Indicator compounds, devices comprising indicator compounds, and methods of making and using the same
Some embodiments disclosed herein pertain to indicator compounds used to detect the presence of and/or an amount of an analyte. In some embodiments, the indicator compounds are fusion proteins. In some embodiments, when the analyte binds to the indicator compound, the indicator compound undergoes a conformational change. In some embodiments, the conformational change results in a luminescent signal that allows quantification of the amount of analyte present.
1. A device for detecting the presence of an analyte in a subject, the device comprising:
a light transmissive material configured to receive an excitation wavelength of light from a light source;
a waveguide comprising a cladding layer that surrounds a core material, the waveguide being configured to receive the excitation wavelength of light via a proximal end of the waveguide and to transmit the excitation wavelength of light along the waveguide to a distal end of the waveguide, the distal end of the waveguide extending from the device, the distal end configured to penetrate the skin of the subject and reside in the dermis of the subject;
a flange coupled to the waveguide and configured to allow the distal end to penetrate to the dermis of the patient;
an adhesive layer contacting the flange, the adhesive layer configured to secure the device to the skin of the patient; and
an indicator compound comprising a fusion protein, the indicator compound being disposed within the waveguide and being configured to receive the excitation wavelength;
wherein the fusion protein comprises:
a luminescent protein domain; and
an analyte binding protein domain;
wherein, when the analyte binds to the analyte binding protein domain, the indicator compound undergoes a conformational change from a first conformation to a second conformation;
wherein, when in the second conformation, the indicator compound is configured to receive the excitation wavelength and to emit a luminescent signal;
wherein the luminescent signal is received by the waveguide and transmitted to the light transmissive material;
wherein the light transmissive material is configured to deliver the luminescent signal to a luminescence detector.
2. The device of claim 1 , wherein the waveguide further comprises a protective polymer layer over the cladding layer.
3. The device of claim 1 , wherein the indicator compound is distributed in the core of the waveguide, at the interface of the core and the cladding layer of the waveguide, in the cladding layer of the waveguide, at the surface of the cladding layer of the waveguide, or combinations of any of the foregoing.
4. The device of claim 1 , wherein the luminescent protein is a split luminescent protein.
5. The device of claim 1 , wherein the indicator compound shares 80% to 100% identity, homology, or similarity to one or more of SEQ ID NOs: 3-13 or 16-20.
6. The device of claim 1 , wherein the analyte binding protein domain is a domain of a periplasmic protein.
7. The device of claim 1 , wherein the analyte binding domain shares 80% to 100% identity, homology, or similarity to one of SEQ ID NOs: 2, 15, 122-221, or 824-1746.
8. The device of claim 1 , wherein the luminescent protein domain is a domain of a fluorescent protein.
9. The device of claim 1 , wherein the luminescent protein domain shares 80% to 100% identity, homology, or similarity to one or more of SEQ ID NOs: 1, 14, 34-121, or 222-823.
10. The device of claim 1 , wherein the waveguide is a biocompatible step-index fiber optical waveguide.
11. The device of claim 1 , wherein the waveguide comprises a fiber having a first refractive index and wherein the cladding layer has a second refractive index, wherein the first and second refractive indices are different.
12. The device of claim 1 , wherein the waveguide comprises one or more of a polyethylene glycol (PEG), an alginate hydrogel, a polyacrylamide hydrogel, an alginate-polyacrylamide hydrogel, a silk, a citrate-based polymeric elastomer, or a combination thereof.
13. The device of claim 1 , wherein the light transmissive material comprises a notch configured to receive the flange and waveguide.
14. A method for detecting an analyte in a patient comprising:
selecting a patient in need of analyte monitoring;
inserting into or attaching the device of claim 1 to the patient;
applying the excitation wavelength of light to the indicator compound.
15. The method of claim 14 , further comprising collecting the luminescent signal from the device.
16. The method of claim 14 , further comprising comparing the luminescent signal to a reference signal indicative of an indicator compound without an analyte bound.
17. The method of claim 14 , further comprising quantifying an amount of luminescent signal as a concentration of analyte.