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A one-pot colloidal reaction strategy was developed to synthesize asymmetric magnetic composite particles (AMCPs) with high anisotropy and magnetic content. The asymmetricity was established by having two portions of the particle composed of both polystyrene and silica, among which the latter was conjugated with magnetite nanoparticles. Phase separation was found to be critical in developing the asymmetric structure between the inorganic and polymer components during miniemulsion polymerization and the sol–gel reaction. Morphological control of the magnetic composite particles was achieved in a straightforward fashion by adjusting the processing parameters. These asymmetric nanomaterials with superparamagnetic and amphiphilic properties will have significant potential in biomedical applications. [ABSTRACT FROM AUTHOR]

To overcome major challenges of non-specific protein adsorption on nanoparticles for nanosensing and nanodiagnosis, an efficient method for robust chemical modification was developed to achieve excellent specific biorecognition and long-term stability in complex biomedia. This method is demonstrated by a highly specific and sensitive immunoassay (IA), using superparamagnetic nanospheres (NSs) with high magnetite content. The non-specific protein adsorption on the NSs was suppressed dramatically when modified with dual functional poly(carboxybetaine methacrylate) (polyCBMA) via surface-initiated atom transfer radical polymerization (SI-ATRP) and chemically grafted with antibodies of the β subunit of human chorionic gonadotrop (anti-β-hCG). The response to hCG of IA NSs with polyCBMA coatings was highly consistent in either phosphate-buffered saline (PBS) or 50% fetal bovine serum (FBS), which is far less variable than the response of the IA NSs without polyCBMA coatings. After all, a very robust platform for IA NSs with excellent specific biorecognition was obtained. It is expected that this method for nanoparticle modification could be widely used in ultrasensitive nanosensing and nanodiagnosis in the future. [ABSTRACT FROM AUTHOR]