Biology subjects

Balzer, B. N.

Publications and source records attributed to Balzer, B. N..

2 recordsLinked to original sources

bioRxiv2023

Adsorbing DNA to mica by cations: Influence of the valency and ion type

Ion-mediated attraction between DNA and mica plays a crucial role in biotechnological applications and molecular imaging. Here, we combine molecular dynamics simulations and single-molecule atomic force microscopy experiments to characterize the detachment forces of single-stranded DNA at mica surfaces mediated by the metal cations Li+, Na+, K+, Cs+, Mg2+ and Ca2+. Ion specific adsorption at the mica/water interface compensates (Li+, Na+) or overcompensates (K+, Cs+, Mg2+ and Ca2+) the bare negative surface charge of mica. In addition, direct and water-mediated contacts are formed between the ions, the phosphate oxygens of DNA and mica. The different contact types give rise to low and high force pathways and a broad distribution of detachment forces. Weakly hydrated ions, such as Cs+ and water-mediated contacts lead to low detachment forces and a high mobility of the DNA on the surface. Direct ion-DNA or ion-surface contacts lead to significantly higher forces. The comprehensive view gained from our combined approach allows us to highlight the most promising cations for imaging in physiological conditions: K+ to overcompensate the negative mica charge and induce long-ranged attractions. Mg2+ and Ca2+ to from a few specific and long-lived contacts to bind DNA with high affinity.

biophysics↗

bioRxiv2019

Proof-of-concept for the detection of early osteoarthritis pathology by endomicroscopy

Osteoarthritis (OA) is a degenerative joint disease and the leading cause of global disability. Clinical trials to date have been unable to pinpoint early and potentially reversible disease states with current clinical technology and hence disease-modifying OA drug candidates cannot be tested early in the disease. To overcome this obstacle, we correlate articular cartilage stiffness changes and cellular spatial organization. The former is a well-understood and functionally relevant OA pathology, while the latter allows discriminating between healthy vs early OA, based on distinct cellular spatial patterns. We demonstrated that an extensive loss of atomic force microscopy-detected stiffness can be seen in cartilage tissues with spatial patterns exhibiting the earliest identifiable OA. In addition, the translation of commercially available clinically usable probe-based confocal laser-endomicroscopy allows us to detect these early OA spatial patterns. This study resolves a major clinical trial obstacle by presenting the proof-of-concept that early OA pathology can be detected by already available clinical technology.\n\nOne Sentence SummaryWe report a correlation between articular cartilage surface nanoscale stiffness and chondrocyte spatial organization; using this correlation enables early pathology detection by currently available clinical optical methods.

biophysics↗