Following incubation of polystyrene-50K-capped spherocylindrical gold nanorods in the DMF/water mixture, a uniform polymer layer separated into two distinct patches engulfing the nanorod tips . Similar polymer segregation towards metal tips occurred for gold nanorods with a dumbbell shape . Patches of polystyrene-50K formed on the edges of silver nanocubes and triangular nanoprisms incubated in a poor solvent , as well as on edges of gold nanocubes in the tetrahydrofuran/water mixture . Other polymer ligands exhibited qualitatively similar surface segregation in a poor solvent. Thiol-terminated poly on gold nanospheres formed into a patch following an increase in pH of an aqueous nanosphere solution from 2.5 to 11.5, at which the polymer became hydrophobic . Thiol-terminated poly ligands split into two patches on the surface of gold nanospheres incubated in the DMF/water mixture . The generation of patchy nanoparticles enabled preliminary exploration of their new selfassembly modalities. In the present work, to produce individual patchy nanoparticles, we suppressed their self-assembly in a poor solvent by using dilute solutions; however, given sufficient time, patchy nanospheres assembled in chains co-existing with small clusters of two to three single-patch nanospheres . We isolated nanospheredimers by centrifugation of the colloidal solution and separation of larger nanosphere assemblies. The ability to control the separation between the gold surfaces by varying polymer grafting density or molecular mass enables control over hot spots of a strong electric field in the gap between the nanospheres in the dimers, making them useful in Raman scattering.

Inspection of isolated chains of patchy nanospheres revealed that they were built from dimers and trimers , dutch buckets system suggesting a sequential mechanism of the self-assembly of patchy nanospheres: a faster assembly of dimers and trimers and a slower assembly of these building blocks in chains, in comparison with the self-assembly of non-patchy nanospheres. A new binding modality was also observed for patchy nanocubes undergoing self-assembly in an open, ‘checkerboard’ structure, owing to the binding of nanocube edges in a poor solvent , markedly different from the face-to-face assembly of the nanocubes uniformly coated with polystyrene ligands . For patchy nanocubes, the face-to-face and the ‘checkerboard’ assembly via the formation of four bonds between the edges may result in a similar reduction in the surface free energy of the system, whereas for nonpatchy nanocubes, the formation of close-packed structures would be favoured, owing to the maximum screening of unfavourable polymer interactions with a poor solvent. The amphiphilic nature of patchy nanospheres led to their assembly at the interface between immiscible liquids, thus reducing the surface energy of the system and behaving as colloidal surfactants. Following the addition of water to the mixture of polystyrene-capped gold nanospheres and non-thiolated free polystyrene molecules in DMF, the reduction in solvent quality led to the formation of patchy nanospheres and polystyrene-rich droplets. The nanospheres self-assembled on the droplet surface, with a polystyrene patch immersed in the droplet . A considerably higher energy of attachment of patchy nanospheres to liquid–liquid interface6 , in comparison with conventional Pickering emulsions, is expected to provide enhanced stabilization properties of emulsions.

Sonication of patchy nanospheres and non-thiolated polystyrene in the DMF/water solution led to the formation of elongated polystyrene species decorated with patchy nanospheres . We have thus developed a new strategy for nanoparticle surface patterning that is governed by thermodynamically controlled segregation of polymer ligands in pinned micelles with a footprint area comparable with the nanoparticle surface area. The experimental results were in excellent agreement with the proposed theoretical model. The described patterning strategy can be used for the generation of reconfigurable nanocolloids: reversible transitions between a smooth polymer shell and surface patches can be triggered by illumination, change in temperature, ionic strength or pH of the solution, that is, the stimuli changing the solvent quality. On demand, polymer patches can be ‘locked’ by permanent crosslinking, which would suppress nanoparticle assembly and enable the utilization of solutions with a higher nanoparticle concentration, thereby increasing the yield of patchy nanoparticles. The utilization of block copolymers will facilitate nanoparticle patterning with a variety of pinned micelle structures, including comicelles, which may tailor new functionalities topatchy nanoparticles. ‘Grafting-from’ surface functionalization and fractionation of nanoparticles with a particular number of patches will enhance control over the number of patches per nanoparticle. Patterning of multicomponent nanoparticles and the self-assembly of patterned nanoparticles into complex, hierarchical structures are other directions to explore. Furthermore, given the remarkable progress in the synthesis of nanoparticles with different shapes, the proposed strategy enables fundamental studies of polymer segregation on surfaces with large curvatures or surfaces with multiple curvatures.The broader community of microbes within a host, the microbiome, can determine the health status of an individual.

