NIR-triggered drug delivery by collagen-mediated second harmonic generation.

Area of Science:

• Biophysics
• Materials Science
• Photochemistry

Background:

• Nonlinear optical processes enable unique light-matter interactions.
• Collagen, a key structural protein, exhibits nonlinear optical properties.
• Second harmonic generation (SHG) is a nonlinear process where two photons are absorbed and one photon with double the energy is emitted.

Purpose of the Study:

• To investigate the SHG properties of collagen.
• To explore the upconversion of near-infrared (near-IR) light to ultraviolet (UV) light by collagen.
• To demonstrate a method for cleaving molecules bound to collagen using UV light generated via SHG.

Main Methods:

• Utilized collagen as a nonlinear material.
• Applied near-IR (730 nm) laser excitation.
• Observed UV (365 nm) emission through SHG.
• Investigated the cleavage of a molecule attached to collagen via a UV-sensitive linker.

Main Results:

• Collagen demonstrated efficient second harmonic generation, upconverting 730 nm near-IR light to 365 nm UV light.
• The generated UV light successfully cleaved a molecule linked to collagen through a UV-sensitive bond.
• This SHG process provides a targeted method for molecular cleavage within a collagenous matrix.

Conclusions:

• Collagen acts as an efficient nonlinear material for SHG-based light upconversion.
• SHG in collagen offers a novel, light-activated mechanism for targeted molecular cleavage.
• This technique has potential applications in biomaterials and targeted drug delivery.