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Graphene nanoribbons (GNR), can be prepared in bulk quantities for large-area applications by reducing the product from the lengthwise oxidative unzipping of multiwalled carbon nanotubes (MWNT). Recently, the biomaterials application of GNR has been explored, for example, in the pore to be used for DNA sequencing. Therefore, understanding the polymer behavior of GNR in solution is essential in predicting GNR interaction with biomaterials. Here, we report experimental studies of the solution-based mechanical properties of GNR and their parent products, graphene oxide nanoribbons (GONR). We used atomic force microscopy (AFM) to study their mechanical properties in solution and showed that GNR and GONR have similar force-extension behavior as in biopolymers such as proteins and DNA. The rigidity increases with reducing chemical functionalities. The similarities in rigidity and tunability between nanoribbons and biomolecules might enable the design and fabrication of GNR-biomimetic interfaces.

Single-walled nanotubes (SWNT) have attracted significant attention because of the substance’s superior crystal quality, high thermal conductivity and current carrying capacity, thus emerging as an attractive material for nanoelectrics. To optimize the selection of SWNT structures in large-scale synthesis, an understanding of their growth mechanism is necessary. We report studies of the helicity distributions of SWNT using electron nanodiffraction. The overall statistical distribution of helicity has peaks at 0° and 30°. The peak evident at 0° was found to be a sharp local maximum, while the peak at 30° was broader. We also found that the helicity distribution varies from region to region of micrometer size. This observation indicates that local environment affects nanotube growth, resulting in different structural distributions. Keywords: carbon nanotube; helicity; growth mechanism 1. Introduction The unique physical properties and potential applications of single-walled carbon nanotubes (SWNT) have been well documented since their discovery, using both theory and experiment [1-6]. It is evident that the useful electronic properties of SWNT are largely dependent on the atomic structures of individual nanotubes, which can be accurately defined using the tube diameter

Quantifying the basic intra- and inter-molecular forces of DNA has helped us to better understand and further predict the behavior of DNA. Single molecule technique elucidates the mechanics of DNA under applied external forces, sometimes under extreme forces. On the other hand, ensemble studies of DNA molecular force allow us to extend our understanding of DNA molecules under other forces such as electrostatic and hydration forces. Using a variety of techniques, we can have a comprehensive understanding of DNA molecular forces, which is crucial in unraveling the complex DNA functions in living cells as well as in designing a system that utilizes the unique properties of DNA in nanotechnology.

Single-molecule manipulation techniques provide a unique tool for a close-up investigation of the complex biological properties and interactions. During the force measurement, a single molecule is pulled while its force response is monitored. However, quantifying these non-equilibrium data and using them to understand the structure-function relationship of biological systems have been challenging. We describe the mechanics of nanoscale biomolecules and the use of these force measurements for the free energy reconstruction using the recently derived non-equilibrium work theorem, i.e., Jarzynski’s equality. We also compare the results with those from other phenomenological approaches. Finally, mechanical characterization of systems such as overstretching transitions of DNA are presented, and the implications and challenges of these single-molecule force studies are discussed.

The mechanical force-induced activation of the adhesive protein von Willebrand Factor (VWF), which experiences high hydrodynamic forces, is essential in initiating platelet adhesion. The importance of the mechanical force-induced functional change is manifested in the multimeric VWF’s crucial role in blood coagulation, when high fluid shear stress activates plasma VWF (pVWF) multimers to bind platelets. Here we showed that a pathological level of high shear stress exposure of pVWF multimers results in domain conformational changes, and the subsequent shifts in the unfolding force allow us to use force as a marker to track the dynamic states of multimeric VWF. We found that shear-activated pVWF multimers (spVWF) are more resistant to mechanical unfolding than non-sheared pVWF multimers, as indicated in the higher peak unfolding force. These results provide insight into the mechanism of shear-induced activation of pVWF multimers.

Mechanical force is present in all aspects of living systems. It affects the conformation of molecules, the shape of cells, and the morphology of tissues. All of these are crucial in architecture-dependent biological functions. Nanoscience of advanced materials has provided knowledge and techniques that can be used to understand how mechanical force is involved in biological systems, as well as to open new avenues to tailor-made bio-mimetic materials with desirable properties. In this article, we describe models and show examples of how force is involved in molecular functioning, cell shape patterning, and tissue morphology.

Recent advances in nanoscale manipulation and piconewton force detection provide a unique tool for studying the mechanical and thermodynamic properties of biological molecules and complexes at the single-molecule level. Detailed equilibrium and dynamics information on proteins and DNA have been revealed by single-molecule manipulation and force detection techniques. The atomic force microscope (AFM) and optical tweezers have been widely used to quantify the intra- and inter-molecular interactions of many complex biomolecular systems. In this article, we describe the background, analysis, and applications of these novel techniques. Experimental procedures that can serve as a guide for setting up a single-molecule manipulation system using the AFM are also presented.