Search

Classical local anesthetics are unsuitable to treat regional pain lasting several days due to their limited duration and systemic toxicity. Self-delivery nano systems without excipients were designed for long-term sensory blocks. 1a self-assembled into different vehicles with different fractions of intermolecular π–π stacking, transported itself into nerve cells, and released single molecules slowly to achieve long-term duration for rats' sciatic nerve block for 11.6 h in water, 12.1 h in water with CO2 and 3.4 h in NS (normal saline). After the counter ions were changed to SO42−, 1e can self-assemble into vesicles and prolong the duration to 43.2 h, which was much longer than the 3.8 h led by (s)-bupivacaine hydrocloride (0.75%). This was mainly caused by the enhancement of self-release and counter ion exchange inside nerve cells, which were affected by the gemini surfactant structure, pKa of the counter ions and π–π stacking interactions. [ABSTRACT FROM AUTHOR]

Lidocaine salts self-assembled into different nano systems in water at a clinical dosage (2%, 0.2 mL) without excipient addition, and led to different sensory block durations and acute systemic toxicities, which were affected by the self-delivery and self-release behaviors of the salts in vivo. These differences were mainly caused by intermolecular π–π stacking under different conditions, which was proved by the unique supramolecular arrangement of gourd-shaped Janus particles. π–π stacking in lidocaine nano systems can be enhanced by carbon dioxide addition or the exchange of counter ions from Br− to Cl−. Without π–π stacking, nano systems self-assembled by lidocaine hydrobromide achieved 7.8 h sensory block by intradermal administration on rats, which is much longer than the efficacy of classical local anesthetics and more suitable for postoperative treatment. [ABSTRACT FROM AUTHOR]

A series of atypical asymmetric gemini surfactants with an amphiphilic carbonate group (–O–CO–O–) have been prepared. Some of these compounds could self-assemble in water into gourd-shaped Janus particles (JPs). Initial results suggested that the formation of JPs was highly likely to be related to their atypical gemini surfactant structure. To our knowledge, this is the first report on JPs that are self-assembled from a single kind of small organic molecule. We believe that our results will be utilized in many fields. [ABSTRACT FROM AUTHOR]