Rach Dixon (soon to be Dr Dixon officially) successfully defended her PhD thesis. The title of her thesis was Development of a Minimally Invasive Microneedle Immunosensor to Detect Biomarkers in the Skin.
Congratulations, Rach!
Rach’s work has brought many firsts to our group, including a new microfabrication technique and a new signal detection platform. It’s been a pleasure working with her and we are utterly delighted for her success.
The examiners were Dr Al Edwards (University of Southampton) and Dr Neil Keegan (Newcastle University). The examination was chaired by Professor Sarah Slight. We thank them for conducting a smooth PhD examination. Thanks also to the administrative staff involved in organising it.
Keng has published a new paper out with Dr Othman Al Musaimi and co-workers. In this paper, we report the development of a self-assembling hydrogel formulation based on peptide sequences derived from elastin.
Elastin is a naturally occurring protein found in many connective tissues in the body, including the skin and blood vessels. These peptide sequences have been selected carefully to promote self-assembly of the hydrogels and confer the desired mechanical properties to the hydrogel. This hydrogel can be an interesting drug delivery system. The ability for the hydrogel to self-assemble at room temperature makes it easier to incorporate drugs into the hydrogel matrix. The mechanical properties will determine the rate at which the drugs can then be released from the hydrogel.
The paper is open access and free to read, so head over there now to read the full text for free.
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).
Don’t get me wrong, we do socialise daily, but we don’t document it the way we document our experiments meticulously. So, before people start to disappear for their summer breaks, Wing had the brilliant idea of a lab photo and a meal together.
It was a shame that we couldn’t get everyone in one photo, but people deserve to take their holidays when they want them! So, we gathered up the boffins on two separate occasions and collected photographic evidence of them in full PPE (personal protective equipment, for the uninitiated), thoroughly committed to their research and enjoying it. We then headed off for a meal and a afternoon chat filled with laughter, talking mostly about ‘safe hobbies’.
We test our microneedles a lot to examine how they fail. The most common technique we use to quantify the mechanical strength of the microneedles is by applying axial compression (crushing the microneedles from the tip towards the base) on a texture analyser, and pinpointing the minimum force that results in microneedle failure. We’re fortunate that our lab is well equipped to perform these tests. We get a live video feed of what’s happening to each microneedle as it’s being compressed. We can also playback the videos and analyse them synchronously with the force-displacement data. This technique has proved invaluable in making sure our microneedles perform as they should.
Hence, when Dr Choon Fu Goh invited me (Keng) to contribute to this paper on the mechanical testing of microneedle strength, I jumped at the opportunity. This is our first paper together and I really enjoyed working on this. I hope the microneedle community finds it useful.
Bohan Zhou, who spent several weeks as a research intern in our lab last year, has rejoined us to study a PhD in microneedle biosensing. We have a very interesting project lined up. Welcome back, Bohan!
Many congratulations to Grace Young who has passed her PhD viva – without corrections, I might add. This is an incredible feat. Congratulations, Dr Young! This is very well deserved.
Grace was supervised by Dr Wing Man Lau, Professor Nick Jakubovics and myself. The title of her thesis is “Development of a novel antimicrobial and drug delivery strategy to combat biofilm”.
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.
I was at the APS PharmSci conference in Reading. The veterans among us may remember the British Pharmaceutical Conference many, many years ago. That morphed into the APS PharmSci conference, which remains one of the major pharmaceutical science conferences to this day.
Of course I didn’t go there empty-handed. Our group presented two posters—one on a microneedle fabrication method (by Emma), the other on an impedimetric microneedle immunosensor (by Rach).
You can’t say that about many things nowadays, but the conference was both informative and enjoyable. There were many talks on 3D printing, which is a current passion of mine. It was also great to catch up with many old friends, colleagues and mentors, whom I had missed since moving away from Reading. I have only two regrets: I couldn’t attend the parallel sessions simultaneously, and I didn’t take enough photos. I did manage one tweet, and I deem that a notable achievement.
