Currently, there is great interest in the development of methods suitable for determining the stoichiometry of biomolecules attached to nanoparticles. We describe the use of the dynamic light-scattering technique (DLS) to determine the stoichiometry of the protein cytochrome P450_BSβ attached to CdS and CdSe quantum dots (QDs). The enzyme-conjugated QDs have different diffusion characteristics compared to the QD and enzyme precursors, expressed in their size, scattering intensity as well as zeta-potential values. The significant enhancement of the scattering intensity of QDs observed upon conjugation with the P450_BSβ due to the refractive-index increment and the systematic variation in zeta potential resulting from charge neutralization of the anionic QDs by the cationic histidine-tagged P450_BSβ have been used for stoichiometry determination.

Tenside sind amphiphile Moleküle, die sich an Grenzflächen anreichern und im Inneren von Lösungen definierte Aggregate (Mizellen) bilden. Im Bereich höherer Konzentrationen dienen die Mizellen wiederum als Bausteine für komplexe, dreidimensionale Strukturen, die isotrope oder anisotrope Eigenschaften besitzen. All diese verschiedenen Phasen bilden sich durch Prozesse der Selbstorganisation; eine fundamentale Eigenschaft, die auch lebende Systeme kennzeichnet. Aufgrund ihrer geringen Größe, der leichten Herstellung und der verschiedenen Gestalt besitzen Tensidfilme und Tensidaggregate interessante Eigenschaften, die zur Herstellung verschiedener Arten von Kristallen und Nanomaterialien gezielt genutzt werden können.

Surfactants are molecules that tend to adsorb at fluid interfaces and form aggregates (micelles) in aqueous solutions. In the regime of elevated concentrations, micellar aggregates can serve as components for more complex, three-dimensional lyotropic mesophases, which possess isotropic or anisotropic properties. Surfactant films and aggregates are automatically formed by processes of self-organization; a fundamental phenomenon of living matter. On grounds of well-defined sizes, easy handling and different shapes, surfactant films and micelles possess interesting properties, which can successfully be used to synthesize different types of crystals and nano-materials.