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Breast cancer is the most common type of cancer observed in women. Communication with the tumor microenvironment allows invading breast cancer cells, such as triple negative breast cancer cells, to adapt to specific substrates. The substrate topography modulates the cellular behavior among other factors. Several different materials and micro/nanofabrication techniques have been employed to develop substrates for cell culture. Silicon-based substrates present a lot of advantages as they are amenable to a wide range of processing techniques and they permit rigorous control over the surface structure. We investigate and compare the response of the triple negative breast cancer cells (MDA-MB-231) on laser-patterned silicon substrates with two different topographical scales, i.e., the micro- and the nanoscale, in the absence of any other biochemical modification. We develop silicon surfaces with distinct morphological characteristics by employing two laser systems with different pulse durations (nanosecond and femtosecond) and different processing environments (vacuum, SF6 gas, and water). Our findings demonstrate that surfaces with microtopography are repellent, while those with nanotopography are attractive for MDA-MB-231 cell adherence. [ABSTRACT FROM AUTHOR]

Heavy metal ions are major contaminants in present day water supply. In this work the fabrication and evaluation of a DNAzyme functionalized capacitive micromechanical sensor array for the detection of lead ions is presented. The catalytic strand of a “8–17” DNAzyme can cleave a substrate DNA strand that has one ribonucleotide base, in the presence of Pb 2+ , dissociating the complex into three fragments. The DNAzyme strand is laser printed and immobilized on the sensor surface and hybridized with the substrate strand. When self-cleaving occurs, the surface stress changes, which is then registered as change in the capacitance of the device. The sensor was able to detect 10 μM of Pb 2+ , whilst in a reverse procedure the re-hybridization of the immobilized catalytic strand with the substrate strand was demonstrated. The reactions were validated by tagging the catalytic strand with FAM (6-carboxyfluorescein), while the substrate strand was tagged with Dabcyl, a quencher. [ABSTRACT FROM AUTHOR]

Although scaling phenomena have long been documented in crystalline plasticity, the universality class has been difficult to identify due to the rarity of avalanche events, which require large system sizes and long times in order to accurately measure scaling exponents and functions. Here we present comprehensive simulations of two-dimensional dislocation dynamics under shear, using finite-size scaling to extract scaling exponents and the avalanche profile scaling function from time-resolved measurements of slip avalanches. Our results provide compelling evidence that both the static and dynamic universality classes are consistent with the mean-field interface depinning model. [ABSTRACT FROM AUTHOR]

Abstract: This work presents a comparative study between two functionalization techniques, gold (Au) and 3-glycidoxypropyl-tri-methoxy silane (GOPTS) that were used to immobilize thiol-modified oligonucleotides on low temperature oxide (LTO) on silicon (Si) surfaces toward the fabrication of a micromembrane array capacitive DNA biosensor. In the effort to increase the surface stress that develops upon probe immobilization and target hybridization and thus enhance the sensor''s sensitivity, a number of parameters were investigated such as probe and target concentrations as well as the thickness and roughness of the functionalization layers. Our results indicate that GOPTS is better suited as a functionalization layer for the development of microcantilever or micromembrane-based biosensors due to the enhanced hybridization efficiencies achieved, its relative stability over time and the ability to regenerate the surfaces following analyte recognition. Furthermore, with the use of Laser Induced Forward Transfer, probe oligonucleotides were uniformly deposited at the micron scale on GOPTS-functionalized surfaces, thus allowing for the realization of a micromembrane array capacitive DNA biosensor. [Copyright &y& Elsevier]

Abstract: This work presents the direct laser printing of thiol-modified oligonucleotides onto the surface of 3- glycidoxypropyltrimethoxysilane (GOPTS)-functionalized LTO on Si planar substrates and onto (GOPTS)- functionalized capacitive sensor membranes. The (GOPTS)-functionalized planar LTO on Si surfaces have been used to select the optimum deposition conditions and to confirm the ability of the oligonucleotides to recognize their complementary targets in solution. This reaction was confirmed by fluorescence microscopy. The purpose of those experiments was the fabrication of a label-free biosensor. [Copyright &y& Elsevier]

This paper describes the construction of a labeless immunosensor for the antibiotic ciprofloxacin and its interrogation using an AC impedance protocol. Commercial screen-printed carbon electrodes were used as the basis for the sensor. Polyaniline was electrodeposited onto the sensors and then utilized to immobilize a biotinylated antibody for ciprofloxacin using classical avidin-biotin interactions. Electrodes containing the antibodies were exposed to solutions of antigen and interrogated using an AC impedance protocol. The faradaic component of the impedance of the electrodes was found to increase with increasing concentration of antigen. Control samples containing a non-specific IgG antibody were also studied and calibration curves obtained by subtraction of the responses for specific and non-specific antibody-based sensors, thereby eliminating the effects of non-specific adsorption of antigen. [ABSTRACT FROM AUTHOR]