Color-Based Breast Milk Analyses Using Test Strips
20230384293 · 2023-11-30
Inventors
Cpc classification
G01N33/92
PHYSICS
International classification
G01N33/52
PHYSICS
Abstract
Color-based (colorimetric) breast milk analyses using test strips (paper-based assays) read with the smartphone camera to quantify the concentration in accordance with embodiments of the invention are disclosed. In one embodiment, a color-based strip for testing breast milk is provided, the strip including: a first portion including a protein reagent pad where exposing the protein reagent pad to breast milk results in a first enzymatic reaction for measurement of total protein concentration in the breast milk, a second portion including a fat regent pad where exposing the fat reagent pad to breast milk results in a second enzymatic reaction for measurement of fat concentration in the breast milk, and a third portion comprising a lactose reagent pad where exposing the lactose reagent pad to breast milk results in a third enzymatic reaction for measurement of lactose concentration in the breast milk.
Claims
1. A color-based (colorimetric) strip having unique enzymatic reagent pads for testing breast milk, the strip comprising: a portion comprising a protein reagent pad, wherein exposing the protein reagent pad to breast milk results in a first enzymatic reaction for measurement of total protein concentration in the breast milk; and wherein the protein reagent pad comprises at least one protein test enzyme and wherein the protein pad has a baseline color of green which, upon exposure to the breast milk, produces a color change to purple, wherein an intensity of the purple is proportional to the protein concentration in the breast milk. Based on reading the image with the smartphone, splitting the image into different color channels and then quantifying the concentration based on a pre-loaded calibration curve.
2. The color-based strip of claim 1, wherein the protein reagent pad tests the protein concentration using a modified BCA assay.
3. The color-based strip of claim 2, wherein the modified BCA assay uses copper (II)-neocuproine and a chromophore.
4. The color-based strip of claim 1, wherein the protein reagent pad has a test range of 0.1-5.0 g/dl.
5. The color-based strip of claim 1, wherein the protein reagent pad uses a working solution made by mixing a first reagent and a second reagent, wherein the second reagent is 2-4 gm cupric sulfate in 10 ml distilled water.
6. The color-based strip of claim 1, wherein the protein concentration is derived by calculating a first spectrum value associated with the intensity of purple and converting the first spectrum value to the protein concentration.
7. The color-based strip of claim 1 further comprising: a second portion comprising a fat reagent pad, wherein exposing the fat reagent pad to breast milk results in a second enzymatic reaction for measurement of fat concentration in the breast milk; and wherein the fat reagent pad comprises at least one fat test enzyme and wherein the fat pad has a baseline color of off white which, upon exposure to the breast milk, produces a color change to pink, wherein an intensity of the pink is proportional to the fat concentration in the breast milk.
8. The color-based strip of claim 7, wherein the at least one fat test enzyme comprises one or more Lipoprotein Lipase, G-30, Horseradish peroxidase, and Galactose kinase.
9. The color-based strip of claim 8, wherein the fat reagent pad tests the fat concentration based on a measurement of triglycerides.
10. The color-based strip of claim 9, wherein the measurement of the triglycerides is based on an enzymatic hydrolysis of triglycerides to glycerol and free fatty acids.
11. The color-based strip of claim 10, wherein the measurement of the triglycerides further based on a measurement of released glycerol.
9. The color-based strip of claim 10, wherein the fat reagent pad has a test range of 0.1-10.0 g/dl.
13. The color-based strip of claim 7, wherein the fat concentration is derived by calculating a second spectrum value associated with the intensity of the pink and converting the second spectrum value to the fat concentration.
14. The color-based strip of claim 1 further comprising: a third portion comprising a lactose reagent pad, wherein exposing the lactose reagent pad to breast milk results in a third enzymatic reaction for measurement of lactose concentration in the breast milk; and wherein the lactose reagent pad comprises at least one lactose test enzyme and wherein the lactose reagent pad has a baseline color of light green which, upon exposure to the breast milk, produces a color change to a blue then/yellow tone, wherein an intensity of blue or yellow is proportional to the lactose concentration in the breast milk.
15. The color-based strip of claim 14, wherein the at least one test lactose enzyme comprises one or more beta-galactosidase, peroxidase and galactose oxidase.
