> For the complete documentation index, see [llms.txt](https://reclone-latam-uncuyo.gitbook.io/building-a-reagent-collaborative-network-in-latam/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://reclone-latam-uncuyo.gitbook.io/building-a-reagent-collaborative-network-in-latam/general-protocols/plasmid-storage.md).

# PLASMID STORAGE

This page describes two validated methods for plasmid preservation and shipment without the need for cold chain transport: drying on filter paper and ethanol precipitation.

***

[Plasmid Storage by Filter Paper and Ethanol Precipitation](https://dx.doi.org/10.17504/protocols.io.j8nlkrq3wv5r/v1)

***

### <mark style="color:red;">📄 Method 1: Storage Plasmids on Filter Paper</mark>

#### 🧪 Materials

* Clean Whatman No. 1 filter paper (or equivalent)
* Sterile scissors or punch
* DNA plasmid solution (≥0.3 μg)
* Sealed plastic bag (e.g., Ziploc)
* Heat sealer (optional)
* Sterile microcentrifuge tubes

#### 📌 Drying and Packaging

1. Using a clean Whatman No.1 filter paper (or equivalent), mark a circle with a pencil. Avoid using ink or markers.
2. Spot approximately **0.3 µg** of plasmid DNA (ideally in 1 µL with 0.3 µg of plasmid) into the marked circle.
3. Let the spot **air-dry** at room temperature in a sterile environment.
4. Place the dried paper in a **plastic bag** and seal it (preferably heat-sealed).
5. Send the sealed paper via standard mail or courier.

#### 📌 Recovery

1. Using clean gloves and sterile scissors, cut out the marked circle.
2. Place the paper in a **1.5 mL microcentrifuge tube**.
3. Add **50 μL of** Nuclease-free ddH₂O, vortex briefly, and incubate for **5 minutes at room temperature**.
4. Vortex again and spin down briefly.
5. Use **2-5  μL of the supernatant** for **bacterial transformation** by electroporation or chemical methods.

*Note: A pipette tip can also be used to gently grind the filter paper inside the tube to improve plasmid release before vortexing.*

6. This DNA is suitable only for transformation and plasmid propagation, not for direct enzymatic reactions or sequencing.
7. Store the plasmid at **−20°C or −80°C** as a backup.

***

### <mark style="color:red;">🧪 Method 2: Plasmid DNA Precipitation with Ethanol</mark>

#### 🧪 Materials

* Plasmid DNA (1 ng–2 μg)
* Sterile water (ddH₂O)
* 100% ethanol
* 3M sodium acetate (NaAc)
* 75% ethanol (cold)
* 1.7 mL microcentrifuge tubes
* Centrifuge (10,000 rpm)
* Heat block or speed-vac

#### 📌 Precipitation and Shipping

1. Transfer plasmid DNA to a **0.5 or 1.5 mL Eppendorf tube**.
   * If the volume is <50 μL, add ddH₂O to reach 50 μL
2. Add **2 volumes of 100% ethanol**.
3. Add **0.1 volume of 3M sodium acetate**.
4. Mix and incubate at **−20°C for 30 minutes** (overnight improves recovery).
5. Centrifuge at **10,000 rpm for 15 minutes**.
6. Discard the supernatant.
7. Wash the pellet with **100 μL of cold 75% ethanol**.
8. Centrifuge at **10,000 rpm for 10 minutes**.
9. Remove all remaining ethanol.
10. Dry the pellet using a **speed-vac**, or leave it open at **room temperature** or at **37°C**.

#### 📌 Rehydration

* Before use, add **10 μL of ddH₂O** to resuspend the DNA.
* Proceed with bacterial transformation

*Note: This DNA is suitable only for transformation and plasmid propagation, not for direct enzymatic reactions or sequencing.*