Exploring the influence of silicon oxide microchips shape on cellular uptake using imaging flow cytometry

particles plays a vital role in their biodistribution and their interaction with cells. However, analysing how microparticles

are taken up by cells presents methodological challenges. Qualitative methods like microscopy provide detailed imaging

but are time-consuming, whereas quantitative methods such as flow cytometry enable high-throughput analysis but struggle

to differentiate between internalised and surface-bound particles. Instead, imaging flow cytometry combines the best of

both worlds, offering high-resolution imaging with the efficiency of flow cytometry, allowing for quantitative analysis at the

single-cell level. This study focuses on fluorescently labelled silicon oxide microchips of various morphologies but related

surface areas and volumes: rectangular cuboids and apex-truncated square pyramid microchips fabricated using photolithography

techniques, offering a reliable basis for comparison with the more commonly studied spherical particles. Imaging

flow cytometry was utilised to evaluate the effect of particle shape on cellular uptake using RAW 264.7 cells and revealed

phagocytosis of particles with all shapes. Increasing the particle dose enhanced the uptake, while macrophage stimulation had

minimal effect. Using a ratio particle:cell of 10:1 cuboids and spheres showed an uptake rate of approximately 50%, in terms

of the percentage of cells with internalised particles, and the average number of particles taken up per cell ranging from about

1–1.5 particle/cell for all the different shapes. This study indicates how differently shaped micro-carriers offer insights into

particle uptake variations, demonstrating the potential of non-spherical micro-carriers for precise drug delivery applications.