Effect of PFDS on the immobilization of Cs+ by metakaolin-based geopolymers in complex environments.

Metakaolin-based geopolymers are very promising materials for improving the safety of low and intermediate level radioactive waste disposal, with respect to ordinary Portland cement, due to their excellent immobilization performance for Cs+ and superior chemical stability. However, their application is limited by the fact that the leaching behavior of Cs+ is susceptible to the presence of other ions in the environment. Here, we propose a way to modify a geopolymer using perfluorodecyltriethoxysilane (PDFS), successfully reducing the leaching rate of Cs+ in the presence of multiple competitive cations due to blocking the diffusion of water. The leachability index of the modified samples in deionized water and highly concentrated saline water reached 11.0 and 8.0, respectively. The reaction mechanism between PDFS and geopolymers was systematically investigated by characterizing the microstructure and chemical bonding of the material. This work provides a facile and successful approach to improve the immobilization of Cs ions by geopolymers in real complex environments, and it could be extended to further improve the reliability of geopolymers used in a range of applications.

Enhancing adoptive T cell therapy for solid tumor with cell-surface anchored immune checkpoint inhibitor nanogels.

The efficacy of Adoptive Cell Therapy (ACT) for solid tumor is still mediocre. This is mainly because tumor cells can hijack ACT T cells' immune checkpoint pathways to exert immunosuppression in the tumor microenvironment. Immune Checkpoint Inhibitors such as anti-PD-1 (aPD1) can counter the immunosuppression, but the synergizing effects of aPD1 to ACT was still not satisfactory. Here we demonstrate an approach to safely anchor aPD1-formed nanogels onto T cell surface via bio-orthogonal click chemistry before adoptive transfer. The spatial-temporal co-existence of aPD1 with ACT T cells and the responsive drug release significantly improved the treatment outcome of ACT in murine solid tumor model. The average tumor weight of the group treated by cell-surface anchored aPD1 was only 18 % of the group treated by equivalent dose of free aPD1 and T cells. The technology can be broadly applicable in ACTs employing natural or Chimeric Antigen Receptor (CAR) T cells.

Velvet antler polypeptide-loaded polyvinyl alcohol-sodium alginate hydrogels promote the differentiation of neural progenitor cells in 3D towards oligodendrocytes in vitro.

Three-dimensional (3D) culture of neural progenitor cells (NPCs) in hydrogels represents a powerful means for recapitulating neurodevelopment, disease modelling and drug discovery. However, the differentiation of NPCs to oligodendrocytes in 3D scaffolds remains a great challenge. In this study, polyvinyl alcohol (PVA) - sodium alginate (SA) composite hydrogels intended for NPC culture in 3D were fabricated by ionic crosslinking between SA and calcium ions. It was demonstrated that adding PVA to the composite hydrogels resulted in increases in pore size and swelling rate and decreases in elastic moduli as the PVA proportion was enhanced. In addition, the composite hydrogels were biocompatible with mouse NPCs and improved the proliferation of the encapsulated NPCs compared with SA hydrogels. Moreover, when velvet antler polypeptides (VAPs), which were capable of facilitating the differentiation of NPCs to oligodendrocyte fate in 2D, were loaded into PVA-SA hydrogels, NPCs differentiated into neurons, astrocytes and oligodendrocytes, with the presence of VAPs promoting oligodendrogenesis in a dose-dependant manner. The present composite hydrogels provide a suitable scaffold for the construction of neural tissue engineering and neurological disease modelling.

Multispectral optoacoustic tomography (MSOT) for imaging the particle size-dependent intratumoral distribution of polymeric micelles.

PURPOSE: This study proposes the utilization of multispectral optoacoustic tomography (MSOT) to investigate the intratumoral distribution of polymeric micelles and effect of size on the biodistribution and antitumor efficacy (ATE). MATERIALS AND METHODS: Docetaxel and/or optoacoustic agent-loaded polymeric micelles (with diameters of 22, 48, and 124 nm) were prepared using amphiphilic block copolymers poly (ethylene glycol) methyl ether-block-poly (D,L lactide) (PEG2000-PDLLAx). Subcutaneous 4T1 tumor-bearing mice were monitored with MSOT imaging and IVIS® Spectrum in vivo live imaging after tail vein injection of micelles. The in vivo results and ex vivo confocal imaging results were then compared. Next, ATE of the three micelles was found and compared. RESULTS: We found that MSOT imaging offers spatiotemporal and quantitative information on intratumoral distribution of micelles in living animals. All the polymeric micelles rapidly extravasated into tumor site after intravenous injection, but only the 22-nm micelle preferred to distribute into the inner tumor tissues, leading to a superior ATE than that of 48- and 124-nm micelles. CONCLUSION: This study demonstrated that MSOT is theranostically a powerful imaging modality, offering quantitative information on size-dependent spatiotemporal distribution patterns after the extravasation of nanomedicine from tumor blood vessels.