Co-electrospraying of tumour cell mimicking hollow polymeric microspheres for diffusion magnetic resonance imaging

Abstract

Diffusion magnetic resonance imaging (dMRI) is considered as a useful tool to study solid tumours. However, the interpretation of dMRI signal and validation of quantitative measurements of is challenging. One way to address these challenges is by using a standard reference material that can mimic tumour cell microstructure. There is a growing interest in using hollow polymeric microspheres, mainly prepared by multiple steps, as mimics of cells in healthy and diseased tissue. The present work reports on tumour cell-mimicking materials composed of hollow microspheres for application as a standard material in dMRI. These microspheres were prepared via one-step co-electrospraying process. The shell material was poly(D,L-lactic-co-glycolic acid) (PLGA) polymers with different molecule weights and/or ratios of glycolic acid-to-lactic, while the core was polyethylene glycol (PEG) or ethylene glycol. The resultant co-electrosprayed products were characterised by optical microscopy, scanning electron microscopy (SEM) and synchrotron X-ray micro-CT. These products were found to have variable structures and morphologies, e.g. from spherical particles with/without surface hole, through beaded fibres to smooth fibres, which mainly depend on PLGA composition and core materials. Only the shell material of PLGA polymer with ester terminated, Mw 50,000-75,000 g mol-1, and lactide:glycolide 85:15 formed hollow microspheres via the co-electrospraying process using the core material of 8 wt.% PEG/chloroform as the core. A water-filled test object (or phantom) was designed and constructed from samples of the material generated from co-electrosprayed PLGA microspheres and tested on a 7 tesla MRI scanner. The preliminary MRI results provide evidence that hollow PLGA microspheres can restrict/hinder water diffusion as cells do in tumour tissue, implying that the phantom may be suitable for use as a quantitative validation and calibration tool for dMRI.

Fabrication and Characterisation of Stimuli Responsive Piezoelectric PVDF and Hydroxyapatite-Filled PVDF Fibrous Membranes

“…Apparent water-in-air contact angle measurements showed no significant difference in wettability between the pre-conditioned scaffolds (treated overnight with cell culture media) and untreated SBS fibre membranes. All fibrous membranes exhibited hydrophobic character with contact angle values >90° [41,49]; untreated SBS fibre membranes had a higher average contact angle of ~113°, in comparison to the trend observed for ES membranes and all treated membranes (Figure 3a). The contact angle values of ~100° observed for treated samples were lower than that of the non-treated fibre groups (Figure 3a.).…”

“…Electrospinning (ES) was conducted on both medium and high molecular weight PVDF using the mixed solvent between 16% and 21% w / v (polymer mass to solvent volume) in an effort to produce sub-micron and micron-sized PVDF fibres. The ES equipment used was similar to the one previously described [49]; polymer solutions were injected through a blunt stainless steel 21G needle with the positive electrode attached. Concentrations above 21% w / v lead to interrupted spinning and gelification of the precursor solution at the needle tip and were not investigated.…”

Rapid One-Step Fabrication of Graphene Oxide-Decorated Polycaprolactone Three-Dimensional Templates for Water Treatment

“…The possibility to obtain well-orchestrated polymeric architectures represents an emerging field of materials science for the development of advanced materials, including drug delivery devices, mimics of biological tissues, nanoreactors, and multifunctional coatings. − Dry jet-wet electrospinning (or electrospraying) is one of the most promising techniques to fabricate 3D scaffolds, along with centrifugal spinning and pressurized gyration . In fact, beyond the rapidity of the process, this approach provides accuracy in size control and tunable surface morphologies, including surface roughness and wettability, by adjusting process parameters .…”

Pore size estimation in axon‐mimicking microfibers with diffusion‐relaxation MRI

“…It is important to mention that this is not the first study using phantoms of hollow axon-mimicking fibers. Similar phantoms built with the co-electrospinning technique 45,[56][57][58] have been used previously to validate other dMRI techniques, including diffusion tensor imaging and fiber tracking, 45,59 microscopic fractional anisotropy using q-space trajectory encoding, 60 anomalous diffusion, 61 estimation of pore sizes in tumor tissue phantoms, 62,63 as well as to investigate the stability and reproducibility of various dMRI-derived parameters, 64 the validation of multidimensional dMRI sequences with modulated gradients, 65 and to estimate pore sizes in similar complex microfiber environments using multi-shell dMRI. 47 This study has some limitations.…”