Quantum Dot Nanomaterials: Preparation, Characterization, Advanced Bio-Imaging and Therapeutic Applications

Abstract

The bio-imaging technology is one of the most significant modern applications used in several fields, including early diagnosis of many illnesses that are most important diseases facing humanity and other vital uses. The primary advancement in nanotechnology is the creation of innovative fluorescence probes called quantum dots (QDs). The use of molecular tagging in research, in vivo, and in vitro studies is revolutionized by quantum dots. The application of QD indicates conversion in natural imaging and photography has demonstrated extraordinary appropriateness in bio-imaging, the discovery of novel drugs, and delivery of targeted genes, biosensing, photodynamic therapy, and diagnosis. New potential methods of early cancer detection and treatment management are being researched as a result of the special physical and chemical characteristics of QD probes. The bio-imaging technique depends on the fluorescent emission of the used materials, which is paired with living cells that are easy to see it in 3D without any surgical intervention. Therefore, the use of QDs many types that have unique and appropriate properties for use in that application; In terms of fluorescent emission strength, duration and luminosity.This review article displays some methods of preparation for QDs nanomaterials and the devices used in this. In addition, it presentssome of challenges that must be avoided for the possibility of using them in the bio-imaging field; as toxicity, bio-compatibility, and hydrophilization. It's reviewed some of the devices that use QDs in bio-imaging technique, the QDs application in cell analysis-imaging, and QDs application in vivo imaging.

Keywords: Bio-imaging; Fluorescence Emission; Quantum dot Applications; Quantum dot Techniques; Vivo Imaging.

Fig. 1

Flowchart of challenge in preparation of quantum dot nanomaterials for his bio-imaging applications

Fig. 2

Jablonski diagrams. (A) Example of the electronic states of a fluorophore that is excited by a light with the appropriate wavelength (e.g., Blue). The transition from low-energy electronic state S₀ to a higher vibrational ground state, S₁, is caused by the absorption of energy given by the excitation light. The return to the S₀ electronic state generates the emission of a photon (fluorescence) of lower energy (longer wavelength, such as green) [15]

Fig. 3

Basic architecture of core shell ligands in QDs [39]

Fig. 4

Chemical diagram of the bio-functionalized core/shell QDs. A, B, C andD are carboxyl, thiol, amino and streptavidin coated core/shell QDs, respectively [54]

Fig. 5

Various applications of Quantum dots in bioimaging and diagnosis

Fig. 6

Modified Jablonski Diagram illustrating the key photophysical processes involved PDT

Fig. 7

QD-based drug carriers integrate drug delivery tracing, loading of various types of drugs (e.g. hydrophobic small-molecule drugs between the QD core and polymer coating or hydrophilic drugs on the exterior surface of the polymeric shell), and targeting functionality. Intermediate size of such carriers ensures slower renal filtration as well as RES uptake, thus increasing blood circulation time and improving delivery efficiency [136]

Fig. 8

Schematic representation of mitomycin C encapsulated quantum dots–chitosan nanocarrier system for treatment of non-muscle invasive bladder cancer [136]