16. The color-based strip of claim 14, wherein the at least one test lactose enzyme comprises one or more beta-galactosidase, peroxidase and galactose oxidase.
17. The color-based strip of claim 14, wherein the lactose reagent pad has a test range of 5.0-10.0 g/dl.
18. The color-based strip of claim 14, wherein the lactose reagent pad uses a working solution made by mixing a buffer, an enzyme and a chromogen solution.
19. The color-based strip of claim 18, wherein the buffer comprises a citrate buffer and is adjusted to pH=range of 6-8.
20. The color-based strip of claim 14, wherein the lactose concentration is derived by calculating a third spectrum value associated with the intensity of the color change, splitting the image into different color channels and quantifying the concentration based on a pre-loaded calibration curve, converting the third spectrum value to the lactose concentration.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.
[0029] The various embodiments of the present colorimetric BM analyses now will be discussed in detail with an emphasis on highlighting the advantageous features. These embodiments depict the novel and non-obvious colorimetric BM analyses shown in the accompanying drawings, which are for illustrative purposes only. These drawings include the following figures:
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DETAILED DESCRIPTION OF THE DRAWINGS
[0048] The following detailed description describes the present embodiments with reference to the drawings. In the drawings, reference numbers, label elements of the present embodiments. These reference numbers are reproduced below in connection with the discussion of the corresponding drawing features.
[0049] Turning now to the drawings, color-based breast milk analyses using test strips are provided. In many embodiments, a client device may be used to measure macronutrients in breast milk, including, but not limited to, concentrations of protein, fat, and carbohydrates (e.g., lactose). In various embodiments, color-based breast milk analyses may include using an enzyme-based test strip a plurality of reagent pads that may each change color with color intensity proportional to a concentration of a macronutrient. For example, each of the plurality of reagent pads may include a specific chemical coating that produces specific enzymatic reactions coupled with a colorimetric dye, resulting in a color change on the test strip depending on the concentration of macronutrient (e.g., fat, carbohydrates, and/or protein, and micronutrients: not limited to vitamins, minerals and other analytes) present in the breast milk sample. Each of the reagent pads uses a novel chemistry made from a novel composition of chemistry, making the reagent pad more stable, as described below. As a result of the novel chemistry, each of the reagent pads has a novel color scheme, making it more accurate for examination. Further the image processing capabilities of the app allow for quantification of each analyte.
[0050] In some embodiments, a client device having a camera may be used to capture the color change and the color intensity. For example, test strips may be scanned using a built-in camera of client devices such as, but not limited to, smart phones, tablets, etc. In several embodiments, the cameras may be used to measure absorbance of light (e.g., color intensity) for macronutrient concentration quantification. In some embodiments, the use of a camera may be more sensitive and thus more accurate as opposed to comparison of colors with the naked eye. In many embodiments, color-based breast milk analyses using test strips may also be utilized to determine total energy (e.g., calories) of a breast milk sample and/or other clinical assessments, as further described below. In addition, color-based breast milk analyses using test strips may aid in the nutritional management of newborns and infants. BM analyses using client devices in accordance with embodiments of the invention are further discussed below.
Color-Based Breast Milk Analyses Using Client Devices
[0051] Macronutrient breast milk test strips and associated client device applications (e.g., smartphone applications) may create an analytical system for measuring the concentration of fat, carbohydrates (e.g., lactose), and protein in human milk. These measurements are then used to calculate the energy (calories of the sample). As further described below, the present embodiments may be utilized at point of care using enzyme-based (colorimetric)test strips with various reagent pads. For example, a test strip may include three or more different reagent pads. Further, a smartphone camera and application may operate as a spectrometer to measure the color change on the various reagent pads which may then be used to calculate macronutrient concentrations, as further described below.
[0052] In many embodiments, these measurements may determine the total energy (calories) of a breast milk sample and in combination with other clinical assessments, may be used to aid in the nutritional management of newborns, allowing for rapid measurement of essential macronutrients in milk.
