Transdermal drug delivery is an appealing option except for oral and hypodermic administration. With the advancement of skin penetration strategies, various anticancer therapeutics ranging from lipophilic small-molecule drugs to hydrophilic biomacromolecules, can be administered transdermally, offering an optional regimen to treat skin cancers. In addition, the activation of the skin immune systems can also assist the treatment of distal sites. Current approaches on enhancing the transdermal delivery efficacy of anticancer drugs are summarized in this review. We also survey recent advances in micro- and nanotechnology-based transdermal formulations for cancer treatment, such as chemotherapy, gene therapy, immunotherapy, phototherapy and combination therapy. New penetration enhancers, materials, formulations and their hypothesized mechanisms for transdermal delivery are highlighted. Advantages and limitations regarding the state-of-the-art transdermal delivery technologies, as well as future perspective are also discussed.

The capping agents for liquid metal (LM) nanodroplets in aqueous solutions are restricted to thiol-containing and positively-charged molecules or macromolecules. However, both thiolate-metal complex and electrostatic interaction are liable to detachment upon strong mechanical forces such as sonication, leading to limited stability and applications. To address this, we utilized ultrasmall water soluble melanin nanoparticles (MNPs) as the capping agent, which exhibited strong metal binding capability with the oxide layer of gallium based LMs and resulted in enhanced stability. Interestingly, shape-controlled synthesis of LM nanodroplets can be achieved by the incorporation of MNPs. Various EGaIn nanostructures including nanorice, nanosphere and nanorod were obtained by simply tuning the feed ratio, sonication time, and suspension temperature. Among these shapes, EGaIn nanorice has the best photothermal conversion efficiency, which could be leveraged for photothermal therapy.

Controlling postprandial glucose levels for diabetic patients is critical to achieve the tight glycemic control that decreases the risk for developing long-term micro- and macrovascular complications. Herein, we report a glucose-responsive oral insulin delivery system based on Fc receptor (FcRn)-targeted liposomes with glucose-sensitive hyaluronic acid (HA) shell for postprandial glycemic regulation. After oral administration, the HA shell can quickly detach in the presence of increasing intestinal glucose concentration due to the competitive binding of glucose with the phenylboronic acid groups conjugated with HA. The exposed Fc groups on the surface of liposomes then facilitate enhanced intestinal absorption in an FcRn-mediated transport pathway. In vivo studies on chemically-induced type 1 diabetic mice show this oral glucose-responsive delivery approach can effectively reduce postprandial blood glucose excursions. This work is the first demonstration of an oral insulin delivery system directly triggered by increasing postprandial glucose concentrations in the intestine to provide an on-demand insulin release with ease of administration.