Colloids for studying molecular recognition

Abstract

During the past decades, organic and inorganic colloids have been widely used for biological or biotechnological applications. In the last decade, colloidal organic / inorganic composites, namely super-paramagnetic particles, have constituted a real improvement for some of these applications. Very recently, we have developed a new way of using such colloidal composites in the fundamental domain of molecular recognition and in the closely linked but more industrial field of immunological diagnosis.Résumé -Colloïdes pour l'étude de la reconnaissance moléculaire. Au cours des décennies passées, les colloïdes organiques et inorganiques ont été largement mis à contribution pour des applications biologiques ou biotechnologiques. Lors des dix dernières années, les composites colloïdaux organique/inorganique , et précisément les particules superparamagnétiques, ont constitué une véritable amélioration dans le cadre de certaines de ces applications. Très récemment, nous avons développé une nouvelle méthode d'utilisation de tels composites colloïdaux dans le domaine de la reconnaissance moléculaire et dans celui, étroitement lié mais plus industriel, du diagnostic immunologique.

Magnetic Iron Oxide Nanoparticles: Synthesis, Stabilization, Vectorization, Physicochemical Characterizations, and Biological Applications

“…It can therefore be expressed as W = k fast / k , where k fast is the rate constant describing rapid aggregation (every collision leads to an aggregation) and k is the aggregation rate constant at the salt concentration used. This stability factor can be achieved through light scattering (static or dynamic) or turbidimetric measurements. – The stability factor as a function of added salt gives access to the critical concentration of coagulation. At this concentration, the double electrostatic layer is entirely suppressed and k = k fast becomes independent of the salt concentration.…”

“…This stability factor can be achieved through light scattering (static or dynamic) or turbidimetric measurements. [267][268][269][270][271][272][273] The stability factor as a function of added salt gives access to the critical concentration of coagulation. At this concentration, the double electrostatic layer is entirely suppressed and k ) k fast becomes independent of the salt concentration.…”

Ultrasonic enhancement of bead-based bioaffinity assays

“…In general, the sensitivity of ELISA tests is in the pM-range. 49 A bead-based homogeneous assay is an assay where the binding reactants (i.e., the receptor-coated beads) and the analyte-containing sample is mixed, incubated and detected in bulk solution without the need for any separation steps. Such single-step, separation-free assays have the advantage of being more simple and straightforward, which results in low costs, fast solution-phase kinetics and reduced test time.…”

“…57 However, most agglutination tests suffer from low sensitivity with detection limits in the nM-range. 49 The limiting factors are mainly the relatively high bead concentrations needed for sufficiently high particle collision rates, and nonspecific agglutination (NSA) of beads. These factors will be described in more detail below.…”