No abstract

Both plants and animals possess analogous tissues containing hierarchical networks of pores, with pore size ratios that have evolved to maximize mass transport and rates of reactions. The underlying physical principles of this optimized hierarchical design are embodied in Murray's law. However, we are yet to realize the benefit of mimicking nature's Murray networks in synthetic materials due to the challenges in fabricating vascularized structures. Here we emulate optimum natural systems following Murray's law using a bottom-up approach. Such bio-inspired materials, whose pore sizes decrease across multiple scales and finally terminate in size-invariant units like plant stems, leaf veins and vascular and respiratory systems provide hierarchical branching and precise diameter ratios for connecting multi-scale pores from macro to micro levels. Our Murray material mimics enable highly enhanced mass exchange and transfer in liquid–solid, gas–solid and electrochemical reactions and exhibit enhanced performance in photocatalysis, gas sensing and as Li-ion battery electrodes.

Nitric oxide (NO) has been well identified as a specific free radical molecule possessing wide-ranging therapeutic effects. Targeted delivery and controlled release of NO are highly desired to realize precision gas therapy, but are still challenging owing to the non-targetability and uncontrollability of NO itself. Herein, we propose a new concept of MRI-guided and ultrasound-triggered gas release for precision gas therapy. Based on this concept, we develop a novel ultrasound-responsive BNN-type NO-releasing molecule (NORM) and an advanced rattle-type nano-carrier of superparamagnetic iron oxide-encapsulated mesoporous silica nanoparticles (SPION@hMSN), and use them to construct a new intelligent nanomedicine (BNN6-SPION@hMSN) for the first time. The BNN6-SPION@hMSN nanomedicine exhibits excellent passive tumor-targeting capability, high MRI-guided tumor localization performance and a unique ultrasound-triggered NO release profile. The tumor-targeted, MRI-guided and ultrasound-triggered release profiles of the developed nanomedicine enable the tumor site-specific controlled release of NO in favor of high-efficacy and safe NO gas therapy of tumor.

Magnetic and ferroelectric properties are investigated for the polycrystalline Bi2Fe4O9 ceramics with different grain sizes (60–2000 nm) synthesized by a modified Pechini method. It shows that magnetic and ferroelectric properties are strongly dependent on the grain size. For the 60 nm samples, the magnetization curves exhibit a superimposed behavior of antiferromagnetic (AFM) with ferromagnetic (FM) component. As the grain size increases, FM component is suppressed and AFM interaction becomes dominant. Simultaneously, the Néel temperature (TN) shifts to high temperatures as the grain size increases. Compared with the 60 nm sample, ferroelectric hysteresis loops at room temperature are observed for the samples with large grain sizes (>200 nm) due to the reduced leakage currents. Among all samples, the 900 nm sample is found to have the smallest leakage current density (<10−6) and the largest remnant polarization (0.21 μC/cm2).