Skeletal muscle cells opto-stimulation by intramembrane molecular transducers

Optical stimulation and control of muscle cell contraction opens up a number of interesting applications in hybrid robotic and medicine. Here we show that recently designed molecular phototransducer can be used to stimulate C2C12 skeletal muscle cells, properly grown to exhibit collective behaviour. C2C12 is a skeletal muscle cell line that does not require animal sacrifice Furthermore, it is an ideal cell model for evaluating the phototransducer pacing ability due to its negligible spontaneous activity. We study the stimulation process and analyse the distribution of responses in multinuclear cells, in particular looking at the consistency between stimulus and contraction. Contractions are detected by using an imaging software for object recognition. We find a deterministic response to light stimuli, yet with a certain distribution of erratic behaviour that is quantified and correlated to light intensity or stimulation frequency. Finally, we compare our optical stimulation with electrical stimulation showing advantages of the optical approach, like the reduced cell stress.A study on the stimulation of cells with light, thanks to a photochromic molecule, called Ziapin2. It shows the difference between the light stimulation and the electrical stimulation in terms of cell viability and performance

Ultrafast photochromism and bacteriochromism in one dimensional hybrid plasmonic photonic structures

Hybrid plasmonic photonic structures combine the plasmonic response with the photonic band gap, holding promise for utilization as optical switches and sensors. Here, we demonstrate the active modulation of the optical response in such structures with two different external stimuli, e.g. laser pulses and bacteria. First, we report the fabrication of a miniaturized (5 x 5 mm) indium tin oxide (ITO) grating employing femtosecond laser micromachining, and we show the possibility to modulate the photonic band gap in the visible via ultrafast photoexcitation in the infrared part of the spectrum. Note that the demonstrated time response in the picosecond range of the spectral modulation have an industrial relevance. Moreover, we manufacture one-dimensional photonic crystals consisting of a solution-processed dielectric Bragg stack exposing a top-layer of bio-active silver. We assign the bacterial responsivity of the system to polarization charges at the Ag/bacterium interface, giving rise to an overall blue shift of the photonic band gap.Comment: 7 pages, 4 figure

Simplified 3D hydrodynamic flow focusing for lab-on-chip single particle study

Abstract Accurately control of the position of a fluid and particle within lab-on-a-chip platform is a critical prerequisite for many downstream analysis processes, such as detection, trapping and separation, moving the sensing at the single-particle level. With the development of microfluidic fabrication technology, particle/cell focusing has shifted from two to three dimensions. 3D hydrodynamic focusing, which sorts and aligns the incoming cloud of particles so that they pass through the interrogation area one by one, enables new possibilities and breakthroughs in the single-cell analysis system. Despite the excellent results shown in literature, there is still a lack of a device that can simultaneously fulfilling the requirements of high throughput, compactness, high integrability, and ease of use operation to become a widely accepted work center for biomedical research and clinical applications. Here, we proposed a unique 3D flow focusing microfluidic device buried in fused silica substrate that potentially combines all this advantages. By designing a sample channel suspended inside a larger buffer channel, manufactured by exploiting the laser-assisted micromachine technique, a not size-dependent focusing capability is shown. A spatially and temporally stable central flow of a mixture of 15 μm and 6 μm PS particles to a 1 μm PS microsphere solution has been obtained with high accuracy. Finally, to test the achievable focusing resolution, the chip was tested for the detection of Escherichia Coli bacteria in water solution as proof of concept of biological application

Large scale indium tin oxide (ITO) one dimensional gratings for ultrafast signal modulation in the visible spectral region

