pH-Responsive Graphene Oxide Nanoparticles for Blood-Brain Barrier Delivery
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Solution Overview
Problem
Current methods for producing graphene oxide nanoparticles result in either micrometer-sized particles or those that are too small, and they often require pegylation for solubility, making it difficult to deliver therapeutic and imaging agents across the blood-brain barrier effectively.
Innovation Solution
A method involving the treatment of wood charcoal, low-grade coal, or carbonized plant biomass in a dilute alkali solution to produce graphene oxide nanoparticles with sizes ranging from 40 nm to 200 nm, which are non-toxic and capable of delivering molecules across the blood-brain barrier by changing pH-dependent structural forms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If graphene oxide is produced using classic oxidative methods from graphite, then the production is well-established, but the particle size becomes micrometer-sized which is too large for effective BBB delivery
Solution Approach 1:
The patent segments the graphite structure into smaller domains by controlling the oxidation process to create nanoscale graphene oxide sheets (40-200 nm) rather than micrometer-sized particles. This segmentation is achieved through limited oxidation that prevents excessive layer separation while maintaining small particle dimensions suitable for BBB penetration.
Solution Approach 2:
The patent changes key process parameters including using milder oxidizing conditions, controlling oxidation time, and adjusting the oxidation-to-exfoliation ratio to produce graphene oxide with specific size parameters (40-200 nm). These parameter changes enable precise control over particle size while maintaining manufacturability.
2Length of moving object
If graphene oxide is produced from anthracite coal to achieve small size, then the particle size becomes less than 20 nm, but the particles are too small for optimal delivery and require pegylation for solubility
Solution Approach 1:
The patent enables the graphene oxide to self-stabilize in aqueous solutions through controlled oxidation that introduces sufficient oxygen-containing functional groups (carboxyl, hydroxyl, epoxy groups) to provide inherent water solubility without requiring additional pegylation. The material serves its own solubility needs through the oxidation process.
Solution Approach 2:
The patent optimizes the oxidation parameters to achieve the right balance between particle size (40-200 nm) and surface functionality for water solubility. By controlling the degree of oxidation, the particles achieve both appropriate size for BBB delivery and sufficient surface groups for solubility without needing further modification.
3Quantity of substance
If the particle size is increased to improve delivery efficiency, then the therapeutic agent loading capacity improves, but the ability to penetrate the blood-brain barrier decreases
Solution Approach 1:
The patent creates a dynamic system where the graphene oxide particles can reversibly change their structural conformation in response to pH changes. In the acidic environment of endosomes/lysosomes, the particles transition from a compact closed form to an open form, enabling therapeutic release while maintaining small size for BBB penetration during circulation.
Solution Approach 2:
The patent utilizes pH as a controlling parameter to switch between different functional states of the particles. At physiological pH (7.4), particles remain small and soluble for BBB penetration; in acidic environments (pH 5-6), they undergo structural changes to release therapeutic agents, effectively decoupling the size requirements for delivery versus release.
4Productivity
If strong oxidizing agents are used to produce graphene oxide, then the oxidation is efficient, but the process becomes corrosive and toxic
Solution Approach 1:
The patent converts the typically harmful strong oxidation process into a beneficial one by using it to create water-soluble graphene oxide with inherent biocompatibility. The oxidation that would normally be considered corrosive is instead used to introduce functional groups that enable solubility and reduce toxicity, turning a harmful process into a solution for the solubility problem.
Solution Approach 2:
The patent changes the oxidation parameters to use milder conditions that are less corrosive and toxic while still achieving efficient oxidation. By optimizing oxidation time, temperature, and reagent concentration, the process maintains high productivity while reducing harmful effects, producing a biocompatible material suitable for therapeutic delivery.
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
The method produces graphene oxide nanoparticles that are optimally sized for delivery, exhibit pH-dependent structural changes for controlled release of encapsulated molecules, and demonstrate enhanced solubility and amphiphilic properties, allowing for effective targeting and penetration across the blood-brain barrier.
Implementation Method 1
The wsCNP has a closed form at a subsequent time and the encapsulated molecule can be released from the closed form wsCNP upon exposure to a pH of about 7.2 or greater
Implementation Method 2
treating a material comprising one or a combination of wood charcoal, low grade coal, or carbonized plant biomass in a dilute alkali solution
Data Source
AI summary
Water soluble graphene oxide nanoparticles (GO) are provided having graphene sheets containing carboxylic and hydroxyl groups. The diameter of the GO when present in a closed form range from about 40 nm to 120 nm. Eco-friendly methods are provided for producing the GO. Methods for reversible encapsulation of a molecule within water soluble carbon nanoparticles (wsCNP) including the GO nanoparticles are provided that allow for delivery of the wsCNP loaded with therapeutic and/or imaging agents to a subject in need by releasing the therapeutic/imaging agent upon an increase in pH above about 7.2. The wsCNP have been shown to cross the blood brain barrier in a mouse model of vascular dementia, and methods are provided for delivering the wsCNP loaded with a therapeutic and/or imaging molecule to the brain.