . Xu et al. encapsulated
[74]
hepatic model. Treating the biomimetic hepatic RGFP966 nanoparticle into 3D printed nerve
model with an inducer, they characterized the conduits to improve nerve regeneration and repair
expression levels of CYP which includes several (Figure 4B) . Taking theophylline as the model
[75]
key enzymes for drug metabolism. They found drug, Hossam et al. used PEGDA at various
significant increases in three key enzymes. The concentrations to fabricate tablets (Figure 4C).
positive response indicated that the inducer can be Then, they studied the release of theophylline from
cleared by liver. the printed tablets. The DLP-based 3D printing is
5.2 Drug delivery flexible in fabricating personalized drug delivery
systems by changing printed structure, polymer
As a manufacturing technology, DLP-based concentration, and printer parameters, including
3D printing technology can also be used in the light intensity and wavelength and exposure time.
preparation of the drug delivery system with Therefore, this printing technology has great
[44]
customized dosages, shapes, sizes, and release potential in fabricating personalized drugs .
ways. In 2015, the FDA approved a 3D-printed Taking advantage of DLP-based 3D printing
drug to accurately control the structure and dosage technology, printed products can significantly save
of the drug. Through 3D printing technology, the the drug discovery time and cost and accelerate the
tablet is constructed in microporous structures, accuracy of drug screening. Meanwhile, the printed
which will dissolve immediately after oral tissues or cancer models formed by the patient’s own
administration. Patients who have difficulties cells could be used for precision medicine. Last but
in swallowing can easily take the tablet . This not least, the DLP-based 3D printed drugs or drug
[71]
technology also encourages the development of 3D carriers can be designed with specific structures,
printed drug delivery system. The delivery system precise dosages, and personalized release ways.

22 International Journal of Bioprinting (2020)–Volume 6, Issue 1