Optical characterization of an individual polymer-shelled microbubble structure via digital holography

Saglimbeni, Filippo; Bianchi, S.; Bolognesi, Guido; Paradossi, Gaio; Leonardo, R. Di

doi:10.1039/c2sm26099a

Cited by 19 publications

(13 citation statements)

References 32 publications

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“…In this way, it was possible to derive a more rigorous analytical expression that could fit our experimental results. As reported in Section 4.2, the shell thickness values provided using this model fall between 200 nm and 400 nm, in striking similarity with existing literature [12,27,40,41]. Interestingly enough, the comparison with the linearized Hoff model shows that the viscoelastic values are not affected significantly by the thin shell approximation except for t (see Fig.…”

Section: Acoustic Attenuation Modelsupporting

confidence: 85%

“…The average outer diameter and the standard deviation were determined for each ageing day, analysed on a population of ∼200 MBs using the Nikon software EZ-C1 (version 3.9). The effect of ageing on the shell thickness t, which is independent of the MB radius R o as previously reported [27], was also estimated by comparative analysis of the fluorescence intensity spatial profiles acquired on the newer (day 15) and the older (day 75) MB populations (see Fig. S3).…”

Section: Optical Microscopymentioning

confidence: 94%

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Long-term physical evolution of an elastomeric ultrasound contrast microbubble

Domenici

Brasili

Oddo

et al. 2019

Journal of Colloid and Interface Science

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Hypothesis One of the main assets of crosslinked polymer-shelled microbubbles (MBs) as ultrasound-active theranostic agents is the robustness of the shells, combined with the chemical versatility in modifying the surface with ligands and/or drugs. Despite the long shelf-life, subtle modifications occur in the MB shells involving shifts in acoustic, mechanical and structural properties. Experiments We carried out a long-term morphological and acoustic evolution analysis on elastomeric polyvinyl-alcohol (PVA)-shelled MBs, a novel platform accomplishing good acoustic and surface performances in one agent. Confocal laser scanning microscopy, acoustic spectroscopy and AFM nanomechanics were integrated to understand the mechanism of PVA MBs ageing. The changes in the MB acoustic properties were framed in terms of shell thickness and viscoelasticity using a linearised oscillation theory, and compared to MB morphology and to nanomechanical analysis. Findings We enlightened a novel, intriguing ageing time evolution of the PVA MBs with double behaviour with respect to a crossover time of ∼50 days. Before, significant changes occur in MB stiffness and shell thickness, mainly due to a massive release of entangled PVA chains. Then, the MB resonance frequency increases together with shell thickening and softening. Our benchmark study is of general interest for emerging viscoelastomeric bubbles towards personalised medicine.

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Section: Acoustic Attenuation Modelsupporting

confidence: 85%

Section: Optical Microscopymentioning

confidence: 94%

Long-term physical evolution of an elastomeric ultrasound contrast microbubble

Domenici

Brasili

Oddo

et al. 2019

Journal of Colloid and Interface Science

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“…24,25 The MBs used in the present study were designed as a contrast agent based on poly(vinyl alcohol) (PVA) macromeres. 26 The macromeres are cross-linked by acetalization, thereby forming spheres containing air with a polymer shell thickness ranging between 0.2 m and 0.5 m. 27 Magnetic nanoparticles, i.e., SPION, can be embedded into the polymer shell of the MBs to enable their use as a dual modality imaging agent for both ultrasound and MR imaging. [24][25][26] The incorporation of SPION into MBs reduces the signal intensity on T2 and T2* weighted images due to a faster spin-spin relaxation rate (R2*) of the water molecules surrounding the SPION MBs.…”

Section: Introductionmentioning

confidence: 99%

Dynamic MR Imaging, Biodistribution and Pharmacokinetics of Polymer Shelled Microbubbles Containing Spion

Barrefelt

Paradossi

Asem

et al. 2014

NANO

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Magnetic Resonance Imaging (MRI) is a noninvasive diagnostic method that provides information on morphological and physiological changes of the internal organs over time. Imaging and measurements can be repeated on the same subject, thereby reducing inter-individual variability effects and hence the number of subjects required. A potential MRI contrast agent consisting of microbubbles embedded with superparamagnetic iron oxide nanoparticles (SPION) in the shell (SPION MBs) was injected intravenously into rats to determine their biodistribution and pharmacokinetics using MR imaging. Agarose phantoms containing SPION MBs were scanned using 3 T MRI to construct a standard curve. Rats were injected with SPION MBs, free SPION or plain MBs and scanned dynamically at 3 T using a clinical MR scanner. The relaxation rate (R2*) was studied over time as a measure of the iron oxide concentrations to enable calculation of the pharmacokinetic parameters. The kinetics of SPION MBs in the liver was fitted to a one-compartment model. Furthermore, the biological fate of SPION MBs was examined via a histological survey of tissue samples using Perls' Prussian blue staining and immunohistochemistry (IHC). 1.2 h after injection of SPION MBs, T2* of the liver had decreased to its minimum. The elimination half-life of SPION MBs was 598.2 ± 97.3 h, while the half-life for SPION was 222.6 ± 26.4 h. Moreover, our study showed that SPION MBs were taken up by the macrophages in the lungs, spleen and liver. MBs labeled with SPION can be used for MR imaging. Moreover, MRI is a reliable and noninvasive tool that can be utilized in pharmacokinetic investigations of future contrast agents using SPION MBs and SPION in the rat.

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“…Since our particles are dispersed in water, instead of fitting n w , we use the values in [18] for water refractive index as a function of pressure. The fitting procedure requires the calculation of a few hundreds holograms of 124 × 124 pixels, thus we exploited the computational power of a CUDA based graphic processing unit (GTX-470) in order to speed-up the computation [19,20]. The limited numerical aperture of our objective (NA=0.3) prevents the light scattered at an angle larger than arcsin(NA) to be observed.…”

Section: Methodsmentioning

confidence: 99%

Holographic tracking and sizing of optically trapped microprobes in diamond anvil cells

et al. 2016

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We demonstrate that Digital Holographic Microscopy can be used for accurate 3D tracking and sizing of a colloidal probe trapped in a diamond anvil cell (DAC). Polystyrene beads were optically trapped in water up to Gigapascal pressures while simultaneously recording in-line holograms at 1 KHz frame rate. Using Lorenz-Mie scattering theory to fit interference patterns, we detected a 10% shrinking in the bead's radius due to the high applied pressure. Accurate bead sizing is crucial for obtaining reliable viscosity measurements and provides a convenient optical tool for the determination of the bulk modulus of probe material. Our technique may provide a new method for pressure measurements inside a DAC.

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Optical characterization of an individual polymer-shelled microbubble structure via digital holography

Cited by 19 publications

References 32 publications

Long-term physical evolution of an elastomeric ultrasound contrast microbubble

Long-term physical evolution of an elastomeric ultrasound contrast microbubble

Dynamic MR Imaging, Biodistribution and Pharmacokinetics of Polymer Shelled Microbubbles Containing Spion

Holographic tracking and sizing of optically trapped microprobes in diamond anvil cells

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