Polyethylene Glycol6000/carbon Nanodots as Fluorescent Bioimaging Agents

Abstract

Photoluminescent nanomaterials have immense potential for use in biological systems due to their excellent fluorescent properties and small size. Traditional semiconductor quantum dots are heavy-metal-based and can be highly toxic to living organisms, besides their poor photostability and low biocompatibility. Nano-sized carbon quantum dots and their surface-modified counterparts have shown improved characteristics for imaging purposes. We used 1,3, 6-trinitropyrene (TNP) and polyethylene glycol6000 (PEG6000) in a hydrothermal method to prepare functional polyethylene glycol6000/carbon nanodots (PEG6000/CDs) and analyzed their potential in fluorescent staining of different types of bacteria. Our results demonstrated that PEG6000/CDs stained the cell pole and septa of gram-positive bacteria B. Subtilis and B. thuringiensis but not those of gram-negative bacteria. The optimal concentration of these composite nanodots was approximately 100 ppm and exposure times varied across different bacteria. The PEG6000/CD composite had better photostability and higher resistance to photobleaching than the commercially available FM4-64. They could emit two wavelengths (red and green) when exposed to two different wavelengths. Therefore, they may be applicable as bioimaging molecules. They can also be used for differentiating different types of bacteria owing to their ability to differentially stain gram-positive and gram-negative bacteria.

Effect of Solvent on Fluorescence Emission from Polyethylene Glycol-Coated Graphene Quantum Dots under Blue Light Illumination

“…Graphene quantum dots (GQDs) have experienced a surge in attention compared to other nanomaterials thanks to their superior physicochemical properties including excellent solubility, high stability, and low toxicity [ 1 ]. In particular, due to their stable photoluminescence and ultra-high resistance to photobleaching, GQDs have been widely used in the architecture of various devices such as bio-imaging instruments [ 2 ], high-precision sensors [ 3 ], electrochemical energy devices [ 4 , 5 , 6 , 7 , 8 , 9 , 10 ], light-emitting apparatus [ 11 ], and solar reactors [ 12 ]. It is well established that GQDs with an average particle size of <10 nm exhibit quantum confinement, and as a result, photoluminescence (PL) with variable wavelength and photobleaching impedance can be designed and engineered [ 13 ].…”

Facile Synthesis of Surface-Modified Carbon Quantum Dots (CQDs) for Biosensing and Bioimaging

“…Such a phenomenon is called the quantum confinement effect [ 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ]. Quantum dots may be applied in bioimaging and biodiagnostics [ 16 , 17 , 18 , 19 ]. Various types of these nanomaterials were successfully used for this purpose such as CdS, CdSe, CdTe, MoS 2 or PbS.…”

Carbon dot composites for bioapplications: a review

“…, TNP and chitosan) using the same preparation method but different reaction conditions and composited with PEG. 193…”