So, you want to utilize blockchain technology to your online portal as a database... forget it.

But you can develop an API which utilizes "signed message" as an ownership system which the user can only unlock his written article using his private keys. However, the data weren't stored in a fault-tolerant/uneditable way but users can use it without even registering an account, they can use the addresses as a donation/pay-to-open (needs more sophisticated techniques) address and the ownership issues can be easily solved (unless your site can't be trusted).

It's up to you or your developer on how you can implement such system, but theoretically, it's possible.

For example:

• 1) You online portal acts as a wallet and users can request an/some address/private key pair as his personal keys.
• 2) Everytime he 'save' his article the site will sign it using the user's session-entered (like MAW) private key, it will be saved as a text file in a signed message format and the signature shall be displayed for the user to copy (if he didn't have an account).
• 3) With this, a user can also import the private key to any wallet that can import keys then use the client to sign the article and paste the signature if it is 100% match to the saved article's signature.

But as they said, if you're planning to use blocks and POW as the database, it will going to be more stubbornly-unnecessary than my idea above.  
Nobody asked you why? Planning to start an ICO that advertises blockchain tech to online portals?