COVID-19 Spike Protein (S2) ELISA Kit (AEFI01341)

Product Name:	COVID-19 Spike Protein (S2) ELISA Kit
SKU:	AEFI01341
Size:	96T
Reactivity:	Universal
Range:	31.2-2000pg/ml
Sensitivity:	18.75pg/ml
Detection Method:	Sandwich ELISA, Double Antibody
Detection Wavelength:	OD450
Reaction Duration:	4 hours
Synonyms:	Spike Protein S2 ELISA Kit

Kit Components:

Components	Quantity		Storage
	48T	96T
ELISA Microplate(Dismountable)	8×6	8×12	Put the rest strips into a sealed foil bag with the desiccant. Stored for 1 month at 2-8°C; Stored for 6 month at -20°C
Lyophilized Standard	1vial	2vial	Put the rest standards into a desiccant bag. Stored for 1 month at 2-8°C; Stored for 6 month at -20°C
Biotin-labeled Antibody(Concentrated, 100X)	60ul	120ul	2-8°C (Avoid Direct Light)
HRP-Streptavidin Conjugate(SABC, 100X)	60ul	120ul
TMB Substrate	5ml	10ml
Sample Dilution Buffer	10ml	20ml	2-8°C
Antibody Dilution Buffer	5ml	10ml
SABC Dilution Buffer	5ml	10ml
Stop Solution	5ml	10ml
Wash Buffer(Concentrated, 25X)	15ml	30ml
Plate Sealer	3 pieces	5 pieces
Manual	1 copy	1 copy

Other Materials Required (Not provided)

Microplate reader (wavelength: 450nm)
37°C incubator (CO2 incubator for cell culture is not recommenced.)
Automated plate washer or multi-channel pipette/5ml pipettor (for manual washing purpose)
Precision single (0.5-10μL, 5-50μL, 20-200μL, 200-1000μL) and multi-channel pipette with disposable tips(Calibration is required before use.)
Sterile tubes and Eppendorf tubes with disposable tips
Absorbent paper and loading slot
Deionized or distilled water

This kit is based on Double antibody-Sandwich ELISA detection method and takes 4h assay time. The microplate provided in this kit has been precoated with anti S2 antibody. Add standard and properly diluted sample into relevant well respectively. After incubation, wash unbound components. Add biotinylated detection antibody. Then, it binds with S2 bound to precoated antibody. Wash unbound components and add HRP-Streptavidin Conjugate (SABC). Wash unbound components again and add TMB substrate solution. Then, TMB was catalyzed by HRP to produce a blue color product that turned yellow after adding a stop solution. Read the O.D. absorbance at 450nm in a microplate reader. Calculate the concentration of S2 in the sample by plotting standard curve. The concentration of the target substance is proportional to the OD450 value.

Recovery:

Add a certain amount of S2 into the sample. Calculate the recovery by comparing the measured value with the expected amount of S2 in the sample.

Sample Type	Recovery Range(%)	Average(%)
Serum(n=5)	90-103	100
EDTA Plasma(n=5)	86-103	94
Heparin Plasma(n=5)	87-105	94

Linearity:

Dilute the sample with a certain amount of S2 at 1:2, 1:4 and 1:8 to get the recovery range.

Sample Type	1:2	1:4	1:8
Serum(n=5)	86-99%	89-100%	92-99%
EDTA Plasma(n=5)	91-104%	90-100%	88-98%
Heparin Plasma(n=5)	91-103%	90-100%	89-100%

Precision:

Intra-assay Precision: samples with low, medium and high concentration are tested 20 times on the same plate.

Inter-assay Precision: samples with low, medium and high concentration are tested 20 times on three different plates.

Item	Intra-assay Precision			Inter-assay Precision
Sample	1	2	3	1	2	3
n	20	20	20	20	20	20
Mean (pg/ml)	58.26	246.7	996.7	59.99	252.1	974.1
Standard deviation	2.84	14.43	58.61	3.56	12.3	52.8
CV(%)	4.87	5.85	5.88	5.93	4.88	5.42

*Note:The below protocol is a sample protocol. Protocols are specific to each batch/lot. For the correct instructions please follow the protocol included in your kit.

Step	Protocol
1.	Add 100ul standard or sample into each well, seal the plate and statically incubate for 90 minutes at 37°C.
2.	Washing: Wash the plate twice without immersing.
3.	Add 100ul biotin-antibody working solution, seal the plate and statically incubate for 60 minutes at 37°C.
4.	Washing: Wash the plate three times and immerse for 1min each time.
5.	Add 100ul HRP-Streptavidin Conjugate (SABC) working solution, seal the plate and statically incubate for 30 minutes at 37°C.
6.	Washing: Wash the plate five times and immerse for 1min each time.
7.	Add 90ul TMB substrate solution, seal the plate and statically incubate for 10-20 minutes at 37°C. (Accurate TMB visualization control is required.)
8.	Add 50ul stop solution. Read at 450nm immediately and calculate.

