Near-IR photoactivation using mesoporous silica-coated NaYF4:Yb,Er/Tm upconversion nanoparticles

Area of Science:

• Biomedical Engineering
• Nanotechnology
• Photomedicine

Background:

• Photoactivation offers noninvasive therapeutic control but is limited by light penetration depth.
• Conventional UV/visible light poses challenges due to poor tissue penetration and potential toxicity.
• Developing methods for deep-tissue photoactivation is crucial for advanced therapeutic applications.

Purpose of the Study:

• To present a protocol utilizing upconversion nanoparticles (UCNs) for photoactivation via near-infrared (NIR) light.
• To demonstrate the application of UCNs in photodynamic therapy (PDT) and photoactivated gene expression control.
• To enable deep-tissue therapeutic activation using biologically compatible NIR light.

Main Methods:

• Synthesis and characterization of UCNs functionalized with mesoporous silica.
• Loading UCNs with photosensitizers for PDT and caged nucleic acids for gene therapy.
• In vitro and in vivo evaluation of UCN performance in cellular assays and animal models.
• Surface modification of UCNs with polyethylene glycol (PEG) and folic acid for targeted PDT delivery.

Main Results:

• UCNs successfully convert NIR light to UV-visible wavelengths for therapeutic activation.
• Demonstrated efficacy of UCN-mediated PDT for tumor cell killing via singlet oxygen production.
• Achieved photoactivated gene knockdown in tumors using UCN-delivered caged nucleic acids.
• Protocol details nanoparticle preparation, characterization, and functional assessment within a ~36-day timeframe.

Conclusions:

• UCNs serve as effective light transducers for deep-tissue photoactivation.
• This approach expands the utility of photoactivatable therapeutics beyond superficial applications.
• The protocol provides a framework for developing advanced NIR-activated therapies for various medical conditions.