Many microbes provide beneficial functions for the host including metabolism and immunity. In honey bees, certain Lactobacillus strains offered protection against a microsporidian and bacterial pathogen. Similarly, in bumble bees, increased microbiome diversity was linked to reduced infection by the trypanosomatid parasite Crithidia. In Osmia ribofloris, the pollen provision microbiome is crucial for larval development. Therefore, it is important to characterize and understand the microbiome to understand bee health. Our current knowledge on the microbiome of bees is predominantly based on honey bees , and to a lesser degree bumble bees. Both of these are highly social and closely related members of the corbiculate apid bees, and as such they share a very similar core microbiome. Outside of these genera, the bee microbiomes sequenced so far do not conform to the Apis and Bombus models. Even within the corbiculates, the stingless bees and the orchid bees lack some of the most common symbionts of Apis and Bombus, although several related symbionts are shared amongst the corbiculates. Looking more broadly, bacteria that were previously classified as Lactobacillus but have been recently split into the genera Apilactobacillus, Bombilactobacillus and Lactobacillus sensu strictu are some of the few symbionts common to multiple bee taxa including Apis, Bombus, the small carpenter bee Ceratina, megachilid and halictid bees. Microbe acquisition in Apis and Bombus occurs within the hive, facilitated by nestmate interactions or transfer from feces. While honey and bumble bees live in large groups, this level of sociality is rare among bees, the vast majority of bee species being solitary. Indeed, in the other bee species studied so far, much of their microbiota appears to be gained from the environment rather than through social transmission. Therefore, differences in environmental and pollen-associated bacteria may have larger impacts on wild bee development than for the highly social corbiculate bee species. Microbial acquisition from the environment may be influenced by the diet of the bee. As for bees, flowers harbor a variety of microbes, which can potentially be passed to foraging bees. Crithidia can be transmitted between foraging Bombus at flowers and communities of pollinators have been found to share microbes. For bees that use foliage to line their nests, both flower and foliar source affect their pollen provision microbiome. However, dutch buckets there are also many more complex factors to consider such as flower morphology, volatiles and even the secondary compounds produced by the microbes themselves, that can alter floral bacterial communities and transmission to pollinators. Therefore, diet may be an important factor to consider when looking at the wild bee microbiome, which is thought to be largely environmentally sourced. To conserve wild bees, we need to understand their health, and their associated microbial symbionts. It seems likely that the microbes present in the environment, and therefore those gained environmentally by bees, will vary geographically with changes in climate, interacting insect species and floral communities. Ceratina calcarata Robertson, 1900 is a small carpenter bee species that is a widespread and prominent pollinator across eastern North America. This species nests in the dead stems of various plants, commonly raspberry and sumac. The plants it nests in also produce flowers, potentially biasing pollen collection and thereby microbial acquisition. This bee constructs separate brood cells within the stem nest, each provisioned with a single pollen ball on which an egg is laid. This brood provision is the only source of food given to the offspring until it reaches maturity. Study of these brood provisions from nests at the northern extent of its range found they contain multiple pollen species and a diversity of microbes dominated by Lactobacillus, Wolbachia, Acinetobacter and Sodalis. However, C. calcarata is found across a broad geographic range in eastern North America and acquires at least part of its microbiome from the environment, therefore its microbiome may vary geographically with corresponding changes in climate and floral landscape. The aim of this project was to investigate whether the microbiome of C. calcarata varies geographically by sequencing brood provisions spanning this species’ range across the eastern United States.

Specifically, we asked whether pollen or bacterial species vary in composition or diversity among sites and if there are identifiable plant/microbe associations. We also asked whether foraging was biased by the proximity of nest plant flowers.We considered Faith’s phylogenetic diversity as a measure of taxonomic richness; comparisons between groups were made with Kruskal–Wallis analysis . Abundance data were compared through PERMANOVA analysis of both Bray–Curtis dissimilarity and weighted unifrac indices as measures of beta-diversity and phylogenetic beta-diversity, respectively. Additional statistical comparisons were performed with Kruskal–Wallis and Wilcoxon tests in R v.1.0.136. Co-associations between the pollen and bacterial components of the brood provisions were assessed using SparCC and CoNet. Both programs were used as SparCC and CoNet use correlation and dissimilarity methods, respectively, and the differences in the algorithms between these two approaches can lead to different results. New Hampshire was not considered due to the exclusion of the rbcl data for this site, and these analyses have been previously reported for New Hampshire in [20]. Analyses were run on a combined dataset of all bacterial and plant ESVs identified to genus level from Georgia and Missouri. This was then repeated on separate datasets of reads from Georgia and Missouri separately to look for site differences in co-associations. Pseudo p-values in SparCC were calculated based on 100 bootstrap replicates. In CoNet, network edge scores were calculated with Pearson, Spearman, mutual information, Bray Curtis and Kullback Leibler. Bootstraps were calculated using Brown p-value merging and Benjamini–Hochberg multiple test correction. Positive correlations were only considered if recovered in both SparCC and CoNet with p ≤ 0.01.The floral resources utilized by C. calcarata differed between regions, brood provisions being dominated by different pollen genera in each state, showing this generalist bee’s local adaptation to regional floral communities . Foraging preference was not biased towards flowers present on the host nest plant, indicating that spatial assortment of floral resources alone does not determine foraging preferences. Despite changes in floral resources, the same core microbes dominated brood provisions across all states, although the relative abundance of these groups did vary between region . Our overall network analyses identified some correlations in plant and bacterial occurrences, however the broad changes in floral diet between states did not correspond to large changes in the bacterial community, suggesting that these floral–bacterial associations are transient or non-obligate . There were a number of core bacterial genera found across all sites but the relative abundance of these varied strongly . Comparison to McFrederick and Rehan’s study in New Hampshire suggests there may also be annual variation within sites. In 2016, Lactobacillus was the most common genus, while we recovered Sodalis and Wolbachia as the top two genera in the current study . Being obligate facultative endosymbionts in many insect species, the occurrence of Wolbachia and Sodalis is likely due to contamination from mites or other parasites, or transfer directly from the mother’s crop rather than through any specific floral sources. A major limitation of amplicon sequencing studies is that they can only determine the presence or absence of an organism’s DNA, not whether that organism is metabolically active, and this holds true for all bacteria recovered in our samples. This aside, it is interesting that Wolbachia contamination is so prevalent, and future microscopic examination of pollen material for mite infestation and tests of possible vertical transmission via pollen are needed. Lactobacillus was only present in 2.2% of reads in the New Hampshire samples for this study. Within Georgia, the abundance of bacterial ESVs differed between nests in Rubus and Rhus but significant differences disappeared when the phylogenetic similarity of bacteria was considered. This suggests there could be some differences in the abundance of microbial species or strains between nesting substrates but overall the taxonomic distribution of bacteria in the brood provisions is similar.