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Bones are the building blocks of our skeletons—they give our bodies structure and allow us to walk, dance, and pick things up. Healthy bones are strong, lightweight, hard, and even able to fix themselves when they get worn out or damaged. But if bones get sick, they can no longer repair themselves and they start to break down. One disease that makes bones sick is called osteoporosis and it can be very painful. Currently, doctors cannot cure osteoporosis. While there are medications to slow bone loss, there are no safe treatments to repair bone that is already damaged. Therefore, doctors and scientists are working together to find ways to prevent and even cure diseases like osteoporosis. One important challenge that needs to be addressed is: how can medicine be delivered to sick bones? In this article, we discuss how tiny carbon nanoparticles could help doctors deliver medicine to sick bones to repair them.

C-dots synthesized from carbon nanopowder (oxidation, hydrothermal) are particularly attractive theragnostic agents for bone-related injuries and disease due to their bright fluorescence and high binding affinity and specificity for bones, as demonstrated in a larval animal model. Larval bone development, however, is significantly different from the bone growth, repair and regeneration processes occurring in adults. Using adult zebrafish, we investigated C-dots’ interactions with adult skeletal structures. Upon injection, C-dots were observed at the surface of bones, at sites of appositional growth. In regenerating bones, C-dots were observed at the core and on the surface of the bones depending on the age of the tissue. C-dot’s deposition occurred within 30 min of delivery and it was highly selective. Importantly, their deposition did not interfere with bone regeneration or the animal’s health. Together, these properties establish C-dots as novel tools for the diagnostic and treatment of adult bone-related injuries and diseases.

Canonical and non-canonical Wnt signaling, as well as the Pax/Six gene network, are involved in patterning the freshwater sponge aquiferous system. Using computational approaches to identify transcription factor binding motifs in a freshwater sponge genome, we located putative PaxB binding sites near a Secreted Frizzled Related Protein (SFRP) gene in Ephydatia muelleri. EmSFRP is expressed throughout development, but with highest levels in juvenile sponges. In situ hybridization and antibody staining show EmSFRP expression throughout the pinacoderm and choanoderm in a subpopulation of amoeboid cells that may be differentiating archeocytes. Knockdown of EmSFRP leads to ectopic oscula formation during development, suggesting that EmSFRP acts as an antagonist of Wnt signaling in E. muelleri. Our findings support a hypothesis that regulation of the Wnt pathway by the Pax/Six network as well as the role of Wnt signaling in body plan morphogenesis was established before sponges diverged from the rest of the metazoans.