QI Mode - New Perspectives in Microbiology

_{KEYWORDS: Atomic Force Microscopy; AFM; AFM Mode; Quantitative Imaging; QI Mode; Viruses; Bacteria; Algae; Yeast Cells; Life Sciences}

Atomic force microscopy (AFM) is well known as a multipurpose tool for investigating a wide range of different samples with nanometer scale resolution under controlled environmental conditions. AFM technology offers a closer look into the nanometer world and can be used as a force sensor to measure interaction forces and to obtain mechanical properties of different kinds of samples. Nevertheless, the traditional imaging modes demonstrated well known drawbacks for challenging samples that have steep edges, are soft, sticky, or loosely attached to the surface. The most common modes have to deal with undesired forces that might damage or compress the investigated objects. High lateral forces that can be applied in contact mode are able to damage or stretch soft biological objects and loosely attached objects can be moved as a result of these forces.

Bruker has now developed a brand-new mode which works without applying any lateral force and allows the user to control the vertical force at each pixel. This offers new perspectives in AFM measuring. In this app note, the benefits and principles of QI mode are detailed and exemplified.

Readers can expect to learn about:

• The basic principles and benefits of QI mode for investigating soft biological objects;
• High-resolution AFM topography imaging and advanced mechanical characterization of those objects; 
• Prominent examples of AFM's potential for investitating various types of viruses, algea, bacteria and yeast cells.