Perfluorodecalin-soluble fluorescent dyes for the monitoring of circulating nanocapsules with intravital fluorescence microscopy

High-Contrast and Fast-Removable 19 F-MRI Labels with Perfluoro-tert-Butyl Substituents

19 F MRI is a unique technique for tracking and quantifying the indicator (19 F-MRI label) in vivo without the use of ionizing radiation. Here we report new 19 F-MRI labels, which are compounds with perfluoro-tert-butyl groups: 1,2-bis(perfluoro-tert-butoxy)ethane (C10 F18 H4 O2 ) and 1,3-bis(perfluoro-tert-butyl)propane (C11 F18 H6 ). Both substances contain 18 equivalent 19 F atoms, constituting 68.67 % and 71.25 % of the molecule, respectively. The emulsions with 19 F molecules were prepared and used in 19 F MRI studies in laboratory rats in vivo. The substances demonstrated high contrast properties, good biological inertness and the ability to be rapidly eliminated from the body. We showed that at a dose of 0.34 mg/g of body weight in rats, the time for complete elimination of C10 F18 H4 O2 and C11 F18 H6 is ∼30 days. The results turned out to be promising for the use of the presented compounds in 19 F MRI applications, especially since they are quite easy to synthesize.

A Nanomotor-Based Active Delivery System for Intracellular Oxygen Transport

Active transport of gas molecules is critical to preserve the physiological functions of organisms. Oxygen, as the most essential gas molecule, plays significant roles in maintaining the metabolism and viability of cells. Herein, we report a nanomotor-based delivery system that combines the fast propulsion of acoustically propelled gold nanowire nanomotors (AuNW) with the high oxygen carrying capacity of red blood cell membrane-cloaked perfluorocarbon nanoemulsions (RBC-PFC) for active intracellular delivery of oxygen. The oxygen delivery capacity and kinetics of the AuNW nanomotors carrying RBC-PFC (denoted as "Motor-PFC") are examined under ultrasound field. Specifically, the fast movement of the Motor-PFC under an acoustic field accelerates intracellular delivery of oxygen to J774 macrophage cells. Upon entering the cells, the oxygen loaded in the Motor-PFC is sustainably released, which maintains the cell viability when cultured under hypoxic conditions. The acoustically propelled Motor-PFC leads to significantly higher cell viability (84.4%) over a 72 h period, compared to control samples with free RBC-PFC (44.4%) or to passive Motor-PFC (32.7%). These results indicate that the Motor-PFC can act as an effective delivery vehicle for active intracellular oxygen transport. While oxygen is used here as a model gas molecule, the Motor-PFC platform can be readily expanded to the active delivery of other gas molecules to various target cells.

Spatiotemporally controlled nano-sized third harmonic generation agents

Here, we present a new class of third harmonic generation (THG) imaging probes that can be activated with precise spatiotemporal control using non-linear excitation. These probes consist of lipid-coated perfluorocarbon nanodroplets with embedded visible chromophores. The droplets undergo phase transition from liquid to gas upon heating mediated by two-photon absorption of NIR light by the embedded dyes. Resulting microbubbles provide a sharp, local refractive index mismatch, which makes an excellent source of THG signal. Potential applications of these probes include activatable THG agents for biological imaging and "on-demand" delivery of various compounds under THG monitoring.

Biomimetic Nanoemulsions for Oxygen Delivery In Vivo

Blood transfusion is oftentimes required for patients suffering from acute trauma or undergoing surgical procedures in order to help maintain the body's oxygen levels. The continued demand worldwide for blood products is expected to put significant strain on available resources and infrastructure. Unfortunately, efforts to develop viable alternatives to human red blood cells for transfusion are generally unsuccessful. Here, a hybrid natural-synthetic nanodelivery platform that combines the biocompatibility of the natural RBC membrane with the oxygen-carrying ability of perfluorocarbons is reported. The resulting formulation can be stored long-term and exhibits a high capacity for oxygen delivery, helping to mitigate the effects of hypoxia in vitro. In an animal model of hemorrhagic shock, mice are resuscitated at an efficacy comparable to whole blood infusion. By leveraging the advantageous properties of its constituent parts, this biomimetic oxygen delivery system may have the potential to address a critical need in the clinic.