Engineering Magnetic Nanoclusters for Highly Efficient Heating in Radio-Frequency Nanowarming

Effective thawing of cryopreserved samples requires rapid and uniform heating. This is achievable through nanowarming, an approach that heats magnetic nanoparticles by using alternating magnetic fields. Here we demonstrate the synthesis and surface modification of magnetic nanoclusters for efficient nanowarming. Magnetite (Fe3O4) nanoclusters with an optimal diameter of 58 nm exhibit a high specific absorption rate of 1499 W/g Fe under an alternating magnetic field at 43 kA/m and 413 kHz, more than twice that of commercial iron oxide cores used in prior nanowarming studies. Surface modification with a permeable resorcinol-formaldehyde resin (RFR) polymer layer significantly enhances their colloidal stability in complex cryoprotective solutions, while maintaining their excellent heating capacity. The Fe3O4@RFR nanoparticles achieved a high average heating rate of 175 °C/min in cryopreserved samples at a concentration of 10 mg Fe/mL and were successfully applied in nanowarming porcine iliac arteries, highlighting their potential for enhancing the efficacy of cryopreservation.

Ultrasmall Nanocapsules Obtained by Controlling Ostwald Ripening

We describe here a method to synthesize ultrasmall nanocapsules with a diameter of 6 nm, exhibiting a well-defined core-shell morphology. Remarkably, the nanocapules are synthesized in a miniemulsion process without the need of large amounts of surfactant as commonly used in the microemulsion process. Ultrasmall nanocapsules with an oil core and a silica shell are formed by the concurrent processes of a sol-gel reaction and Ostwald ripening. Using solvents with different water solubilities and alkoxysilanes with different reactivities, we demonstrate that sizes of obtained nanocapsules depend on the ripening rate and alkoxysilane conversion rate. The method can be also used for encapsulating natural oils such as peppermint oil and limonene. This work shows that the Ostwald ripening phenomenon can be employed beneficially for the preparation of very small colloids.

BODIPY-loaded polymer nanoparticles: chemical structure of cargo defines leakage from nanocarrier in living cells

Hydrophobicity of a fluorescent cargo loaded into PLGA nanoparticles is crucial for minimizing its leakage in biological media.

Photoresponsive Drug/Gene Delivery Systems

Light as an external stimulus can be precisely manipulated in terms of irradiation time, site, wavelength, and density. As such, photoresponsive drug/gene delivery systems have been increasingly pursued and utilized for the spatiotemporal control of drug/gene delivery to enhance their therapeutic efficacy and safety. In this review, we summarized the recent research progress on photoresponsive drug/gene delivery, and two major categories of delivery systems were discussed. The first category is the direct responsive systems that experience photoreactions on the vehicle or drug themselves, and different materials as well as chemical structures responsive to UV, visible, and NIR light are summarized. The second category is the indirect responsive systems that require a light-generated mediator signal, such as heat, ROS, hypoxia, and gas molecules, to cascadingly trigger the structural transformation. The future outlook and challenges are also discussed at the end.

Synthesis of Core-Shell Structured Porous Nitrogen-Doped Carbon@Silica Material via a Sol-Gel Method

Core-shell structured nitrogen-doped porous carbon@silica material with uniform structure and morphology was synthesized via a sol-gel method. During this process, a commercial triblock copolymer and the in situ formed pyrrole-formaldehyde polymer acted as cotemplates, while tetraethyl orthosilicate acted as silica precursor. The synergetic effect of the triblock copolymer and the pyrrole-formaldehyde polymer enables the formation of the core-shell structure. Herein, the pyrrole-formaldehyde polymer acted as not only the template, but also the nitrogen-doped carbon precursor of the core. The obtained core-shell structured porous material possesses moderate Brunauer-Emmett-Teller specific surface area (410 m² g^-1) and pore volume (0.53 cm³ g^-1). Moreover, corresponding hollow silica spheres or nitrogen-doped porous carbon spheres can be synthesized by calcining the core-shell structured material in air or etching it with HF. The X-ray photoelectron spectroscopy results reveal that the nitrogen states of the obtained material are mainly pyridinic-N and pyridonic-N/pyrrolic-N, which are beneficial for carbon dioxide adsorption. The carbon dioxide uptake capacity of the nitrogen-doped carbon spheres can reach 12.3 wt % at 273 K and 1.0 bar, meanwhile, the material shows good gas adsorption selectivities for CO₂/CH₄ and CO₂/N₂.