[0053] A diagram illustrating a breast milk test strip (may also be referred to as “test strip”) in accordance with an embodiment of the invention is shown in
[0054] The reagent pads 102, 104, 106 may utilize specific colors in quantifying concentrations. In many embodiments, a camera of a user's smartphone may be used to capture image data (e.g., by taking a picture of the breast milk strip) that may be used to calculate concentrations based on color intensity based on a pre-loaded calibration curve. For example, in several embodiments, the first regent pad 102 may change from a baseline color of green to purple, where the intensity of the purple color may be used to calculate the concentration of protein in the breast milk sample. In some embodiments, the second regent pad 104 may change from a baseline color of white to pink, where the intensity of the pink color may be used to calculate the concentration of fat in the breast milk sample. In some embodiments, the third regent pad 106 may change from a baseline color of light green to purple, where the intensity of the purple color may be used to calculate the concentration of lactose in the breast milk sample.
[0055] Screen shots from a client device application for testing breast milk in accordance with an embodiment of the invention are shown in
[0056] A screen shot 140 illustrating an initial step-by-step instruction is shown in
[0057] A screen shot 160 illustrating a process for dipping the test strip and beginning the timer is shown in
[0058] A screen shot 170 illustrating a process for taking a photo of the test strip is shown in
[0059] A screen shot 180 illustrating a process for selecting the photo of the test strip to use is shown in
[0060] A screen shot 190 illustrating displayed results of the scanned test strip displayed as total fat g/dL, total protein g/dL, and carbohydrates as lactose g/dL in accordance with an embodiment of the invention is shown in
[0061] A calibration reference card for a client device in accordance with an embodiment of the invention is illustrated in
[0062] Screen shots from a client device application for testing breast milk in accordance with an embodiment of the invention are shown in
[0063] In the screen shot 520 in
[0064] In the screen shot 540 in
[0065] Although specific test strips and client device applications for testing breast milk are discussed above with respect to
Breast Milk Test Workflows
[0066] Various workflows may be used to perform breast milk testing using breast milk test strips and the client device applications as described herein. A diagram of a breast milk test and client device application workflow in accordance with an embodiment of the invention is shown in
[0067] In reference to
[0068] Although a specific breast milk test workflow is discussed above with respect to
Reagent Pads of Test Strips
[0069] The reagent pads of test strips may use various assays to determine the concentrations of macronutrients. For the assays, the reagent pads may employ various compositions of chemistry, which may result in various color change schemes when exposed to breast milk. An example of color change on a reagent pad based on the concentration of a macronutrient in the breast milk in accordance with an embodiment of the invention is illustrated in
[0070] The protein reagent pad may use various assays to determine the concentration of protein in the breast milk. In many embodiments, the enzymatic reaction for the protein test-pad is based on a modified BCA assay. The method specifically uses copper (II)-neocuproine and a chromophore, which is a simple, rapid, reproducible, and sensitive analysis. When the test pad gets in contact with a BSA standard solution or breastmilk sample after a period of incubation (ranging from 1-5 minutes) the assay reaction then produces a characteristic color. Protein detection ranges from 0.1-5.0 g/dl.
[0071] The protein reagent pad may employ various compositions of chemistry to react with protein. As an example, the specific composition of chemistry for the protein reagent pad is as follows. Step 1 is to make a reagent A from: a) 1.5 gm sodium bicinchoninate (BCA), b) 2 gm sodium carbonate, 0.16 gm sodium tartrate, c) 0.4 gm NaOH, and d) 0.95 gm sodium bicarbonate, brought to 100 ml with distilled water. Step 2 is to adjust the pH to 11.25 with 10 M NaOH. In some embodiments, the pH can range from 9-11.5. The solution is typically pale pink in color, clear and odorless. Step 3 is to leave the solution at room temperature. Step 4 is to make a reagent B from: 3 gm cupric sulfate (5 × hydrated) in 10 ml distilled water. In some embodiments, the amount of cupric sulfate can range from 2-4 gm. The solution is typically a bright blue color. The extra copper sulfate forms a precipitate at the bottom. Step 5 is to refrigerate the solution. Step 6 is to make a standard working solution by mixing 100 volumes reagent A with 2 volumes reagent B. The stock solutions are stable. The working solution is stable for 1 week and should be green. The working solution is bright green, and the coated paper is a green color. The intensity of the purple color correlated with the amount of protein in the sample. Although the steps are shown in a specific order, the invention is not limited thereto.
