Near-infrared light-responsive composite microneedles for on-demand transdermal drug delivery.

This study presents near-infrared (NIR) light-responsive polymer-nanostructure composite microneedles used for on-demand transdermal drug delivery. Silica-coated lanthanum hexaboride (LaB6@SiO2) nanostructures were incorporated into polycaprolactone microneedles, serving as an NIR absorber. When the microneedles were irradiated with NIR light, light-to-heat transduction mediated by the LaB6@SiO2 nanostructures caused the microneedle melting at 50 °C. This increased the mobility of the polymer chains, enabling drug release from the matrix. Drug release from the microneedles was evaluated for four laser on/off cycles. In each cycle, the samples were irradiated until the temperature reached 50 °C for 3 min (laser on); the laser was then turned off for 30 min (laser off). The results showed that light-induced phase transition in the polymer triggered drug release from the melted microneedles. A stepwise drug-release behavior was observed after multiple cycles of NIR light exposure. No notable drug leakage was found in the off state. This NIR-light-triggerable device exhibits excellent reproducibility, low off-state leakage, and noninvasive triggerability and, thus, represents an advance in transdermal delivery technology.

Vancomycin-modified LaB6@SiO2/Fe3O4 composite nanoparticles for near-infrared photothermal ablation of bacteria.

LaB6 nanoparticles possess excellent near-infrared (NIR) photothermal conversion properties. Vancomycin can interact strongly with a broad range of Gram-positive and Gram-negative bacteria. Fe3O4 nanoparticles could be used as the carrier for magnetic separation. In this work, vancomycin and Fe3O4 nanoparticles were successfully bound onto the surface of LaB6 nanoparticles with a silica coating and carboxyl functionalization to fabricate vancomycin-modified LaB6@SiO2/Fe3O4 (Van-LaB6@SiO2/Fe3O4) composite nanoparticles as a novel nanomaterial for the NIR photothermal ablation of bacteria. From the analyses of absorption spectra, transmission electron microscopy images and X-ray diffraction patterns, the formation of Van-LaB6@SiO2/Fe3O4 composite nanoparticles was confirmed. The resulting Van-LaB6@SiO2/Fe3O4 composite nanoparticles possessed nearly superparamagnetic properties, retained the excellent NIR photothermal conversion property of LaB6 nanoparticles and could capture the bacteria Staphylococcus aureus and Escherichia coli efficiently. Owing to these capabilities, they were demonstrated to be quite efficient for the magnetic separation and NIR photothermal ablation of S. aureus and E. coli. Furthermore, the magnetic property made the Van-LaB6@SiO2/Fe3O4 composite nanoparticles useful for the magnetic assembling of bacteria, which could further enhance the photothermal ablation efficiency.

One-pot green synthesis of silver/iron oxide composite nanoparticles for 4-nitrophenol reduction.

Silver/iron oxide composite nanoparticles have been synthesized successfully via a facile one-pot green route by the use of l-arginine, which created an aqueous solution of about pH 10 and acted as a reducing agent for the successive formation of iron oxide and Ag nanoparticles. The product was characterized to be silver-coated iron oxide and iron oxide hydroxide composite nanoparticles with a mean diameter of about 13.8 ± 3.0 nm and 8.53% of Ag in weight. It exhibited good catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol with sodium borohydride. The reduction reaction followed the pseudo-first-order kinetics. The corresponding rate constants increased with the increases of temperature and catalyst amount but decreased with the increase of initial 4-NP concentration, revealing an activation energy of 28.2 kJ/mol and a diffusion controlled mechanism. In addition, this product had quite good stability. No significant activity loss was observed after reuse for 5 cycles.