抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

We report on nanometer-scale patterning of single layer graphene on SiO2/Si substrate through femtosecond laser ablation. The pulse fluence is adjusted around the single-pulse ablation threshold of graphene. It is shown that, even though both SiO2 and Si have more absorption in the linear regime compared to graphene, the substrate can be kept intact during the process. This is achieved by scanning the sample under laser illumination at speeds yielding a few numbers of overlapping pulses at a certain point, thereby effectively shielding the substrate. By adjusting laser fluence and translation speed, 400 nm wide ablation channels could be achieved over 100 μm length. Raster scanning of the sample yields well-ordered periodic structures, provided that sufficient gap is left between channels. Nanoscale patterning of graphene without substrate damage is verified with Scanning Electron Microscope and Raman studies.

Nanoscale patterning of graphene through femtosecond laser ablation

Ultrafast laser materials processing has undergone an important change with the development of non-diffracting beams. These beams enable overcoming many of the difficulties usually encountered with standard Gaussian-beam focusing in materials. We review the techniques of non-diffracting and accelerating beam shaping that generates lines, tubes or curved segments of focused light on distances that exceed the Gaussian Rayleigh range by several orders of magnitude. We review the benefits and applications of nondiffracting beams for laser micro- and nano-processing in the general context of materials processing with ultrashort pulses in the filamentation regime. We highlight applications on ultra-high aspect ratio nano-drilling and direct laser processing along curves.

https://hal.archives-ouvertes.fr/hal-02392845/document

[INVITED] Ultrafast laser micro- and nano-processing with nondiffracting and curved beams: Invited paper for the section : Hot topics in Ultrafast Lasers

Optofluidic devices combining micro-optical and microfluidic components bring a host of new advantages to conventional microfluidic devices. Aspects, such as optical beam shaping, can be integrated on-chip and provide high-sensitivity and built-in optical alignment. Optofluidic microflow cytometers have been demonstrated in applications, such as point-of-care diagnostics, cellular immunophenotyping, rare cell analysis, genomics and analytical chemistry. Flow control, light guiding and collecting, data collection and data analysis are the four main techniques attributed to the performance of the optofluidic microflow cytometer. Each of the four areas is discussed in detail to show the basic principles and recent developments. 3D microfabrication techniques are discussed in their use to make these novel microfluidic devices, and the integration of the whole system takes advantage of the miniaturization of each sub-system. The combination of these different techniques is a spur to the development of microflow cytometers, and results show the performance of many types of microflow cytometers developed recently.

Optofluidic Device Based Microflow Cytometers for Particle/Cell Detection: A Review.

Reversible switching of wetting properties and erasable patterning of polymer surfaces using plasma oxidation and thermal treatment

Nanoslit arrays are fabricated on thin metal film coated glass slides using femtosecond laser pulses with Bessel beam profiles. The optical properties of the fabricated structures with different periodicities are characterized with transmission spectroscopy. Experimental results reveal the existence of two separate surface plasmon resonance modes occurring at the metal-air and metal-glass interfaces. These two resonance modes cause two minima in the high transmission spectra of the sub-skin depth thick thin films in the visible and near infrared regions. The existence of double surface plasmon resonance modes is verified with additional experiments, theoretical and numerical studies. Due to its relaxed alignment constraints, reduced aberrations, scalability property to shorter wavelengths, and resulting shorter dimensions, nanofabrication with diffraction-free Bessel beams is an easy, cheap, and advantageous alternative to regular lithography techniques to fabricate nanoslit arrays. The shift of the resonance wavelength with a change in the refractive index of the surrounding medium can be exploited for enhanced sensing.

Bessel-beam-written nanoslit arrays and characterization of their optical response

Versatile liquid-core optofluidic waveguides fabricated in hydrophobic silica aerogels by femtosecond-laser ablation

We demonstrate controlled guiding of nanoliter emulsion droplets of polar liquids suspended in oil along shallow hydrophilic tracks fabricated at the base of microchannels located within microfluidic chips. The tracks for droplet guiding are generated by exposing the glass surface of polydimethylsiloxane (PDMS)-coated microscope slides via femtosecond laser ablation. The difference in wettability of glass and PDMS surfaces together with the shallow step-like transverse topographical profile of the ablated tracks allows polar droplets wetting preferentially the glass surface to follow the track. In this study, we investigate guiding of droplets of two different polar liquids (water/ethylene glycol) with and without surfactant suspended in an oil medium along surface tracks of different depths of 1, 1.5, and 2 
 $$\upmu$$
 m. The results of experiments are also verified with computational fluid dynamics simulations. Guiding of droplets along the tracks as a function of the droplet composition and size and the surface profile depth is evaluated by analyzing the trajectories of moving droplets with respect to the track central axis, and conditions for stable guiding are identified. The experiments and numerical simulations indicate that while the track topography plays a role in droplet guiding using 1.5- and 2-
 $$\upmu$$
 m deep tracks, for the case of the smallest track depth of 1 
 $$\upmu$$
 m, droplet guiding is mainly caused by surface energy modification along the track rather than the presence of a topographical step on the surface. Our results can be exploited to sort passively different microdroplets mixed in the same microfluidic chip, based on their inherent wetting properties, and they can also pave the way for guiding of droplets along reconfigurable tracks defined by surface energy modifications obtained using other external control mechanisms such as electric field or light.

Guiding of emulsion droplets in microfluidic chips along shallow tracks defined by laser ablation

Fabrication of femtosecond laser written depressed-cladding waveguides in Tm3+:BaY2F8 crystal and laser operation near 2 μm

We present a new method to form liquid-core optofluidic waveguides inside hydrophobic silica aerogels. Due to their
unique material properties, aerogels are very attractive for a wide variety of applications; however, it is very challenging
to process them with traditional methods such as milling, drilling, or cutting because of their fragile structure. Therefore,
there is a need to develop alternative processes for formation of complex structures within the aerogels without
damaging the material. In our study, we used focused femtosecond laser pulses for high-precision ablation of
hydrophobic silica aerogels. During the ablation, we directed the laser beam with a galvo-mirror system and,
subsequently, focused the beam through a scanning lens on the surface of bulk aerogel which was placed on a three-axis
translation stage. We succeeded in obtaining high-quality linear microchannels inside aerogel monoliths by
synchronizing the motion of the galvo-mirror scanner and the translation stage. Upon ablation, we created multimode
liquid-core optical waveguides by filling the empty channels inside low-refractive index aerogel blocks with highrefractive
index ethylene glycol. In order to demonstrate light guiding and measure optical attenuation of these
waveguides, we coupled light into the waveguides with an optical fiber and measured the intensity of transmitted light as
a function of the propagation distance inside the channel. The measured propagation losses of 9.9 dB/cm demonstrate the
potential of aerogel-based waveguides for efficient routing of light in optofluidic lightwave circuits.

/pdf/optofluidic-waveguides-written-in-hydrophobic-silica-3845h49kmh.pdf

Yagiz Morova

Papers

Bessel-beam-written nanoslit arrays and characterization of their optical response

Versatile liquid-core optofluidic waveguides fabricated in hydrophobic silica aerogels by femtosecond-laser ablation

Guiding of emulsion droplets in microfluidic chips along shallow tracks defined by laser ablation

Fabrication of femtosecond laser written depressed-cladding waveguides in Tm3+:BaY2F8 crystal and laser operation near 2 μm

Optofluidic waveguides written in hydrophobic silica aerogels with a femtosecond laser