Structural Determinants of Stimuli-Responsiveness in Amphiphilic Macromolecular Nano-assemblies.

Stimuli-responsive nano-assemblies from amphiphilic macromolecules could undergo controlled structural transformations and generate diverse macroscopic phenomenon under stimuli. Due to the controllable responsiveness, they have been applied for broad material and biomedical applications, such as biologics delivery, sensing, imaging, and catalysis. Understanding the mechanisms of the assembly-disassembly processes and structural determinants behind the responsive properties is fundamentally important for designing the next generation of nano-assemblies with programmable responsiveness. In this review, we focus on structural determinants of assemblies from amphiphilic macromolecules and their macromolecular level alterations under stimuli, such as the disruption of hydrophilic-lipophilic balance (HLB), depolymerization, decrosslinking, and changes of molecular packing in assemblies, which eventually lead to a series of macroscopic phenomenon for practical purposes. Applications of stimuli-responsive nano-assemblies in delivery, sensing and imaging were also summarized based on their structural features. We expect this review could provide readers an overview of the structural considerations in the design and applications of nanoassemblies and incentivize more explorations in stimuli-responsive soft matters.

In Situ Formation of Polymeric Nanoassemblies Using an Efficient Reversible Click Reaction.

Polymer-drug conjugates are promising as strategies for drug delivery, because of their high drug loading capacity and low premature release profile. However, the preparation of these conjugates is often tedious. In this paper, we report an efficient method for polymer-drug conjugates using an ultrafast and reversible click reaction in a post-polymerization functionalization strategy. The reaction is based on the rapid condensation of boronic acid functionalities with salicylhydroxamates. The polymer, bearing the latter functionality, has been designed such that the reaction with boronic acid bearing drugs induces an in situ self-assembly of the conjugates to form well-defined nanostructures. We show that this method is not only applicable for molecules with an intrinsic boronic acid group, but also for the other molecules that can be linked to aryl boronic acids through a self-immolative linker. The linker has been designed to cause traceless release of the attached drug molecules, the efficiency of which has been demonstrated through intracellular delivery.

Conferring liver selectivity to a thyromimetic using a novel nanoparticle increases therapeutic efficacy in a diet-induced obesity animal model.

Optimization of metabolic regulation is a promising solution for many pathologies, including obesity, dyslipidemia, type 2 diabetes, and inflammatory liver disease. Synthetic thyroid hormone mimics-based regulation of metabolic balance in the liver showed promise but was hampered by the low biocompatibility and harmful effects on the extrahepatic axis. In this work, we show that specifically directing the thyromimetic to the liver utilizing a nanogel-based carrier substantially increased therapeutic efficacy in a diet-induced obesity mouse model, evidenced by the near-complete reversal of body weight gain, liver weight and inflammation, and cholesterol levels with no alteration in the thyroxine (T4) / thyroid stimulating hormone (TSH) axis. Mechanistically, the drug acts by binding to thyroid hormone receptor ß (TRß), a ligand-inducible transcription factor that interacts with thyroid hormone response elements and modulates target gene expression. The reverse cholesterol transport (RCT) pathway is specifically implicated in the observed therapeutic effect. Overall, the study demonstrates a unique approach to restoring metabolic regulation impacting obesity and related metabolic dysfunctions.

Microstructure and Wear Resistance of Laser-Clad Ni-Cu-Mo-W-Si Coatings on a Cu-Cr-Zr Alloy.

