apoptotic pathways of u937 leukemic monocytes investigated by infrared microspectroscopy and flow cytometry

Infrared microspectroscopy and flow cytometry were used to study apoptosis in starved and CCCP-treated U937 monocyte cells

Can hippocampal neurites and growth cones climb over obstacles?

Guidance molecules, such as Sema3A or Netrin-1, can induce growth cone (GC) repulsion or attraction in the presence of a flat surface, but very little is known of the action of guidance molecules in the presence of obstacles. Therefore we combined chemical and mechanical cues by applying a steady Netrin-1 stream to the GCs of dissociated hippocampal neurons plated on polydimethylsiloxane (PDMS) surfaces patterned with lines 2 \ub5m wide, with 4 \ub5m period and with a height varying from 100 to 600 nm. GC turning experiments performed 24 hours after plating showed that filopodia crawl over these lines within minutes. These filopodia do not show staining for the adhesion marker Paxillin. GCs and neurites crawl over lines 100 nm high, but less frequently and on a longer time scale over lines higher than 300 nm; neurites never crawl over lines 600 nm high. When neurons are grown for 3 days over patterned surfaces, also neurites can cross lines 300 nm and 600 nm high, grow parallel to and on top of these lines and express Paxillin. Axons - selectively stained with SMI 312 - do not differ from dendrites in their ability to cross these lines. Our results show that highly motile structures such as filopodia climb over high obstacle in response to chemical cues, but larger neuronal structures are less prompt and require hours or days to climb similar obstacles

Integrating Microfabrication into Biological Investigations: the Benefits of Interdisciplinarity

The advent of micro and nanotechnologies, such as microfabrication, have impacted scientific research and contributed to meaningful real-world applications, to a degree seen during historic technological revolutions. Some key areas benefitting from the invention and advancement of microfabrication platforms are those of biological and biomedical sciences. Modern therapeutic approaches, involving point-of-care, precision or personalized medicine, are transitioning from the experimental phase to becoming the standard of care. At the same time, biological research benefits from the contribution of microfluidics at every level from single cell to tissue engineering and organoids studies. The aim of this commentary is to describe, through proven examples, the interdisciplinary process used to develop novel biological technologies and to emphasize the role of technical knowledge in empowering researchers who are specialized in a niche area to look beyond and innovate

A multi-culture array for modelling numerous mechanisms of cutaneous drug reactions

We report a novel multi-culture array(MCA) with quantitative skin sensitizing assay to recapitulate liver-mediated metabolites generation, antigen presenting cells(APCs) activation and FasLigand(FasL)-mediated keratinocytes apoptosis. This was accomplished by designing a quadruple-compartment microfluidic coculture array with microdiffusion channels, capable of maintaining four different types of cells and their respective functions within the microfluidic architecture to perform skin sensitizing assay. This quantitative assay integrates with digital logic gates system to compute multiple readouts from a single experiment to predict the skin sensitization potential of drugs that are administered into the systemic circulation with 81.81% accuracy, 71.43% sensitivity and 57.14% accuracy.</p

Boehmite filled hybrid sol\u2013gel system as directly writable hard etching mask for pattern transfer

We discuss some preliminary results on the development of a new kind of positive tone resist whose peculiarity is an extreme dry etch resistance. This profitable property is obtained by loading and compatibilizing with ceramic nano particles a radiation sensitive sol-gel silica based hybrid organic/inorganic system. With an appropriate choice of the nano particles, the investigated approach is suitable to be adapted and optimized for achieving high selectivity in plasma etching processes of different materials. Here, we specifically demonstrate how the filling with boehmite nano particles (aluminum hydroxide, y-AIO(OH)) confers a much higher selectivity (>60) to the radiation sensitive silica based system when used for the etching of silicon, that show a selectivity <2 if unloaded. The patterning of the new resist was carried out by X-ray lithography while the dry etching tests were made with a fluorine-based chemistry

SU-8 bonding protocol for the fabrication of microfluidic devices dedicated to FTIR microspectroscopy of live cells

Here we present a new bonding protocol for SU-8 negative tone photoresist that exploits the chemical modifications induced in the resin by exposure to 254 nm (UVC) light. Fourier Transform Infrared microspectroscopy (\u3bc-FTIR) was used to carry out a thorough study on the chemical processes and modifications occurring within the epoxy resin by exposure to 365 nm and 254 nm light. In particular, we established that UVC light promotes the opening of the epoxy rings bypassing the post-exposure bake. The possibility to promote a further activation of the resin, already patterned with standard UV lithography, was exploited to produce closed microfluidic devices. Specifically, we were able to fabricate fluidic chips, characterized by broadband transparency from mid-IR to UV and long term stability in continuous flow conditions. CaF2 was used as substrate, coated by sputtering with a nanometric silicon film, in order to make surface properties of this material more suitable for standard fabrication processes with respect to the original substrate. The fabricated microfluidic chips were used to study by \u3bc-FTIR the biochemical response of live breast cancer MCF-7 cells to osmotic stress and their subsequent lysis induced by the injection of deionized water in the device. \u3bc-FTIR analyses detected fast changes in protein, lipid and nucleic acid content as well as cytosol acidification

Microfabrication of sharp blazed gratings by a two-step height amplification process based on soft and deep X-ray lithography

We describe a scheme for the fabrication of sharp blazed gratings involving two cascaded steps of X-ray lithography (XRL) with electroplating (EP) steps interposed. The adopted iterative scheme enables the amplification by two orders of magnitude of the height of high-resolution structures of an original X-ray mask produced by Electron Beam Lithography (EBL), while minimizing the loss of lateral resolution. Nickel structures of up to 200 μm in height with blazed grating profile were obtained with &#60;500 nm resolution details.&lt;p&gt;&lt;/p&gt; The described approach is suitable for the fabrication of nickel structures, to be used in particular as master tools in hot embossing processes, in a broad range of optical applications requiring non-binary microstructures