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Description
Rat SPD ELISA KitProduct Specification Usage Experimental equipment required for the experiment: 1. Microplate reader (450nm) 2. High precision pipette and gun tips: 0. 5 10uL, 5 50uL, 20 200uL, 200 1000uL 3. 37 constant temperature box 4. Distilled water or deionized water Sample processing and requirements: 1. Serum: Place the whole blood sample collected in the serum separation tube at room temperature for 2 hours or at 4 overnight, then centrifuge at 1000g for 20
Product Specification
| Usage |
Experimental equipment required for the experiment: 1. Microplate reader (450nm) 2. High-precision pipette and gun tips: 0.5-10uL, 5-50uL, 20-200uL, 200-1000uL 3. 37℃ constant temperature box 4. Distilled water or deionized water Sample processing and requirements: 1. Serum: Place the whole blood sample collected in the serum separation tube at room temperature for 2 hours or at 4℃ overnight, then centrifuge at 1000×g for 20 minutes, and take the supernatant, or store the supernatant at -20℃ or -80℃, but avoid repeated freezing and thawing. 2. Plasma: Collect the specimen using EDTA or heparin as an anticoagulant and centrifuge it at 1000×g for 15 minutes at 2-8°C within 30 minutes of collection. The supernatant can be tested or stored at -20°C or -80°C. However, repeated freezing and thawing should be avoided. 3. Other biological fluids: Centrifuge at 1000xg for 20 minutes, remove the supernatant, and test. Pre-test preparation: 1. Remove the test kit from the refrigerator 10 minutes in advance and equilibrate to room temperature. 2. Prepare the standard gradient working solution: Add 1mL of universal diluent to the lyophilized standard, let it stand for 15 minutes to completely dissolve, then gently mix (concentration is 500pg/mL). Then dilute to the following concentrations: 500pg/mL, 250pg/mL, 125pg/mL, 62.5pg/mL, 31.25pg/mL, 15.625pg/mL, 7.8125pg/mL, and 0pg/mL. Serial dilution method: Take seven EP tubes and add 500uL of universal diluent to each tube. Pipette 500uL of the 500pg/mL standard working solution into the first EP tube and mix thoroughly to make a 250pg/mL standard working solution. Repeat this procedure for subsequent tubes. The last tube serves as a blank well; there is no need to pipette liquid from the penultimate tube. See the figure below for details. 3. Preparation of biotinylated detection antibody working solution: Centrifuge the concentrated biotinylated antibody at 1000×g for 1 minute 15 minutes before use. Dilute the 100× concentrated biotinylated antibody to a 1× working concentration with universal diluent (e.g., 10uL concentrate + 990uL universal diluent). Prepare and use immediately. 4. Prepare the enzyme conjugate working solution: 15 minutes before use, centrifuge the 100× concentrated enzyme conjugate at 1000×g for 1 minute. Dilute the 100× concentrated HRP enzyme conjugate to a 1× working concentration with universal diluent (e.g., 10 μL of concentrate + 990 μL of universal diluent). Prepare immediately. 5. Prepare the 1× wash solution: Dispense 10 mL of 20× wash solution into 190 mL of distilled water (concentrated wash solution removed from the refrigerator may crystallize; this is normal. Allow to stand at room temperature until the crystals have completely dissolved before preparing). Procedure: 1. Remove the desired strips from the aluminum foil bag after equilibration at room temperature for 10 minutes. Seal the remaining strips in a ziplock bag and return to 4°C. 2. Sample addition: Add 100 μL of sample or standard of varying concentrations to the corresponding wells. Add 100 μL of universal diluent to the blank wells. Cover with a film and incubate at 37°C for 60 minutes. (Recommendation: Dilute the sample to be tested at least 1-fold with universal diluent before adding it to the ELISA plate. This will reduce the impact of matrix effects on the test results. The sample concentration should be multiplied by the corresponding dilution factor when calculating the final sample concentration. It is recommended to run replicates for all test samples and standards.) 3. Add Biotinylated Antibody: Remove the ELISA plate and discard the liquid without washing. Add 100 μL of Biotinylated Antibody Working Solution directly to each well. Cover with a film and incubate at 37°C for 60 minutes. 4. Wash: Discard the liquid and add 300 μL of 1x Wash Solution to each well. Let stand for 1 minute, shake off the wash solution, and pat dry on absorbent paper. Repeat this process three times (a plate washer can also be used). 5. Add Enzyme Conjugate Working Solution: Add 100 μL of Enzyme Conjugate Working Solution to each well. Cover with a film and incubate at 37°C for 30 minutes. 6. Washing: Discard the liquid and wash the plate five times as in step 4. 7. Adding substrate: Add 90 μL of substrate (TMB) to each well, cover with a sealing film, and incubate at 37°C in the dark for 15 minutes. 8. Adding stop solution: Remove the ELISA plate and add 50 μL of stop solution directly to each well. Immediately measure the OD value of each well at a wavelength of 450 nm. Calculating experimental results: 1. Calculate the average OD value of the standard and sample replicates and subtract the OD value of the blank well as a correction factor. Plot the standard curve of the four-parameter logistic function on double-logarithmic graph paper, with concentration as the horizontal axis and OD value as the vertical axis. 2. If the sample OD value is higher than the upper limit of the standard curve, dilute the sample appropriately and retest. Multiply the sample concentration by the corresponding dilution factor. |
