Nanobiomechanics

Nanobiomechanics (also bionanomechanics) is an emerging field in nanoscience and biomechanics that combines the powerful tools of nanomechanics to explore fundamental science of biomaterials and biomechanics.

Since the introduction by its founder Prof. Y. C. Fung, the field of biomechanics has established as one of the branches of mechanics and bioscience. For many years, biomechanics was focused on tissue level. Through advancements in nanoscience, the scale of the forces that could be measured and also the scale of observation of biomaterials was reduced to "nano" and "pico" level. Consequently it became possible to measure examine the mechanical properties of biological materials at nanoscale.

Most of the biological materials have different hierarchical level, and the smallest ones usually fall in the nanoscale. For example bone has up to seven level of hierarchy, and the smallest level, i.e., single collagen fibril and hydroxylapatite minerals have dimensions well below 100 nm. Therefore, being able to probe properties at this small scales provide a great opportunity for a better understanding of the fundamental properties of these materials. For example measurements has shown that there exits nanomechanical heterogeneity even within a single collagen fibrils as small as 100 nm.^[1]

One of the other most relevant topics in this field is measurement of tiny forces on living cells to recognize changes caused by different diseases. For example, it has been shown that red blood cells infected by malaria are 10 times stiffer than normal cells.^[2] Likewise, it has been shown that cancer cells are 70 percent softer than normal cells.^[3] Early signs of aging cartilage and Osteoarthritis has been shown by looking at the changes in the tissue at the nanoscale.^[4]

Methods and Instrumentation

The common methods in nanobiomechanics are summarized below:

• Atomic force microscope
• Optical tweezers
• Magnetic twisting cytometry

Examples of relevant materials

High resolution AFM image of cortical bone and single collagen fibril (inset)

• bone<^[5] and its hierarchical constituents such as single collagen fibrils
• single living cells
• actin filaments and microtubules^[6]

• synthetic peptide nonotubes

Computational nanobiomechanics

In addition to experimental aspect, research has been expanding through computational methods. Molecular dynamics (MD) simulations have provided a wealth of knowledge in this area. Although, the MD simulation are still limited to a small number of atoms and molecules, due to limitation in the computational performance, they have proved to be an instrumental branch of this emerging field.

References

1. ^ Minary-Jolandan, Majid; Yu, Min-Feng (2009). "Nanomechanical heterogeneity in the gap and overlap regions of type I collagen fibrils with implications for bone heterogeneity". Biomacromolecules 10 (9): 2565–70. doi:10.1021/bm900519v. PMID 19694448. 
2. ^ Michael Fitzgerald (March/April 2006). "Nanobiomechanics". Technology Review. MIT. http://www.technologyreview.com/biomedicine/16475/. Retrieved February 23, 2011. 
3. ^ Katherine Bourzac (December 4, 2007). "The Feel of Cancer Cells". Technology Review. MIT. http://www.technologyreview.com/biomedicine/19808/. Retrieved February 23, 2011. 
4. ^ Stolz M, Gottardi R, Raiteri R, Miot S, Martin I, Imer R et al. (2009). "Early detection of aging cartilage and osteoarthritis in mice and patient samples using atomic force microscopy". Nature Nanotechnology 4 (3): 186–92. doi:10.1038/nnano.2008.410. PMID 19265849. 
5. ^ Tai K, Dao M, Suresh S, Palazoglu A, Ortiz C (2007). "Nanoscale heterogeneity promotes energy dissipation in bone". Nature Materials 6 (6): 454–62. doi:10.1038/nmat1911. PMID 17515917. http://nanomechanics.mit.edu/papers/NatureMater_2007_Bone_nanoindent.pdf. 
6. ^ Kiss et al. (2002). "Nanomechanics of Microtubules". Physical Review Letters 89 (24). doi:10.1103/PhysRevLett.89.248101.