Preface to Special Topic: Microfluidics in Drug Delivery |
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| Authors: | Brigitte Stadler |
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| Institution: | Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus, Denmark |
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| Abstract: | In this special topic of Biomicrofluidics, the importance of microfluidics in the field of drug delivery is highlighted. Different aspects from cell-drug carrier interactions, delivery vehicle assembly to novel drug delivery devices are considered. The contributing reviews and original articles illustrate the synergistic outcomes between these two areas of research with the aim to have a positive impact on biomedical applications.Microfluidics is certainly one of the huge success stories when it comes to anticipated impact and fulfilled promises in academic research environments. Microfluidic approaches are game changers in many disciplines in natural science, including (bio)medical science. In the latter case, the fields of biosensing/diagnostics, tissue engineering, and drug discovery/delivery have benefited from concepts which allow for the fast throughput manipulation of fluids at the submillimeter length scale.A key aim in microfluidic-assisted drug discovery is the development of strategies which will facilitate the identification of potential “hits”—new drugs with the anticipated therapeutic benefit. In this context, “organ(disease)-on-chips” are considered as highly sophisticated in vitro models with lower cost and less ethical issues compared to extensive testing in animals. This technology is still very young with countless research challenges to be addressed and eventually overcome, but the few current reports are promising, and include “gut-on-chip,” “cancer-on-chip,” or “blood vessel-on-chip.” Additionally, intravenously injected drug delivery vehicles are exposed to the blood stream and the induced mechanical forces which are likely to affect their interaction with cells and tissue. Therefore, understanding the diffusion phenomena of biomolecules in microfluidic devices as reviewed by Yesil-Celiktas and coworkers in the current special content is crucial.1 What is more, the contribution by Hosta-Rigau and colleagues provides a comprehensive overview over the interaction of drug carriers and cells in microfluidic-based systems which deliver a simple, but yet more realistic model of the dynamic in vivo situation.2 Further, to illustrate the relevance of shear stress when assessing the potential of nanocarriers for drug delivery applications, we assembled novel block copolymers consisting of poly(cholesteryl acrylate) as the hydrophobic core and poly(N-isopropylacrylamide) as the hydrophilic extensions together with lipids into vesicles using the evaporation-rehydration method.3 Following on, we biologically evaluated the assemblies with applied shear stress using macrophages. In a related report by the Chakraborty group, a biocompatible acoustic microfluidic system was outlined including the effect of microbubbles with the applied acoustic field on biological cells.4From a different perspective, droplet microfluidics has become a popular method to assemble a huge diversity of particles of different size, shape, and morphology equipped with options for active or passive drug release. Microfluidics provides unique opportunities and flexibility to fabricate decent amounts of mono-disperse drug carriers using monomers, polymers, lipids, or inorganic precursor materials as building blocks. The assembly of size-tunable polymer/lipid particles by Sun et al.,5 and the fabrication of poly (lactic-co-glycolic acid) nanoparticles incorporated within poly (ethylene glycol) (PEG) microgels by the Chen group,6 provide interesting examples in this context. Further, artefacts associated with this technique have to be addressed and understood to avoid inaccurate and misleading data as reported by Litten et al.7 Microfluidic techniques can also be employed for cell encapsulation. Fan et al. demonstrated the trapping of human colon cancer cells in hydrogel particles with preserved viability and response to inflammatory stimuli.8Novel drug delivery devices which consider microfluidic concepts and set-ups are an interesting addition to traditional approaches. Implantable drug delivery systems provide an alternative to ensure constant drug level in blood without relying on the compliance of the patient while circumventing challenges involved in oral drug delivery coming from drug instability or limited absorbance among others. Yi and coworkers propose a reservoir approach in combination with a heat responsive valve towards the long term delivery of solid drugs.9 What is more, nebulizers, as alternative to inhalers for pulmonary drug delivery, suffer from miniaturization and drug degradation issues. Cortez-Jugo et al. report on a novel portable acoustomicrofluidic device, which successfully nebulized monoclonal antibodies into a fine aerosol mist including the first positive biological evaluation.10Further, combining microfluidics with sensing concepts as illustrated by Knoll and coworker11 is of importance, since the design of drug delivery vehicles strongly relies on the fundamental understanding of the interaction between biomolecules, cells, and tissue.Taken together, these articles give an overview over the use of microfluidics in the area of drug delivery, which goes beyond the assembly of drug carries, but also provides a platform for their biological evaluation or the design of entirely new drug delivery devices. I hope that this collection of articles will stimulate new ideas and future collaborations between engineers/chemists/physicist and biologists towards the common goal to provide solutions for biomedical challenges. Finally, I would like to thank Professor Leslie Yeo for the invitation to be the guest editor for this special topic, and Christine Urso and other editorial and production staffs of Biomicrofluidics for making it a reality. |
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