This journal is © The Royal Society of Chemistry 2014 Chem. Soc. Rev. Cite this: DOI: 10.1039/c4cs00176a Quantitative biomolecular imaging by dynamic nanomechanical mapping Shuai Zhang,† Hu ¨ snu ¨ Aslan,† Flemming Besenbacher and Mingdong Dong* The ability to ‘see’ down to nanoscale has always been one of the most challenging obstacles for researchers to address fundamental questions. For many years, researchers have been developing scanning probe microscopy techniques to improve imaging capability at nanoscale. Among them, atomic force microscopy (AFM) has received considerable attention, which allows probing topography of biological species at real space under physiological environment. Importantly, force measurements in AFM enable researchers to reveal not only the topography but also the relevant physical–chemical properties. AFM-based dynamic nanomechanical mapping (DNM) provides insights into the functions of biological systems by the interpretation of ‘force’, which are inaccessible by most of the other analytic techniques. This review is aiming to shed light on these recently developed AFM-based DNM techniques for biomolecular imaging, and discuss the relative applications in biological research from the nanomechanical point of view. 1. Introduction Biomolecular imaging is to characterize biological processes at the molecular and cellular levels, including optical imaging, electron microscopy, magnetic imaging, scanning probe microscopy (SPM), ultrasound imaging and others. 1,2 Biomolecular imaging techni- ques are preferred to be easy to use, high-resolution, high-speed, label/stain-free, non-destructive, non-invasive and performed in situ. Although there are many imaging options, all of them lack at least one of the desired properties. In addition, for most imaging methods the only accessible information is structure, but structural information is not sufficient to provide an understanding to the processes and underlying mechanisms of bio-phenomena. It needs to be enriched with information that can correlate to sample’s biophysical and chemical pro- perties. ‘‘Quantitative biomolecular imaging’’ refers to imaging methodologies that can simultaneously provide such detailed information from multiple channels. Atomic force microscopy (AFM)-based dynamic nanomechanical mapping (DNM) is a quantitative biomolecular imaging option to meet all mentioned requirements. 3–6 Since its invention in 1986, 7 AFM has been playing a key role in the field of nanotechnology and visualization. On the one hand, The Interdisciplinary Nanoscience Center (iNANO), Aarhus University, The iNANO House 1590-244, Aarhus C 8000, Denmark. E-mail: dong@inano.au.dk; Tel: +45 8715 6729 Shuai Zhang Shuai Zhang obtained his MSc in Nanoscience from Aarhus University, Denmark in 2012. Right now he is a PhD candidate at iNANO Center, Aarhus University. His research mainly focuses on the utilization of dynamic nanomechnical mapping for biomolecular imaging and functional material study. Hu ¨snu ¨ Aslan Hu ¨snu ¨ Aslan obtained his MSc in Applied Physics from Sabanci University, Turkey. In 2013, he started his PhD in Bio-SPM group at iNANO, Aarhus University, Denmark. Currently, he focuses on the development of scanning probe microscopy techniques and its relative appli- cations for monitoring bio- molecular activity. † These authors contributed equally to this work. Received 19th May 2014 DOI: 10.1039/c4cs00176a www.rsc.org/csr Chem Soc Rev REVIEW ARTICLE Published on 08 August 2014. Downloaded by Aarhus University Library on 09/08/2014 11:40:13. View Article Online View Journal