Sangmin Jeon

laser was used to convert the surface of basswood to graphitic carbon layers (GCL), and various grid patterns of GCL were created on wood. The low thermal conductivity of wood suppressed heat loss to bulk water, and the presence of the grooves in the grid increased the evaporation rate by increasing the surface area to absorb more sunlight. In addition, the supply of bulk water through the grooves endowed the SSG with salt resistance and self-regeneration properties. The salt resistance was maintained in a 20-wt % NaCl solution for the duration of the experiment (2 weeks), which indicates that the developed SSG can be used in saline water for long-term operation.

A CO2 laser engraver was used to synthesize conductive graphitic carbon directly on cellulose nanofiber (CNF) substrates under ambient conditions. CNFs were prepared via a TEMPO (2,2,6,6-tetramethylpiperidin-1-oxyl radical)-mediated oxidation reaction of bleached pulp, and a porous paper or a transparent film was obtained based on the drying conditions employed. Laser irradiation on a porous CNF paper led to the formation of amorphous carbon owing to an increase in temperature. Subsequent lasing converted the amorphous carbon to conductive graphitic carbon. The conductivity of this carbon increased from 3 μS/cm to 60 mS/cm as the number of irradiations increased from one to four. Although the CNF paper was converted to graphitic carbon by means of multiple lasing, graphitic carbon was obtained for the CNF film by a single run of lasing owing to its very low oxygen permeability. The conversion of the CNF substrates to graphitic carbon under ambient conditions was attributed to the presence of sodium in CNFs. A control experiment using a CNF in which sodium was replaced with hydrogen demonstrated that only amorphous carbon was produced by laser exposure.

Theranostic nanoparticles hold great promise for simultaneous diagnosis of diseases, targeted drug delivery with minimal toxicity, and monitoring of therapeutic efficacy. However, one of the current challenges in developing theranostic nanoparticles is enhancing the tumor-specific targeting of both imaging probes and anticancer agents. Herein, we report the development of tumor-homing echogenic glycol chitosan-based nanoparticles (Echo-CNPs) that concurrently execute cancer-targeted ultrasound (US) imaging and US-triggered drug delivery. To construct this novel Echo-CNPs, an anticancer drug and bioinert perfluoropentane (PFP), a US gas precursor, were simultaneously encapsulated into glycol chitosan nanoparticles using the oil in water (O/W) emulsion method. The resulting Echo-CNPs had a nano-sized particle structure, composing of hydrophobic anticancer drug/PFP inner cores and a hydrophilic glycol chitosan polymer outer shell. The Echo-CNPs had a favorable hydrodynamic size of 432 nm, which is entirely different from the micro-sized core-empty conventional microbubbles (1-10 μm). Furthermore, Echo-CNPs showed the prolonged echogenicity via the sustained microbubble formation process of liquid-phase PFP at the body temperature and they also presented a US-triggered drug release profile through the external US irradiation. Interestingly, Echo-CNPs exhibited significantly increased tumor-homing ability with lower non-specific uptake by other tissues in tumor-bearing mice through the nanoparticle's enhanced permeation and retention (EPR) effect. Conclusively, theranostic Echo-CNPs are highly useful for simultaneous cancer-targeting US imaging and US-triggered delivery in cancer theranostics.