Generally, carbon nanoparticles with a size of 10 nm (or less) are called carbon quantum dots (CQDs, C-dots or CD), which have created huge excitement due to their advantages in chemical inertness, high water solubility, excellent biocompatibility, resistance to photobleaching and various optical superiority. In this article, we describe the recent advancements in the area of CQDs; concentrating on their synthesis techniques, size control, surface modification approaches, optical properties, luminescent mechanism, and their applications in bioimaging, biosensing, drug delivery and catalysis.

Current strategies of tissue engineering are focused on the reconstruction and regeneration of damaged or deformed tissues by grafting of cells with scaffolds and biomolecules. Recently, much interest is given to scaffolds which are based on mimic the extracellular matrix that have induced the formation of new tissues. To return functionality of the organ, the presence of a scaffold is essential as a matrix for cell colonization, migration, growth, differentiation and extracellular matrix deposition, until the tissues are totally restored or regenerated. A wide variety of approaches has been developed either in scaffold materials and production procedures or cell sources and cultivation techniques to regenerate the tissues/organs in tissue engineering applications. This study has been conducted to present an overview of the different scaffold fabrication techniques such as solvent casting and particulate leaching, electrospinning, emulsion freeze-drying, thermally induced phase separation, melt molding and rapid prototyping with their properties, limitations, theoretical principles and their prospective in tailoring appropriate micro-nanostructures for tissue regeneration applications. This review also includes discussion on recent works done in the field of tissue engineering.

In this study to further improve surface characteristics of tissue engineering scaffolds, a novel composite based on chitosan–gelatin/nanohydroxyapatite–polyaniline (CS-Gel/nHA-PANI) was prepared by blending the synthesized nHA and PANI with chitosan and gelatin solution followed by lyophilization technique. The prepared composite scaffold was characterized using Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy techniques. The effects of nHA and PANI on the physicochemical properties of the scaffold including swelling ratio, density, biodegradation, biomineralization, and mechanical behavior were investigated. The composite scaffold was highly porous with the mean pore size of 200 μm. Compared with CS-Gel and CS-Gel/nHA scaffolds, the CS-Gel/nHA-PANI scaffold exhibited lower degradation rate and higher biomineralization and mechanical strength. Preliminary evaluation of the biocompatibility and cytotoxicity of the CS-Gel/nHA-PANI composite scaffold was performed by MTT assay using bovine leukemia virus fetal lamb kidney cell line (BLV-FLK) and then cell attachment studies were assessed using dental pulp stem cells. Results indicated no toxicity, and cells attached and proliferated on the pore surfaces of the scaffold. These findings suggested that the developed scaffold possess the prerequisites and can be used as a scaffold for hard tissues regeneration.