The application of a cardiac patch over the epicardial surface has shown positive effects in protecting cardiac function postinfarction. Electroactive patches could enhance electrical signal propagation among cardiac cells. In the present study, an electrically active composite of collagen and graphene oxide (Col-GO) was fabricated as a cardiac patch. Col scaffolds were fabricated using a freeze-drying method and coated covalently with GO. Some scaffolds were also reduced by a reduction agent to restore the high conductivity of GO. GO was shown to be a single layer with suitable lateral size for biological application. The Col-GO scaffolds contained randomly oriented interconnected pores with appropriate pore sizes of 120-138 AE 8 μm. GO flakes were also well distributed in the pore walls. By increasing the GO concentration, the tensile strength of the scaffolds was enhanced from 75 kPa for Col-GO-5 to 162 kPa for Col-GO-90. Young modulus also followed the same trend. Electrical conductivity of the scaffolds was in the range of semi-conductive materials (~10 −4 S/m), which is suitable for cardiac tissue engineering applications. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay indicated no toxic effects on human umbilical vein endothelial cells (HUVECs) after 96 h. Also, a 10-days degradation product of the samples was compatible with HUVECs. Reduced scaffolds supported neonatal cardiomyocyte adhesion and upregulated the expression of the cardiac genes, including Cx43, Actin4, and Trpt-2 than their nonconductive counterparts. The obtained results confirmed the angiogenic properties of reduced Go-containing materials for cardiovascular applications where angiogenesis plays an important role, especially postinfarction.

Chemically nickel oxide nanoparticles (NiONPs) involve the synthesis of toxic products, which restrict their biological applications. Hence, we developed a simple, eco-friendly, and cost-efficient green chemistry method for the fabrication of NiONPs using fresh leaf broth of Rhamnus triquetra (RT). The RT leaves broth was used as a strong reducing, capping, and stabilizing agent in the formation of RT-NiONPs. The color change in solution from brown to greenish black suggests the fabrication of RT-NiONPs which was further confirmed by absorption band at 333 nm. The synthesis and different physicochemical properties of RT-NiONPs were investigated using different analytical techniques such as UV-Vis (ultraviolet−visible spectroscopy), XRD (X-ray powder diffraction), FT-IR (Fourier-transform infrared spectroscopy), SEM (scanning electron microscopy), TEM (transmission electron microscopy), EDS (energy-dispersive X-ray spectroscopy), DLS (dynamic light scattering) and Raman. Further, RT-NiONPs were subjected to different in vitro biological activities and revealed distinctive biosafe and biocompatibility potentials using erythrocytes and macrophages. RT-NiONPs exhibited potential anticancer activity against liver cancer cell lines HUH7 (IC50: 11.3 µg/mL) and HepG2 (IC50: 20.73 µg/mL). Cytotoxicity potential was confirmed using Leishmanial parasites promastigotes (IC50: 27.32 µg/mL) and amastigotes (IC50: 37.4 µg/mL). RT-NiONPs are capable of rendering significant antimicrobial efficacy using various bacterial and fungal strains. NiONPs determined potent radical scavenging and moderate enzyme inhibition potencies. Overall, this study suggested that RT-NiONPs can be an attractive and eco-friendly candidate. In conclusion, current study showed potential in vitro biological activities and further necessitate different in vivo studies in various animal models to develop leads for new drugs to treat several chronic diseases.

Droplet-based microfluidic systems have been employed to manipulate discrete fluid volumes with immiscible phases. Creating the fluid droplets at microscale has led to a paradigm shift in mixing, sorting, encapsulation, sensing, and designing high throughput devices for biomedical applications. Droplet microfluidics has opened many opportunities in microparticle synthesis, molecular detection, diagnostics, drug delivery, and cell biology. In the present review, we first introduce standard methods for droplet generation (i.e., passive and active methods) and discuss the latest examples of emulsification and particle synthesis approaches enabled by microfluidic platforms. Then, the applications of droplet-based microfluidics in different biomedical applications are detailed. Finally, a general overview of the latest trends along with the perspectives and future potentials in the field are provided.

Over the decades, researchers have strived to synthesize and modify nature-inspired biomaterials, with the primary aim to address the challenges of designing functional biomaterials for regenerative medicine and tissue engineering....

Tissue reconstruction requires the utilization of multiple biomaterials and cell types to replicate the delicate and complex structure of native tissues. Various three-dimensional (3D) bioprinting techniques have been developed to fabricate customized tissue structures; however, there are still significant challenges, such as vascularization, mechanical stability of printed constructs, and fabrication of gradient structures to be addressed for the creation of biomimetic and complex tissue constructs. One approach to address these challenges is to develop multimaterial 3D bioprinting techniques that can integrate various types of biomaterials and bioprinting capabilities towards the fabrication of more complex structures. Notable examples include multi-nozzle, coaxial, and microfluidics-assisted multimaterial 3D bioprinting techniques. More advanced multimaterial 3D printing techniques are emerging, and new areas in this niche technology are rapidly evolving. In this review, we briefly introduce the basics of individual 3D bioprinting techniques and then discuss the multimaterial 3D printing techniques that can be developed based on combination of these techniques for the engineering of complex and biomimetic tissue constructs. We also discuss the perspectives and future directions to develop state-of-the-art multimaterial 3D bioprinting techniques for engineering tissues and organs.