Recent applications of bacteriophage-based electrodes: A mini-review

The constant search for new materials applicable in electrochemical sensors and electronic devices is encouraging scientists to turn to interdisciplinary research. Particularly interesting in this context is the combination of biology with chemistry and material sciences. Recently, bacteriophages (viruses that infect bacteria) have been increasingly used in electrochemical applications, e.g. as recognition elements in biosensors or as templates to create new electrode materials for batteries and biofuel cells. Here we present a short review of recent applications of bacteriophage-based electrodes and methods for preparing them. Keywords: Bacteriophage, Biosensor, Bioreceptor, Biotemplate, Electrode, Electrochemistr

Immunosensor Based on Long-Period Fiber Gratings for Detection of Viruses Causing Gastroenteritis

Since the norovirus is the main cause of acute gastroenteritis all over the world, its fast detection is crucial in medical diagnostics. In this work, a rapid, sensitive, and selective optical fiber biosensor for the detection of norovirus virus-like particles (VLPs) is reported. The sensor is based on highly sensitive long-period fiber gratings (LPFGs) coated with antibodies against the main coat protein of the norovirus. Several modification methods were verified to obtain reliable immobilization of protein receptors on the LPFG surface. We were able to detect 1 ng/mL norovirus VLPs in a 40-min assay in a label-free manner. Thanks to the application of an optical fiber as the sensor, there is a possibility to increase the user’s safety by separating the measurement point from the signal processing setup. Moreover, our sensor is small and light, and the proposed assay is straightforward. The designed LPFG-based biosensor could be applied in both fast norovirus detection and in vaccine testing

Langmuir and Langmuir–Blodgett Films of Unsymmetrical and Fully Condensed Polyhedral Oligomeric Silsesquioxanes (POSS)

The search for novel building blocks for preparation of nanostructures of unique properties is crucial for development of functional nanomaterials. Polyhedral oligomeric silsesquioxanes (POSS) may be regarded as organic–inorganic nanoparticles of unusual characteristics, i.e., monodisperse size, high temperature resistance, and small dielectric constant. Here, we study four derivatives of fully condensed polyhedral oligomeric octasilsesquioxanes. Seven corners of the POSS cages are substituted with isobutyl groups forming a hydrophobic tail, whereas the eighth substituent acts as a hydrophilic head due to a judiciously chosen functional group. Such design assures amphiphilic character of POSS molecules with well-defined hydrophilic head and hydrophobic tail. The combination of amphiphilicity, well-defined size and composition, and rheological properties of monolayers makes studied POSS interesting model for self-assembly, thin films, and interfacial investigations. The Langmuir–Blodgett technique is used as a method that provides the best control over the parameters of thin films formation. The functional hydrophilic group strongly influences the behavior of POSS at the air/water interface. The mercapto derivative, which seems most promising for preparation of complex nanostructures, appears to form aggregates and multilayer films. Three other studied derivatives (bearing glycerol unit, maleamic acid, and amino group) behave as classical amphiphiles at the air/water interface

Bacteriophage-Based Bioconjugates as a Flow Cytometry Probe for Fast Bacteria Detection

Robust detection of bacteria can significantly reduce risks of nosocomial infections, which are a serious problem even in developed countries (4.1 million cases each year in Europe). Here we demonstrate utilization of novel multifunctional bioconjugates as specific probes for bacteria detection. Bifunctional magnetic-fluorescent microparticles are coupled with bacteriophages. The T4 bacteriophage, due to its natural affinity to bacterial receptors, namely, OmpC and LPS, enables specific and efficient detection of Escherichia coli bacteria. Prepared probes are cheap, accessible (even in nonbiological laboratories), as well as versatile and easily tunable for different bacteria species. The magnetic properties of the bioconjugates facilitate the separation of captured target bacteria from other components of complex samples and other bacteria strains. Fluorescence enables simple analysis. We chose flow cytometry as the detection method as it is fast and widely used for biotests. The capture efficiency of the prepared bioconjugates is close to 100% in the range of bacteria concentrations from tens to around 10⁵ CFU/mL. The limit of detection is restricted by flow cytometry capabilities and in our case was around 10⁴ CFU/mL