Advances of scanning probe microscopy in biomedical applications

The author is grateful for the financial support of Russian Foundation for Basic Research (project N 17-52-560001)

Scanning capillary microscopy: new achievements and opportunities

The author is grateful for the financial support of Russian Foundation of Basic Research (projects N 17-52-560001 and 16-29-06290)

The AFM Observation of Single Polyethylene Molecules in Coiled State on Mica

Abstract. Single polyethylene molecules and their small aggregates have been deposited on mica from diluted solutions at elevated temperatures and visualized by AFM in coiled and crystalline states. Coils have two-dimensional conformations with both highly tangled sites and locally extended segments with a length much exceeding the persistent length in a solution. The length measurements of coils reveal a wide distribution with the length of a maximum much smaller than the length of fully stretched molecules, moreover the long coils have been observed indicating the existence of linear multimolecular aggregates. Two models have been considered for the explanation of the observed deficit in the coils length, correspondingly the model implying the substantial smoothing of a winding chain trajectory due to the lack of the AFM resolution and the model of locally extended surface conformations with the long intramolecular folds. The roots of the apparent negative AFM height contrast of coils have been discussed

Scanning Probe Microscopy of DNA on Mica and Graphite

Abstract. Method of modification of highly oriented pyrolytic graphite (HOPG) is proposed for deposition of biological objects especially DNA for scanning probe microscopy. Atomic force microscopy (AFM) images of DNA on HOPG are compared with those on conventional support -mica. The advantages of HOPG as a substrate for DNA for using in STM imaging and DNA mapping are discussed

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