Capabilities of polymer-modified monodisperse colloidal silica particles as biomaterial carrier

Modern biomaterials: a review - bulk properties and implications of surface modifications

This review concerns the importance of length and time on physicochemical interactions between living tissue and biomaterials that occur on implantation. The review provides information on material host interactions, materials for medical applications and cell surface interactions, and then details the extent of knowledge concerning the role(s) that surface chemistry and topography play during the first stage of implant integration, namely protein adsorption. The key points are illustrated by data from model in vitro studies. Host implant interactions begin nanoseconds after first contact and from then on are in a state of flux due to protein adsorption, cell adhesion and physical and chemical alteration of the implanted material. The many questions concerning the conformational form and control of bound proteins and how this may impact on cell adhesion in the first instance and later on cell signalling and implant integration can be answered by systematic investigations using model materials. Only then we will be in a more informed position to design new materials for use in the body.

Ultrasonic enhancement of coated particle agglutination immunoassays: influence of particle density and compressibility

The detection rate and sensitivity (analyte concentration limit) of coated particle agglutination immunoassays are increased in ultrasonic standing waves. The influence of particle volume, density and compressibility, properties that modify the ultrasonic radiation, and interaction forces the particles experience, on assay sensitivity with latex and silica particles in the range 0.25-1.0 microm is examined here. Streptavidin-coated 0.3-microm silica particles and 0.25-microm and 1.0-microm latex particles were examined for agglutination with biotinylated bovine serum albumin (bBSA) following exposure on axis in a 4.6-MHz radial standing wave. The lowest detection limit, 2 ng/mL bBSA, was achieved with the 0.3-microm silica. The detection limit decreased with increasing latex particle size. The limit of an ultrasound-enhanced agglutination immunoassay of rabbit antimouse immunoglobulin was 6-fold better with 1.0-microm coated silica than with equal-sized latex particles. Calculations show that the particle density-dependent ultrasonic interaction force dominates the particle compressibility force for the present case. The density-dependent force on silica, but not on latex particles, is shown to be comparable in magnitude to both the long-range van der Waal's attractive force and the electrostatic repulsion between the particles. This density-dependent force may explain the improved enhancement of analyte detection by coated silica compared with latex particles.