When carrying out an ELISA assay it is important to prepare your samples in order to achieve the best possible results. Below we have a list of procedures for the preparation of samples for different sample types.

Sample Type	Protocol
Serum	Place whole blood sample at room temperature for 2 hours or at 2-8°C overnight. Centrifuge for 20min at 1000xg and collect the supernatant to detect immediately. Or you can aliquot the supernatant and store it at -20°C or -80°C for future’s assay..
Plasma	EDTA-Na2/K2 is recommended as the anticoagulant. Centrifuge samples for 15 minutes at 1000×g 2-8°C within 30 minutes after collection. Collect the supernatant to detect immediately. Or you can aliquot the supernatant and store it at -20°C or -80°C for future’s assay. For other anticoagulant types and uses, please refer to the sample preparation guideline..
Tissue Sample	Generally tissue samples are required to be made into homogenization. Protocol is as below: 3.1. Place the target tissue on the ice. Remove residual blood by washing tissue with pre-cooling PBS buffer (0.01M, pH=7.4). Then weigh for usage. 3.2. Use lysate to grind tissue homogenates on the ice. The adding volume of lysate depends on the weight of the tissue. Usually, 9mL PBS would be appropriate to 1 gram tissue pieces. Some protease inhibitors are recommended to add into the PBS (e.g. 1mM PMSF). 3.3. Do further process using ultrasonic disruption or freeze-thaw cycles (Ice bath for cooling is required during ultrasonic disruption; Freeze-thaw cycles can be repeated twice.) to get the homogenates. 3.4. Homogenates are then centrifuged for 5 minutes at 5000×g. Collect the supernatant to detect immediately. Or you can aliquot the supernatant and store it at -20°C or -80°C for future’s assay. 3.5. Determine total protein concentration by BCA kit for further data analysis. Usually, total protein concentration for Elisa assay should be within 1-3mg/ml. Some tissue samples such as liver, kidney, pancreas which containing a higher endogenous peroxidase concentration may react with TMB substrate causing false positivity. In that case, try to use 1% H2O2 for 15min inactivation and perform the assay again. Notes:PBS buffer or the mild RIPA lysis can be used as lysates While using RIPA lysis, make the PH=7.3. Avoid using any reagents containing NP-40 lysis buffer, Triton X-100 surfactant, or DTT due to their severe inhibition for kits’ working. We recommend using 50mM Tris+0.9%NaCL+0.1%SDS, PH7.3. You can prepare by yourself or contact us for purchasing.
Cell Culture Supernatant	Collect the supernatant: Centrifuge at 2500 rpm at 2-8℃ for 5 minutes, then collect clarified cell culture supernatant to detect immediately. Or you can aliquot the supernatant and store it at -80°C for future’s assay..
Cell Lysate	5.1. Suspension Cell Lysate: Centrifuge at 2500 rpm at 2-8℃ for 5 minutes and collect cells. Then add pre- cooling PBS into collected cell and mix gently. Recollect cell by repeating centrifugation. Add 0.5-1ml cell lysate and appropriate protease inhibitor (e.g. PMSF, working concentration: 1mmol/L). Lyse the cell on ice for 30min-1h or disrupt the cell by ultrasonic disruption. 5.2. Adherent Cell Lysate: Absorb supernatant and add pre-cooling PBS to wash three times. Add 0.5-1ml cell lysate and appropriate protease inhibitor (e.g. PMSF, working concentration: 1mmol/L). Scrape the adherent cell with cell scraper. Lyse the cell suspension added in the centrifuge tube on ice for 30min-1h or disrupt the cell by ultrasonic disruption. 5.3. During lysate process, use the tip for pipetting or intermittently shake the centrifugal tube to completely lyse the protein. Mucilaginous product is DNA which can be disrupted by ultrasonic cell disruptor on ice. (3~5mm probe, 150-300W, 3~5 s/time, 30s intervals for 1~2s working). 5.4. At the end of lysate or ultrasonic disruption, centrifuge at 10000rpm at 2-8℃ for 10 minutes. Then, the supernatant is added into EP tube to detect immediately. Or you can aliquot the supernatant and store it at - 80°C for future’s assay. Notes:Read notes in tissue sample.
Other Biological Sample	Centrifuge samples for 15 minutes at 1000×g at 2-8℃. Collect the supernatant to detect immediately. Or you can aliquot the supernatant and store it at -80°C for future’s assay..

Sample Type:	Serum, Plasma, Cell culture supernatant, Cell or tissue lysate, Other liquid samples
Storage:	2-8°C(Sealed), Don't cryopreserve.
Specificity:	Specifically binds with S2 , no obvious cross reaction with other analogues.