The invention of atomic force microscopy (AFM) has provided new technology for measuring specific molecular interaction forces. Using AFM single-molecule force spectroscopy (SMFS) techniques, CD20-Rituximab rupture forces were measured on purified CD20 proteins, Raji cells, and lymphoma patient B cells. Rituximab molecules were linked onto AFM tips using AFM probe functionalization technology, and purified CD20 proteins were attached to mica using substrate functionalization technology. Raji cells (a lymphoma cell line) or lymphoma patient cells were immobilized on a glass substrate via electrostatic adsorption and chemical fixation. The topography of the purified CD20 proteins, Raji cells, and patient lymphoma cells was visualized using AFM imaging and the differences in the rupture forces were analyzed and measured. The results showed that the rupture forces between the CD20 proteins on Raji cells and Rituximab were markedly smaller than those for purified CD20 proteins and CD20 proteins on lymphoma patient B cells. These findings provide an effective experimental method for investigating the mechanisms underlying the variable efficacy of Rituximab. The invention of atomic force microscopy (AFM) [1] allows researchers to investigate the topographical structure and specific molecular interactions between individual live cells and molecules, thereby revolutionizing the research methods used in the field of life sciences. The resolution of light microscopy is limited to the wavelength of the light source and, therefore, information on a nanometer scale is not accessible; also, electron microscopy requires vacuum conditions, which means that live samples cannot be examined using this technique [2]. Compared with light microscopy and electron microscopy, AFM has sub-nanometer resolution [3], can work under various conditions such as air, liquid, and/or a vacuum, and allows the visualization of live cells and native biomolecules without the need for staining or fixation [4]. These advantages make AFM widely applicable to life sciences, a field in which research into individual cells/molecules using AFM is at the frontier [5][6][7]. As a result of significant advances over the last two decades, AFM has evolved into a multifunctional tool [4]. Chemical treatment of the AFM tip and substrate allows the measurement of specific protein-protein binding forces using the force curve mode, a technique known as singlemolecule force spectroscopy (SMFS) [8]. In SMFS, ligands/antibodies are linked to AFM tips and receptors/antigens are then bound to a substrate. Using the functionalized tip to obtain force curves for the protein-coated

Elucidating the underlying mechanisms of cell physiology is currently an important research topic in life sciences. Atomic force microscopy methods can be used to investigate these molecular mechanisms. In this study, single-molecule force spectroscopy was used to explore the specific recognition between the CD20 antigen and anti-CD20 antibody Rituximab on B lymphoma cells under near-physiological conditions. The CD20-Rituximab specific binding force was measured through tip functionalization. Distribution of CD20 on the B lymphoma cells was visualized three-dimensionally. In addition, the relationship between the intramolecular force and the molecular extension of the CD20-Rituximab complex was analyzed under an external force. These results facilitate further investigation of the mechanism of Rituximab's anti-cancer effect.atomic force microscopy, single-molecule force spectroscopy, CD20 antigen, Rituximab Citation:Li M, Liu L Q, Xi N, et al. Detecting CD20-Rituximab specific interactions on lymphoma cells using atomic force microscopy.

Abstract. This paper presents a modeling and transition algorithm of a novel wall-climbing robot with biped-wheel hybrid mechanism. In order to realize robot transitions between inclined surfaces, the robot's locomotion gait is analyzed and a locomotion gait planning model based on Finite State Machine (FSM) is established. Moreover a transition algorithm between inclined surfaces is proposed based on multi-sensors data fusions and logical reasoning networks. The results of simulations and experiments show that the model and algorithm are valid and can be applied for the wall-climbing robot's transition between the concave surfaces.