Regulating MDA-MB-231 breast cancer cell adhesion on laser-patterned surfaces with micro- and nanotopography.

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.

A highly sensitive impedimetric aptasensor for the selective detection of acetamiprid and atrazine based on microwires formed by platinum nanoparticles.

A novel impedimetric biosensor was developed for the detection of the two extensively used pesticides, acetamiprid and atrazine. By employing the sputtering and e-beam lithography techniques, platinum nanoparticles (Pt NPs) were deposited in a bridge-like arrangement, in between interdigitated electrodes (IDEs). The resulting Pt NP microwires were chemically functionalized to allow the covalent immobilization of aptamers against the two target analytes onto the sensor surfaces. The biosensing platform facilitated charge transfer through the microwire-bridged IDEs, while upon analyte binding to the immobilized aptamers electron transfer was hindered, resulting in an increase of the electrochemical cell's impedance. The combination of Pt NPs microwires and aptamers allowed the sensitive and highly selective detection of acetamiprid with a linear range of response in the range of 10pM to 100nM with a limit of detection (LoD) at 1pM, and of atrazine with a linear range of responses from 100pM to 1µM and a LoD at 10pM respectively. Its performance was tested against a number of other commonly used pesticides as well as in real water samples.