To improve the wear resistance of high-strength and high-conductivity Cu-Cr-Zr alloys in high-speed and heavy load friction environments, coatings including Ni-Cu, Ni-Cu-10(W,Si), Ni-Cu-10(Mo,W,Si), and Ni-Cu-15(Mo,W,Si) (with an atomic ratio of Mo,W to Si of 1:2) were prepared using coaxial powder-feeding laser cladding technology. The microstructure and wear performance of coatings were chiefly investigated. The results revealed that (Mo,W)Si2 and MoNiSi phases are found in the Ni-Cu-10(Mo,W,Si) and Ni-Cu-15(Mo,W,Si) coating. WSi2 phases are found in the Ni-Cu-10(W,Si) coating. The degree of grain refinement in Ni-Cu-10(Mo,W,Si) was greater than that of the Ni-Cu-10(W,Si) coating after the effect of Mo. The excellent wear resistance and micro-hardness of the Ni-Cu-15(Mo,W,Si) coating were attributed to the increase in its dispersion phase, which were approximately 34.72 mg/km and 428 HV, 27.1% and 590% higher than the Cu-Cr-Zr substrate, respectively. The existence of silicide plays an important role in grain refinement due to the promotion of nucleation and the inhibition of grain growth. In addition, the wear mechanism transformed from adhesive wear in the Ni-Cu coating with no silicides to abrasive wear in the Ni-Cu-15(Mo,W,Si) coating with high levels of silicides.

[Preparation of in situ gel systems for the oral delivery of ibuprofen and its pharmacokinetics study in beagle dogs].

The in situ gel systems can form gel in situ after administration to achieve sustained release, thus provides a promising strategy for drug delivery systems. The aim of this study was to design and prepare in situ gel systems for the oral delivery of ibuprofen (IBU-ISG) and study its pharmacokinetics in Beagle dogs. The characteristics of the basic material of gellan gum (Kelcogel, Kel) and sodium alginate (Manugel, M) were studied through investigating the complex viscosity of the Kel or M solution with or without different concentrations of calcium ion or sodium citrate to ascertain the amount range of the excipients. The measurement of complex viscosity of the solution (0. 5% Kel and 1% M) with different concentrations of sodium citrate and calcium ion was carried out to select the suitable proportion of calcium ion and sodium citrate. The formulation of binary IBU-ISG was optimized by monitoring the complex viscosity before gelling in vitro release property. The optimized formulation contains 1.0% sodium alginate, 0.5% gellan gum, 0. 21% sodium citrate and 0.056% calcium chloride. A single oral dose of IBU-ISG and reference formulation (IBU suspension) were given to each of the 6 healthy Beagle dogs, ibuprofen in plasma at different sampling times was determined by RP-HPLC. The pharmacokinetics parameters in 6 Beagle dogs were calculated. The Tmax of IBU-ISG and reference formulation were (1.8 +/- 0.6) and (0.4 +/- 0. 1) h. The Cmax values were (29.2 +/- 7.6) and (37.8 +/- 2.2) microg x mL(-1). The T(1/2) were (2.3 +/- 0.5) and (2.0 +/- 0.9) h, and the AUC(0-t) were (131.0 +/- 38.6) and (117.3 +/- 23.1) microg x mL(-1) x h, respectively. The binary IBU-ISG was successfully prepared.

Two new isoquinoline alkaloids from Scolopendra subspinipes mutilans induce cell cycle arrest and apoptosis in human glioma cancer U87 cells.

Two new isoquinoline alkaloids 1-2 and seven known compounds 3-9 were isolated from the ethanol extract of centipede Scolopendra subspinipes mutilans L. Koch. The structures were elucidated by a combination of spectroscopic analyses including 1D and 2D NMR, and HRESIMS. Compounds 1-2 exhibited good cytotoxicity with IC50 values ranging from 1.19 to 31.28µM against six human cancer cell lines and low cytotoxicity against human normal liver L-02 cell lines, suggesting that compounds 1-2 had high specific cytotoxicity on human cancer cell lines. Further analyses showed that compounds 1-2 inhibited U87 cells proliferation by arresting cell cycle progress at G0/G1 phase and inducing apoptosis through loss of mitochondrial membrane potential (MMP), activation of caspase 9/3 and down-regulation of the Bcl-2/Bax protein ratio. The results suggest that compounds 1-2 induce apoptosis in U87 cells through the mitochondria apoptosis pathway, and they deserve further research as potential anti-glioma cancer agents.