Browsing by Author "P.A. Joy"

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Biomimetic synthesis of superparamagnetic iron oxide particles in proteins
(Materials Research Society, 2003) Arvind Sinha; Suprabha Nayar; G.V.S. Murthy; P.A. Joy; V. Rao; P. Ramachandrarao
Matrix-mediated in situ synthesis of monodispersed magnetite and maghemite nanoparticles (2-16 nm) was carried out using the cavities present in gels of globular proteins such as egg white and bovine serum albumin. Under stringent conditions, spatial-charge-distribution-assisted molecular recognition of proteins for inorganic ions led to the site- and polymorph-specific synthesis of superparamagnetic iron oxide particles. A transformation from magnetite to maghemite as a nucleating phase could be observed by partially denaturing the egg white protein, signifying the delicate role of quaternary structure of proteins under different reaction conditions, in determining the size and shape of the polymorph.
Magnetic field-induced biomimetic synthesis of superparamagnetic poly (vinyl alcohol)-maghemite composite
(2004) Arvind Sinha; Jui Chakraborty; P.A. Joy; P. Ramachandrarao
Poly (vinyl alcohol)-mediated synthesis of monodisperse, self-assembled, superparamagnetic maghemite particles was carried out through a magnetic field-induced biomimetic route. Modifying the kinetics of precipitation, the magnetic field promoted the nucleation of the maghemite phase over magnetite and also induced a self-assembly-assisted shape anisotropy during the precipitation of the particles in the polymer matrix. © 2004 Materials Research Society.