3D Antibody-Antigen Binding Chamber

Textbook binding curves assume antibody and antigen are perfectly mixed, but real neutralization happens one physical collision at a time. This chamber simulates antigen and antibody molecules diffusing through 3D space via Brownian motion; a binding event can only occur once a pair actually collides, at which point the association rate constant kon sets the probability the collision "sticks" into an immune complex, while the dissociation rate constant koff governs how readily that complex falls back apart. The result is diffusion-limited kinetics — the same regime very high-affinity antibodies operate in, where physical encounter rate, not chemistry, caps how fast neutralization proceeds. Tune kon, koff and antibody count to see collision frequency and sticking probability trade off.