Ratiometric Nanothermometer Based on a Radical Excimer for In Vivo Sensing.

Ratiometric fluorescent nanothermometers with near-infrared emission play an important role in in vivo sensing since they can be used as intracellular thermal sensing probes with high spatial resolution and high sensitivity, to investigate cellular functions of interest in diagnosis and therapy, where current approaches are not effective. Herein, the temperature-dependent fluorescence of organic nanoparticles is designed, synthesized, and studied based on the dual emission, generated by monomer and excimer species, of the tris(2,4,6-trichlorophenyl)methyl radical (TTM) doping organic nanoparticles (TTMd-ONPs), made of optically neutral tris(2,4,6-trichlorophenyl)methane (TTM-αH), acting as a matrix. The excimer emission intensity of TTMd-ONPs decreases with increasing temperatures whereas the monomer emission is almost independent and can be used as an internal reference. TTMd-ONPs show a great temperature sensitivity (3.4% K-1 at 328 K) and a wide temperature response at ambient conditions with excellent reversibility and high colloidal stability. In addition, TTMd-ONPs are not cytotoxic and their ratiometric outputs are unaffected by changes in the environment. Individual TTMd-ONPs are able to sense temperature changes at the nano-microscale. In vivo thermometry experiments in Caenorhabditis elegans (C. elegans) worms show that TTMd-ONPs can locally monitor internal body temperature changes with spatio-temporal resolution and high sensitivity, offering multiple applications in the biological nanothermometry field.

CCL21-loaded 3D hydrogels for T cell expansion and differentiation.

Recent achievements in the field of immunotherapy, such as the development of engineered T cells used in adoptive cell therapy, are introducing more efficient strategies to combat cancer. Nevertheless, there are still many limitations. For example, these T cells are challenging to manufacture, manipulate, and control. Specifically, there are limitations in producing the large amounts of therapeutic T cells needed for these therapies in a short period of time and in an economically viable manner. In this study, three-dimensional (3D) poly(ethylene) glycol (PEG) hydrogels covalently combined with low molecular weight heparin are engineered to resemble the lymph nodes, where T cells reproduce. In these hydrogels, PEG provides the needed structural and mechanical properties, whereas heparin is used as an anchor for the cytokine CCL21, which is present in the lymph nodes, and can affect cell migration and proliferation. The 3D structure of the hydrogel in combination with its loading capacity result in an increased primary human CD4+ T cell proliferation compared to the state-of-the-art expansion systems consisting of artificial antigen presenting cells. Thus, we present a new tool for adoptive cell therapy to help achieving the large numbers of cells required for therapy of selected phenotypes targeted against cancer cells, by mimicking the lymph nodes.