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Green chemistry of industrially important zein protein was explored in aqueous phase toward the synthesis of bioconjugated gold (Au) nanoparticles (NPs), which allowed us to simultaneously understand the unfolding behavior of zein with respect to temperature and time. Synthesis of Au NPs was monitored with simultaneous measurements of UV–visible absorbance due to the surface plasmon resonance (SPR) of Au NPs that triggered the adsorption of zein on the NP surface and thus resulted in its unfolding. Surface adsorption of zein further controlled the crystal growth of Au NPs, which relied on the degree of unfolding and fusogenic behavior of zein due to its predominant hydrophobic nature. The latter property induced a marked blue shift in the SPR rarely observed in the growing NPs during the nucleation process. A greater unfolding of zein in fact was instrumental in generating zein-coated faceted NPs that were subjected to their hemolytic response for their possible use as drug release vehicles. Zein coating significantly reduced the hemolysis and made bioconjugated Au NPs the best models for biomedical applications in nanotechnology.

The aim of this study was to determine the evolving trends of retinopathy of prematurity (ROP) at a tertiary neonatal intensive care unit. In an ongoing screening programme for ROP, we estimated the incidence of ROP among at-risk neonates in a tertiary care unit. We compared our data over the last 12 months (1999-2000; period II) to the previously published data (1993-94; period I) to study changes in the spectrum of the disease. The overall incidence of ROP in period II was not significantly different from the incidence in period I (32 vs. 20 per cent, p > 0.05). However, a decreasing trend in the proportion of severe ROP (stage III) from 46 to 21 per cent in the later period was noted. The need for cryotherapy also dropped significantly compared with the earlier period (8 vs. 46 per cent respectively, p < 0.05). On multivariate analysis, apnea (p < 0.001; RR = 12.5; 95 per cent CI, 3.03-50.9; clinical sepsis (p < 0.001; RR = 5.7; 95 per cent CI, 1.6-20.7); and male sex (p < 0.001; RR = 6.3; 95 per cent CI 1.6-25.5) emerged as significant risk factors. Although the incidence of ROP is static, the more severe form of the disease (stage III) is showing a decline. Our data suggests that efficient management of apnea and sepsis may be crucial in further minimizing the risk of ROP.

Self-assembled gold (Au) nanoparticles (NPs) were synthesized in micelle surface cavities of a L121 block polymer in the presence of zwitterionic (viz. DPS, TPS, and HPS) and sugar surfactants (OG and DDM) in aqueous phase at 70 °C by using the surface cavities of L121 as reducing sites for converting Au(III) into Au(0). All reactions were monitored simultaneously by UV-visible spectroscopy to determine the growth kinetics in gold nucleating centers on the basis of surface plasmon resonance that also helped in tracing the structure micelle transitions over a wide temperature range of 10-70 °C. The surfactant/L121 mole ratio was changed systematically from 0.5 to 2.5 by keeping L121 and HAuCl4 concentrations constant at 10 and 0.25 mM, respectively, to determine the shape and size of the micelles and their relation to the self-assembled behavior of Au NPs. TEM studies were used to have a direct insight into the morphology of micelle templates and their shape and size for self-assembled NPs. L121 along with DPS (C12 carbon chain) produced well-defined micelles loaded with tiny NPs of 3-6 nm in the L121-rich region of the mixture, while large flower-like compound micelles with a clear core-shell morphology were produced in the DPS-rich region. TPS and HPS (C14 and C16 hydrocarbon chains, respectively) with stronger hydrophobicity than DPS also produced almost similar micelles loaded with tiny NPs in the L121-rich region, but they disappear in the surfactant-rich region. Replacement of zwitterionic with ionic surfactants did not yield micelle templates for self-assembled NPs. Results conclude that well-defined micelles of L121 are the fine templates for self-assembled NPs that can only be achieved in the presence of a neutral surfactant with low concentration and low hydrophobicity.

Interactions between the components of lysozyme/cytochrome c (lysozyme/ Cyt,c) and lysozyme/zein protein mixtures were determined by following the in vitro synthesis of gold (Au) nanoparticles (NPs). Both UV−visible and fluorescence studies were employed to monitor the interactions and simultaneous synthesis of protein coated NPs. Protein coated NPs were characterized by gel electrophoresis and TEM studies. Lysozyme/ Cyt,c complex coated NPs showed remarkable pH responsive behavior due to their amphiphilic nature, while lysozyme/zein complex coated NPs were not pH sensitive because of the predominantly hydrophobic nature. The results were further supported by molecular dynamics studies (MD) of protein−protein interactions and interactions of protein with the gold surface. Molecular simulations helped us to identify the amino acids that drove such interactions. Biological applications of protein coated NPs were determined from hemolytic and antimicrobial studies to demonstrate their potential in pharmaceutical and food industries. The results clearly differentiated between the greater applicability of predominantly amphiphilic lysozyme/Cyt,c complex coated NPs in comparison to predominantly hydrophobic lysozyme/zein complex coated NPs.

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