Polysaccharide hydrogel optical fibers and their fabrication and use
Optical fibers containing wet-spun multi-layer hydrogel cladding with ionic-crosslinked polysaccharides are provided. Optical fibers can be formed with step- or gradient-index architectures, fusion splicing, and facile rare-earth ion doping. Plasmonic nanoparticles, functionalized light-sensitive quantum dots, or particles can be incorporated into the fiber core to generate a resonance light shift upon the presence and binding of molecular biotargets for biosensor applications. The integration of plasmonic hydrogel fibers with medical swabs provides for rapid detection of pathogens such as severe acute respiratory syndrome coronavirus 2 (SARS-COV-2). The inclusion of living cells allows for the non-invasive digitalization and quantification of complex biological responses such as cancer proliferative invasion and discovery of anti-cancer drug susceptibility thresholds.
1 . An optical fiber comprising:
a) one or more hydrogel cladding layers comprising polysaccharides crosslinked ionically by metal cations; and
b) a core, wherein the core is an ionically crosslinked hydrogel core, a liquid core, a hollow core, or a gaseous core, wherein the core is encapsulated by the one or more hydrogel cladding layers, wherein the hydrogel cladding layers have a lower refractive index than the core of the optical fiber.
2 . The optical fiber of claim 1 , wherein the hydrogel cladding layers comprise gellan gum or alginate.
3 . The method of claim 2 , wherein the hydrogel cladding layers comprise about 0.1 weight % to 1.0 weight % gellan gum or about 1.0 weight % to 2.0 weight % alginate.
4 . A method of activating a photoactivatable prodrug, the method comprising:
administering the photoactivatable prodrug to a subject;
exposing the photoactivatable prodrug to excitation light guided by the optical fiber of claim 1 , wherein activity of the prodrug is increased in response to exposure to the excitation light.
5 . A method of performing photodynamic therapy (PDT), the method comprising:
administering a photosensitizing chemical substance to a subject; and
exposing the photosensitizing chemical substance to excitation light guided by the optical fiber of claim 1 , wherein radicals or reactive oxygen species are generated by the photosensitizing chemical substance in response to exposure to the excitation light.
6 . The optical fiber of claim 1 , wherein the metal cations comprise alkaline earth metal cations.
7 . A method of monitoring expression of a fluorescently labeled protein in a cell, the method comprising:
introducing the cell into the core of the optical fiber of claim 1 , wherein the fluorescently labeled protein is expressed in the cell;
exposing the cell to excitation light guided by the optical fiber; and
monitoring fluorescent light or a decrease in excitation-range light transmission intensity output from the optical fiber.
8 . A method of guiding light to a target using the optical fiber of claim 1 , the method comprising:
introducing the target into the core of the optical fiber of claim 1 ; and
aligning a light source with an end of the optical fiber, wherein light from the light source passes through the optical fiber to the target.
9 . The optical fiber of claim 1 , wherein the hydrogel core comprises alginate or gellan gum.
10 . The method of claim 9 , wherein the hydrogel core comprises about 2 weight % to about 7 weight % alginate or about 1.0 weight % to about 1.5 weight % gellan gum.
11 . A method of monitoring proliferation of a cell, the method comprising:
culturing the cell within the core of the optical fiber of claim 1 ;
aligning a light source with an end of the optical fiber; and
monitoring output light power from the optical fiber, wherein the output light power decreases with increasing cell density resulting from proliferation of the cell.
12 . The optical fiber of claim 1 , wherein the core has a continuous diameter, a varying diameter, or is discontinuous along the length of the optical fiber.
13 . The optical fiber of claim 1 , wherein the hydrogel core comprises a mixture of at least two ionically crosslinked polysaccharides or at least one ionically crosslinked polysaccharide and a non-polysaccharide hydrogel polymer.
14 . The optical fiber of claim 1 , further comprising an endotracheal tube or a medical swab coupled to the optical fiber.
15 . The optical fiber of claim 1 , wherein the hydrogel cladding layers and the hydrogel core have a step-index or gradient-index architecture, or wherein the optical fiber has a gradient of refractive index values along the length of the optical fiber.
16 . The optical fiber of claim 1 , wherein the hydrogel cladding layers have alternating refractive index values.
17 . The optical fiber of claim 1 , wherein the hydrogel core comprises polysaccharides crosslinked ionically by metal cations.
18 . The optical fiber of claim 17 , wherein the hydrogel core is doped with rare earth metal cations.
19 . A method of guiding light to a target using the optical fiber of claim 1 , the method comprising:
placing the optical fiber of claim 1 such that a first end of the optical fiber is attached to or near the target; and
aligning a light source with a second end of the optical fiber, wherein light from the light source passes through the optical fiber to the target.
20 . The method of claim 19 , further comprising introducing a bubble into the core of the optical fiber.
21 . The method of claim 19 , further comprising applying an acoustic stimulus, an electric stimulus, a magnetic stimulus, or a mechanical stimulus to the optical fiber, wherein optical output from the optical fiber is modulated.
22 . A photonic device comprising the optical fiber of claim 1 and a light source coupled to the optical fiber.
23 . The photonic device of claim 22 , further comprising optics to focus light from the light source into the core of the optical fiber.
24 . The photonic device of claim 22 , further comprising a photodetector.
25 . The method of claim 22 , wherein the light source is a laser diode, a light-emitting diode (LED), a superluminescent diode, a microfocus X-ray source, or a lamp.
26 . The optical fiber of claim 1 , wherein the optical fiber has a multi-input architecture or a multi-output architecture or both a multi-input architecture and a multi-output architecture.
27 . The optical fiber of claim 1 , further comprising a shielding layer.
28 . The optical fiber of claim 27 , wherein the shielding layer comprises alginate or gellan gum.
29 . The method of claim 28 , wherein the shielding layer comprises 1 weight % to 2 weight % alginate or 0.5 weight % to 1.5 weight % gellan gum.
30 . The optical fiber of claim 1 , further comprising a plasmonic nanoparticle or a quantum dot, wherein the plasmonic nanoparticle or the quantum dot is encapsulated within the core, wherein the plasmonic nanoparticle comprises a noble metal, a metal-oxide, a transition metal nitride, or a plasmonic metal-metal oxide nanocomposite.
31 . A method of detecting a target of interest, the method comprising measuring the plasmonic response of the plasmonic nanoparticle or the spectral response or change in photoluminescent lifetime of the quantum dot encapsulated within the core of the optical fiber of claim 30 upon binding of the target of interest to the capture agent.
32 . The optical fiber of claim 30 , further comprising a capture agent that selectively binds to a target of interest, wherein said capture agent is attached to the outer surface of the plasmonic nanoparticle or the quantum dot, wherein the capture agent comprises an antibody, an antibody mimetic, an aptamer, a peptoid, or a ligand, and wherein the target of interest is an antigen, an antibody, a protein, a nucleic acid, a metabolite, a toxin, a drug, a pollutant, a cell, a virus, a bacterium, a parasite, a tissue, an organoid, or an organism.
33 . The optical fiber of claim 32 , wherein the capture agent comprises an antibody that selectively binds to a spike protein of severe acute respiratory syndrome coronavirus 2 (SARS-COV-2).