Hydrogels are a popular drug delivery vehicle. You can encapsulate drugs including large biological macromolecules like proteins in them, to be released in the body. Some hydrogels use chemical crosslinking to create the hydrogel matrix – with the drug in it. Can protein drugs encapsulated this way participate in those crosslinks? What if they do? How will that affect their subsequent release?
We started asking these questions when attempting to deliver protein drugs by encapsulating them in hydrogel-forming microneedle array patches. These were important questions, and now we have the answers.
In this paper, we address these questions using bovine serum albumin as a model drug, and a genipin-chitosan hydrogel as the drug delivery vehicle. Using a combination of empirical fluorometry data and mathematical modelling, we investigate the kinetics of the interactions of the protein drug and genipin (the crosslinker).
Our hands-free, ‘vac-and-fill’ micromoulding technique prevented air entrapment and bubble formation in viscous formulations when degassed under vacuum. Image from Smith E, et al. Int J Pharm 2024;650:123706. Licence: CC BY 4.0 Deed.
This paper reports the solution to a problem that took us several months to solve. We were trying to mould a microneedle array patch. There are basically two ways to do it: you fill the mould with the liquid formulation and either centrifuge it or degas it under vacuum. Both techniques are widely reported in the literature. They have been designed to force any air out of the microcavities in the mould, so that the formulation can enter them to form the microneedles. We didn’t have the right rotor to go with the centrifuge, so we opted for the vacuum degassing technique, fully expecting it to be a walk in the park. What a disappointment that turned out to be! We discovered that our formulation was too viscous to allow the air to escape. We ended up with a lot of air bubbles trapped in the liquid formulation.
We quickly realised that the vacuum degassing technique reported in the literature had used low polymer concentrations, which meant that their liquid formulations were not as viscous as ours. To micromould the microneedle array patch successfully from our viscous formulation, we had to remove the air first before filling the formulation into the mould. But how would one fill the mould under vacuum?
The answer: a modified syringe, a 3D-printed part, some painstaking calibration, and viola! The paper describes our solution in full, but here’s a peek of the contraption in action.
This is Emma’s first paper and our first together with Dr Katarina Novakovic‘s group. Congratulations, Emma, and thank you team for the hard work!
2023 seemingly left in a haste. Stepping into 2024, we welcomed our collaborators from The Hong Kong Polytechnic University (PolyU) to Newcastle, to conduct a joint study on microneedle formulation for drug delivery and diagnostics. Merab Naveed, Hubert Chan and Dr Thomas Lee from PolyU’s Biomedical Engineering Department spent nearly two weeks with us, running experiments and exchanging ideas with us. Newcastle University students, Begho Obale and Jakub Masloch, who completed their MPharm research projects with us, also lent their expertise to this joint study. Among other things, Begho made a dancing microneedle mould – the first ever reported. It was a most wonderful way to start the new year.
So how did our guests find it? I know Hubert enjoyed the unique learning experience – his words, not mine. I’m really pleased that we’re able to organise this research exchange programme. Thanks also go to Dr Wing Man Lau and Dr Hin Chung Lau of PolyU, the other two academic advisors on the project, for making this happen.
We’re pleased to announce that a PhD studentship is now available in our laboratory and open for applications. The PhD studentship, generously funded by the EPSRC, will fund the tuition fees, living expenses (stipend) and research support (e.g. consumables) for one PhD student for 3.5 years. The student will work under the guidance of Keng, Wing and Katarina to develop a microimplant for drug delivery.
Interested candidates should apply online by following any one of the links below, which also contain full details of the studentship:
Just as we were about to wind down our lab operations for Christmas, we welcomed postdoctoral research associate, Dr Hassan Elsana, into our team this week. Hassan will be working on an EPSRC-funded project researching microneedle-mediated drug delivery in the skin.
This project is a collaboration with Dr Wing Man Lau (School of Pharmacy) and Dr Katarina Novakovic (School of Engineering). We have high hopes for this project.
Exciting times ahead, and I don’t just mean Christmas!
There are currently a couple of PhD studentships available within the pharmaceutics team at the School of Pharmacy, Newcastle University. Please click through the following links to find out more:
