This work studies the effect of dopamine (DA) and adenosine triphosphate (ATP) on lipid membranes using a number of complementary experimental methods. These methods include Dynamic Light Scattering to measure electrostatic surface potentials, solid-state Nuclear Magnetic Resonance to measure the degree of lipid acyl chain order, Electron Paramagnetic Resonance to measure changes in membrane viscosity, and X-ray diffuse scattering to measure structural and material parameters of lipid bilayers. It is shown that both DA and ATP have a measurable affinity to the lipid-water interface even in the absence of specialized biological receptors. These results are important for understanding the function of DA and ATP in cellular processes.