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| Theory | This kit utilizes a double-antibody sandwich enzyme-linked immunosorbent assay (ELISA). Sample, standard, biotin-labeled detection antibody, and HRP conjugate are sequentially added to microwells pre-coated with a Surfactant Associated Protein D (SPD) capture antibody. After incubation and washing, the sample is developed using the substrate TMB. TMB is converted to blue by HRP peroxidase and to yellow by acid. The intensity of the color is positively correlated with the amount of Surfactant Associated Protein D (SPD) in the sample. The absorbance (OD) is measured at 450 nm using a microplate reader to calculate the sample concentration. | |||||||||||||||||||||||||||||||||
| Source | Rat | |||||||||||||||||||||||||||||||||
| Synonym | Rat Surfactant Associated Protein D ELISA Kit | |||||||||||||||||||||||||||||||||
| Detection Type | Double antibody sandwich method | |||||||||||||||||||||||||||||||||
| Composition |
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| Background | Surfactant-associated protein D (SPD) is a pattern recognition molecule and a key component of the mucosal immune system of the reproductive tract (FRT). In addition to its host defense function in the FRT, it also has immunomodulatory roles in labor and preterm birth. Its deficiency impairs female fertility, highlighting the role of SPD in ovarian and uterine physiology. | |||||||||||||||||||||||||||||||||
| General Notes | 1. Strictly adhere to the specified incubation time and temperature to ensure accurate results. All reagents must be at room temperature (20-25°C) before use. Refrigerate reagents immediately after use. 2. Improper plate washing may result in inaccurate results. Ensure that all liquid in the wells is aspirated thoroughly before adding substrate. Do not allow the wells to dry out during incubation. 3. Remove any residual liquid and fingerprints from the bottom of the plate, as this will affect the OD value. 4. The substrate developer solution should be colorless or very light in color. Do not use substrate solution that has turned blue. 5. Avoid cross-contamination of reagents and specimens to prevent erroneous results. 6. Avoid direct exposure to strong light during storage and incubation. 7. Do not expose any reagents to bleaching solvents or the strong fumes emitted by bleaching solvents. Any bleaching agent will destroy the biological activity of the reagents in the kit. 8. Do not use expired products, and do not mix components with different product numbers and batches. 9. Recombinant proteins from sources other than the kit may not be compatible with the antibodies in this kit and will not be recognized. 10. If there is a possibility of disease transmission, all samples should be managed properly and samples and testing devices should be handled according to prescribed procedures. |
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| Storage Temp. | If the unopened kit is stored at 4°C, the shelf life is 6 months. | |||||||||||||||||||||||||||||||||
| Test Range | 7.8-500 pg/mL | |||||||||||||||||||||||||||||||||
| Applications | Serum, plasma, peritoneal lavage fluid, and other biological fluids |
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4.3 ★★★★★
Based on 7 reviews
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Product Reviews
★★★★★ 4
The end is only the beginning
Format: Kindle
Theo appears in a small fictional Georgia town named Golden. He’s a distinguished old man with a mysterious past. He’s a quiet observer; then he makes friends in a coffee house and there pursues a plan to personally gift every portrait drawing on the wall to the townsfolk simply pictured there.
As an artist, I appreciated the detailed descriptions of each face, and then the invited dialogue with each person behind those drawings. The characters Theo gets to know are varied and storied. Of even more value to me was Theo’s visit to the studio of the originator of all the portraits. Layers start getting unpeeled in this tale. I started to highlight phrases when the motivation for doing the work got uncovered between them.
There were times when I felt the main character was “too good” to be believable. I personally appreciated the subtle (and sometimes not so subtle) references to Theo being a Christ figure. But remember that Jesus was the one who said “woe to you when all men speak well of you”. The Theo who is pictured in this book, and the reactions of most around him is maybe a little too syrupy? A friend who is in my book club felt herself being “manipulated” when reading this book. I ponder that. There was a plethora of reactions to Jesus too, but I don’t think any honest quester ever felt manipulated. He let them walk freely away.
