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Optomechanical crystals for spatial sensing of submicron sized particles.

ABSTRACT: Optomechanical crystal cavities (OMC) have rich perspectives for detecting and indirectly analysing biological particles, such as proteins, bacteria and viruses. In this work we demonstrate the working principle of OMCs operating under ambient conditions as a sensor of submicrometer particles by optically monitoring the frequency shift of thermally activated mechanical modes. The resonator has been specifically designed so that the cavity region supports a particular family of low modal-volume mechanical modes, commonly known as -pinch modes-. These involve the oscillation of only a couple of adjacent cavity cells that are relatively insensitive to perturbations in other parts of the resonator. The eigenfrequency of these modes decreases as the deformation is localized closer to the centre of the resonator. Thus, by identifying specific modes that undergo a frequency shift that amply exceeds the mechanical linewidth, it is possible to infer if there are particles deposited on the resonator, how many are there and their approximate position within the cavity region. OMCs have rich perspectives for detecting and indirectly analysing biological particles, such as proteins, viruses and bacteria.

SUBMITTER: Navarro-Urrios D

PROVIDER: S-EPMC8035185 | biostudies-literature | 2021 Apr

REPOSITORIES: biostudies-literature

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Optomechanical crystals for spatial sensing of submicron sized particles.

Navarro-Urrios D D Kang E E Xiao P P Colombano M F MF Arregui G G Graczykowski B B Capuj N E NE Sledzinska M M Sotomayor-Torres C M CM Fytas G G

Scientific reports 20210409 1

Optomechanical crystal cavities (OMC) have rich perspectives for detecting and indirectly analysing biological particles, such as proteins, bacteria and viruses. In this work we demonstrate the working principle of OMCs operating under ambient conditions as a sensor of submicrometer particles by optically monitoring the frequency shift of thermally activated mechanical modes. The resonator has been specifically designed so that the cavity region supports a particular family of low modal-volume m ...[more]

PMID: 33837262

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Project description:BackgroundNanoparticle (NP) toxicity testing comes with many challenges. Characterization of the test substance is of crucial importance and in the case of NPs, agglomeration/aggregation state in physiological media needs to be considered. In this study, we have addressed the effect of agglomerated versus single particle suspensions of nano- and submicron sized gold on the inflammatory response in the lung. Rats were exposed to a single dose of 1.6 mg/kg body weight (bw) of spherical gold particles with geometric diameters of 50 nm or 250 nm diluted either by ultrapure water or by adding phosphate buffered saline (PBS). A single dose of 1.6 mg/kg bw DQ12 quartz was used as a positive control for pulmonary inflammation. Extensive characterization of the particle suspensions has been performed by determining the zetapotential, pH, gold concentration and particle size distribution. Primary particle size and particle purity has been verified using transmission electron microscopy (TEM) techniques. Pulmonary inflammation (total cell number, differential cell count and pro-inflammatory cytokines), cell damage (total protein and albumin) and cytotoxicity (alkaline phosphatase and lactate dehydrogenase) were determined in bronchoalveolar lavage fluid (BALF) and acute systemic effects in blood (total cell number, differential cell counts, fibrinogen and C-reactive protein) 3 and 24 hours post exposure. Uptake of gold particles in alveolar macrophages has been determined by TEM.ResultsParticles diluted in ultrapure water are well dispersed, while agglomerates are formed when diluting in PBS. The particle size of the 50 nm particles was confirmed, while the 250 nm particles appear to be 200 nm using tracking analysis and 210 nm using TEM. No major differences in pulmonary and systemic toxicity markers were observed after instillation of agglomerated versus single gold particles of different sizes. Both agglomerated as well as single nanoparticles were taken up by macrophages.ConclusionPrimary particle size, gold concentration and particle purity are important features to check, since these characteristics may deviate from the manufacturer's description. Suspensions of well dispersed 50 nm and 250 nm particles as well as their agglomerates produced very mild pulmonary inflammation at the same mass based dose. We conclude that single 50 nm gold particles do not pose a greater acute hazard than their agglomerates or slightly larger gold particles when using pulmonary inflammation as a marker for toxicity.

Project description:Flow cytometry allows multiparameter analysis on a single-cell basis and is currently the method of choice to rapidly assess heterogeneity of cell populations in suspension. With the research field of extracellular vesicles (EV) rapidly expanding, there is an increased demand to address heterogeneity of EV populations in biological samples. Although flow cytometry would be the ideal technique to do so, the available instruments are in general not equipped to optimally detect the dim light scatter signals generated by submicron-sized particles like EV. Although sideward scatter light and fluorescence are currently used as a threshold signal to identify EV within samples, the forward scatter light (FSC) parameter is often neglected due to the lack of resolution to distinguish EV-related signals from noise. However, after optimization of FSC detection by adjusting the size of the obscuration bar, we recently showed that certain EV-subsets could only be identified based on FSC. This observation made us to further study the possibilities to enhance FSC-detection of submicron-sized particles. By testing differently sized obscuration bars and differently sized pinholes in the focal plane behind the FSC detection lens, we generated a matrix that allowed us to determine which combination resulted in the lowest optical background in terms of numbers of events regarding FSC detection of submicron-sized particles. We found that a combination of an 8-mm obscuration bar and a 200-μm pinhole reduced optical background in a reproducible manner to such extent that it allowed a robust separation of 100-nm polystyrene beads from background signals within the FSC channel, and even allowed thresholding on FSC without the interference of massive background signals when both beads and EV were measured. These technical adaptations thus significantly improved FSC detection of submicron-sized particles and provide an important lead for the further development and design of flow cytometers that aid in detection of submicron-sized particles. © 2020 The Authors. Cytometry Part A published by Wiley Periodicals, Inc. on behalf of International Society for Advancement of Cytometry.

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Optomechanical crystals for spatial sensing of submicron sized particles.

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Optomechanical crystals for spatial sensing of submicron sized particles.

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