Biosensors & Bioelectronics

This paper outlines efficient hardware architecture of detection of bacteria and alga in microscopic images, using Xilinx System Generator (XSG). XSG is a high-level design tool based on blocks. It gives bit and cycle accurate simulation. The approach of detection used is the Hough transform. The latter is a very efficient approach of location of parametric curves in an image, especially lines. System was implemented on Virtex-V FPGA. To demonstrate the quality of the system, some experiments on microscopic images are given.

A low-cost, simple, rapid and selective nucleic-acid based lateral flow strip biosensor (LFSB) for possible dengue viral RNA detection is described in this study. The detection is based on competitive binding, where gold nanoparticles (AuNPs), with average size of ~10 nm confirmed using UV-Vis, TEM and AFM images, are used as visualizing agents. These are bioconjugated with DNA which competitively binds with its complementary strand either in the sample or in the test line of the LFSB. The detection scheme reduces the number of probes which effectively lowers the cost for the design of the test strip. The whole test took less than five minutes to complete and a red line signifies a negative result, while the absence of the line signifies a positive result. Quantification of the intensity of the red band reveals proportionality of the color to the amount of DNA present in the sample. The visual limit of detection of the LFSB is 10-7 M. It demonstrates selectivity in a blood matrix and selectivity over a syntheticm Influenza. This study brings us closer to an amplification-free, point-of-care method for dengue detection.

Titanium dioxide nanoparticles (TiO2 NPs) are generally considered to be biologically inert. However, TiO2 occurs in several crystalline forms, the two most common being rutile and anatase. Although both forms are tetragonal, the different crystalline forms give rise to different physical and chemical characteristics such as hardness, refractive index and photocatalytic ability. We hypothesized that the two forms of TiO2 NPs would also elicit different cellular responses. Three cell-based biosensors, using B-cell Translocation Gene 2 (BTG2), heat shock protein70B' (HSP70B') and nuclear factor kappa B (NF-кB) sensor cells, were used to determine if the different forms of TiO2 NPs cause different cellular responses. The cellular responses induced by TiO2 NPs were detected using HSP70B' and NF-кB sensor cells; we found that the different forms of TiO2 NPs resulted in the same HSP70B' and NF-кB response. BTG2 expression is up-regulated by DNA damage via p53 activation. A cellular DNA damage response stimulated by different forms of TiO2 NPs was detected by our cell-based DNA damage biosensor. The results showed that an increased DNA damage response is elicited by the anatase form compared to the rutile or mixed rutile/anatase forms. Our work indicates that the crystalline form of NPs is an important point to investigate when studying the interaction between nanomaterials and cells.

The production of reactive oxygen species due to increased energy demand during physical exercise can increase the cellular and blood oxidation state. The reducing power of biological samples reflects its antioxidant capacity, largely maintained by Low Molecular Weight Antioxidants (LMWA), which donate electrons to radical species. LMWA include antioxidants such as uric acid, vitamins C and E and lipoic acid, among others. The electroanalytical technique of Differential Pulse Voltammetry (DPV) presents a good methodological alternative to quantify acute and chronic modulations of the antioxidant capacity from biological fluids in response to metabolic adaptations caused by physical exercise. However, when biological samples are analyzed, proteins are an important preanalytical interfering in the technique. The proteins can be adsorbed on the electrode surface during the potential application, resulting in a significant decrease of voltammetric signal. The aim of the present study was to investigate
the applicability of cationic surfactant Cetyl Pyridinium Chloride (CPC) as a micellar system for the improvement of DPV technique for serum and saliva analysis. Forty individuals' samples were analyzed. The obtained data revealed that the use of CPC increased the sensitivity and stability of the voltammetric signal, enabling the application of the method DPV for serum and saliva samples. Our data suggest that the voltammetric signal of samples is influenced mainly by the uric acid concentration.