NIR-switchable local hydrogen generation by tandem bimetallic MOFs nanocomposites for enhanced chemodynamic therapy

The inadequate quantity of hydrogen peroxide(H_(2)O_(2))in cancer cells promptly results in the constrained success of chemodynamic therapy(CDT).Significant efforts made throughout the years;nevertheless,researchers are still facing the great challenge of designing a CDT agent and securing H_(2)O_(2) supply within the tumor cell.In this study,taking advantage of H_(2)O_(2) level maintenance mechanism in cancer cells,a nanozyme-based bimetallic metal-organic frameworks(MOFs)tandem reactor is fabricated to elevate intracellular H_(2)O_(2) levels,thereby enhancing CDT.In addition,under nearinfrared excitation,the upconversion nanoparticles(UCNPs)loaded into the MOFs can perform photocatalysis and generate hydrogen,which increases cellular susceptibility to radicals induced from H_(2)O_(2),inhibits cancer cell energy,causes DNA damages and induces tumor cell apoptosis,thus improving CDT therapeutic efficacy synergistically.The proposed nanozyme-based bimetallic MOFs-mediated CDT and UCNPs-mediated hydrogen therapy act as combined therapy with high efficacy and low toxicity.

Advances in hydrogel-based vascularized tissues for tissue repair and drug screening

The construction of biomimetic vasculatures within the artificial tissue models or organs is highly required for conveying nutrients,oxygen,and waste products,for improving the survival of engineered tissues in vitro.In recent times,the remarkable progress in utilizing hydrogels and understanding vascular biology have enabled the creation of three-dimensional(3D)tissues and organs composed of highly complex vascular systems.In this review,we give an emphasis on the utilization of hydrogels and their advantages in the vascularization of tissues.Initially,the significance of vascular elements and the regeneration mechanisms of vascularization,including angiogenesis and vasculogenesis,are briefly introduced.Further,we highlight the importance and advantages of hydrogels as artificial microenvironments in fabricating vascularized tissues or organs,in terms of tunable physical properties,high similarity in physiological environments,and alternative shaping mechanisms,among others.Furthermore,we discuss the utilization of such hydrogels-based vascularized tissues in various applications,including tissue regeneration,drug screening,and organ-on-chips.Finally,we put forward the key challenges,including multifunctionalities of hydrogels,selection of suitable cell phenotype,sophisticated engineering techniques,and clinical translation behind the development of the tissues with complex vasculatures towards their future development.

Supercritical fluid-assisted controllable fabrication of open and highly interconnected porous scaffolds for bone tissue engineering

Recently tremendous progress has been evidenced by the advancements in developing innovative three-dimensional(3 D)scaffolds using various techniques for addressing the autogenous grafting of bone. In this work, we demonstrated the fabrication of porous polycaprolactone(PCL) scaffolds for osteogenic differentiation based on supercritical fluid-assisted hybrid processes of phase inversion and foaming. This eco-friendly process resulted in the highly porous biomimetic scaffolds with open and interconnected architectures. Initially, a 2^3 factorial experiment was designed for investigating the relative significance of various processing parameters and achieving better control over the porosity as well as the compressive mechanical properties of the scaffold. Then, single factor experiment was carried out to understand the effects of various processing parameters on the morphology of scaffolds. On the other hand, we encapsulated a growth factor, i.e., bone morphogenic protein-2(BMP-2), as a model protein in these porous scaffolds for evaluating their osteogenic differentiation. In vitro investigations of growth factor loaded PCL scaffolds using bone marrow stromal cells(BMSCs) have shown that these growth factor-encumbered scaffolds were capable of differentiating the cells over the control experiments. Furthermore, the osteogenic differentiation was confirmed by measuring the cell proliferation, and alkaline phosphatase(ALP) activity, which were significantly higher demonstrating the active bone growth. Together, these results have suggested that the fabrication of growth factor-loaded porous scaffolds prepared by the eco-friendly hybrid processing efficiently promoted the osteogenic differentiation and may have a significant potential in bone tissue engineering.

(Metal yolk)/(porous ceria shell)nanostructures for high-performance plasmonic photocatalysis under visible light

We describe a route to the preparation of(metal yolk)/(porous ceria shell)nanostructures through the heterogeneous growth of ceria on porous metal nanoparticles followed by the calcination-induced shrinkage of the nanoparticles.The approach allows for the control of the ceria shell thickness,the metal yolk composition and size,which is difficult to realize through common templating approaches.The yolk/shell nanostructures with monometallic Pt and bimetallic PtAg yolks featuring plasmon-induced broadband light absorption in the visible region are rationally designed and constructed.The superior photocatalytic activities of the obtained nanostructures are demonstrated by the selective oxidation of benzyl alcohol under visible light.The excellent activities are ascribed to the synergistic effects of the metal yolk and the ceria shell on the light absorption,electron-hole separation and efficient mass transfer.Our synthesis of the(metal yolk)/(porous ceria shell)nanostructures points out a way to the creation of sophisticated heteronanostructures for high-performance photocatalysis.

3D bioprinting of conductive hydrogel for enhanced myogenic differentiation

Recently,hydrogels have gained enormous interest in three-dimensional(3D)bioprinting toward developing functional substitutes for tissue remolding.However,it is highly challenging to transmit electrical signals to cells due to the limited electrical conductivity of the bioprinted hydrogels.Herein,we demonstrate the 3D bioprinting-assisted fabrication of a conductive hydrogel scaffold based on poly-3,4-ethylene dioxythiophene(PEDOT)nanoparticles(NPs)deposited in gelatin methacryloyl(GelMA)for enhanced myogenic differentiation of mouse myoblasts(C2C12 cells).Initially,PEDOT NPs are dispersed in the hydrogel uniformly to enhance the conductive property of the hydrogel scaffold.Notably,the incorporated PEDOT NPs showed minimal influence on the printing ability of GelMA.Then,C2C12 cells are successfully encapsulated within GelMA/PEDOT conductive hydrogels using 3D extrusion bioprinting.Furthermore,the proliferation,migration and differentiation efficacies of C2C12 cells in the highly conductive GelMA/PEDOT composite scaffolds are demonstrated using various in vitro investigations of live/dead staining,F-actin staining,desmin and myogenin immunofluorescence staining.Finally,the effects of electrical signals on the stimulation of the scaffolds are investigated toward the myogenic differentiation of C2C12 cells and the formation of myotubes in vitro.Collectively,our findings demonstrate that the fabrication of the conductive hydrogels provides a feasible approach for the encapsulation of cells and the regeneration of the muscle tissue.