Functionalized Flexible Soft Polymer Optical Fibers for Laser Photomedicine

Abstract

Optical waveguides allow propagating light through biological tissue in optogenetics and photomedicine applications. However, achieving efficient light delivery to deep tissues for long‐term implantation has been limited with solid‐state optical fibers. Here, a method is created to rapidly fabricate flexible, functionalized soft polymer optical fibers (SPOFs) coupled with silica fibers. A step‐index core/cladded poly(acrylamide‐co‐poly(ethylene glycol) diacrylate)/Ca alginate SPOF is fabricated through free‐radical polymerization in a mold. The SPOF is integrated with a solid‐state silica fiber coupler for efficient light delivery. The cladded SPOF shows ≈1.5‐fold increase in light propagation compared to the noncladded fiber. The optical loss of the SPOF is measured as 0.6 dB cm−1 at the bending angle of 70° and 0.28 dB cm−1 through a phantom tissue. The SPOF (inner Ø = 200 µm) integrated with a 21 gauge needle (inner Ø = 514 µm) is inserted within a porcine tissue. The intensity of light decreases ≈60%, as the SPOF is implanted as deep as 2 cm. Doped with fluorescent dye and gold nanoparticles, the SPOF fiber exhibits yellow‐red and red illumination. Living cells can also be incorporated within the SPOF with viability. The flexible SPOFs may have applications in photodynamic light therapy, optical biosensors, and photomedicine.

Agarose-based structured optical fibre

“…Another promising application is the monitoring of biochemical variables, wherein the waveguide can be used both as the sensing probe and encapsulation medium for microorganisms 4 . Moreover, localized and controlled light incidence is suitable for optical actuation purposes, including drug-delivery, laser-assisted surgeries 5 , photothermal therapy 6 , and neuronal stimulation through optogenetics 7 .…”

“…For instance, slab waveguides made of poly(ethylene glycol) (PEG) coupled to standard optical fibres were developed for detecting heavy metal ions in vivo, either by encapsulating cells or embedding fluorescent nanoparticles 7,18 . Hydrogel-based fibres were also conceived with PEG core and alginate cladding structure 1,6,19 , wherein the monomer solution is injected in a tube and cured using UV light to form the fibre core. Then, the material is removed from the mould and coated by dipping the fibre in a sodium alginate and calcium chloride solution, yielding low relative transmission losses, and the capability to assess blood oxygen saturation 1 and glucose concentration 19 .…”

Light-assisted electrospinning monitoring for soft polymeric nanofibers

“…For instance, we adopted geometrical optics approaches for simplicity, however the changing physical properties in the droplet-jet transition region add to the complexity of light-matter interaction. The soft matter properties of the EF do not allow a remarkable effective L, because the longitudinal components of the electric field propagating into the optical fiber are not negligible, and outstanding radiation are scattered and exit at the EF-space interface 42 . Also a more accurate estimation of the optical losses would thus require a very detailed thermo-optical characterization, the implementation of Fresnel equation at the interface between different media and to consider the effect of absorbance along the fiber, aspects that would go beyond the scope of the present study.…”

Biocompatible and Implantable Optical Fibers and Waveguides for Biomedicine

“…Besides the conventional thermal drawing method, molding, printing and microfabricating process are all employed to form a fiber or create a novel waveguide structure. Molding provides a universal solution to implantable fibers and waveguides, for example, combined with dip coating, step-index fibers are made from hydrogels or elastomers and demonstrate diverse functions for phototherapy, biosensing and imaging [ 36 , 63 , 71 ]. Printing and microfabrication method are mainly used for planar waveguide devices, among which the utility still needs further development.…”

“…The low optical loss measured in tissue phantoms is about 0.28 dB/cm. Their unique mechanical properties attract lots of attention in medical applications such as phototherapy and photomedicine [ 63 ]. Researchers have also manufactured a fluorescence slab waveguide made of hydrogels and doped with carbon dots to detect heavy metal ions, such as Hg 2+ ions [ 64 ].…”