Bioluminescence, due to its high sensitivity, has been exploited in various analytical and imaging applications. In this work, we report a highly stable, cell-transductable and wavelength-tunable bioluminescence system achieved with an elegant and simple design. Using aqueous in-situ polymerization on bioluminescent enzyme anchored with polymerizable vinyl groups, we obtained nano-sized core-shell nanocapsules with enzyme as the core and crosslinked thin polymer net as the shell. These nanocapusles possess greatly enhanced stability, retained bioactivity, and readily engineered surface. In particular, by incorporating polymerizable amines in the polymerization, we endowed the nanocapsules with efficient cell-transduction and sufficient conjugation sites for follow-up modification. Following in-situ polymerization, decorating the polymer shell with fluorescent quantum dots allowed us to access continuous tunable wavelength, which extends the application of such bioluminescent nanocapsules, especially in deep tissue. In addition, the unique core-shell structure and adequate conjugation sites on surface enabled us to maximize the BRET efficiency by adjusting the QD/enzyme conjugation ratio. Bioluminescence1, the light emission resulted from enzymatic reactions within living organisms, is commonly used for various applications2 -3, such as whole-cell biosensors, immunoassays, nucleic-acid hybridization assays and in-vivo imaging. Many of these applications, however, require transfection of bioluminescent reporter genes, accompanied with many other limitations, such as safety. Moreover, the wavelengths of bioluminescence are still limited to blue/green light, which hinders its use in deep-tissue applications 4 -5.Herein, we report a novel class of bioluminescent nanocapsules (BNs) that are robust, cellpermeable, and tunable in wavelength. Scheme 1 illustrates our synthesis strategy. Starting with a bioluminescent protein, mild chemical modification attaches the protein with polymerizable vinyl groups; subsequent polymerization in an aqueous solution containing acrylamide (AAm) and N-(3-aminopropyl)methacrylamide (APMAAm) wraps the protein * mingyan@ucla.edu; chenwei0226@yahoo.com.cn; luucla@ucla.edu . Supporting Information Available:Full experimental details for preparation of bioluminescent nanocapsules; TEM images; fluorescence and bioluminescence spectra; cell internalization protocols. This material is available free of charge via the Internet at http://pubs.acs.org. NIH Public AccessAuthor Manuscript J Am Chem Soc. Author manuscript; available in PMC 2011 September 22. This unique architecture endows the BNs with many advantages: 1) the thin polymer layer stabilizes the protein and enables rapid transport of the substrate to the encased protein, ensuring bioactivity and stability of the BNs7; 2) fluorophores can be attached to the protein conjugates with controlled density, ensuring an efficient BRET. Particularly, quantum dots (QD), a class of fluorophores with high photo-stability and quantum efficien...

[1] The focus of this paper is to study the relationship between sporadic Fe (Fe s ) and Na (Na s ) layers through simultaneous and common volume Fe and Na lidar observations. A total of 37 sporadic layering events were identified from one year (195 hours) of observations at Wuhan (30.5°N, 114.4°E), China. Out of the 37 events, 23 (62%) are characterized by the simultaneous formation of Fe s and Na s layers. The most prominent feature for each of the 23 events is that the Fe s and Na s layers occurred in overlapping altitude ranges and moved following almost the same track. On occasion the Fe s and Na s layers exactly simultaneously reached their maximum peak densities at nearly the same altitude. These observational results strongly suggest that Fe s and Na s layers are formed via the same or very similar mechanisms. This conclusion contradicts the previous suggestion based on those independent observations of Fe s and Na s layers, that the Fe s and Na s layers may be formed via different mechanisms. Out of the 37 events, 14 (38%) belong to single-species sporadic layering events. It is noticed that the formation of each single-species sporadic atom layer was usually accompanied by a weak density enhancement in the other metal atom. This supports the suggestion that Fe s and Na s layers are formed via the same or very similar mechanisms. Both the Fe s and Na s layers over Wuhan showed a tendency to strengthen with decreasing occurrence altitude. This tendency is consistent with the earlier Na s layer observations at high and low latitudes. Moreover, it is noticed by comparing the currently available Fe s and Na s layer characteristics, which came from the observations at five different locations (including Wuhan) during different periods, that a lower average altitude could link to a higher average peak density and vice versa. The statistics-based link might perhaps represent a universal feature of sporadic layers. From our simultaneous Fe and Na density data we have found that the undersides of the normal Fe and Na layers follow nearly the exact movements and occur at nearly the same altitude. The normal Fe layer tended to be narrower than the corresponding Na layer nearly at all times, and this difference was generally reflected in the extent of the upper edge of the layer. The nearly persistent underside overlap strongly suggests that on the undersides of these meteoric metal layers there exist some sink mechanisms leading to the concurrent removal of different sorts of free neutral metal atoms.

[1] High-accuracy atom density profiles, obtained by the simultaneous and commonvolume Fe and Na lidar measurements at Wuhan, China (30.5°N, 114.4°E), reveal some ubiquitous features of the Fe and Na layers on their borders. The Fe and Na lower boundaries show consistently a delicate stratification in which the lower boundary of the Fe layer is in general slightly higher than or coincident with that of the Na layer, with an overall mean altitude difference being about 0.2 km. Despite the existence of considerable vertical displacements, the two lower boundaries vary always following almost the same track. The overall correlation coefficient between them is as high as 0.96. This ubiquitous delicate stratification of the measured lower boundaries (nearly coincident density cutoff ) suggests strongly that the undersides of Fe and Na layers are controlled by the same or very similar processes. The upper boundary of the Na layer is always several kilometers higher than that of the Fe layer. A relatively weak positive correlation is also persistently observed between the two upper boundaries. Weak sporadic layering events frequently occur on the upper extent of the metal layers. They may impair the correct determination of the upper boundaries of the normal metal layers and consequently weaken the correlation. Both the Fe and Na layers often show an evidently steeper density gradient on the underside than on the upper extent, and the borders of the Fe layer are clearly steeper than those of the Na layer. The explanation to these ubiquitous features needs further experimental and modeling efforts.

[1] The complete seasonal variation patterns of the nocturnal mesospheric Na and Fe layers over Wuhan, China (30°N), have been established on the basis of several years of Na and Fe lidar measurements. Both the Na and Fe layer column abundances show strong annual variations as well as moderate semiannual variations with maxima in winter and double minima from late spring to midautumn (note that only one night of Fe data is presently available between mid-May and mid-July). The seasonal variation in the Fe abundance is evidently stronger than that of Na. The Na layer abundance has an annual mean of $2.5 Â 10 9 cm À2 , while this value for Fe is $7.5 Â 10 9 cm À2 . The Na and Fe centroid heights are dominated by semiannual oscillations with similar phases. The mean centroid heights are $91.4 km for Na and $88.7 km for Fe. The Na RMS width exhibits a strong semiannual oscillation with the layer slightly broader in winter, whereas the Fe width varies principally annually with a maximum in winter. The mean RMS widths of the Na and Fe layers are 4.5 and 4.1 km, respectively. The seasonal characteristics of the Na and Fe layers observed at 30°N have been compared with those currently available at other latitudes. The seasonal ratios of their abundances are smaller compared with 40°N and the South Pole. Their centroid heights and RMS widths also show less seasonal variations than the counterparts at all other latitudes. The annual mean Na and Fe abundances are about 60-77% of the counterparts at 40°N, 18°N, and the South Pole. This suggests that both the nocturnal Na and Fe layers have a low-abundance region around 30°N. On the basis of the results observed at the three latitudes in the Northern Hemisphere, the annual mean Fe layer width decreases with increasing latitude.