Hydrogels have been developed as extracellular matrix (ECM) mimics both for therapeutic applications and basic biological studies. In particular, elastin-like polypeptide (ELP) hydrogels, which can be tuned to mimic several biochemical and physical characteristics of native ECM, have been constructed to encapsulate various types of cells to create in vitro mimics of in vivo tissues. However, ELP hydrogels become opaque at body temperature because of ELP’s lower critical solution temperature behavior. This opacity obstructs light-based observation of the morphology and behavior of encapsulated cells. In order to improve the transparency of ELP hydrogels for better imaging, we have designed a hybrid ELP-polyethylene glycol (PEG) hydrogel system that rapidly cross-links with tris(hydroxymethyl) phosphine (THP) in aqueous solution via Mannich-type condensation. As expected, addition of the hydrophilic PEG component significantly improves the light transmittance. Coherent anti-Stokes Raman scattering (CARS) microscopy reveals that the hybrid ELP-PEG hydrogels have smaller hydrophobic ELP aggregates at 37 °C. Importantly, this hydrogel platform enables independent tuning of adhesion ligand density and matrix stiffness, which is desirable for studies of cell–matrix interactions. Human fibroblasts encapsulated in these hydrogels show high viability (>98%) after 7 days of culture. High-resolution confocal microscopy of encapsulated fibroblasts reveals that the cells adopt a more spread morphology in response to higher RGD ligand concentrations and softer gel mechanics.

Biodegradable microcapsules with pH-responsibility were fabricated with host–guest interaction between β-cyclodextrin (β-CD) and adamantane (AD). Two biocompatible polymers, dextran-graft-β-CD (Dex-g-β-CD) and poly(aspartic-graft-adamantane) (PASP-g-AD), were assembled on CaCO3 particles. Rhodamine B (Rh B) was captured in the core as a model drug. With CaCO3 particles removed by EDTA, hollow microcapsules loaded with Rh B were obtained. As β-CD was grafted to polyaldehyde dextran (PAD) through pH-sensitive CN bonds, the capsules could degrade and release Rh B in an acidic environment, showing a pH-sensitive release behavior. Confocal laser scanning microscopy (CLSM), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) were used to characterize the capsules. In vitro drug release and degradation of the microcapsules were studied. The capsules were coincubated with HeLa cells at different pH values, further proving the controlled release behavior. In conclusion, the pH-sensitive microcapsules have great application potential in drug delivery.

Magnesium alloys are highly desirable for a wide range of lightweight structural components. However, rolling Mg alloys can be difficult due to their poor plasticity, and the strong texture yielded from rolling often results in poor plate forming ability, which limits their further engineering applications. Here we report a new hard-plate rolling (HPR) route which achieves a large reduction during a single rolling pass. The Mg-9Al-1Zn (AZ91) plates processed by HPR consist of coarse grains of 30–60 μm, exhibiting a typical basal texture, fine grains of 1–5 μm and ultrafine (sub) grains of 200–500 nm, both of the latter two having a weakened texture. More importantly, the HPR was efficient in gaining a simultaneous high strength and uniform ductility, i.e., ~371 MPa and ~23%, respectively. The superior properties should be mainly attributed to the cooperation effect of the multimodal grain structure and weakened texture, where the former facilitates a strong work hardening while the latter promotes the basal slip. The HPR methodology is facile and effective, and can avoid plate cracking that is prone to occur during conventional rolling processes. This strategy is applicable to hard-to-deform materials like Mg alloys, and thus has a promising prospect for industrial application.

A novel, facile and reproducible method was explored to construct uniform folic acid-Au@poly(acrylic acid)/mesoporous calcium phosphate Janus nanoparticles (FA-Au@PAA/mCaP JNPs), which act as an efficient nanoplatform for X-ray computed tomography (CT) imaging and active-targeted chemotherapy in vitro.

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