For me the significance of each face was the key theme, and each face held sorrow. There are some beautiful lines in the book around this. The ambitions: true and false in the “art world” also the business world resonated also. The Pastor’s words during a funeral at the end were valuable. And the little girl’s imagination (prompted by Theo) of all the musical notes flying on their wings into the chandeliers so that they can sing again later was a wonderful metaphor. There are some excellent passages in this book if you remain in it. As one grandmother said in this tale: “Baby, they’s justice and they’s mercy. If you not sure what to do and you gotta choose one or the other, I say always go the mercy way. If you make a mistake, make it for mercy. Bad mercy don’t hurt nearly like bad justice and always remember, the eye of God can see.”
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Reviewed in the United States on May 11, 2026
★★★★★ 5
⭐️ A Beautifully Written Story That Stays With You ⭐️
Format: Paperback, Format: Paperback
Theo of Golden by Allen Levi is one of those rare books that quietly settles into your heart and lingers long after the final page. The writing is intelligent, thoughtful, and beautifully crafted, with storytelling that feels both timeless and deeply human.
The characters are wonderfully developed and feel incredibly real, but Theo himself is unforgettable. I found myself learning so much from him along the way about life, people, kindness, and perspective.
Allen Levi has a gift for creating a world that feels warm, meaningful, and genuine. This was a truly lovely read, full of wisdom, heart, and beautiful prose. An easy five stars for me. 📚✨
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Reviewed in the United States on May 27, 2026
★★★★★ 5
Savor Theo -A Heart & Soul Dish
*No spoilers in this review
I found this book to be an unexpected banquet for my soul. I don’t read fiction very often, but as I read Theo of Golden, I realized I am hungry for what this story offers. Based on its swift and growing popularity, I believe the world is hungry for the gift of Theo of Golden.
When speaking on his book, Mr. Levi shared a quote from David Brooks, “ To write a book about kindness does not make you kind. To read a book about kindness does not make you kind… but to buy a book about kindness, that makes you kind.” 😄
This humor & humility — a “don’t take yourself too seriously” a welcoming accessibility is in the author and this book.
I love this spirit in the story —so much so, if I could hug this book any tighter— it would be behind me. (borrowing generously from Groucho Marx )
I started to do research on Allen Levi - who wrote this gift. He chose well, hundreds of little choices, keeping him close to beauty, kindness, meaningful relationships and community. His choices of early morning devotionals and prayer and regular visits to schools and coffee houses, to write songs instead of watch tv, all feeding the character of the author. I believe you cannot share beyond where you have traveled. He has traveled to deep places. A definite Ode to Joy prior to offering Theo was to write about the last 365 days of his brother’s life they shared after a cancer diagnosis entered. His brother’s early exit from here and entrance into heaven, I believe, prepared the way for one of the greatest fiction writings of our day.
Allen Levi’s habits to avoid technology and be fully present with the people in his life bleeds beautifully onto the characters of Golden. The environment is one which doesn’t talk about technology or politics. Just people connections. He firsts introduces us, then beautifully befriends us to a better way and a place, accessible to us if we would choose to allow mindful relationships to develop. All this making the community of Golden a place to cherish. Ultimately I believe the gift is to see Golden could be grown in a hometown, a neighborhood, with all people… It’s a heart posture- a posture that Theo bestows on the town.
In my ideal world, the author would meet another great songwriter, poet, storyteller: Ray Hughes. Ray is another gift to humanity, in creativity, intelligence, and accessing heaven on earth through words. I believe there would be a powerful explosion of hope, humor and generosity in their meeting, subsequent friendship & collaboration. I’m dreaming here, and lifting a prayer to the heavens- it would be awesome!!
With a grateful heart, I highly recommend Theo of Golden.
Humbly submitted,
Dawn Holley
Author, 22 Keys To Joy for the easily distracted
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Reviewed in the United States on February 13, 2026
★★★★★ 5
A story of art, music and writing
Format: Kindle
Like the face of heaven. That’s how I see Theo, and I hope this will be a movie.
“Theo of Golden” is the debut novel by Allen Levi. He was writing as a personal challenge and just doing some scenes. He began writing in 2019-2020. He had been a songwriter and lawyer. He has no connection to Portugal, which is mentioned in the book quite a bit and led me to try Port wine. This book will lead me to do a lot of things.
Theo is a supremely interesting man! More on that other familiar interesting man in a later post.
The book will make you want to look at the faces of people. Use a gaze that calms and loves. Be kind and generous. Greet people. Be less fearful and exchange stories. Be attentive. Love people up close. Invest in the art of living. Be beautiful, useful and pleasurable. All which I should be doing, but will now do for Lent.
Theo listened with genuine interest, adoringly, encouraging and with gratitude.
Newborns look for their mother’s face, a particular gaze that calms, loves and welcomes them. Someone they recognize, run to greet and someone to bond with.
