In situ control of root-bacteria interactions using optical trapping in transparent soil.

Bacterial attachment on root surfaces is an important step preceding the colonization or internalization and subsequent infection of plants by pathogens. Unfortunately, bacterial attachment is not well understood because the phenomenon is difficult to observe. Here we assessed whether this limitation could be overcome using optical trapping approaches.

Plant-environment microscopy tracks interactions of with plant roots across the entire rhizosphere.

Our understanding of plant-microbe interactions in soil is limited by the difficulty of observing processes at the microscopic scale throughout plants' large volume of influence. Here, we present the development of three-dimensional live microscopy for resolving plant-microbe interactions across the environment of an entire seedling growing in a transparent soil in tailor-made mesocosms, maintaining physical conditions for the culture of both plants and microorganisms. A tailor-made, dual-illumination light sheet system acquired photons scattered from the plant while fluorescence emissions were simultaneously captured from transparent soil particles and labeled microorganisms, allowing the generation of quantitative data on samples ∼3,600 mm in size, with as good as 5 µm resolution at a rate of up to one scan every 30 min.

In situ laser manipulation of root tissues in transparent soil.

Aims: Laser micromanipulation such as dissection or optical trapping enables remote physical modification of the activity of tissues, cells and organelles. To date, applications of laser manipulation to plant roots grown in soil have been limited. Here, we show laser manipulation can be applied in situ when plant roots are grown in transparent soil.

In-vivo correlations between skin metabolic oscillations and vasomotion in wild-type mice and in a model of oxidative stress.

Arterioles in the cutaneous microcirculation frequently display an oscillatory phenomenon defined vasomotion, consistent with periodic diameter variations in the micro-vessels associated with particular physiological or abnormal conditions. The cellular mechanisms underlying vasomotion and its physiological role have not been completely elucidated. Various mechanisms were demonstrated, based on cell Ca oscillations determined by the activity of channels in the plasma membrane or sarcoplasmic reticulum of vascular cells.

Application of cmOCT and continuous wavelet transform analysis to the assessment of skin microcirculation dynamics.

Correlation mapping optical coherence tomography (cmOCT) is a powerful technique for the imaging of skin microvessels structure, based on the discrimination of the static and dynamic regions of the tissue. Although the suitability of cmOCT to visualize the microcirculation has been proved in humans and animal models, less evidence has been provided about its application to examine functional dynamics. Therefore, the goal of this research was validating the cmOCT method for the investigation into microvascular function and vasomotion.

In Vivo Recognition of Human Vascular Endothelial Growth Factor by Molecularly Imprinted Polymers.

One of the mechanisms responsible for cancer-induced increased blood supply in malignant neoplasms is the overexpression of vascular endothelial growth factor (VEGF). Several antibodies for VEGF targeting have been produced for both imaging and therapy. Molecularly imprinted polymer nanoparticles, nanoMIPs, however, offer significant advantages over antibodies, in particular in relation to improved stability, speed of design, cost and control over functionalization.

Polarised light sheet tomography.

The various benefits of light sheet microscopy have made it a widely used modality for capturing three-dimensional images. It is mostly used for fluorescence imaging, but recently another technique called light sheet tomography solely relying on scattering was presented. The method was successfully applied to imaging of plant roots in transparent soil, but is limited when it comes to more turbid samples.

Acoustic force mapping in a hybrid acoustic-optical micromanipulation device supporting high resolution optical imaging.

Many applications in the life-sciences demand non-contact manipulation tools for forceful but nevertheless delicate handling of various types of sample. Moreover, the system should support high-resolution optical imaging. Here we present a hybrid acoustic/optical manipulation system which utilizes a transparent transducer, making it compatible with high-NA imaging in a microfluidic environment.

Myosin-II-mediated cell shape changes and cell intercalation contribute to primitive streak formation.

Primitive streak formation in the chick embryo involves large-scale highly coordinated flows of more than 100,000 cells in the epiblast. These large-scale tissue flows and deformations can be correlated with specific anisotropic cell behaviours in the forming mesendoderm through a combination of light-sheet microscopy and computational analysis. Relevant behaviours include apical contraction, elongation along the apical-basal axis followed by ingression, and asynchronous directional cell intercalation of small groups of mesendoderm cells.

Acoustic tractor beam.

Negative radiation forces act opposite to the direction of propagation, or net momentum, of a beam but have previously been challenging to definitively demonstrate. We report an experimental acoustic tractor beam generated by an ultrasonic array operating on macroscopic targets (>1 cm) to demonstrate the negative radiation forces and to map out regimes over which they dominate, which we compare to simulations. The result and the geometrically simple configuration show that the effect is due to nonconservative forces, produced by redirection of a momentum flux from the angled sides of a target and not by conservative forces from a potential energy gradient.

Optically transparent piezoelectric transducer for ultrasonic particle manipulation.

We report an optically transparent ultrasonic device, consisting of indium-tin-oxide-coated lithium niobate (LNO), for use in particle manipulation. This device shows good transparency in the visible and near-infrared wavelengths and, acoustically, compares favorably with conventional prototype devices with silver electrodes.

Light Sheet Tomography (LST) for in situ imaging of plant roots.

The production of crops capable of efficient nutrient use is essential for addressing the problem of global food security. The ability of a plant's root system to interact with the soil micro-environment determines how effectively it can extract water and nutrients. In order to assess this ability and develop the fast and cost effective phenotyping techniques which are needed to establish efficient root systems, in situ imaging in soil is required.

Mechanical evidence of the orbital angular momentum to energy ratio of vortex beams.

We measure, in a single experiment, both the radiation pressure and the torque due to a wide variety of propagating acoustic vortex beams. The results validate, for the first time directly, the theoretically predicted ratio of the orbital angular momentum to linear momentum in a propagating beam. We experimentally determine this ratio using simultaneous measurements of both the levitation force and the torque on an acoustic absorber exerted by a broad range of helical ultrasonic beams produced by a 1000-element matrix transducer array.

The importance of physics to progress in medical treatment.

Physics in therapy is as diverse as it is substantial. In this review, we highlight the role of physics--occasionally transitioning into engineering--through discussion of several established and emerging treatments. We specifically address minimal access surgery, ultrasound, photonics, and interventional MRI, identifying areas in which complementarity is being exploited.

A water-soluble temperature nanoprobe based on a multimodal magnetic-luminescent nanocolloid.

This communication demonstrates that hybrid nanocolloids can be designed and used to create nanoprobes for remotely sensing the temperature of aqueous media. Such multi-modal nanocolloids combine development opportunities not only for multimodal magnetic-optical imaging but also for non-invasive and remote absolute temperature optical monitoring suitable for hyperthermia treatments and cell poration.

Cellular and colloidal separation using optical forces.

The separation or sorting of cellular and colloidal particles is currently a central topics of research. In this chapter, we give an overview of the range of optical methods for cell sorting. We begin with an overview of fluorescence and magnetically activated cell sorting.

All-optical control of microfluidic components using form birefringence.

The reflection and refraction of light at a dielectric interface gives rise to forces due to changes in the photon momentum. At the microscopic level, these forces are sufficient to trap and rotate microscopic objects. Such forces may have a profound impact in the emergent area of microfluidics, where there is the desire to process minimal amounts of analyte.