PLGA Nanocarriers with NIR-Triggered Thermal Plasticization
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Solution Overview
Problem
Current light-triggered release technologies for biomedical applications using near-infrared (NIR) light face limitations due to biocompatibility issues with metal nanostructures and toxicity concerns with rare-earth elements, and require high-powered lasers that can cause tissue damage.
Innovation Solution
Biodegradable polymer particles, such as those made from poly(lactic-co-glycolic acid) (PLGA), are used to selectively heat confined water using low-power NIR light, inducing thermal plasticization for controlled release of payloads without significant heating of the surrounding solution, utilizing wavelengths between 980 nm to 1200 nm for efficient photon-to-thermal energy conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If gold or metal nanostructures are incorporated into polymer capsules to generate heat upon NIR absorption, then release of therapeutics is achieved, but biocompatibility is compromised and excessive heat is generated that may damage tissue
Solution Approach 1:
The patent introduces an intermediary substance (carbon black or other photothermal agents) that mediates the conversion of NIR light to heat, allowing controlled thermal plasticization of the polymer matrix without requiring metal nanostructures. This intermediary enables therapeutic release while avoiding the biocompatibility issues and excessive heating problems associated with gold nanoparticles
Solution Approach 2:
The patent changes the thermal parameters by using low-power NIR light to achieve localized thermal plasticization of the polymer matrix, raising the temperature just enough to increase polymer chain mobility and enable drug release, but keeping the overall temperature increase minimal (less than 5-10°C) to avoid tissue damage
2Productivity
If high-powered and focused pulsed NIR lasers are used to overcome two-photon photochemistry limitations, then triggered release is achieved, but the energy exceeds the damage threshold of biological tissue
Solution Approach 1:
The patent replaces the mechanical/optical system requiring high-powered pulsed lasers with a thermal system using continuous-wave or low-power NIR lasers. Instead of relying on simultaneous two-photon absorption, the system uses photothermal heating to induce thermal plasticization, substituting high-energy optical processes with lower-energy thermal processes that are biologically safer
3Object-affected harmful factors
If UCNPs are used to convert NIR photons into higher-energy UV photons for photo-responsive polymer nanocarriers, then triggered release is achieved with biologically benign excitation power densities, but rare-earth heavy elements are introduced that may prove toxic
Solution Approach 1:
The patent extracts and removes the problematic rare-earth elements from the system by using alternative photothermal agents such as carbon black, which can be converted to biocompatible forms like carbon dioxide through metabolic processes. This eliminates the toxicity issue while maintaining the ability to use low-power NIR excitation
4Reliability
If gold nanostructures are extensively irradiated with high power NIR light to maintain photothermal responsiveness, then release capability is maintained, but irreversible damage occurs to the metal nanoparticles through melting
Solution Approach 1:
The patent uses biodegradable polymer materials that can be safely degraded in the body through metabolic processes, replacing the need for durable metal nanostructures. The photothermal agents used are either biocompatible or can be converted to harmless substances, eliminating the problem of irreversible damage accumulation
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 approach enables instantaneous and controlled release of payloads with minimal tissue heating, reversible aggregation, and extended release periods, suitable for delivering small molecules to cells or tissues, overcoming biocompatibility and toxicity issues of existing methods.
Implementation Method 1
The wavelength of the NIR light is selected to produce resonance in the water, within a range of about 980 nm to 1200 nm
Implementation Method 2
confined water within biodegradable polymer particles is selectively heated using NIR light
Implementation Method 3
The polymer particles, which are formed from materials lacking inherent light sensitivity, undergo thermal plasticization when exposed to low power NIR light, inducing a phase change that allows the encapsulated payload to diffuse out of the particle
Implementation Method 4
The on-demand rate of release is dependent on the average NIR photon energy administered to the system and inversely proportional to the size of the particles
Data Source
AI summary
Near infrared radiation at a wavelength that induces resonance in water is used to remotely activate thermal plasticization of polymeric particles to trigger the release of encapsulated molecules from the particles. Nanocarriers formed from biocompatible hydrophilic polymers may be used to deliver encapsulated molecules to tissue with a reversible transition that allows repeated activations for extended release of the payload.