Zinc ferrite nanoparticles (ZFO NPs) are a promising magneto-crystalline platform for nanomedicine-based cancer theranostics. ZFO NPs synthesized using co-precipitation method are characterized using different techniques. UV-visible spectroscopy exhibits absorption peaks specific for ZFO. Raman spectroscopy identifies Raman active, infrared active, and silent vibrational modes while Fourier transforms infrared spectroscopic (FTIR) spectra display IR active modes that confirm the presence of ZFO. X-ray diffraction pattern (XRD) exhibits the crystalline planes of single-phase ZFO with a face-centered cubic structure that coincides with the selected area electron diffraction pattern (SAED). The average particle size according to high-resolution transmission electron microscopy (HR-TEM) is 5.6 nm. X-ray photoelectron spectroscopy (XPS) signals confirm the chemical states of Fe, Zn, and O. A superconducting quantum interference device (SQUID) displays the magnetic response of ZFO NPs, showing a magnetic moment of 45.5 emu/gm at 70 kOe. These ZFO NPs were then employed for comparative cytotoxicity evaluation using MTT, crystal violet, and LDH assays on breast adenocarcinoma epithelial cell (MCF-7), triple-negative breast cancer lines (MDA-MB 231), and human embryonic kidney cell lines (HEK-293). Flow cytometric analysis of all the three cell lines were performed in various concentrations of ZFO NPs for automated cell counting and sorting based on live cells, cells entering in early or late apoptotic phase, as well as in the necrotic phase. This analysis confirmed that ZFO NPs are more cytotoxic towards triple-negative breast cancer cells (MDA-MB-231) as compared to breast adenocarcinoma cells (MCF-7) and normal cell lines (HEK-293), thus corroborating that ZFO can be exploited for cancer therapeutics.

In this work, a microfluidic prototype based on polymeric materials was developed to monitor surface processes using surface-enhanced Raman spectroscopy (SERS), keeping the reagents free of environmental contamination. The prototype was fabricated on poly(methyl methacrylic acid) (PMMA). A micrometric membrane of a functional organic polymer (FOP) based on p-terphenyl and bromopyruvic acid monomers was formed on the PMMA surface to promote the formation of metal nanoclusters. Au nanosized film was deposited on the FOP membrane to give rise to the SERS effect. A microchannel was formed on another piece of PMMA using micromachining. A representative 3D model of the prototype layer arrangement was built and simulated in COMSOL Multiphysics^® to approximate the electric field distribution and calculate the power enhancement factor as the Au film changes over time. The fabrication process was characterized using UV–visible and Raman spectroscopies and XPS. The prototype was tested using a Raman microscope and liquid solutions of cysteamine and Escherichia coli (E. coli). The simulation results demonstrated that the morphological characteristics of the Au layer give rise to the SERS effect, and the power enhancement factor reaches values as high as 8.8 × 10⁵ on the FOP surface. The characterization results showed the formation of the FOP and the Au film on PMMA and the surface functionalization with amine groups. The Raman spectra of the prototype showed temporal evolution as different compounds were deposited on the upper wall of the microchannel. Characteristic peaks associated with these compounds were detected with continuous monitoring over time. This prototype offers many benefits for applications like monitoring biological processes. Some advantages include timely surface evaluation while avoiding environmental harm, decreased use of reagents and samples, minimal interference with the process by measuring, and detecting microorganisms in just 1 h, as demonstrated with the E. coli sample.

Fabrication and testing of interdigitated microelectrode arrays whose structure includes non-cytotoxic hydrogenated amorphous silicon-carbon alloy (a-Si_xC_1-x:H) as the surface to be biofunctionalized for capturing enteropathogenic Escherichia coli (E. coli, EPEC) are presented. a-Si_xC_1-x:H films were obtained by enhanced chemical vapor deposition (PECVD). The extract method was used to assess the cytotoxicity of the films. The design of the PIMAs includes two layers of a-Si_xC_1-x:H, one intrinsic layer deposited onto silicon dioxide (SiO₂) before evaporating titanium (Ti), and one doped layer deposited onto the Ti-microelectrodes. Electrical impedance spectroscopy (EIS) was used to know the effects of the biofunctionalization layer, conductivity of the medium and any capture of bacteria by antibodies on the microelectrodes. According to the results, the high hydrogen dilution contributes to low incorporation of CH_n groups improving the non cytotoxicity of the films, and the capture of bacteria on the microelectrodes improves the sensitivity. It manifests itself as a shift of the low cutoff frequency (F_low) of the impedance spectrum to the right, allowing the device to sense at frequencies lower than F_low. A percentage change in impedance of 1600% at 100 Hz was obtained after 5 minutes in contact with medium with EPEC concentration of 8.5 × 10⁸ CFU/mL.

The characterization of a-SixC1−x:H thin films by plasma-enhanced chemical vapor deposition with high hydrogen dilution for biological applications is addressed. A root mean square roughness less than 1 nm was measured via atomic force microscopy for an area of 25 μm2. Structural analysis was done using Fourier transform infrared spectroscopy in the middle infrared region. It was found that under the deposition conditions, the formation of Si–C bonds is promoted. Electrical dark conductivity measurements were performed to evaluate the effect of high hydrogen dilution and to find the relation between carrier transport properties and the structural arrangement. Conductivities of the order of 10−7 to 10−9 S/cm at room temperature for methane–silane gas flow ratio from 0.35 to 0.85 were achieved, respectively. UV-visible spectra were used to obtain the optical band gap and the Tauc parameter. Optical band gap as wide as 3.55 eV was achieved in the regime of high carbon incorporation. Accordingly, deposition under low power density and high hydrogen dilution reduces the roughness, improves the structure of the network, and stabilizes the film properties as a greater percentage of carbon is incorporated. The biofunctionalization of a-SixC1−x:H surfaces with NH2-terminated self-assembled monolayers was obtained through silanization with 3-aminopropyltrimethoxysilane. This knowledge opens a window for the inclusion of these a-SixC1−x:H thin films in devices such as biosensors.