Functional surface engineering of C-dots for fluorescent biosensing and in vivo bioimaging

Thickness-Dependent Full-Color Emission Tunability in a Flexible Carbon Dot Ionogel

Multicolor luminescent materials are of immense importance nowadays, while it still constitutes a challenge to achieve luminescence color tunability, transparency, and flexibility at the same time. Here we show how ultrasmall carbon dots (CDs) fluorescing strongly across the visible spectrum can be surface functionalized and incorporated into highly flexible hybrid materials by combination with ionic liquids within silica gel networks to form CD-ionogels with properties promising for fabrication of flexible displays and other optical technologies without the use of any toxic materials. We demonstrate how the emission from such hybrid materials can be tuned across a large range of the Commission Internationale de l'Enclairage (CIE) display gamut giving full-color performance. We highlight how the rich ladder of emissive states attributable to organic functional groups and CD surface functionalization supports a smooth sequential multiple self-absorption tuning mechanism to red shift continuously from blue emitting n-π* transitions down through the lower energy states.

Ratiometric fluorescence probe for monitoring hydroxyl radical in live cells based on gold nanoclusters

Determination of hydroxyl radical ((•)OH) with high sensitivity and accuracy in live cells is a challenge for evaluating the role that (•)OH plays in the physiological and pathological processes. In this work, a ratiometric fluorescence biosensor for (•)OH was developed, in which gold nanocluster (AuNC) protected by bovine serum albumin was employed as a reference fluorophore and the organic molecule 2-[6-(4'-hydroxy)phenoxy-3H-xanthen-3-on-9-yl]benzoic acid (HPF) acted as both the response signal and specific recognition element for (•)OH. In the absence of (•)OH, only one emission peak at 637 nm ascribed to AuNCs was observed, because HPF was almost nonfluorescent. However, fluorescence emission at 515 nm attributed to the HPF product after reaction with (•)OH--dianionic fluorescein--gradually increased with the continuous addition of (•)OH, while the emission at 637 nm stays constant, resulting in a ratiometric determination of (•)OH. The developed fluorescent sensor exhibited high selectivity for (•)OH over other reactive oxygen species (ROS), reactive nitrogen species (RNS), metal ions, and other biological species, as well as high accuracy and sensitivity with low detection limit to ∼0.68 μM, which fulfills the requirements for detection of (•)OH in a biological system. In addition, the AuNC-based inorganic-organic probe showed long-term stability against light illumination and pH, good cell permeability, and low cytotoxicity. As a result, the present ratiometric sensor was successfully used for bioimaging and monitoring of (•)OH changes in live cells upon oxidative stress.

Carbon dots as nanoantennas for anti-inflammatory drug analysis using surface-assisted laser desorption/ionization time-of-flight mass spectrometry in serum

C-dots assisted LDI MS method has been developed for the detection of Mefenamic acid in serum.

Phosphate-containing metabolites switch on phosphorescence of ferric ion engineered carbon dots in aqueous solution

Room temperature phosphorescence of carbon dots readily engineered by ferric ions in aqueous solution was developed for a novel “off-to-on” approach for cost-effective estimation of ATP level in human blood plasma.

Fluorescent carbon nanomaterials: “quantum dots” or nanoclusters?

Despite many efforts, the mechanisms of light absorption and emission of small fluorescent carbon nanoparticles (C-dots) are still unresolved and are a subject of active discussion.

13C-engineered carbon quantum dots for in vivo magnetic resonance and fluorescence dual-response

¹³C-engineered carbon quantum dots (¹³C-QDs) were used as magnetic resonance (MR) and fluorescence dual-response probe.

Sodium-cutting: a new top-down approach to cut open nanostructures on nonplanar surfaces on a large scale

A new, low-cost and simple top-down approach, “sodium-cutting”, was demonstrated which could eventually lead to the development of “sodium lithography”.

Ultrafast synthesis of nitrogen-doped carbon dots via neutralization heat for bioimaging and sensing applications

Ultrafast synthesis (within 2 min) of nitrogen-doped carbon dots was achieved using neutralization heat with glucose as a precursor. The hydroxyl groups on the dots' surface make them easy to conjugate with boronic acid. The dots were used for zebrafish embryo imaging and ovalbumin sensing.

Simultaneously enhancing up-conversion fluorescence and red-shifting down-conversion luminescence of carbon dots by a simple hydrothermal process

Simultaneously enhancing up-conversion fluorescence and red-shifting down-conversion luminescence of carbon dots has been achieved by a simple hydrothermal process.

A facile, green, and solvent-free route to nitrogen–sulfur-codoped fluorescent carbon nanoparticles for cellular imaging

A simple, solvent-free method was developed for preparation of fluorescent NSCPs by direct pyrolysis of gentamycin sulfate. The NSCPs showed high water-solubility, long lifetime, high quantum yield, excellent stability and low cytotoxicity, and thus can be used for cellular imaging.

Quinoline derivative-functionalized carbon dots as a fluorescent nanosensor for sensing and intracellular imaging of Zn2+

Functionalization of carbon nanodots (C-dots) with quinoline derivatives enables a highly sensitive and specific nanosensor for Zn²⁺ sensing in aqueous solution and Zn²⁺ imaging in vivo.

A dual amplification strategy for ultrasensitive electrochemiluminescence immunoassay based on a Pt nanoparticles dotted graphene–carbon nanotubes composite and carbon dots functionalized mesoporous Pt/Fe

A facile and sensitive ECL immunosensor has been designed using Pt/Gr–CNTs as a platform and Pt/Fe@CDs as bionanolabels.

Fluorescent carbon nanoparticles in medicine for cancer therapy

Nanotechnology provides exciting opportunities for the development of novel, clinically relevant diagnostic and therapeutic multifunctional systems. Fluorescent carbon nanoparticles (CNPs) due to their intrinsic fluorescence and high biocompatibility are among the best candidates. As innovative nanomaterials, CNPs could be utilized both as nontoxic drug delivery system and bioimaging. We foresee a great future for CNPs in cancer diagnostic and therapy.

A new hydrothermal refluxing route to strong fluorescent carbon dots and its application as fluorescent imaging agent

Due to their unique optical and biochemical properties, the water-soluble fluorescent carbon dots (CDs) have attracted a lot of attention recently. Here, strong fluorescent carbon dots with excellent quality have been synthesized by the hydrothermal refluxing method using lactose as carbon source and tris(hydroxymethyl) aminomethane (i.e. Tris) as surface passivation reagent. This facile approach was simple, efficient, economical, green without pollution, and allows large-scale production of CDs without any post-treatment. TEM measurements showed that the resulting particles exhibited an average diameter of 1.5 nm. The obtained CDs possess small particle sizes, good stability in a wide range of pH values (pH 3.5-9.5), high tolerance of salt concentration, strong resistibility to photobleaching, and a fluorescent quantum yield up to 12.5%. The CDs were applied to optical bioimaging of HeLa cells, showing low cytotoxicity and excellent biocompatibility.