Thermosensitive Injectable Gradient Hydrogel-Induced Bidirectional Differentiation of BMSCs.

Osteochondral defects threaten the quality of life of patients to a great extent. To simulate gradient changes in osteochondral tissue, a gradient-mixing injection device consisting of a controller and injection pumps is design. Bioactive glass (BG) and gellan gum (GG) are used to prepare thermosensitive injectable gradient hydrogels (B0.5 G, B1 G) with an upper critical solution temperature (UCST) range of 37.7-40.2 °C using this device for the first time. The mechanical properties of gradient hydrogels are significantly better than those of pure GG hydrogels. The gradients in the composition, structure, and morphology of gradient hydrogels are confirmed via physicochemical characterization. Cytocompatibility tests show that hydrogels, especially B0.5 G gradient hydrogels, promote the proliferation of bone marrow mesenchymal stem cells (BMSCs). Most importantly, qRT-PCR shows that the different components in B0.5 G gradient hydrogels simultaneously induce the osteogenic and chondrogenic differentiation of BMSCs. Experimental injection in porcine osteochondral defects indicates that the B0.5 G gradient hydrogel seamlessly fills irregular osteochondral defects in a less invasive manner by controlling the temperature to avoid cellular and tissue damage arising from crosslinkers or other conditions. These results show that thermosensitive injectable B0.5 G gradient hydrogels have the potential for less invasive integrated osteochondral repair.

Polymyxin B engineered polystyrene-divinylbenzene microspheres for the adsorption of bilirubin and endotoxin.

Hemoperfusion is an important strategy for liver disease treatment. Polystyrene-divinylbenzene (PS-DVB) microspheres are widely applied as absorbents in hemoperfusion to efficiently remove the important toxin bilirubin. However, as another common toxin, endotoxin will remain during this process and cause endotoxemia. Therefore, simultaneous removal of both bilirubin and endotoxin is highly desirable. In the present study, we engineered PS-DVB microspheres with polymyxin B sulfate (PMB) to meet this goal. After modification, the novel PMB-engineered (P-PMB) microspheres displayed excellent biocompatibility and hemocompatibility. Notably, compared to PS-DVB microspheres, P-PMB microspheres exhibited markedly stronger detoxification of both bilirubin and endotoxin, increasing by 17.03% and 42.57%, respectively. Overall, we believe that the novel P-PMB microspheres have considerable potential for liver disease treatment in clinical practice.

Synthesis of Positively Charged Polystyrene Microspheres for the Removal of Congo Red, Phosphate, and Chromium(VI).

Uniform positively charged polystyrene microspheres were synthesized and further examined as a new sorbent for water remediation. The structures of the resulting sorbent were characterized by field-emission scanning electron microscopy, Fourier transform infrared spectroscopy, and 1H nuclear magnetic resonance spectroscopy. The adsorption performance of the sorbent was evaluated using three typical pollutants, namely, Congo red, phosphate, and Cr(VI). The adsorption isotherms were fitted by the Langmuir and Freundlich models, while the adsorption kinetics was analyzed by the pseudo-first-order, pseudo-second-order, and intraparticle diffusion equations. The thermodynamic parameters of the adsorption process including changes of enthalpy, entropy and Gibbs free energy, and binding constant were obtained by isothermal titration calorimetry measurements. The effects of solution pH and competitive ions on the adsorption process were investigated. The adsorption isotherms could be better fitted by the Langmuir model, yielding maximum adsorption capacities of 18, 6.2, and 1.1 mg g-1 for the adsorption of Congo red, Cr(VI), and phosphate, respectively. The adsorption kinetics could be best described by the pseudo-second-order equation. The spent sorbent was regenerated by washing with 1 M KOH and showed outstanding long-term cyclic performance. The findings suggested that the positive charges at the surface of polystyrene microspheres could serve as effective sites for the immobilization of anionic pollutants in solutions owing to the electrostatic attraction.

Efficient extraction of heavy metals from collagens by sulfonated polystyrene nanospheres.

This work reports the feasibility of utilizing sulfonated polystyrene nanospheres (SPS NSs) to extract heavy metals from collagen solutions. We have endeavored to present a detailed study on the adsorption characteristics and mechanism of heavy metals including Pb2+, Mn2+, Cr3+ and Cd2+. The adsorption isotherms were fitted by the Langmuir and Freundlich models while the adsorption kinetics data were described by the pseudo-first-order, pseudo-second-order and intraparticle diffusion equations. The adsorption isotherms were better fitted by the Langmuir model, leading to theoretical maximum capacities of 50.7, 15.0, 8.7 and 39.0 mg g-1 for the adsorption of Pb2+, Mn2+, Cr3+ and Cd2+, respectively. Isothermal titration calorimetry (ITC) measurements were conducted to detect the heat exchange of the adsorption processes. As a proof of concept, SPS NSs were practically applied in sequestrating heavy metals from Talapia-fish-scale derived collagen. The effects of pH of the collagen solutions in the removal of metals were investigated. By a single treatment, the concentrations of the metal ions were decreased to the regulatory standards whilst the concentration of collagen proteins was well maintained.

Gram-scale synthesis of monodisperse sulfonated polystyrene nanospheres for rapid and efficient sequestration of heavy metal ions.

Herein, gram-scale monodisperse sulfonated polystyrene (SPS) nanospheres are synthesized and examined as a sorbent for the removal of heavy metal ions (Pb2+, Zn2+ and Cu2+). The resulting uniform SPS nanospheres exhibit remarkable adsorption capabilities and kinetics, facile regeneration and outstanding recyclability, affording promising applications in food engineering and water cleanup.