[0072] The fat reagent pad may use various assays to determine the concentration of fat in the breast milk. In many embodiments, fat is measured using triglycerides. The fat in breast milk is made up of 98-99%% of triacylglycerols, therefore the colorimetric measure is of triglycerides as they are hydrolyzed completely to free fatty acids and glycerol by lipoprotein lipase, subsequently glycerol kinase, glycerol phosphate oxidase, horseradish peroxidase using a pink dye indicator the amount of total fat as measure by total glycerol correlated with the intensity of the pink dye color. The test pad develops a pink color visible with the naked eye. The intensity of the color is directly proportional to the concentration of the triglycerides present in the sample. Fat as Measured by triglycerides (98%) of total fats ranges from 0.1-10.0.0 g/dl.
[0073] The fat reagent pad may employ various compositions of chemistry to react with fat. As an example, the specific composition of chemistry for the fat reagent pad is as follows. Step 1 is to buffer. In some embodiments, the buffer can be pipes buffer and tris buffer and in other cases a phosphate buffer may be used. Step 2 is to make a 50 mM buffer 1 ml of 1 M buffer mixed with 20 ml of deionized water. The solution is typically milky color. Step 3 is to use drops of 10M NaOH solution to bring pH to 6 (can range from 4-7 (roughly one drop of 10M NAOH=0.1 change in pH). Step 4 is to make working solution from: a) 1 ml of Triton-X solution, b) 10 ml of 50 mM buffer c) one of possible indicators in the anisidine family such as but not limited to ESPA N-ethyl-N-(3-sulfulpropyl)-m-anisidine sodium salt d) CHAPS solution d) magnesium acetate 40-60 mg, e) 4-AAP 4-7 mg, and f) ATP 3 30-40 mg. In some embodiments, the pH value of the buffer can range from 4-7. In some embodiments, the concentration of CHAPS solution can range from 0.5-2%. In some embodiments, the amount of magnesium acetate can range from 30-100 mg. In some embodiments, the amount of 4-AAP can range from 3-10 mg. In some embodiments, the amount of ATP can range from 20-100 mg. Step 5 is to use a PVOH solution to dry the paper. In some embodiments, the concentration of the PVOH solution can range from 1-15%. Step 6 is to make working solution from: a) 5 ml of standard solution, In some embodiments, the amount of lipoprotein lipase can range 60-200 U. In some embodiments, the amount of G-30 can range from 60-100 U. In some embodiments, the amount of HP can range from 100-250 U. In some embodiments, the amount of GK can range from 125-300 U. In some embodiments, the CHAPS solution, triton solution and PVOH solutions including the buffer are made first. Although the steps are shown in a specific order, the invention is not limited thereto.
[0074] The lactose reagent pad may use various assays to determine the concentration of lactose in the breast milk. In many embodiments, the lactose is measured through the reaction of lactose with beta galactosidase, peroxidase and galactose oxidase enzymes. The measurement of lactose with an enzymatic color change method has been shown to be the most sensitive and specific. The enzymatic measurement of lactose in breast milk is to hydrolyze the lactose into glucose and galactose using β-galactosidase. The reaction is as follows: Lactose+H.sub.2O.fwdarw.Glucose+Galactose. In some embodiments, galactose oxidase and horseradish peroxidase are added to β-galactosidase and immobilized onto a paper support with an added chromogen. The strip is dipped in breast milk and forms the color that develops from the added chromogen. Lactose detection ranges from 5-10 g/dl.
