Using Microjets for Painless Drug Delivery
What is the Problem?
Approximately 12 billion needle injections are performed every year for delivery of vaccinations, proteins, and other drugs. Although needles are a common form of treatment, they can cause pain, needle phobia and accidental needlesticks. Needlesticks can often lead to injuries and infections and are commonly due to a patient's fear of a needle and movement during injection.
An alternative to needle injections is to use a conventional Jet Injector. This device, shown in the figure above to the right, uses a piston to create a jet containing the drug. It's ability to deliver drugs without the use of a needle seemed promising. Although this technology has been around for over 50 years, it is not commonly used due to two main reasons:
An alternative to needle injections is to use a conventional Jet Injector. This device, shown in the figure above to the right, uses a piston to create a jet containing the drug. It's ability to deliver drugs without the use of a needle seemed promising. Although this technology has been around for over 50 years, it is not commonly used due to two main reasons:
- The jet's penetration depth is such that it begins to encounter nerves causing the patient to feel pain.
- The jet typically also hits blood capillaries which can cause bruising of the skin.
The Solution: Microjets!
A comparison between a Microjet Injector and a conventional Jet Injector
Microjets
Mitragotri's research partnerships have developed a new method for drug delivery that bypasses pain and bruising. A Microjet, shown in the figure above to the left, is a device that uses a piezoelectric transducer coupled with several springs to "pulse" microjets containing drugs. This device has a nozzle of 50-100 micrometers in diameter and delivers approximately 10 nanoliters. The pulses are fast enough (v >100 m/s) to allow for the microjets to deliver drugs efficiently. On the other hand, the amount of drug is small enough that it does not penetrate as deeply as traditional Jet Injectors.
Conclusions
Microjets are the next big thing for transdermal drug delivery. Currently, in vivo experiments in rats have shown no negative side effects from this treatment. Nevertheless, more testing has to be done to prove the effectiveness and safety of this device.
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Shape Matters
Micro- and Nano-particles for targeted drug delivery
Professor Mitragotri's research lab has paved the way for a new tool in the design of nanoparticles for targeted drug delivery: Shape. Previous studies have shown that shape does have a direct effect on drug delivery. However, this area of research is relatively new and information continues to surface. Professor Mitragotri's group has pioneered much of this research in their quest to discover a new technique for improving drug delivery devices and nanoparticles.
New Shapes to revolutionize Drug Delivery
The figure to the left shows a couple of examples of the types of shapes that the Mitragotri lab has been successful in creating. The role of each shape is still being studied. However, it is clear that by changing the shape, the particles have different properties and will interact differently in their environment than spherical particles. The figure below shows shape-switching particles that can alternate between different shapes depending on numerous factors.
Yoo J.-W. andMitragotri S., “Designing Micro- and Nanoparticles for Treating Rheumatoid Arthritis”,Arch.Dermatol. Res., 34(11), 1887-1897, 2011.
For more information about Professor Mitragotri's research, please visit the Mitragotri Laboratory Webpage.
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Selected Publications
Yoo J.-W. andMitragotri S., “Designing Micro- and Nanoparticles for Treating Rheumatoid Arthritis”,Arch.Dermatol. Res., 34(11), 1887-1897, 2011.
Arora A, Itzhak H., Mitragotri S., "Needle-free delivery of macromolecules across the skin by nanoliter-volume pulsed microjets", PNAS., vol 104 (11), 2007.
Barua, S., Yoo J.-W., Wakankar, Y., Gokarn, Y., and Mitragotri S., “Particle Shape Enhances Specificity of Antibody-displaying Nanoparticles”, in revision
Kolhar P. and Mitragotri, S., “Size and Shape of Microparticles Impact their Localization around the Nucleus after Endocytosis”, Advanced Functional Materials, 28(12): 3759–3764, 2012
Kolhar, P., Doshi, N. and Mitragotri S., “Polymer Nano-needles for Intracellular Drug Delivery”, Small, 7(14):2094-100,2011.
Arora A, Itzhak H., Mitragotri S., "Needle-free delivery of macromolecules across the skin by nanoliter-volume pulsed microjets", PNAS., vol 104 (11), 2007.
Barua, S., Yoo J.-W., Wakankar, Y., Gokarn, Y., and Mitragotri S., “Particle Shape Enhances Specificity of Antibody-displaying Nanoparticles”, in revision
Kolhar P. and Mitragotri, S., “Size and Shape of Microparticles Impact their Localization around the Nucleus after Endocytosis”, Advanced Functional Materials, 28(12): 3759–3764, 2012
Kolhar, P., Doshi, N. and Mitragotri S., “Polymer Nano-needles for Intracellular Drug Delivery”, Small, 7(14):2094-100,2011.