Incorporation strategy for organic dyes into gold nanoparticle supercrystals.

Ordered arrays of plasmonic nanoparticles, supercrystals can lead to the formation of plasmon-polaritons. Coupling light emitters with plasmon polaritons might allow the formation of exciton-plasmon polaritons with properties tuneable by the supercrystal design. To construct such optically active materials, the inclusion of emitters is imperative. The addition of organic dyes without affecting the periodic order of the nanocrystals is difficult, as post-formation protocols might dissolve the supercrystals, and pre-formation addition might affect the self-assembly process. Here, we present an exemplary strategy to functionalize gold nanoparticles prior to self-assembly with a cyanine isothiocyanate dye that was obtained by a straightforward reaction of the amine functionalized dye with carbon disulfide. In the second step, the nanoparticles are functionalized with a thiol-terminated polystyrene, which stabilizes the nanoparticles and governs the self-assembly process. The dye can be integrated in a quantitative fashion, and the nanoparticles can be self-assembled into supercrystals. The strategy should be applicable in general for amine functionalized dyes, which is a common modification.

Larger and near-term baby retinopathy: a rare case series.

PURPOSE: To report retinopathy in a series of four babies unusually beyond the screening standards reported so far in the literature. METHODS: During routine screening for retinopathy of prematurity, we detected retinopathy in four babies who were surprisingly bigger and older than the screening standards. The gestational age (GA), birth weight (BW), post menstrual age at first examination and significant perinatal events were noted. The retinopathy details imaged by the RetCam were classified as per ICROP revisited standards. RESULT: The GA ranged from 36 to 39 weeks and BW from 2.4 to 3.0 kg. Three of them had retinopathy in zone III that regressed spontaneously and one had marked plus with vascular arcades and shunts in zone II that regressed after laser photocoagulation. All of them had fetal distress and multiple systemic comorbidities in the neonatal period. CONCLUSION: This report makes one aware of the possibility of retinopathy in newborn of older GA and larger BW especially with fetal distress and stormy neonatal course.