Synthesis of Doped/Hybrid Carbon Dots and Their Biomedical Application

Abstract

Carbon dots (CDs) are a novel type of carbon-based nanomaterial that has gained considerable attention for their unique optical properties, including tunable fluorescence, stability against photobleaching and photoblinking, and strong fluorescence, which is attributed to a large number of organic functional groups (amino groups, hydroxyl, ketonic, ester, and carboxyl groups, etc.). In addition, they also demonstrate high stability and electron mobility. This article reviews the topic of doped CDs with organic and inorganic atoms and molecules. Such doping leads to their functionalization to obtain desired physical and chemical properties for biomedical applications. We have mainly highlighted modification techniques, including doping, polymer capping, surface functionalization, nanocomposite and core-shell structures, which are aimed at their applications to the biomedical field, such as bioimaging, bio-sensor applications, neuron tissue engineering, drug delivery and cancer therapy. Finally, we discuss the key challenges to be addressed, the future directions of research, and the possibilities of a complete hybrid format of CD-based materials.

Development of Doped Carbon Quantum Dot-Based Nanomaterials for Lubricant Additive Applications

“…In the bottom-up approach, carbon-based molecules are converted into compact discs of carbon materials of the desired size. A number of bottom-up methods have been developed, including sonochemical, microwave, hydrothermal thermal decomposition of organic molecules, pyrolysis of carbon-based materials, and solvothermal reaction synthesis [32]. Furthermore, CDs can be carefully developed and controlled with respect to their composition, structure, morphology, and particle size by choosing appropriate chemical precursors, functional molecules, and synthesis methods [48].…”

“…Here, we have discussed the importance of CD additives in engine performance, as well as the relationship between CDs and wear as a result of formulated oils modified with CDs and doped CD materials. The exclusive and enviable physical and chemical characteristics of CDs and doped CD-based materials have led to their recognition as excellent fluorescence candidates for multifunctional applications in many scientific fields when compared to semiconductor quantum dots [32,45,58,71,72] In recent years, carbon nanomaterials such as CD, graphene quantum dots, nanodiamonds, and nanohorns have been investigated for their potential applications due to their shape effect and chemical inertness. In the tribological field, CDs and CD-derived materials with unique physical properties are capturing significant interest, particularly in lubricant nano-additives that benefit from their anti-wear properties.…”

“…CD refers to a wide variety of nanoscale carbon materials, including graphene quantum dots, polymer quantum dots, and carbon quantum dots. Generally, materials containing a significant proportion of carbon at the nanoscale are referred to as carbon dots [32]. Moreover, CDs shows uniform size distribution, favorable physicochemical properties, negligible toxicity, and eco-friendliness as well as convenient preparation and functionalization [32].…”

“…Generally, materials containing a significant proportion of carbon at the nanoscale are referred to as carbon dots [32]. Moreover, CDs shows uniform size distribution, favorable physicochemical properties, negligible toxicity, and eco-friendliness as well as convenient preparation and functionalization [32]. CDs are also recognized as CQDs (carbon quantum dots) and are very similar to graphene quantum dots (GQDs) [33].…”

“…CDs are also recognized as CQDs (carbon quantum dots) and are very similar to graphene quantum dots (GQDs) [33]. As a zero-dimensional carbon-based nanomaterial, CDs appear to offer a promising solution to a number of challenging scientific and technological problems in the fields of biology, chemistry, and materials [32,[34][35][36]. CDs were incidentally revealed in 2004, when Xu et al were washing carbon nanotubes, because of their excellent photoluminescent properties; CDs were first reported using the laser ablation synthesis method [37].…”