Indium tin oxide (ITO) is a heavily doped semiconductor with a plasmonic response in the near infrared region. When exposed to light, the distribution of conduction band electron induces a change in the real and imaginary parts of the dielectric permittivity. The coupling of the electromagnetic waves with the electrons in the conduction band of metallic nanostructures with ultrashort light pulses results in a nonlinear plasmonic response. Such optical modulation occurring on ultrafast time scales, e.g. picosecond response times, can be exploited and used to create integrated optical components with terahertz modulation speed. Here, we present a photophysical study on a one dimensional ITO grating, realized using a femtosecond micromachining process, a very industrially accessible technology. The geometries, dimensions and pitch of the various gratings analyzed are obtained by means of direct ablation in a controlled atmosphere of a homogeneous thin layer of ITO deposited on a glass substrate. The pitch has been selected in order to obtain a higher order of the photonic band gap in the visible spectral region. Femtosecond micromachining technology guarantees precision, repeatability and extreme manufacturing flexibility. By means of ultrafast pump–probe spectroscopy, we characterize both the plasmon and inter-band temporal dynamics. We observe a large optical nonlinearity of the ITO grating in the visible range, where the photonic band gap occurs, when pumped at the surface plasmon resonance in the near infrared (1500 nm) region. All together, we show the possibility of all-optical signal modulation with heavily doped semiconductors in their transparency window with a picosecond response time through the formation of ITO grating structures

Large Scale Indium Tin Oxide (ITO) One Dimensional Gratings for Ultrafast Signal Modulation in the Visible

We present a photophysical study on an indium tin oxide (ITO) one dimensional grating, realized using femtosecond micromachining technology, a technology very industrially accessible. The geometries, dimensions and pitch of the various gratings analyzed are obtained by means of direct ablation in a controlled atmosphere of a homogeneous thin layer of ITO deposited on a glass substrate. The pitch has been selected in order to obtain a higher order of the photonic band gap in the visible. By means of ultrafast pump-probe spectroscopy we characterize both the plasmon and inter-band temporal dynamics. We observe a large optical non-linearity of ITO grating in the visible range, where the photonic band gap occurs, when pumped at the surface plasmon resonance in the near infrared (1500 nm). All together we show the possibility of all-optical signal modulation with heavily doped semiconductors in their transparency window with a picosecond response time through the formation of ITO grating structures

Optofluidic platform using liquid crystals in lithium niobate microchannel

Abstract We demonstrate the all optical control of the molecular orientation of nematic liquid crystals confined in microfluidic channels engraved in lithium niobate. Microchannels are obtained by a novel approach based on femtosecond pulse laser micromachining carried on in controlled atmosphere. The combined effect of photovoltaic and pyroelectric fields generated by light in lithium niobate crystals on the liquid crystal orientation, is reported for the first time. The total space charge field and its dependence on the incident light intensity can be controlled by changing the direction of pump light propagation through the microfluidic chip. The results reported in this manuscript demonstrate that liquid crystals and lithium niobate can efficiently be combined in microfluidic configuration, in order to push forward a novel class of optofluidic devices

Skeletal muscle cells opto-stimulation by intramembrane molecular transducers

Data of contracting muscle cells upon optical and electrical stimulatio

Optofluidic Flow Cytometer with In-Plane Spherical Mirror for Signal Enhancement

Statistical analysis of the properties of single microparticles, such as cells, bacteria or plastic slivers, has attracted increasing interest in recent years. In this regard, field flow cytometry is considered the gold standard technique, but commercially available instruments are bulky, expensive, and not suitable for use in point-of-care (PoC) testing. Microfluidic flow cytometers, on the other hand, are small, cheap and can be used for on-site analyses. However, in order to detect small particles, they require complex geometries and the aid of external optical components. To overcome these limitations, here, we present an opto-fluidic flow cytometer with an integrated 3D in-plane spherical mirror for enhanced optical signal collection. As a result, the signal-to-noise ratio is increased by a factor of six, enabling the detection of particle sizes down to 1.5 µm. The proposed optofluidic detection scheme enables the simultaneous collection of particle fluorescence and scattering using a single optical fiber, which is crucial to easily distinguishing particle populations with different optical properties. The devices have been fully characterized using fluorescent polystyrene beads of different sizes. As a proof of concept for potential real-world applications, signals from fluorescent HEK cells and Escherichia coli bacteria were analyzed

Skeletal muscle cells opto-stimulation by intramembrane molecular transducers - Code

Code used to analysed contracting vide