Water-Soluble Carbon Dots from Candle Soot
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Solution Overview
Problem
Current methods for producing self-fluorescing quantum carbon dots are difficult to repeat consistently and are not suitable for practical mass production, as they require expensive materials and high temperatures, and existing carbon dots are not inherently fluorescent, requiring additional coatings or modifications to achieve fluorescence.
Innovation Solution
Water soluble carbon dots are isolated from carbon soot and carboxylated to create hydrophilic acid groups on their surface, allowing them to self-fluoresce, with the size of the dots determining the fluorescence color, achieved through heating hydrocarbon wax to produce carbon soot, purifying and oxidatively treating the dots to remove amorphous carbon and introduce carboxylic acid groups.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods (laser ablation, hot-pressing graphite) are used to produce carbon dots, then quantum-sized carbon particles can be obtained, but the process is difficult to repeat consistently and not suitable for mass production
Solution Approach 1:
The patent changes the production parameters from complex high-temperature laser ablation or hot-pressing processes to a simple combustion process using common candles. By changing the temperature range to 500-800°C (candle flame temperature) and using readily available materials (candles, soot collection), the process achieves both consistency and scalability for mass production.
Solution Approach 2:
The patent replaces expensive, specialized materials (graphite powder, cement, argon gas, laser equipment) with inexpensive, readily available materials (candles, air, simple soot collection apparatus). This enables the process to be performed anywhere without specialized equipment, greatly enhancing productivity and consistency.
2Ease of manufacture
If conventional carbon dots are produced without surface modification, then the production process is simpler, but the carbon dots do not self-fluoresce and require additional coatings or fluorescent molecules
Solution Approach 1:
The patent makes the carbon dots self-fluorescent through a self-service mechanism where the combustion process itself creates the fluorescent properties. The carbon dots produced from candle soot inherently exhibit fluorescence without requiring external coatings, proteins, or additional modifications, thus maintaining simplicity while ensuring reliable fluorescence.
3Adaptability or versatility
If carbon dots are made water-soluble through surface passivation with organic molecules, then water solubility is achieved, but the process adds extra costs and complexity
Solution Approach 1:
The patent changes the surface chemistry parameters by controlling the combustion conditions and oxidation state of the carbon dots during formation. The carbon dots are produced with inherent surface characteristics that provide water solubility without requiring additional passivation layers, thus achieving adaptability while maintaining process simplicity.
4Manufacturing precision
If high temperatures (900°C) and specialized materials (graphite powder, cement, argon gas) are used in laser ablation, then quantum-sized carbon particles can be produced, but the process becomes expensive and difficult to scale
Solution Approach 1:
The patent changes the temperature parameter from 900°C (laser ablation) to 500-800°C (candle flame), and replaces specialized materials (graphite powder, cement, argon gas) with common materials (candle wax, air). This parameter change maintains the ability to produce quantum-sized particles while dramatically reducing cost and improving scalability.
Solution Approach 2:
The patent replaces expensive, specialized materials with inexpensive, readily available alternatives. Candle wax, air, and simple collection apparatus replace graphite powder, cement, and argon gas systems, making the process economically viable for mass production.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables the production of water soluble, self-fluorescing quantum carbon dots that can be easily scaled up for industrial use, offering tunable fluorescence and improved stability, making them suitable for bio-imaging and other applications without the need for additional coatings or proteins.
Implementation Method 1
heating a hydrocarbon wax to a temperature of between about 500 degree C. and 800 degree C. under conditions sufficient to produce carbon soot
Implementation Method 2
oxidatively treating the quantum carbon dots to remove amorphous carbon and produce hydrophilic carboxylic acid groups on the surface
Implementation Method 3
water soluble self fluorescing quantum carbon dot comprising a carbon dot isolated from carbon soot and treated to produce hydrophilic carboxylic acid groups on the surface of the carbon dot sufficient to cause fluorescence
Data Source
AI summary
The present invention relates to the water soluble self fluorescent quantum carbon dots (C-dots). These C-dots are isolated from carbon soot in one embodiment a wax soot solvent washed and isolated from other larger material by filtration such as by membrane filtration. The C-dots can be varied in their color by change of their size and by the amount of oxidative groups' position on each C-dot.