Optical tweezers to study single Protein A/Immunoglobulin G interactions at varying conditions

Abstract

Optical tweezers (OT) are ideally suited to study the interaction of single receptor-ligand bonds. Here we introduce a newly developed assay using OT to investigate the interactions between Protein A from Staphylococcus aureus and Immunoglobulin G from rabbit serum (RIgG). We demonstrate that the rupture forces depend on the loading rate and on the sodium chloride concentration. The measured loading rate effect is well known in the literature and the data we obtained were found to be in good agreement with an already published theoretical model. The dependence of the rupture forces on the salt concentration demonstrates the influence of hydrophobic interactions on the bond strength. Our experimental setup can probe the interaction between a single receptor and its specific ligand under changing conditions and hence offers manifold applications in single molecule biotechnology.

Optical Tweezers Studies on Notch: Single-Molecule Interaction Strength Is Independent of Ligand Endocytosis

“…The rupture force between rabbit IgG and PrtA has been reported to be ~ 30 pN at our typical loading rate of 250 pN/sec (Salomo et al, 2008). Laser tweezers analyses of IgG-PrtA rupture force for rabbit, mouse, bovine and goat IgG identified a median rupture force ranging from 25 to 44 pN (Stout, 2001), measured at loading rates ranging from 400 to 5300 pN/sec.…”

Interfacial re-arrangement in initial microbial adhesion to surfaces

“…Neglecting the structural complexity and chemical heterogeneity of microbial cell surfaces [11], indeed a search has been initiated many years ago into microbial zeta potentials [12 • ], contact angles [13 • ], cell surface hydrophobicities [14][15][16], surface free energies [17], and other physico-chemical properties of microbial cell surfaces with the aim of applying surface thermodynamics [17,18 • ] or DLVO theories [6,19 •• ,20] to explain initial microbial adhesion to surfaces. More recently, various groups have been involved in the direct measurement of microbial interaction forces with substratum surfaces, either pristine or conditioning film coated, employing atomic force microscopy (AFM) [21,22] or optical tweezers [23,24].…”

Micro-rheology on (polymer-grafted) colloids using optical tweezers

“…By using strongly focused laser light a dielectric particle is trapped in a focal point. The unique possibility to hold and manipulate the single particle under study in a suitable medium and to measure the forces acting on it without mechanical contact enables one to carry out exciting novel experiments in micro-rheology and materials research [11,[19][20][21][22][23][24][25][26][27][28][29][30][31]].…”