ABSTRACT
Uncontrolled and excessive photothermal heating in photothermal therapy (PTT) inevitably causes thermal damage to surrounding normal tissues, severely limiting the universality and safety of PTT. To address this issue, an intelligent cooling thermal-responsive (ICTR) gel containing poly(N-isopropylacrylamide-co-acrylamide) (P(NIPAM-AM))microgel is applied onto the skin to realize intelligent PTT, which can avoid excessive heating and accidental injury. The high near-infrared (NIR) light transmittance (> 95%) of the ICTR gel ensures effective light delivery at low temperatures, while the refractive index of the P(NIPAM-AM) microgel increases remarkably when the temperature exceeds a predetermined threshold, resulting in progressively enhanced light scattering and weakened photothermal conversion. In animal studies, the negative feedback regulation of ICTR gel on light transmittance and photothermal heating allows the photothermal temperature in the lesion site to be stabilized within the effective therapeutic range (45 °C) while ensuring that the skin surface temperature does not exceed 35 °C. Compared with the severe skin thermal damage found in the histological staining of mice skin receiving conventional PTT, the mice skin receiving the ICTR gel-enabled intelligent PTT remains in good condition. This study establishes an intelligent and universal paradigm for PTT thermal regulation, which is of great significance for achieving safe and effective PTT.
ABSTRACT
Droplet impact is a ubiquitous natural phenomenon that has been widely utilized to inspire and facilitate many industrial applications. Compared to the widely studied water droplet impact onto identical liquid surfaces, the water droplet impact onto an oil layer floating on a water bath (OLW) receives far less attention and its potential application has never been exploited. Herein, the process of water droplet impact onto the OLW is investigated with emphasis on the metastable states and potential applications. It is found that the dramatic deformation of the oil-water interface caused by the water droplet impact leads to two metastable states: oil in water in oil in water (O/W/O/W) and oil in water in oil (O/W/O). Through the subsequent introduction of gelation process, the metastable states can be frozen into floating hydrogel beads with similar shape to the roly-poly toys, which are attempted in gastric retentive drug delivery and algae bloom control. Specifically, the floating hydrogel beads perform well in gastric retentive drug delivery in vitro due to their inherent slow-release properties and floating capability. In addition, the floating hydrogel beads loading photocatalysts can capture more sunshine, and exhibit high photocatalytic efficiency, which is thus responsible for efficient algae bloom control.
