Buying the materials is only the first step. First write down your goal, controls, sample preparation method, and recording method; only after the experiment ends will you know what the results can answer.
First write one sentence stating the question to answer
For example, "whether a certain peptide affects cell migration under this experiment's conditions" is clearer than "see if there is any effect." Then write down the main readout: wound gap width, cell number, or a molecular indicator. Different readouts mean the experiment answers a different question.
Cell migration and cell proliferation can affect some of the same image phenomena. The experiment design needs to explain how to distinguish them, rather than attributing a smaller gap only to migration.
Second thing: verify material identity
The full name, sequence or form, batch number, and specification should go into the records. Whether the study uses a single component or a mixture, whether there is DAC, and whether it is modified all need to be clarified in advance. If the product label information does not match the material description in the original paper, list the differences first.
Third thing: prepare the controls together
Controls show where changes come from. Besides an untreated group, the experiment may also need a matched solvent control, positive control, or sequence control; the specific choice depends on the research question. The solvent and other conditions across groups should have a reasonable correspondence.
If the test group receives a stock solution containing DMSO but the control group does not receive the corresponding solvent, the observed difference may include a solvent effect. Related calculations can be checked together with this site's final DMSO percentage lesson.
Fourth and fifth things: plan sample preparation and detection together
Write clearly the labeled amount, content basis, final volume, and concentration unit. Do not automatically treat how much solvent was added as the final volume, and do not automatically treat a purity percentage as net peptide content. Record the volume taken and the new volume for every dilution.
Then confirm the instrument, method, and reading range. If a sample is below the range the method can reliably quantify, a small number from the instrument does not mean it is accurate enough.
Sixth thing: keep a record that can be repeated
Record materials, sample preparation date, containers, handling steps, measurement method, raw file names, and anomalies. If two people use the same material but different handling steps, the results may not be directly comparable.
After the experiment ends, first check whether the blank, controls, and replicates support comparison, then interpret the results. Repeated injections cannot automatically count as multiple independent experiments. What is given here is preparation thinking; the actual plan should be made according to the research model and method requirements.
| What to record | Where to write it |
|---|---|
| Research question and main readout | First page of the experiment plan |
| Material identity, batch number, and specification | Material record |
| Controls and solvent conditions | Grouping table |
| Concentration basis and dilution steps | Sample preparation record |
| Types and number of replicates | Design description |
| Raw files and anomalies | Results directory and notes |
Download the Chinese worksheet (TXT; copy and edit as needed)
Connect sample preparation with the solvent control
For a hypothetical cell experiment, prepare a final 1.00 mL at 20 μM from a 2 mM stock, equivalent to 2000 μM. The stock volume is 20 × 1.00 ÷ 2000 = 0.010 mL, or 10 μL. Bring the mixture to a final 1.00 mL rather than adding a further 1.00 mL of medium.
If the stock solvent is entirely DMSO, 10 μL in a final 1000 μL gives 1% DMSO. Match the solvent control as required by the design and first establish whether the model tolerates that proportion. The hypothetical 20 μM is not a recommended peptide assay concentration or a human dose.
If the readout does not change, where do you start?
Check units and preparation calculations, then the blank and positive control. Review sample handling, measurement range and the type of replication. A negative finding is easier to interpret when the experimental system can reliably detect the change being tested.
Original sources and further reading
Sources checked on 2026-10-13. Findings apply to the models and materials studied. Batch quality requires records for the actual batch.
Related research materials
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