High-Yield Synthesis of Janus Dendritic Mesoporous Silica@Resorcinol-Formaldehyde Nanoparticles: A Competing Growth Mechanism

Recently, Janus nanostructures that possess two or more different surface functions have attracted enormous attention because of their unique structures and promising applications in diverse fields. In this work, we present that Janus structured dendritic mesoporous silica@resorcinol-formaldehyde (DMS@RF) nanoparticles can be prepared through a simple one-pot colloidal method. The Janus DMS@RF nanoparticle shows a bonsai-like morphology which consists of a dendritic mesoporous silica part and a spherical RF part. After a systematic study on the growth process, we proposed a competing growth mechanism that accounts for the formation of Janus nanostructures. It is believed that suitable polymerization rate of silica and RF resin is critical. Based on the competing growth mechanism, eccentric and concentric core-shell nanostructures have been successfully prepared by tuning the polymerization rates of silica and RF, respectively. Metal-contained ternary Janus nanoparticles that might be used for catalysis have also been prepared. This research may pave the way for the practical applications of delicate nanomaterials with desired structures and properties.

Fluorescent Polymer Nanoparticles Based on Dyes: Seeking Brighter Tools for Bioimaging

Speed, resolution and sensitivity of today's fluorescence bioimaging can be drastically improved by fluorescent nanoparticles (NPs) that are many-fold brighter than organic dyes and fluorescent proteins. While the field is currently dominated by inorganic NPs, notably quantum dots (QDs), fluorescent polymer NPs encapsulating large quantities of dyes (dye-loaded NPs) have emerged recently as an attractive alternative. These new nanomaterials, inspired from the fields of polymeric drug delivery vehicles and advanced fluorophores, can combine superior brightness with biodegradability and low toxicity. Here, we describe the strategies for synthesis of dye-loaded polymer NPs by emulsion polymerization and assembly of pre-formed polymers. Superior brightness requires strong dye loading without aggregation-caused quenching (ACQ). Only recently several strategies of dye design were proposed to overcome ACQ in polymer NPs: aggregation induced emission (AIE), dye modification with bulky side groups and use of bulky hydrophobic counterions. The resulting NPs now surpass the brightness of QDs by ≈10-fold for a comparable size, and have started reaching the level of the brightest conjugated polymer NPs. Other properties, notably photostability, color, blinking, as well as particle size and surface chemistry are also systematically analyzed. Finally, major and emerging applications of dye-loaded NPs for in vitro and in vivo imaging are reviewed.

Multifunctional human serum albumin-modified reduced graphene oxide for targeted photothermal therapy of hepatocellular carcinoma

Multifunctional human serum albumin-modified reduced graphene oxide can specifically target HCC cells and effectively kill them with the help of a NIR laser.

Facile synthesis of N-halamine-labeled silica-polyacrylamide multilayer core-shell nanoparticles for antibacterial ability

Silica-polymer antimicrobial composites with a core-shell nanostructure are often prepared through a polymeric process. However, it is difficult to control the polymerization degree of the polymers to give a uniform size distribution. In this article, we present a facile approach to produce antimicrobial silica@polyacrylamide (SiO₂@PAM) core-shell nanoparticles, which were synthesized via an electrostatic self-assembly method using acyclic N-halamine polymeric polyacrylamide. The morphologies and structures of these as-prepared nanoparticles were characterized by different techniques. And their antibacterial performance against both Gram-positive bacteria and Gram-negative bacteria was also evaluated. Based on the preliminary results, these core-shell nanosized spheres were made of an outer polymer shell which decorated the inner SiO₂ core, showing the encapsulation of silica nanoparticles with PAM polymers. After chlorination, the resultant nanosized particles displayed a powerful and stable bactericidal capability toward both of the two model bacterial species. Bactericidal assessment further suggested a coordinated effect of the well-known antibacterial performance of N-halamines and the flocculation of PAM on the antibacterial behavior. The in vitro cytotoxicity of the prepared nanoparticles with varying concentrations was studied using mouse fibroblast cells (L929). The CCK-8 assay revealed that the SiO₂@PAM composites possessed a non-cytotoxic and favorable response to the seeded cells in vitro. These results indicate the suitability of the SiO₂@PAM composite particles for controlling biocidal activity, demonstrating their potential applications in deactivating bacteria or even disease control.