Accurate and Real-Time Temperature Monitoring during MR Imaging Guided PTT.

Photothermal therapy (PTT) is an efficient approach for cancer treatment. However, accurately monitoring the spatial distribution of photothermal transducing agents (PTAs) and mapping the real-time temperature change in tumor and peritumoral normal tissue remain a huge challenge. Here, we propose an innovative strategy to integrate T1-MRI for precisely tracking PTAs with magnetic resonance temperature imaging (MRTI) for real-time monitoring temperature change in vivo during PTT. NaBiF4: Gd@PDA@PEG nanomaterials were synthesized with favorable T1-weighted performance to target tumor and localize PTAs. The extremely weak susceptibility (1.04 × 10-6 emu g-1 Oe1-) of NaBiF4: Gd@PDA@PEG interferes with the local phase marginally, which maintains the capability of MRTI to dynamically record real-time temperature change in tumor and peritumoral normal tissue. The time resolution is 19 s per frame, and the detection precision of temperature change is approximately 0.1 K. The approach achieving PTT guided by multimode MRI holds significant potential for the clinical application.

Controlling the particle size of interpolymer complexes through host-guest interaction for drug delivery.

A new method to adjust the particle size of interpolymer complexes has been developed by introduction of host-guest interaction into the dilute aqueous solution of poly(acrylic acid) (PAA) and poly(ethylene glycol) (PEG). Because of the cooperative hydrogen-bonding interaction, PAA can form the interpolymer complexes with PEG. Putting beta-cyclodextrin (beta-CD) into dilute PAA/PEG aqueous solution, the competition between host-guest and hydrogen-bonding interactions happens. The beta-CD/PAA/PEG ternary systems have been well characterized by ultraviolet-visible absorption spectroscopy (UV-vis), dynamic light scattering (DLS), transmission electron microscopy (TEM), diffusion NMR spectroscopy, attenuated total reflectance-Fourier transform infrared (ATR-FTIR), and solid-state (13)C NMR spectroscopy. The results indicate that the hydrophobic cavity of beta-CD is threaded by linear polymers so that the hydrophilicity of PAA/PEG interpolymer complexes is improved greatly. Adjusting the amounts of beta-CD, the particle size of the interpolymer complexes can be readily controlled. The low cytotoxicity of various beta-CD/PAA/PEG ternary complexes has been confirmed using the MTT assay in COS-7 cell line. Doxorubicin (DOX), an anticancer drug, has been encapsulated into the beta-CD/PAA/PEG ternary complexes. The DOX-loaded beta-CD/PAA/PEG ternary complexes have been analyzed by confocal laser scanning microscopy (CLSM), flow cytometry analysis, and the MTT assay against human cervical carcinoma cell (Hela). The results indicate that beta-CD/PAA/PEG ternary complexes with controlled particle size could be used as safe and promising drug carriers.

Polymer nanosheets derived porous carbon nanosheets as high efficient electrocatalysts for oxygen reduction reaction.

Porous carbon nanosheets and corresponding heteroatom doped porous carbon nanosheets have shown great potential as active materials for energy conversion and storage in recent years. However, it remains great challenge to prepare such kind of new two-dimensional (2D) polymer nanosheets without using any templates. In this work, thiadiazole-containing expanded heteroazaporphyrinoid was designed as the building blocks for preparation of free-standing N/S-containing polymer nanosheets (PN) without using any templates. Most importantly, such PN can coordinate with transition metal ions to prepare Fe, N, and S containing PN-Fe. By using these PN-Fe as precursors, Fe/N/S co-doped porous carbon nanosheets (PCN-FeNS) can be facilely prepared by direct pyrolysis under inert condition. The N and S contents of PCN-FeNS can reach up to 6.4 at.% and 0.8 at.%, respectively. For proof-of-concept, PCN-FeNS were further used as electrochemical catalysts for oxygen reduction reaction (ORR) in both alkaline and neutral media. Benefiting from the high surface area and rich-doping character, PCN-FeNS exhibited relatively high half-wave potential of down to 0.71 V, via a four-electron transfer mechanism (n = 3.87 at 0.65 V), as well as high diffusion limiting current density (JL = 5.02 mA cm-2), which are comparable to commercial precious metal based electrocatalysts. This study not only offers a new method to prepare conjugated polymer nanosheets, but also provides a new strategy to fabricate Fe/N/S co-doped porous carbon nanosheets for versatile energy-related applications.

Supramolecular self-assembly of inclusion complexes of a multiarm hyperbranched polyether with cyclodextrins.

A new class of crystalline inclusion complexes of a multiarm hyperbranched polyether combined with various cyclodextrins (CDs) was successfully prepared. Using self-condensing ring-opening polymerization, a kind of multiarm polyether with a hyperbranched poly(3-ethyl-3-oxetanemethanol) core and multiple linear poly(ethylene glycol) (PEG) arms was obtained. It has been found that this kind of hyperbranched polyether can be dissolved in water. Adding alpha-CDs to the multiarm hyperbranched polyether solution, molecular recognition results in the formation of crystalline inclusion complexes based on the noncovalent interactions between the linear PEG arms of the polyether particles and the alpha-CDs. These multiarm polyether inclusion complexes have been well characterized. Interestingly, quite different from inclusion complexes of CDs and linear polymeric guests, the complexes of the multiarm hyperbranched polyether with alpha-CDs show a novel lamellar morphology. The experimental results validate that the resultant lamellar crystals have a juxtaposed structure. In addition, the formation mechanism of these inclusion complexes of a multiarm polyether with alpha-CDs has also been well described. Besides the role of displacement of associated water molecules and the presence of hydrogen bonding between CDs in channel structure CD inclusion complexes, the noncovalent intermolecular forces between CDs and polymers also play an important role in the formation of complex architectures.