Levi signs the books “With thanks for the Theo in you.” He greets kids at a high school three days a week. He reads to second graders. He doesn’t mind being around people not like him.
The coffee shop setting is a real place in Columbus, Ga. It’s called Fountain City Coffee. In picking bestowals of the sketches there, Theo looked for someone lost, weary, worried or troubled that the gift would encourage or help.
I got to hear him in a Zoom. A group of women from Vermont who lost their daughters came to Georgia on a pilgrimage. He was a steward of clean rivers and water and said the river still flows after death. He went through a “walking season” in losing his daughter.
In a book about knowing a person, it is mentioned that a bench is a good way to do this. 7 p.m. was Theo’s meeting time with the strangers for bestowals and ended up being the time of the funeral. He also mentioned “Think Little” by Wendell Berry. Do so and if everyone does, it spreads.
Levi was born in 1956. His dad is 98. His mother passed and he lost his brother, whom he called a clone of Theo, at 55. His dad was a forester, explaining his interest in nature. Springtime is an end with a future, said Theo.
One character named Tony runs the Verbivore book store and has the Penny Loafers out there because they haven’t spent a penny and they majored in loafing. Theo and Tony end up having Port together and he told Theo is Viet Nam stories. The Penny Loafers were better than a room full of Senators. They lie. Tony ends up being more of a believer of Jesus at the end because he wasn’t before Theo.
James Ponder has no degrees hanging in his office. Note the “ponder” mentions throughout. He is a dispenser of advice, secret keeper and agent of calm. Secretary Mrs. Gidley was suspicious of Theo at first but comes around. Ponder was Theo’s landlord and mentioned the 18-inch railing and three flights of stairs before the 86 year old decided to live there.
Kendrick reminds me of the custodian who won “America’s Got Talent,” who has an ill daughter Lamisha, who wants to be a physical therapist or artist in the end. Her education will be paid for by Theo as were some of her medical bills. Maria Menendez is the daughter of the “little man” who killed Theo’s wife and daughter in an accident. Maria had cancer.
I don’t want to give away too much, but Theo decided to love Asher, the sketch artist, with two hearts. And there is much more to that.
Simone wears a wardrobe that honors music on stage and guests who come to listen did the same. Cello intricacies became fascinating to me and I looked up some of the music mentioned. His bow was a gift from Theo. He played Fado for Theo at his concert. It ended up being a requiem with three characters, Kendrick and Basil, the busker. Simone’s parents were there and I wasn’t clear if Theo sprang for their trip. At the end, Basil studies to get a doctorate in American literature.
Katherine is the reporter who respects Theo’s wishes while many people she interviews are praise seekers and applause junkies. He was a friend, not a headline.
Ellen rides a bike and I’ll just call her different. He gave her a foldable handsaw, cordless sander, drill and wood burner to make feather boxes. I have made one because of this book. She had $1,600 to her name from selling them, but gave the money to the cello fund after she and Simone were assaulted and the perpetrator was never caught.
Cleave is the poisonous guy—like a snake, hemlock, black widow or “words with no wisdom guy.”
All but Cleve show community in sitting on the same row or pew. They all have sparks of hope.
I loved this line: We walk all roads, long and winding. Road to ruin. Easy Street. Road less traveled.
I’m so mad that my notes from Chapter 10-28 somehow disappeared. I may reread. This post would be longer. I probably have a dozen favorite books and just added this one.
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Reviewed in the United States on February 5, 2026
★★★★★ 5
Recognizing the Hearts that Burn Within Us
Format: Paperback
Yes, Theo of Golden does, at times, border on the melodramatic and the sentimental. It can be repetitive. It can take an awfully long time to make its point. And yet, the novel speaks very significantly of the need for love, compassion, generosity and forgiveness---in a world that is not always kind, in a world where many of us carry secret burdens---where sadness (mixed with intermittent joy) might be viewed as a universal human affliction.
Theo of Golden is, overall, a book of glad tidings. An end with a future. Thoughtfully, warmly and intelligently written. A novel that often addresses the beauty of Art, most notably painting and music. A novel in which I learned what a fado is. In fact, I learned a lot from this novel.
Unlike some readers, I did not see the book as misogynistic or xenophobic. I didn't necessarily see it as "Christian fiction"---unless you mean doing good, striving for strength of spirit and understanding the connection between "the ultimate and the proximate, the wide grace and the narrow way."
Finally, I don't view the novel's conclusion as disappointing, but simply as falling action and resolution. It is, after all, a very traditionally structured work.
Kudos to the author Allen Levi for having written an initially self-published book that was later picked up by a major publishing house. That is, indeed, a rarity.
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Reviewed in the United States on May 17, 2026
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