AFM Specific Identification of Bacterial Cell Fragments on Biofunctional Surfaces

Biointerfaces with a highly sensitive surface designed for specific interaction with biomolecules are essential approaches for providing advanced biochemical and biosensor assays. For the first time, we have introduced a simple AFM-based recognition system capable of visualizing specific bacterial nanofragments and identifying the corresponding bacterial type. For this we developed AFM-adjusted procedures for preparing IgG-based surfaces and subsequently exposing them to antigens. The AFM images reveal the specific binding of Escherichia coli cell fragments to the prepared biofunctional surfaces. Moreover, the binding of bacterial cell fragments to the affinity surfaces can be characterized quantitatively, indicating a 30-fold to 80-fold increase in the quantity of bound antigenic material in the case of a specific antigen-antibody pair. Our results demonstrate significant opportunities for developing reliable sensing procedures for detecting pathogenic bacteria, and the cell can still be identified after it is completely destroyed

Electrochemical Nanoprobes for Single-Cell Analysis

The measurement of key molecules in individual cells with minimal disruption to the biological milieu is the next frontier in single-cell analyses. Nanoscale devices are ideal analytical tools because of their small size and their potential for high spatial and temporal resolution recordings. Here, we report the fabrication of disk-shaped carbon nanoelectrodes whose radius can be precisely tuned within the range 5–200 nm. The functionalization of the nanoelectrode with platinum allowed the monitoring of oxygen consumption outside and inside a brain slice. Furthermore, we show that nanoelectrodes of this type can be used to impale individual cells to perform electrochemical measurements within the cell with minimal disruption to cell function. These nanoelectrodes can be fabricated combined with scanning ion conductance microscopy probes, which should allow high resolution electrochemical mapping of species on or in living cells

10_6_vp_ml-2

Raw data of the experiment after the first regeneration for the graph presented on Figure 1

10_5_vp_ml-1

Raw data of experiments with virus concentration 10^5 vp/m

V6_106.009

AFM image of virus particles partially dipped in the receptor layer on Figure 7

V6_106.010

AFM image of virus particles removed by force and applied by AFM cantilever on Figure 7

10_5_vp_ml-3

Raw data of the third independent experiment with 10^5 vp/ml on Figure

Towards High-Temperature MEMS: Two-Step Annealing Suppressed Recrystallization in Thin Multilayer Pt-Rh/Zr Films

Platinum-based thin films are widely used to create microelectronic devices operating at temperatures above 500 °C. One of the most effective ways to increase the high-temperature stability of platinum-based films involves incorporating refractory metal oxides (e.g., ZrO2, HfO2). In such structures, refractory oxide is located along the metal grain boundaries and hinders the mobility of Pt atoms. However, the effect of annealing conditions on the morphology and functional properties of such multiphase systems is rarely studied. Here, we show that the two-step annealing of 250-nm-thick Pt-Rh/Zr multilayer films instead of the widely used isothermal annealing leads to a more uniform film morphology without voids and hillocks. The composition and morphology of as-deposited and annealed films were investigated using X-ray diffraction and scanning electron microscopy, combined with energy-dispersive X-ray spectroscopy. At the first annealing step at 450 °C, zirconium oxidation was observed. The second high-temperature annealing at 800–1000 °C resulted in the recrystallization of the Pt-Rh alloy. In comparison to the one-step annealing of Pt-Rh and Pt-Rh/Zr films, after two-step annealing, the metal phase in the Pt-Rh/Zr films has a smaller grain size and a less pronounced texture in the direction, manifesting enhanced high-temperature stability. After two-step annealing at 450/900 °C, the Pt-Rh/Zr thin film possessed a grain size of 60 ± 27 nm and a resistivity of 17 × 10−6 Ω·m. The proposed annealing protocol can be used to create thin-film MEMS devices for operation at elevated temperatures, e.g., microheater-based gas sensors

10_7_vp_ml

Raw data of experiments with virus concentration 10^7 vp/ml for the graph presented on Figure