Multiwavelength Photodynamic Therapy Apparatus
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Solution Overview
Problem
Current photodynamic compounds for treating unwanted and hyperproliferating cells, such as cancer, lack photostability, effective absorption in visible and Near InfraRed wavelengths, and functionality in hypoxic environments, and there is a need for compounds that can act as both therapeutic agents and diagnostic tools with improved targeting and oxygen-independent activity.
Innovation Solution
A method involving the use of Ru (II), Os (II), or Rh (II) dyad photodynamic compounds that absorb light at multiple wavelengths to create a predetermined photon density gradient, combined with an apparatus using dual light sources and a controller to optimize light emission, allowing for selective tissue excitation and adjustable depth of activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional organic-based porphyrins are used as photodynamic compounds, then they can be activated with light, but they require relatively short wavelengths and do not function in hypoxic environments
Solution Approach 1:
The patent employs metallosupramolecular complexes with metals such as ruthenium and rhodium, which possess low-lying 3MMCT (metal-to-metal charge transfer) excited states. This changes the photochemical parameters of the photodynamic compound, enabling activation at different wavelengths and providing functionality in hypoxic environments where traditional organic porphyrins fail.
2Illumination intensity
If photodynamic compounds are designed for deep tissue penetration, then NIR absorption is improved, but absorption at activation wavelength may be reduced
Solution Approach 1:
The patent describes a method using multiple light sources with different wavelengths (including both visible and NIR ranges) to activate photodynamic compounds. This multi-functional approach allows the system to achieve both strong absorption at activation wavelength and deep tissue penetration by selectively applying different wavelength components.
3Device complexity
If a single wavelength light source is used for photodynamic therapy, then the system is simple, but the absorbed photon density gradient cannot be optimized for different tissue depths
Solution Approach 1:
The patent divides the light source into multiple independent wavelength components (first light source for visible wavelength, second light source for NIR wavelength). Each wavelength component can be independently controlled to create specific absorbed photon density gradients, allowing optimization for different tissue depths and conditions while maintaining manageable system complexity.
4Adaptability or versatility
If photodynamic compounds are used for both therapy and diagnosis, then versatility is improved, but photostability and absorption characteristics become more difficult to optimize
Solution Approach 1:
The patent employs metallosupramolecular complexes that combine metal centers (ruthenium, rhodium, or osmium) with organic ligands. This composite structure provides both the photostability needed for diagnostic applications and the absorption characteristics required for therapeutic activation, enabling dual functionality while maintaining compositional stability.
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 enhances the therapeutic efficacy of photodynamic therapy by enabling customizable photon density gradients, improving treatment selectivity and effectiveness across different tissue types and disease stages, while ensuring maximal activity regardless of oxygen levels and providing enhanced diagnostic capabilities.
Implementation Method 1
the PS absorbs light at the first wavelength and/or the second wavelength
Implementation Method 2
the second light is more strongly absorbed by the tissue than the first light or the first light is more strongly absorbed by the tissue than the second light, so as to achieve a predetermined absorbed photon density gradient
Data Source
AI summary
A method for treating a condition in a tissue, includes the steps: (1) providing a PS within the tissue; (2) irradiating the tissue containing the PS with a first light of a first wavelength; and (3) irradiating the tissue containing the PS with a second light of a second wavelength so as to treat the condition in the tissue, wherein: (a) the PS absorbs light at the first wavelength and the second wavelength; and (b) the second light is more strongly absorbed by the tissue than the first light or vice versa, so as to achieve a predetermined absorbed photon density gradient. An apparatus for conducting the method includes first and second light sources, a power supply, a focusing device, and a controller which adjusts light emission such that I(d)=I(λ1 at d=0)×exp (μeff (λ1)×d)+I(λ2 at d=0)×exp (μeff(λ2)χd).