Browsing by Author "Suprabha Nayar"

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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.
Microhydrogel-mediated synthesis of sintered hydroxyapatite granules
(2008) Arvind Sinha; Suprabha Nayar; Abhijit Kar; Manoj Kumar Gunjan; Bhupeshawar Mahato; Gautam Das; Arun Kumar; Aman Chabra
Synthesis of macroporous hydroxyapatite (HA) granules with a controlled microarchitecture has been demonstrated by following a polymer microhydrogel mediated synthesis process coupled with sintering. The process is basically based on in situ nucleation and growth of HA nanoparticles in polymer (polyvinyl alcohol) microhydrogels. A systematic variation of polymer concentration has manifested a controlled evolution of a hierarchical macroporous granular structure after sintering. © 2008 American Ceramic Society.
Synthesis of nanosized and microporous precipitated hydroxyapatite in synthetic polymers and biopolymers
(American Ceramic Society, 2003) Arvind Sinha; Suprabha Nayar; Archana Agrawal; Debasish Bhattacharyya; Patcha Ramachandrarao
In situ precipitation of microporous and nanosized hydroxyapatite particles (5-40 nm) has been conducted in poly(vinyl alcohol) and bovine serum albumin gels. The process, which is similar to biomineralization, is highly controlled with respect to microstructural features, such as size and shape, and to precipitation of hydroxyapatite phase having a calcium:phosphorus stoichiometric ratio of 1.67. Nanosized precipitated hydroxyapatite particles show remarkable thermal stability and do not decompose to other calcium phosphate phases, even at higher temperatures.