[0075] As an example, the specific composition of chemistry for the lactose reagent pad is as follows. Step 1 is to make a buffer. In some embodiments, the buffer can be a citrate buffer, TRIS buffer or phosphate buffer. Step 2 is to adjust the pH of the buffer to 5-7Step 3 is to make a chromogen solution from for example using dianisidine per in buffer. Step 4 is to prepare 2 mg of ABTS per milliliter of the buffer. Step 5 is to prepare 1 mg of methyl red or bromocresol purple, per milliliter of the buffer. In some embodiments, methyl red can also be used in step 5. In some embodiments, the solution in step 5 is precipitated and then centrifuged to extract the top layer without precipitate. Step 6 is to make enzyme solution from: 40 U lactase (beta-galactosidase), 200 U horseradish peroxidase,40 U of galactose oxidase in 100 ul of buffer, 1000 U beta-galactosidase in 25 ml of buffer, 5000 U horseradish peroxidase in 25 ml of buffer, and 1000 U of galactose oxidase in 25 ml of buffer. In some embodiments, the amount of the lactase can range from 30-60 U. In some embodiments, the amount of the horseradish peroxidase can range from 100-300 U. In some embodiments, the amount of galactose oxidase can range from 20-80 U in 100 ul of buffer. Step 7 is to mix 100 ul of enzymes and 100 ul of chromogen to 50 ul of glutaraldehyde solution. Step 8 is to prepare glutaraldehyde solution for stabilizing the solution. Stock solution in vial is 25% in 10 ml diluted with deionized water and kept at room temperature. Although the steps are shown in a specific order, the invention is not limited thereto.
[0076] Although the color change on a reagent pad based on the concentration of a macronutrient in the breast milk is discussed above with respect to
Color Transformation Application and Reagent Pad Extraction
[0077] In some embodiments, a client application may perform a transformation of the color on the test strip using a calibration reference card as further described above. A process of color transformation application and reagent pad extraction is illustrated in
[0078] Although a specific process of color transformation application and reagent pad extraction is described above with respect to
Color Calibration
[0079] Based on the color intensity, the concentration value may be determined from the pre-calculated calibration curves created by test-retest methods. Calibration curves for protein, fat and carbohydrates in accordance with an embodiment of the invention are shown
[0080] In some embodiments, the blue channel is chosen for lactose and the green channel is chosen for protein and fat. In some embodiments, each sample is analyzed and photographed in triplicate with a blank test strip. The intensity of the color under the reagent pad is analyzed and the average of the three readings is measured and recorded.
[0081] A concentration curve and standard equation to correlate the reagent pad color intensity against concentration is created. In some embodiments, correlation coefficients of r.sup.2>0.9 are observed in the case of all three macronutrients that demonstrate accuracy of the test strip and the linearity of the model. These three calibration equations are then used to determine the concentration of the sample tested by inputting the corresponding color value extracted from the reagent pad.
[0082] Although a color calibration method is discussed above with respect to
Accuracy Testing and Validation
[0083] The Breast Milk Analyses are tested using samples whose macronutrient compositions are determined in a third-party lab using gold standard methods. For each of the samples, test-retest experiments are done where test strips were dipped in the same milk sample and are scanned in different lighting conditions. Post color correction, the color values are extracted for each of the test strips under each lighting condition and for each macronutrient.
[0084] An example comparison of concentration of protein, fat and carbohydrates observed versus actual measured from a third-party lab in accordance with an embodiment of the invention is shown in
[0085] Based on the comparison between the observed concentration and the actual concentration, an error rate and a mean difference are calculated for the present breast milk analyses. Typically, the error rate for the observed concentration of protein is ±4.17%, and the mean difference is 0.04 g/dl. The error rate for the observed concentration of fat is ±4.19%, and the mean difference is 0.12 g/dl. The error rate for the observed concentration of carbohydrates is ±5.86%, and the mean difference is 0.43 g/dl. Those error rates and mean differences are tolerable.
[0086] Although a specific accuracy testing and validation method is discussed above with respect to
Processes for Testing Breast Milk
[0087] A flow chart illustrating a process for testing breast milk for macronutrient concentration(s) using a test strip in accordance with an embodiment of the invention is shown in
[0088] A flow chart illustrating a process for analyzing (906) a first region of a test strip for protein concentration in accordance with an embodiment of the invention is shown in
[0089] A flow chart illustrating a process for analyzing (906) a second region of a test strip for fat concentration in accordance with an embodiment of the invention is shown in
[0090] A flow chart illustrating a process for analyzing a third region of a test strip for lactose concentration in accordance with an embodiment of the invention is shown in
[0091] Although specific processes are discussed above with respect to